2016 Vol. 31, No. 5

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Stability research on step milling of GH4169G blisk
LIU Qiang, LIU Wan-zhu
2016, 31(5): 1025-1031. doi: 10.13224/j.cnki.jasp.2016.05.001
Abstract PDF(1107KB) icon1276 icon753
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Finite element analysis was applied to solve the problem of instability during milling blisk blade made of high strength superalloy GH4169G. Both methods of milling along the major diameter and axial direction were studied to analyze the machining stability. The effects of both the step milling and general symmetry milling on the machining stability were analyzed in the milling process of the blisk blade. Results show that the limit cutting depth in the stability lobe is less than the probable maximum cutting depth, the machining parameters such as the spindle speed and cutting depth can be chosen in a small range when the blade is cut by layers along the major diameter. The limit cutting depth in the stability lobe is larger than the probable maximum cutting depth when the blade is milled axially by layers. The rigidity of the blisk blade is improved by the step milling method. The maximum deformation of blade is 60% lower than that of the general symmetry milling in the same load. Compared with the general symmetry milling, the step milling method has the higher frequencies at the first six modes and the better stability, and the blades machined can meet the design requirements.
Bird strike model calibration for an aero engine wide-chord fan blade
CHAI Xiang-hai, HOU Liang, WANG Zhi-qiang, TANG Zhong-bin
2016, 31(5): 1032-1038. doi: 10.13224/j.cnki.jasp.2016.05.002
Abstract PDF(922KB) icon1507 icon776
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To establish a quantitative prediction method for the anti bird-strike capability of aero engine fan blade, a set of equivalent bird strike tests were performed with the impact parameters, e.g. the velocity and angle of the bird under typical engine operation conditions for a particular titanium wide-chord fan blade design. Then, an explicit dynamic simulation model was built to simulate the bird strike. Through sensitivity analysis, the blade material parameters, the bird body parameters and the blade-bird coupling contact parameters in the simulation model were calibrated based on the test results. The results show that the blade failure mode predicted by the calibrated bird-strike model is consistent with the test, and the prediction error of the failure location is within 10% compared with the test observation error.
Modeling algorithm of aero-propeller dynamic balancing
MENG Xian-zhao, ZHANG Hong-tao, TANG Xiao-bo, FU Xiao-rong
2016, 31(5): 1039-1046. doi: 10.13224/j.cnki.jasp.2016.05.003
Abstract PDF(990KB) icon1309 icon720
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The aero-propeller will vibrate in high-speed rotation. The way of resisting vibration is to perform a dynamic balancing procedure to this propeller. Compared with the traditional balancing algorithm, this algorithm of modeling balancing based on the feature model of the propeller to be balanced, and with the vector decomposition algorithm, enables to accurately calculate the total amount and the installing positions of counterweights to be installed, thus effectively solving the actual problem of inconformity between the positions of actual light-spot and preset counterweights on the propeller to be balanced in engineering practice. The practice result shows that it is easy to reduce the vibration level of the propeller to the "best" range of less than 1.27×10-3m/s(0.05IPS) with the modeling balancing algorithm, and absolutely keep the vibration level within acceptable range with only one balancing for the qualified threshold value of not more than 4.826×10-3m/s(0.19IPS).
Life prediction of ion thruster based on sputtering erosion failure of accelerator grid
LI Jun-xing, ZHANG Yong-bo, WANG Zhi-hua, FU Hui-min, LIU Jia
2016, 31(5): 1047-1052. doi: 10.13224/j.cnki.jasp.2016.05.004
Abstract PDF(901KB) icon1099 icon690
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A crucial failure mode restricting the life of ion thruster lies in the sputtering erosion of accelerator grid. For the characteristics of long life and multi-power working, a corresponding model was used to predict the life of ion thruster based on the accelerator grid pit and groove erosion data. Firstly, by analyzing the change law between accelerator grid groove depth and operating time under various power segments, it was found that the operating power sequence had little influence on the erosion rate of groove. And then the fatigue accumulation damage was introduced to establish the life prediction model for ion thruster operating under multi-power segments. At last, the life prediction model was used to predict the life of NASA's Evolutionary Xenon Thruster (NEXT). The predicted result of 46041h coincides with the test well.
