2014 Vol. 29, No. 2

  Previous Issue | Next Issue 
Display Method:
Experiment on flow and heat transfer characteristics inside leading edge of lamilloy cooling turbine blade
HU Ya-ping, LU Yuan-li, JI Hong-hu, WANG Ming
2014, 29(2): 241-249. doi: 10.13224/j.cnki.jasp.2014.02.001
Abstract PDF(978KB) icon2256 icon1175
Abstract:
Base on similarity theory, experimental investigation of flow and heat transfer characteristics were conducted on two amplificatory leading edge models of lamilloy colling turbine blade, including one model with rhombus pin-fins and the other without pin-fins, the flow resistance coefficient, temperature and surface heat transfer coefficient on target surface were compared between two models. The temperature was measured by infrared thermograph technique, and the local heat flux density was simulated by ANSYS. The results show that the flow resistance of two models increases gradually with the increase of inlet Reynolds number. And the model with rhombus pin-fins has larger flow resistance on the whole. The distribution of local surface heat transfer coefficient on the target surface of two models is similar while the model with rhombus pin-fins has slightly higher value. The difference of average surface heat transfer coefficient for the target surface of two models is also little and the value of the model with rhombus pin-fins is at most 7% larger than the that of other model at the same inlet Reynolds number.
Experiment on spray characteristic of single head of dual-swirl cup combustor
JIN Ren-han, LIU Yong, FENG Zhi-peng, WANG Suo-fang
2014, 29(2): 250-258. doi: 10.13224/j.cnki.jasp.2014.02.002
Abstract PDF(1079KB) icon2083 icon1144
Abstract:
In order to obtain fuel spray characteristics of dual-swirl cup combustor,the particle image velocimetry (PIV) was applied to measure the spray field of its single head.Through the experiment,the fuel spray characteristics were obtained with different fuel flow distributions and locations of the pilot atomizer.Under the experimental conditions,the results show that:(1) Volume fraction of the droplet size of 80μm is the largest,while volume fraction of the other droplet sizes not equal to 80μm decreases sharply.(2) When the fuel flow increase,the spray quality deteriorates with only pilot fuel atomizer available,and differs little with only primary atomizer available.(3) The fuel spray field of pilot fuel atomizer at swirler outlet has better performance than that of pilot atomizer at throat position.(4) When the pilot and primary fuel atomizer operate at the same time,atomization quality is improved with increase of primary fuel flow rate while inlet fuel air ratio is kept unchanged.
Fighter's infrared characteristics between 8 and 14μm and infrared stealth effect of low emissivity materials
LIU Jian, GONG Yu, JI Hong-hu
2014, 29(2): 259-267. doi: 10.13224/j.cnki.jasp.2014.02.003
Abstract PDF(1382KB) icon2152 icon1148
Abstract:
The infrared integral radiant intensity of a typical fighter within the waveband between 8μm and 14μm and its detection range detected by infrared search/tracking system was calculated by taking into account the influence of the atmospheric transmissivity. The infrared stealth effect of the fighter with use of low emissivity materials was also analyzed. The flow field was calculated by Flunt software,while the infrared radiation characteristics and detection range were simulated by using self-developed software NUAA-IRSE. The results show that the infrared integral radiant intensity increases with the increasing of circumference angle and pitch angle. When applying low emissivity materials, the infrared integral radiant intensity decreases in all directions, leading to an improved infrared stealth effect.
Cooling effectiveness comparison between effusion cooling and impingement/effusion cooling
YANG Qian, LIN Yu-zhen, ZHANG Chi, XU Quan-hong
2014, 29(2): 268-276. doi: 10.13224/j.cnki.jasp.2014.02.004
Abstract PDF(1038KB) icon1997 icon1077
Abstract:
In order to acquire the optimal cooling approach of aero-engine chamber,experimental approaches were taken to study the cooling effectiveness of effusion cooling and impingement/effusion cooling.Cooling effectiveness of these two types of cooling configurations were investigated on the same hot/cold air conditions of inlet,such as position of effusion holes,inlet temperature of hot/cool side,mass flow of hot/cool air,pressure drop between hot/cool sides.Infrared camera was used to measure the temperature of effusion cooled surfaces on the side of hot main stream to get the cooling effectiveness,and analyzed the cooling effectiveness of these two cooling configurations.The results show that on the condition of the same opening area and hot/cold air conditions of inlet,double wall cooling gets higher cooling effectiveness than effusion cooling configurations by approximately 30%, owing to the heat transfer enhancement within the gap of the double walls.