Mistuned blade arrangement with non-linear friction based on parallel annealing algorithm
ZHAO Tian-yu, YUAN Hui-qun, YANG Wen-jun, ZHANG Hong-yuan
2016, 31(5): 1053-1064. doi: 10.13224/j.cnki.jasp.2016.05.005
Abstract PDF(1364KB) icon1100 icon656
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Based on mistuned blades parameters obtained by modal experiment, a lumped parameter model of mistuned bladed disk system was established considering the non-linear friction damping. Blade arrangement optimization method using simulated annealing evolutionary algorithm additional tabu list was proposed by combining the local search ability of simulated annealing algorithm and global searching ability of genetic algorithm. At the same time, a parallel algorithm was designed based on the computation unified device architecture (CUDA)in combination with graphic processing unit. The results show that based on parallel framework optimization, the acceleration of 4.5 times can be obtained. Meanwhile bladed disk system vibration response of the largest amplitude and variance can be significantly reduced when using optimized arrangement.
Mission reliability analysis of repairable space TT&C system based on OBDD
MENG Li, WU Xiao-yue
2016, 31(5): 1065-1072. doi: 10.13224/j.cnki.jasp.2016.05.006
Abstract PDF(1033KB) icon1288 icon644
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Based on the ordered binary decision diagram (OBDD) theory, a new OBDD data structure in view of the characteristics of space telemetry, tracking and command system (TT&C system) was defined, and an approach to mission reliability analysis of repairable TT&C system was proposed. By dividing time windows of each station into phases, component logic relationship of each phase was analyzed, and the OBDD model of each phase was established. Then the final mission OBDD model was established by combining all single phase OBDD models together. Continuous time Markov chain (CTMC) was adopted to analyze the transition behaviors of each repairable component, and the mission reliability calculating algorithm was presented based on the new OBDD data structure. The result of a contrastive analysis with Markov method and simulation method reveals that: the proposed method can be used to analyze the mission reliability of repairable TT&C system accurately; the algorithm efficiency is higher than Markov method when there are more than 30 components.
Life prediction model of 7B04-T6 aluminum alloy under alternate action of corrosion and fatigue
LI Chang-fan, HE Yu-ting, ZHANG Sheng, LI Xu, DU Xu, ZHANG Teng
2016, 31(5): 1073-1080. doi: 10.13224/j.cnki.jasp.2016.05.007
Abstract PDF(1020KB) icon1275 icon657
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The alternate test of corrosion and fatigue and pre-corrosion test were carried out on 7B04-T6 aluminum alloy. The test results showed that the life of alternate test in sequence of "corrosion+fatigue+corrosion+fatigue+……" was longer than pre-corrosion test under the same corrosion time. According to the test results, the life prediction model of alternate action corrosion and fatigue was built based on the theory of damage mechanics and nonlinear damage cumulative theory. The damage exponent described the relationship of corrosion damage and the fatigue damage of the alternate action of corrosion and fatigue. The effects of damage exponent on precision and hysteretic factor of the model were discussed. Fatigue cycles had more serious effect on the total life than the corrosion time in the progress of alternation action of corrosion and fatigue. The total life got longer with the increase of fatigue cycles.
Effect analysis of delamination damage on the residual strength of notched composite laminates
XIAO Meng-li, ZHANG Yong-bo, WANG Zhi-hua, FU Hui-min, YANG Xin
2016, 31(5): 1081-1086. doi: 10.13224/j.cnki.jasp.2016.05.008
Abstract PDF(892KB) icon1301 icon763
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Based on CCF300/QY8911 notched composite laminates static tensile test, three-dimension prediction finite element model consistent with its failure mode was established. The growth of delamination in the process of tension was simulated by introducing Cohesive interface element, the simulation result had a good agreement with experimental data, the relative error of failure load between experimental data and numerical prediction was less than 5%. Given the delamination defects produced around the hole edge in the process of manufacturing and utilization of composite laminates, a prefab delamination was set near the hole for analysis, and the effect on the residual strength of laminates was investigated. The effect of embedded delamination near the surface layer on the residual strength was small, while the embedded delamination could disable delamination produced in advance near the free edge.
Numerical study on cross-type multi-stream plate-fin heat exchanger
LI Jun, JIANG Yan-long, ZHOU Nian-yong, XU Lei, SHI Hong, ZHENG Wen-yuan
2016, 31(5): 1087-1096. doi: 10.13224/j.cnki.jasp.2016.05.009
Abstract PDF(1088KB) icon1104 icon688
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Heat transfer mechanism of cross-type multi-stream plate-fin heat exchanger (MPFHE) was analyzed and the mathematical model by finite volume method was established based on the research of parallel-counter type MPFHE, and then the distance between fins was separated with cell size by reasonable assumption, expanding the application of former mathematical model. Besides, discussion about choice of cell size was conducted for the airborne cross-type three-stream plate-fin heat exchanger; while the analysis of transverse heat transfer of flow within a cell on the same channel was applied to demonstrate the possibility of ignoring the transverse heat transfer in this direction, so as to increase calculation efficiency under the constant computational accuracy; moreover, experiment of different inlet flow rates or temperatures was carried out to verify the veracity of numerical method. The calculation uncertainty is less than 7.9% compared with the test record, thus proving the rationality of numerical method.
Altitude characteristis of the thermal management system of diesel engine
ZHOU Bing, LAN Xu-dong, XU Xiang-hua, LIANG Xin-gang
2016, 31(5): 1097-1104. doi: 10.13224/j.cnki.jasp.2016.05.010
Abstract PDF(941KB) icon1197 icon711
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The effects of altitude on the heat transfer performance of the radiator in diesel engine were investigated based on the environmental characteristics of the flight height and high elevation plateau. The flow and heat transfer models of the thermal management system (TMS) of diesel engine were then established to investigate the effects of altitude on the TMS. Furthermore, the method for matching the operating parameters of the TMS under different working conditions was given based on the principle of minimum power consumption. The results under prescribed heat load conditions show that, at flight height, the heat transfer performance of the radiator increases first and then decreases with the increasing altitude, and the temperatures of the coolant and oil in the TMS decrease first and then increase whilst the minimum power consumption of the TMS decreases first and then increases. In the elevated plateau area, the heat transfer performance decreases with the increasing plateau altitude, and the temperatures of the coolant and oil in the TMS increase significantly, causing the engine overheating. The minimum power consumption of the TMS increases remarkably with the increasing plateau altitude in order to provide enough heat dissipation ability for the engine.
Experiment of ignition process based on statistical analysis of image processing
CAI Zun, WANG Zheng-guo, SUN Ming-bo, WANG Hong-bo, LIANG Jian-han
2016, 31(5): 1105-1112. doi: 10.13224/j.cnki.jasp.2016.05.011
Abstract PDF(884KB) icon1239 icon659
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As for the ignition process at the inflow conditions of Mach 2.1 with stagnation temperature of 846K and pressure of 0.7MPa high speed photography was used to observe the ethylene ignition experiments with the active cavity injection. Based on the high speed photography image synthesis and statistical analysis, a new method for analyzing the cavity flame stabilization and the flame distribution quantitatively was proposed. At the overall equivalent ratio of 0.15 and 0.17(the active injection equivalent ratio of 0.04 and 0.06 correspondingly), the ignition process of the scheme using ramp injection and the scheme using a combined parallel and ramp injection were compared by applying this method. Besides, the cavity flame stabilization and the flame distribution of the ignition schemes were investigated in quantitatively. At the active equivalent ratio of 0.04, the local pressure feedback is weak and the flame exists in a discontinuous form. At the active equivalent ratio of 0.06, the flame distribution of the combustor is more even. As for the ignition process transient images in a supersonic flow, qualitative and quantitative analysis could be made effectively by using this method.
Investigation on experimental correlations for aircraft spraycooling system in non-boiling area
ZHOU Nian-yong, WANG Yu, JIANG Yan-long, REN Zhe-fan, SUN Cheng-bing, ZHENG Wen-yuan
2016, 31(5): 1113-1120. doi: 10.13224/j.cnki.jasp.2016.05.012
Abstract PDF(1042KB) icon1117 icon599
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Experimental correlations of aircraft spray cooling system experiment in non-boiling area under different heating surfaces were investigated. On the basis of summarizing predecessors' work and establishing experiment bench as well as completing the experiment, four non-dimensional parameters influencing the spray cooling performance were provided while non-dimensional correlations of Nusselt number for different heating surfaces were calculated. The deviation between predicted value obtained by experimental correlation of smooth heating surface and experiment value was within 8.5%. The influence of each non-dimensional parameters on precision was also analyzed. For drilling surface, enhancing factor was applied for correction of the correlation, the value range and value basis were provided to enable the predicted values obtained by correlations falling within the deviation of ±15%. On the other hand, the experimental correlation for straight fin surface was proposed, and not influenced by fin structure and fin number. The correlation above is also suitable for water, salt solution as well as alcohol solution.