Experiment of anti-icing and icing on inlet strut of aero-engine
YANG Jun, ZHANG Jing-zhou, GUO Wen, LIU Hua
2014, 29(2): 277-283. doi: 10.13224/j.cnki.jasp.2014.02.005
Abstract PDF(907KB) icon2176 icon1415
Abstract:

In order to understand the icing law on the inlet strut of an aero-engine and the anti-icing law of the inlet strut with the hot-gas,the anti-icing experiment, ice melting experiment and the icing experiment were carried out on the inlet strut in the icing wind tunnel.The results indicate that the heat flow of the inlet strut increases with increasing entrance velocity but decreases with increasing entrance temperature. Ice mostly appears on the leading edge of the strut and the thickest ice appears close to the stagnation location.The glaze ice occurs easily when the initial temperature of the strut is relatively high and drops slowly.The rime ice occurs easily when the entrance temperature is relatively high and the temperature of the surface drops precipitately.Besides,the results provide a basis for the design calculation of the inlet strut and some references for aero-engine anti-icing system design.
Spray angle tracking based on active contour method
ZENG Qing-hua, FAN Hui-jie, WANG Yue, KONG Wen-jun
2014, 29(2): 284-289. doi: 10.13224/j.cnki.jasp.2014.02.006
Abstract PDF(858KB) icon1954 icon1111
Abstract:
Active contour model (ACM) was developed to track spray angle of atomizer. Through debugging and testing, ACM successfully captured the boundary of atomizer spray. The feature of spray contraction at downstream part of spray was also obtained, and spray angle was got exactly. The verification results show that, the relative errors between the spray angle values measured by the ACM tracking and the shadowgraph measurement are less than 1.5%. The ACM tracking spray angle can reduce cost of engineering applications with an identical measuring accuracy.
Experiment on coupled jet-in-crossflow trajectory of 5mm diameter warped hole
YAO Shang-hong, LEI Yu-bing
2014, 29(2): 290-297. doi: 10.13224/j.cnki.jasp.2014.02.007
Abstract PDF(1053KB) icon1752 icon1026
Abstract:
Particle image velocimetry (PIV) was used for learning the 5mm diameter warped hole flow field in jet-in-crossflow. The result shows that: the jet angle differs from the warped hole angles, the larger of the warped hole angle means the larger jet angle; there will be a useful parameter named effective diameter from the experiment data. Jet flow trajectory curves were fitted in condition of two types of velocity, four different warped hole angles and three tunnels with different depth. The curve is well fitted with the real jet flow, contributing to the future flow field design in micro combustors or other small tunnels.
Experiment on heat transfer characteristics inside the casing of high pressure turbine with active clearance control
ZHANG Jing-shan, MAO Jun-kui, LI Yi, SHEN Yi, LU Hai-ying
2014, 29(2): 298-304. doi: 10.13224/j.cnki.jasp.2014.02.008
Abstract PDF(970KB) icon1969 icon1218
Abstract:
According to a typical heat transfer structure of the casing of a high pressure turbine with active clearance control system,experiments were conducted to investigate the local heat transfer characteristics of a mutillayer casing structure.In the experiments,the inlet Reynolds number (10000-24000),the angle of jet impingement (30°,45°,60°) and the diameter of jet impingement hole (1.0,1.5,2.0mm) were changed to investigate the local and average heat transfer coefficients of the casing surface with ribs.It was found that the existence of the ribs affected the local heat transfer coefficient of the casing surface significantly.At the same time,due to the local heat transfer enhancement by the jet impingement,the heat transfer coefficient of the casing inner surface varied considerably at different locations.The results show that the local and average heat transfer coefficients are improved with the increasing inlet Reynolds number of cold air.Within the range of research parameters,maximum heat transfer can be obtained when the diameter of the jet holes is 2mm and the number of jet holes is 23.Compared with the angle of jet impingement 30° and 60°,45 ° can result in higher heat transfer rate.