Internal heat transfer and skin temperature reduction law of engine nacelle
WANG Xing-tao, ZHANG Jing-zhou, SHAN Yong
2016, 31(5): 1121-1126. doi: 10.13224/j.cnki.jasp.2016.05.013
Abstract PDF(934KB) icon1128 icon607
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A simplified physical model of engine nacelle was established. The effects of ventilation cooling and radiation shelter on reducing skin temperature were investigated by numerical simulation and experimental research. The internal heat transfer of the engine nacelle was also analyzed. Results show that the computational temperature distribution on the skin surface is in good accordance with the experimental result. Under the present zonal thermal boundary conditions of the heated wall, the ratio of total heat flux imposing on the inner surface of skin to the heat flux of heated wall is about 78% in case of no ventilation and radiation shelter. This ratio reduces to 20% when the ventilating velocity of the engine nacelle is 1m/s. When the ventilating velocity is increased from 0m/s to 3.5m/s, the maximum temperature on the skin is reduced about 10% relatively. The maximum temperature on the skin with radiation shelter is reduced about 6% in relative to the case without radiation shelter under no ventilation condition. Combination of ventilation and radiation shelter can achieve 50K reduction of maximum skin temperature in relative to the case of no ventilation and radiation shelter, with about 14% relative reduction.
Experiment on combustion performance of single channel wave rotor combustor
GONG Er-lei, LI Jian-zhong, HAN Qi-xiang, LIU Bo-qiang
2016, 31(5): 1127-1132. doi: 10.13224/j.cnki.jasp.2016.05.014
Abstract PDF(931KB) icon1111 icon618
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An experimental system of a simplified single channel wave rotor combustor was established. Experimental investigations were conducted to evaluate the influences of igniting position, jet acting time and initial pre-mixing equivalence fuel/air ratio of premixed gas on the combustion performance. Continuous hot jet was applied to ignite the premixed gas. Results show that ignition is most difficult when the distance between the nozzle exit and the wave rotor channel is approximately 38mm. However, the igniting position has little influence on development of the flame front. The influences of jet acting time on the pressure gain depend on equivalence fuel/gas ratio. The tilt angle of flame front decreases as jet acting time increases. When the equivalence fuel/gas ratio is 2.0, the combustion is unsatisfactory in the wave rotor. Meanwhile, reverse inclination of the flame front emerges with 58 degree tilt angle.
Impact of heptadecance and octadecane on physical properties and SMD of kerosene
ZHOU Ting-ya, LI Jiang-hong, TAN Ruo-qiao, GAN Zhi-wen, YANG Xiao-yi
2016, 31(5): 1133-1141. doi: 10.13224/j.cnki.jasp.2016.05.015
Abstract PDF(1020KB) icon1135 icon585
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The impact of n-alkanes (C17~C18) on the physical properties of kerosene, including kinematic viscosity, density and surface tension was dicussed, and the effects of n-alkanes (C17~C18) on SMD (Sauter mean diameter) were investigated. The density fitting equation used Key's blending law, Tat blending law and polynomial fitting. The viscosity fitting equation used Key's blending law and logarithmic fitting. This fitting equation in this investigation have optimal accuracy. The atomization experiment shows that the SMD of blending fuels increases with the mass percentage of n-alkanes, which means that the added n-alkanes have negative effect to the atomization performance. The SMD of C18 blending fuels is larger than C17 blending fuels'. The fitting equation of physical properties are used to predict SMD of the blending fuels, and its error is less than 0.3%.
Effects of inlet velocity distortion on outlet temperature distribution of a reverse-flow combustor
LIANG Zhi-peng, LIN Yu-zhen, XU Quan-hong, ZHANG Chi, DAI Wei
2016, 31(5): 1142-1148. doi: 10.13224/j.cnki.jasp.2016.05.016
Abstract PDF(949KB) icon1233 icon655
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In order to study the effect of combustor inlet velocity distortion on the reverse-flow combustor outlet temperature distribution, the radial distortion and circumferential distortion plates were designed according to the compressor outlet velocity profile, and the distortion was validated by numerical simulation. And an experiment on the outlet temperature distribution of three sector rectangle model combustors was conducted. The results show that radial distortion and circumference distortion could cause uneven distribution of temperature and bring overall temperature distribution factor (OTDF) a significant increase, and the effect of circumference distortion seems greater. In addition, from the temperature contour and radial temperature distribution factor (RTDF) contour, the radial distortion and circumferential distortion will make the combustor outlet temperature a zig-zag fluctuation close to the inner wall, and present a cyclical trend, making outlet temperature distribution nonuniform.
Influence of the injecting position of self recirculation casing treatment on compressor performance
ZHANG Hao-guang, WU Jun, WANG Yun-peng, CHU Wu-li, WU Yan-hui
2016, 31(5): 1149-1158. doi: 10.13224/j.cnki.jasp.2016.05.017
Abstract PDF(1834KB) icon1113 icon566
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A numerical investigation was carried out on the transonic axial-flow compressor Rotor 67 to clarify the stall mechanism and the influence of self recirculation casing treatment(with three injection positions) on its performance. The result showed that low-speed region in the tip leakage vortex played a major role in stall. Casing treatments with three different injection positions improved the aerodynamic stability of compressor, and those with forward injector gives less improvement (2.72%) on stall margin than those with center (13.43%) and backward (9.47%) injectors. Casing treatment with center or backward injector performed better in suppressing the tip leakage flow, thus reducing the spreading of low energy fluid. Additionally, the backward injector showed no effect in accelerating the blockage around pressure side leading edge and suppressing the low energy leakage, so the ability of improving flow-filed of backward injector was lower than that of center injector.
Numerical study on the design error stabilities of 3-dimensional streamline curvature inverse method for centrifugal impellers
TIAN Xiao-pei, SHAN Peng
2016, 31(5): 1159-1169. doi: 10.13224/j.cnki.jasp.2016.05.018
Abstract PDF(1435KB) icon1030 icon604
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Two groups of the high speed centrifugal impellers were both designed by the 3-dimensional streamline curvature inverse method and a quasi-3-dimensional inverse method with a slip factor model. One group had different blade numbers, while the other group had different total pressure ratios. The impeller performances were predicted by a commercial computational fluid dynamics (CFD) solver. The design error stabilities of the two methods were compared. The impacts of the splitter blades on the design errors were also studied. The results showed that the 3-dimensional streamline curvature inverse method could realize a proper adjustment to the blade shape according to the blade loading. And compared with the quasi-3-dimensional inverse method, the total pressure ratios of the impellers designed by the 3-dimensional streamline curvature inverse method were generally higher. Therefore, with the increase of blade loading, the design errors of the 3-dimensional streamline curvature inverse method changed much smaller than those of the quasi-3-dimensional inverse method; namely, the design error stability of the 3-dimensional streamline curvature inverse method was much better. In addition, for the quasi-3-dimensional method, the impacts of the splitter blades on the blade design results were much smaller.
Influence of up-and downstream blades on the rotor blade flutter characteristics
YANG Hui, SHEN Zhen, ZHENG Yun
2016, 31(5): 1170-1177. doi: 10.13224/j.cnki.jasp.2016.05.019
Abstract PDF(1056KB) icon1123 icon588
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Flutter characteristics of rotor blades including up-and downstream interaction were simulated by self-developed unsteady flow simulation programs. Influence of wakes and potential waves on blade aerodynamic damping were studied. Energy exchange method was used to calculate the damping values. Variation of aerodynamic damping with different axial gaps was identified by FFT transformation of unsteady pressures on rotor blade surfaces. Interaction effects on the flutter characteristics of rotor/stator and IGV/rotor configurations were assessed by comparing the damping data with that of the single rotor. The results show that the positive damping was obtained at 100% chord axial gap for IGV/rotor configuration, in contrast with the aeroelastic stability prediction of the isolated rotor. This indicates the interaction must be considered in flutter analysis. The results also illustrate that wake and potential wave effects are intensified with reducing axial gaps, and both destabilize the rotor blades.
Experiment on rotor plane cascade of transonic compressor
GAO Yu, ZHONG Jing-jun, LI Xiao-dong, YANG Ling
2016, 31(5): 1178-1185. doi: 10.13224/j.cnki.jasp.2016.05.020
Abstract PDF(1088KB) icon1570 icon673
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The flow field of plane cascade with the blade root profile of a transonic compressor rotor was surveyed in detail at different incidences and inlet isentropic Mach numbers, and the characteristic curve of incidence and the static pressure coefficients of blade surface and end wall were gained. Results showed that the total pressure loss coefficients at the cascade outlet changed a little with different inlet isentropic Mach numbers at negative and zero incidences, and changed largely at positive incidences. With the same inlet isentropic Mach number, the blade load was high at negative and zero incidences, and decreased due to the flow separation, but the total pressure loss coefficients at the cascade outlet increased at positive incidences. With the increase of incidence, the stagger angle increased, and the total pressure loss with the minimum value of 0.034 slowed down and then up. With the increase of inlet isentropic Mach numbers, the total pressure loss coefficients at the cascade outlet increased at the same incidence.