Reliability analysis on aero-engine using Bayesian model averaging
WANG Hua-wei, GAO Jun, WU Hai-qiao
2014, 29(2): 305-313. doi: 10.13224/j.cnki.jasp.2014.02.009
Abstract PDF(1009KB) icon2039 icon1157
Abstract:
Considering the characteristics of different failure modes with use of monitoring information, Gamma process, Wiener process and Weibull distribution were selected to build the reliability analysis models on aero-engine. Bayesian model averaging (BMA) was used to integrate different models into one framework for reliability analysis on aero-engines, given its function for dynamically evaluating different failure mode effects. The reliability of some onwing aero-engine was analyzed by numerical example, showing that the reliability analysis model using BMA had less error than single reliability analysis model, and computation error rate of BMA was less than 1%. The results demonstrate the effectiveness of the reliability analysis of multi-model integration.
Friction/wear behaviors and predication of graphite seal material under high temperature
YAN Yu-tao, LI Xue-juan, HU Guang-yang, HU Tian-qi, SUN Zhi-li
2014, 29(2): 314-320. doi: 10.13224/j.cnki.jasp.2014.02.010
Abstract PDF(906KB) icon1843 icon1426
Abstract:
The tribological properties of graphite M210 seal material under high temperature were investigated on a HT-1000 high temperature friction/wear tester.The worn surface of graphite pin was observed by scanning electronic microscope (SEM).The predication model on friction coefficient and wear rate was established by grey theory GM (1, 1) based on the test data.The results show that the friction coefficient of graphite M210 seal material gradually augmented,then gradually diminished,and reached a steady value with the test time.The value of friction coefficient was minimal when the temperature was 450℃.The wear rate increased with the temperature rise.The worn surface was characterized by obvious adhesion,laceration and unordered plastic flow under temperature 300℃.The plastic flow trace had obvious directivity,and the desquamation and the rift were found on the worn surface when the temperature was above 400℃.The lubrication action was mostly dependent of the physically absorbed film by water vapor at lower temperature.With the temperature rise,the lubrication action turned to reaction film,and the lubrication of physical adsorbed film disappeared.The predication model for friction coefficient and wear rate was established based on test data by the gray theory,and the precision grade of the model was the first grade by the grade verification.
Effects on structure and mechanical properties of TC11 titanium alloy by laser shock peening
NIE Xiang-fan, HE Wei-feng, ZANG Shun-lai, WANG Xue-de, LI Yu-qin, CHAI Yan
2014, 29(2): 321-327. doi: 10.13224/j.cnki.jasp.2014.02.011
Abstract PDF(864KB) icon2301 icon1127
Abstract:
TC11 titanium alloy was treated by laser shock peening (LSP), while microstructure, residual stress and microhardness without/with LSP in different laser impacts were examined and compared via transmission electron microscope (TEM), X-ray diffractometer and microhardness tester. The high-cycle vibration fatigue test of TC11 titanium alloy standard vibration specimens was conducted to verify effects of LSP on the high-cycle fatigue property. The results indicated that severe plastic deformation was formed and grains on the surface were refined with high-density dislocations, dislocation cells. Nanocrystals were generated successively with increasing laser impact. The maximum residual stress reached -632.5MPa in 10 impacts with 1500μm thick plastic deformation layer. The microhardness was increased by 19% with 700μm thick affected layer. The affected depth increased with the laser impact, but amplitude was limited. Fatigue limit of TC11 titanium alloy standard vibration specimens treated by LSP in 3 impacts had been improved from 483MPa to 593MPa.
Bi-stable mechanical behavior of shallow thin spherical shell with elliptical bottom
ZHANG Ping, ZHOU Li, QIU Tao, CHENG Wen-jie
2014, 29(2): 328-336. doi: 10.13224/j.cnki.jasp.2014.02.012
Abstract PDF(1052KB) icon1655 icon1155
Abstract:
To meet the design requirements of a morphing bump surface,a research was conducted on the bi-stable mechanical behavior of a hinged shallow thin spherical shell with elliptical bottom surface.The conversion mechanism and required condition of the shell's two stable configurations were analyzed by simulation method.Also the snap-through type,which occurred in the transition process of stable configurations,and its influential factors,were analyzed.Finally the effects of the loading position and shape parameters on the critical driving force and structural strain were given under different driving modes.The results show that the bi-stability condition of the hinged structure requires a certain ratio of shell height to shell thickness;there exist combinations of local and overall snap-through phenomena during the transition process of the structural stable configurations,which could be controlled by the loading position and structural parameters;in case of structure snap,the critical load and structural strain are related to the load methods and structural parameters.