Numerical investigation of bleeding effect on performance of multistage axial compressor
YAO Ding-fu, CHENG Jin-xin, CHEN Jiang, DU Gang
2016, 31(5): 1186-1195. doi: 10.13224/j.cnki.jasp.2016.05.021
Abstract PDF(1173KB) icon1301 icon632
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In the first place, with the single-stage axial compressor NASA-Stage 35 as research object, the bleeding mechanism of single-stage axial compressor was investigated by numerical simulation, and the research conclusion was applied to the bleeding investigation of the nine-stage axial compressor. The results show that bleeding effect on inner flow-field of single-stage and multistage axial compressors is basically the same, and there is some difference of overall performance between single-stage and multistage axial compressors with the effect of inner-stage matching.Rotor endwall bleeding can remove low-energy fluid in tip clearance and enhance the radial flow in rotor channel, therefor, the tip loss is reduced and the pressure ratio and efficiency of stage are increased.Stator endwall bleeding can reduce the endwall loss of stator and increase the efficiency of stage.
Full-annulus numerical simulation of near stall and rotating stall in an axial flow compressor
SHI Song, TU Bao-feng
2016, 31(5): 1196-1204. doi: 10.13224/j.cnki.jasp.2016.05.022
Abstract PDF(1158KB) icon1293 icon626
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To study stall inception of the axial flow compressor, full-annulus numerical simulation in the first stage of a two-stage low-speed axial flow compressor was presented. Results showed that there existed a kind of velocity fluctuation in the circumference scale in stall inception, which was closely related to the uneven boundary layer separation that first happened on the suction of stator blade rows. With further throttling of the compressor, the fluctuation amplitude increased gradually, and eventually it induced several rotor channels to generate serious boundary layer separation, blocking these channels. The compressor system led to the rotating stall condition. The rotational stall frequency with full development had good coincidence with the experimental result.
Experiment on the performance of propeller plasma flow control
CHEN Qing-ya, TIAN Xi-hui, JIANG Jia-wen, NIE Wan-sheng, CHE Xue-ke
2016, 31(5): 1205-1211. doi: 10.13224/j.cnki.jasp.2016.05.023
Abstract PDF(979KB) icon1088 icon559
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Based on two kinds of mechanisms that the attached wall plasma jet restrains the boundary layer separation, the experiment was operated to study the microsecond impulse plasma jet control performance at three-dimensional flow separation of propeller supported by the experiment platform for propeller plasma flow control. According to the mechanisms, two kinds of plasma jets, synclastic jet in the same direction of airflow, and reverse jet in the opposite direction of airflow, were used in the experiment. It is found that when the propeller rotation speed is 300r/min, voltage amplitude gets 8.5kV, and pulse frequency is within the range of 10-160Hz, the twisting moment of propeller decreases with synclastic jet and increases with reverse jet. The thrust and efficiency of propeller both are improved under the control of two kinds of plasma jets, but the plasma flow control performance is obviously influenced by pulse frequency. In the experimental conditions the propeller efficiency increases 11.56% with synclastic jet, and 2.79% with reverse jet respectively.
Experiment on influences of nozzle deflection on aeroengine characteristic
LI Jian-rong, BAI Wei
2016, 31(5): 1212-1218. doi: 10.13224/j.cnki.jasp.2016.05.024
Abstract PDF(899KB) icon1128 icon623
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Based on the engine overall performance ground test and parameter analysis in case of nozzle deflection under different working conditions, the effect of nozzle deflection on engine thrust loss, deflection efficiency and engine working characteristics were obtained. The experimental results showed that the engine thrust loss increased and deflection efficiency increased at first and then decreased with the increase of geometric vector angle when compressor speed remained unchanged. The engine thrust loss increased at first and then decreased, and the deflection efficiency increased with the increase of rotor speed when geometric vector angle remained unchanged, but the deflection efficiency was always less than 1. Engine speed difference increased with the increase of geometric vector angle when engine worked in throttle rating and speed difference almost kept constant with the increase of geometric vector angle when engine worked in middle rating. Fan co-operating line moved upward and fan surge margin decreased in case of nozzle deflection. So the method of expanding stability should be adopted for the engineering application of vectoring nozzles.
Effects on extracting power from low-pressure spool on HALE UAV engine
LIANG Zhen-xin, TIAN Cheng-jian, WANG Zhao-guang
2016, 31(5): 1219-1225. doi: 10.13224/j.cnki.jasp.2016.05.025
Abstract PDF(863KB) icon1172 icon551
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The mathematical models of high-altitude long-endurance unmanned aerial vehicles (HALE UAV) engines with the corrected method of Reynolds number for engine components characteristics were built, and the corresponding programs were developed. The effects of extracting power from low-pressure spool on different small and medium thrust turbofans engine and the core engine, as well as the effects of extracting power from two spools on the engine were calculated and analyzed under high-altitude flight condition; the proper proportion of power extraction between different spools was analyzed. It is shown from the computation results that compared with extracting power from high-pressure spool under high-altitude flight condition, extracting power from low-pressure spool can observably improve the fan/compressor surge margins for turbofan without booster and the booster surge margins for turbofan engine with booster, remarkably increase the power extraction of turbofan without/with booster on the premise of maintaining engine operation stability; also this can realize a 9% to 14.8% improvement in spool speed, correlated mass flow and pressure ratio of the core engine for developing potential of the core engine.
Low-Reynolds-number wake flows of a triangular prism
LU Jian-zhou, TAO Jian-jun
2016, 31(5): 1226-1233. doi: 10.13224/j.cnki.jasp.2016.05.026
Abstract PDF(1116KB) icon909 icon678
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The two-dimensional incompressible Newtonian flows passing an isosceles triangular prism were numerically investigated at low Reynolds numbers, which were defined with the base length. Two geometrical orientations of the prism were used the upwind arrangement (apex facing the flow) and the backwind arrangement (base facing the flow). This revealed that for large aspect ratio of the cross section, the upwind arrangement was prone to be unsteady than the backwind arrangement at the same Reynolds numbers, hence suffering transverse force but with relatively smaller drag coefficient which can be reduced by at most 19.4% when Reynolds numbers was 160. In addition, the Reynolds number effects on the lift coefficient, drag coefficient and vortex-shedding frequency of the prism at different aspect ratios were discussed for the two arrangements as well.
Effects of distributed roughness on Mach 4.5 boundary-layer transition
ZHANG Cun-bo, LUO Ji-sheng, GAO Jun
2016, 31(5): 1234-1241. doi: 10.13224/j.cnki.jasp.2016.05.027
Abstract PDF(998KB) icon1050 icon566
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The influence of small distributed surface roughness on disturbance amplification in a Mach 4.5 Blasius boundary-layer was investigated by numerical simulation of Navier-Stokes (N-S) equations. Distributed roughness was simulated by applying the wall boundary condition onto the smooth wall through a method of Taylor expansion. Different parameters of roughness and disturbance were considered including height, spacing, length of roughness and frequency of disturbances. Results show that distributed roughness affects the disturbance amplification by altering the basic flow. Distributed roughness shifts the unstable area to lower frequency for upstream flow field and to higher frequency for downstream flow field. Generally, for lower frequency disturbances near the lower branch of the neutral stability curve in the vicinity of roughness, the amplification was damped, while for higher frequency disturbances near the upper branch of the neutral stability curve, the amplification was amplified.
Influence of back pressure on shock train structure in isolator
HE Can, XING Jian-wen, XIAO Bao-guo, LIU Wei-xiong
2016, 31(5): 1242-1251. doi: 10.13224/j.cnki.jasp.2016.05.028
Abstract PDF(1304KB) icon1187 icon531
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In order to investigate the characteristics of axisymmetric cylindrical isolator under different back pressures, the flow field of the isolator was simulated with different inviscid flux schemes and turbulence models. Compared with the experimental data, the most suitable model and scheme were chosen. Three-dimensional simulations of the isolator and combustor were employed to study the flow field structure, exit parameter and shock train under different back pressure ratios. The limit back pressure was found. The structures of the shock train under two kinds of back pressure were compared. Results show that the inviscid flux scheme and turbulence model, which are critical for the isolator simulation, have a significant impact on the structure and length of the shock train. The parameter of the isolator exit is affected by the back pressure. When the exit of the isolator is in the mixing region, the static pressure distribution is more uniform. And when the exit is in the shock train region, the pressure is non-uniform. For this axisymmetric cylindrical isolator and combustor, there is no obvious difference on structure and initial position of the shock trains respectively induced by the combustion back pressure and cold back pressure.