Research on fretting fatigue life of anisotropic materials
SHI Wei, WEN Wei-dong, CUI Hai-tao
2014, 29(2): 337-342. doi: 10.13224/j.cnki.jasp.2014.02.013
Abstract PDF(818KB) icon1665 icon991
Abstract:
A fretting fatigue test apparatus was designed and manufactured for the fretting fatigue damage process test of the specimens of anisotropic materials DD3 and DZ125 superalloys contacted with pad of powder metallurgy superalloy FGH95.The fretting fatigue experiments were conducted with DD3 and DZ125 superalloys to demonstrate the capability of the fretting fatigue test apparatus.The fretting damage parameters were introduced and the quantitative research on the new fretting fatigue life prediction model of anisotropic material was carried out.The results confirm the validity of the life prediction model of anisotropic materials by comparing the predicted fretting fatigue life with the experimental life.And the errors are both within 2.8 times of dispersion band.
Dynamic characteristics of low loss motorized spindle suspended by magnetic bearings
XU Xin, XIE Zhen-yu, LONG Ya-wen
2014, 29(2): 343-349. doi: 10.13224/j.cnki.jasp.2014.02.014
Abstract PDF(1011KB) icon1598 icon944
Abstract:
A low loss motorized spindle suspended by magnetic bearings with two radial homopolar active magnetic bearings (AMB) and one axial permanent magnetic bearing (PMB) was established,and the main design procedure and configuration parameters of the system were presented.The dynamic characteristics of the system were analyzed by theoretical calculations and verified by high-speed rotation tests.The results show that the system has simpler structure,less power consumption,and is able to get across the first two critical speeds and operate at 40000r/min safely,with maximum amplitude of the rotor up to 7μm.
Aerodynamic design principle of aspirated and low-reaction axial-compressors
WANG Song-tao, HU Ying-jiao, WANG Zhong-qi
2014, 29(2): 350-362. doi: 10.13224/j.cnki.jasp.2014.02.015
Abstract PDF(1086KB) icon1666 icon1034
Abstract:
For subsonic,supersonic and transonic axial-compressors,comprehensive explanation was made for the low reaction aerodynamic design principle of the aspirated compressor stages.The specific implementation form of this principle was put forward,while the application conditions and mutual interactions between aerodynamic parameters,such as twist speed and axial velocity,were analyzed.For subsonic axial-compressors,the diffusion factor could be reduced by increasing the rotor exit axial velocity or by enlarging the positive pre-swirl of the rotor entrance flow.For transonic or supersonic axial-compressors,the flow in the rotor could attain large turning efficiently by increasing the axial velocity after the entrance shock.The specific value of the outlet axial velocity could be chosen depending on the rotor efficiency and the requirements of the entrance Mach number and absolute flow angle of the downstream stator.At last,the progresses made on this design principle were summarized.
Prediction of detached shockwaves from leading edge of supersonic cascade
QIU Ming, ZHOU Zheng-gui, LIU Long-long
2014, 29(2): 363-373. doi: 10.13224/j.cnki.jasp.2014.02.016
Abstract PDF(1189KB) icon1601 icon1012
Abstract:
In order to accurately predict detached shockwaves from the supersonic cascade leading edge,the supersonic cascade detached shockwaves model based on Moeckel method was built by analysis and formula derivation.Firstly,Moeckel method was improved to increase symmetrical detached shockwaves approximation accuracy on the uniform flow condition.And then,Moeckel method was extended to approximate the asymmetric detached shockwaves on the uniform flow condition.Finally,the detached shockwaves model was constructed according to supersonic cascade flow characteristics.The resulting model was used for three supersonic cascades to predict the shape and position of detached shockwaves from leading edge of cascades.And the predicted results were compared with the CFD solved results.The results show that improved Moeckel method can more accurately approximate symmetrical detached shockwaves and also can be used for predicting asymmetric detached shockwaves,while the shape and location of detached shockwaves obtained by the model is consistent with those obtained by CFD software.