Flow field characteristics in an axisymmetric bend duct with struts
BU Huan-xian, TAN Hui-jun, HE Xiao-ming, AN Li-ping, HUANG Ping
2016, 31(5): 1252-1259. doi: 10.13224/j.cnki.jasp.2016.05.029
Abstract PDF(1198KB) icon990 icon537
Abstract:
An axisymmetric bend duct was investigated numerically and experimentally to obtain the flow field characteristics in its internal passage with/without struts. The wake characteristics and influences of exit Mach numbers were also analyzed in detail. Results indicate that experiments agree well with simulations. The airflow accelerated at first and then decelerated in the bend duct. And two local low-pressure areas were generated respectively at both leeward sides of the two bends. Moreover, struts had a great effect on the flow structure in the bend duct, inducing wake and vortexes. At different radial positions near the wake, the total pressure distributions were quite different. In addition, with the increase of exit Mach number, the static pressure on the wall surface and the total pressure recovery of the outlet cross section decreased, but the adverse pressure gradients near the two bends increased. So this indicates a greater risk of boundary layer separation.
Turbofan engine gas path components fault diagnosis based on adaptive cubature Kalman filter
HU Yu, ZHANG Shi-ying, LUO Lei, ZHU Jie-tang, MA Hong-fei
2016, 31(5): 1260-1267. doi: 10.13224/j.cnki.jasp.2016.05.030
Abstract PDF(1109KB) icon1220 icon591
Abstract:
In order to realize better filtering accuracy and adaptability given different statistic characteristics of noises, an adaptive square root cubature Kalman filter (ASRCKF) was proposed for the turbofan engine gas path components fault diagnosis. In the ASRCKF algorithm, the mean and covariance of the engine nonlinear function were calculated by three-order cubature rule-based numerical integration method and used as a substitute of nonlinear model to avoid the parameters selection problem of nonlinear unscented Kalman filter. The latest information of measurement parameters in the recursion and filtering process was used to estimate and self-adjust the noise cross-covariance by removable window method, so as to realize higher filtering accuracy and adaptability of different noises. The comparison of simulation results indicates that the accuracy of the ASRCKF is improved by 40%-50% than the SRCKF, showing a better adaptability to different noises than other algorithms.
Method and apply of sensor signal reconfiguration for civil aero-engines
ZHANG Rong, HOU Ling-feng, ZHAO Xu-dong, HU Zhong-zhi
2016, 31(5): 1268-1274. doi: 10.13224/j.cnki.jasp.2016.05.031
Abstract PDF(986KB) icon1113 icon523
Abstract:
A method of aero-engine high accuracy sensor signal reconfiguration and its applications were presented. Two synthesized rotor speed signals in a civil aero-engine were demonstrated separately as the example of the design. These were achieved by selecting proper engine parameters for the synthesis and construction of the steady-state synthesis and transient compensation. The synthesized signals were then imported to the digital simulation rig. The simulation results show the high accuracy of this design method, indicating that the steady-state error is less than 1% and the transient error is less than 3%.
Experiment on jet noise reduction with a liquid column driven by rocket engine gas jet
ZHANG Lei, RUAN Wen-jun, WANG Hao, WANG Zheng-wei
2016, 31(5): 1275-1280. doi: 10.13224/j.cnki.jasp.2016.05.032
Abstract PDF(1137KB) icon943 icon567
Abstract:
In order to investigate the effective method of individual rocket burned gas jet noise reduction, a designed liquid column was placed in the tail tube. The dispersion processes of high-temperature high-pressure combustion-gas driving the liquid column in the air was observed by using a high-speed photographic system, and gas-liquid mixture jet noise was also measured; the test results of jet were compared under two conditions of no-water-column and water-column. The experimental results show that then liquid column was put in the tail tube, the jet flow structure was changed and the jet flow parameters were decreased due to the interaction of gas jet with water. It is concluded that the sound pressure level peak is reduced to some extent in whole test points region with the liquid column, compared with the result of no liquid column gas jet; and the impact of the ground on the acoustic wave is weakened. With the increasing angle of the measuring points deviating from the jet central axis, the sound pressure level peak decreases. So the liquid column plays an important role in suppressing noise, the peak sound pressure level decreases by 6.4dB at the angle of 45°, validating the feasibility of noise reducing scheme.

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