Mechanism investigation of aerodynamic effect on the inlet flow distortion in a transonic axial-flow compressor
LI Mao-yi, YUAN Wei, LU Ya-jun, SONG Xi-zhen
2014, 29(2): 374-383. doi: 10.13224/j.cnki.jasp.2014.02.017
Abstract PDF(1246KB) icon1739 icon1057
Abstract:
An inlet flow distortion with plugboard was simulated.The flow-field characteristics,circumferential distribution of shock wave and stall mechanism were analyzed in detail.Experiment and numerical simulation were conducted.The experimental and numerical simulation results show that the positive and negative pre-rotation were generated in front of the compressor at different circumferential respectively,and the circumferential distribution of velocity in front of the rotor constantly changed along axial direction.The axial velocity of distortion sector was larger near the rotor leading edge.The air flow was under positive pre-rotation in non-shock wave region at transition sector A where the rotor was rotated into the low pressure sector.It was under negative pre-rotation in strong shock wave region at transition sector B where the rotor was rotated out of the low pressure sector.The leakage vortex of transition sectors was stronger than any other sectors.So the transition sectors were the regions where unstable flow occurred in advance.
Experiment on axial-compressor stability enhancement by blade tip injection
SHI Pei-jie, QIAO Wei-yang, WANG Liang-feng, CHEN Wei-jie, XU Kun-bo
2014, 29(2): 384-390. doi: 10.13224/j.cnki.jasp.2014.02.018
Abstract PDF(921KB) icon1692 icon935
Abstract:
Experimental study of blade tip injection effects on the stability of a axial-compressor was carried out. The rotating stall signal was verified and spike type stall inception was detected when there was no injection, and it was found that the type of the stall inception signal did not change after tip injection was used. The effects of the number of tip injectors, circumferential distribution of injectors and yaw angle of injector on the effectiveness of stability enhancement were measured and analyzed. From the experimental results, it can be concluded that the stability was enhanced by either decreasing the number of injectors while keeping the total mass flow of injectors constant, or by increasing the number of injectors under the condition that the mass flow of a single injector keeps constant, and the stability was decreased by increasing the unevenness of injectors. It was also found that effectiveness of stability enhancement by tip injection was related to the parameters of injection flow in the relative frame of rotor. The association relation between the momentum component of the injection flow along the flow direction of zero incidence angle in the relative coordinate, which is scaled by the momentum of main flow, and effectiveness of stability enhancement was built.
Preliminary experiment of suppressing flow separation in cascade by micro pulsed jet without external device
ZHU Jian-feng, HUANG Guo-ping, FU Xin, FU Yong
2014, 29(2): 391-397. doi: 10.13224/j.cnki.jasp.2014.02.019
Abstract PDF(951KB) icon1797 icon933
Abstract:
Based on a micro pulsed jet without external device control technology suitable for high-load compressor, experimental investigation at low Mach number state was carried out on the cascade tunnel, and the steady and dynamic pressure characteristics in no-control state were obtained. The characteristic frequency of the separated vortex was found to be about 478Hz, and the corresponding Strouhal number was about 0.2. The experiment of controlling separation flow by micro pulsed jet was performed, with the frequency of the micro pulsed jet from 148Hz to 840Hz. Results show that when the frequency of the micro pulsed jet ranges from 0.85 to 1.20 of characteristic frequency of the separated vortex, the control effect is more obvious. Compared with blade slot treatment in other steady control methods, the suction mass flow ratio of this micro pulsed control method is few, and the influence of suction phenomena on the flow characteristics of pressure side and overall performance has been decreased significantly.
Design and experiment of gaseous hydrogen/oxygen engine igniting with electric spark igniting in vacuum
WU Jing, ZHANG Guo-zhou, CAI Guo-biao
2014, 29(2): 398-404. doi: 10.13224/j.cnki.jasp.2014.02.020
Abstract PDF(988KB) icon1831 icon1133
Abstract:
In order to investigate the vacuum plume effects of a large-thrust hydrogen/oxygen engine, a shrink ratio gaseous hydrogen/oxygen engine of 60N-thrust with torch igniting method was designed. The mass flow rate was controlled by a sonic nozzle with ball-end seal, such that 3 sealing faces were reduced in every assembly compared to the traditional one. The vacuum igniting scheme was designed, and the feasibility of igniting with electric spark was confirmed in theory. The experiment system was devised and the heat test run was conducted in both ground and vacuum conditions. The results show that when the chamber pressure reaches nominal 0.6MPa, the thermal protective structure of the engine works well, the experiment system is reasonable, and the scheme of igniting with electric spark in vacuum is feasible, laying a solid foundation for the vacuum plume effect investigation.
Performance comparison of aero-ramp and transverse injector based on gas-pilot flame
SONG Gang-lin, ZHANG Yan, WEI Bao-xi, TIAN Liang, XU Xu
2014, 29(2): 405-419. doi: 10.13224/j.cnki.jasp.2014.02.021
Abstract PDF(1609KB) icon1247 icon882
Abstract:
A direct performance comparison between the four-hole aero-ramp injector and single transverse injector in a dual-mode scramjet combustor was conducted. The mixing characteristics of two injectors were calculated by solving the three-dimensional (3-D) compressible Reynolds-averaged Navier-Stokes equations (RANS), with the help of the shear-stress-transport (SST) k-ω turbulence model. The numerical results show that the far field mixing efficiency of the aero-ramp injector is higher than that of the single transverse injector. High enthalpy vitiated air was heated to a total temperature of 1200K by hydrogen-oxygen combustion, entering the isolator entrance at a Mach number of 2.0. Non-reacting experimental conditions involved sonic injection of nitrogen to safely simulate ethylene injected into the combustor at a jet-to-free stream momentum flux ratio of 2.6. Schlieren photographs were obtained to analyze the shock structure around the injectors. Reacting test conditions involved sonic injection of ethylene at the jet-to-free stream momentum flux ratios ranging from 0.5 to 2.7. High speed camera was used to capture the flame structures in the near-field combustion. The experimental results show that the aero-ramp injector produce sustained combustion over a wider range of fuel-air ratios than the single transverse injector. At the identical jet-to-free stream momentum flux ratio, the aero-ramp has a larger isolator margin than the single transverse injector, demonstrating a better ability for avoiding overflows. However, the air specific impulse and total temperature recovery of two injectors, which are calculated by the one-dimensional (1-D) performance analysis code, are almost identical.
Simulation of flow characteristics and performance of vortex cooling thrust chamber
LI Gong-nan, YU Nan-jia, LU Qiang
2014, 29(2): 420-426. doi: 10.13224/j.cnki.jasp.2014.02.022
Abstract PDF(1016KB) icon1858 icon931
Abstract:
Numerical simulation of 3-D full-size model was conducted for 2000N gas hydrogen/gas oxygen vortex cooling thrust chamber.Velocity distribution characteristics of the flow field were obtained,and existence of the bidirectional vortex structure was verified.The interface of inner and outer vortexes accounted for 86% of the thrust chamber cylinder radius,and the combustion zone took up 70% of the thrust chamber cylinder radius.Analysis showed that the outer vortex cooling layer was mainly influenced by incoming stream velocity and geometric parameters of thrust chamber. The pressure and density of the inner vortex maintained stable due to the viscosity and combustion.The average temperature of the thrust chamber sidewall was 388K.The specific efficiency was above 92%.The results of computation were consistent with the experiment results.
Fault tree analysis of complex multistate system with fault statistically dependent components
HOU Jin-li, JIN Ping, CAI Guo-biao
2014, 29(2): 427-433. doi: 10.13224/j.cnki.jasp.2014.02.023
Abstract PDF(856KB) icon1284 icon1172
Abstract:
To exactly estimate the reliability of reusable rocket engine, a Boolean algebra with restriction on variables was introduced to properly combine fault tree analysis with state analysis, and the reliability analysis of complex multistate system with statistically depent components were performed. Both the multistate of pipes and the statistical dependence between preburner and turbopump of space shuttle main engine (SSME) were deeply studied. The result show that the Boolean algebra can well eliminate statistical dependence among components to simplify the fault tree analysis of complex multistate system, and the statistical dependence has significant influence on the system reliability, so further research is required for higher performance of the reusable rocket engine.
Real-time modeling of propeller in a turboprop engine
DENG Zhi-wei, HUANG Xiang-hua, TIAN Chao
2014, 29(2): 434-440. doi: 10.13224/j.cnki.jasp.2014.02.024
Abstract PDF(1072KB) icon2066 icon1172
Abstract:
Based on strip theory and force analysis on the blade element, calculation equations of propeller drag and power was deduced, and then a real-time mathematical model of propeller was built. It was concluded that resolution of the model was decided by the interfercence angle interation, and the key problems of guaranting real-time calculation lied in the iteration of convergence rate of interference angle. After analysis of iteration function and its derivative, method of setting initial iterative value of interference angle was proposed and secant method was adopted to accelerate the iterative instead of derivation method. Comparison between the experiment data and computational propeller properties of mathematical model showed that,the propeller drag and power deduced from strip theory and force analysis on the blade element has satisfactory precision, and the convergence rate of the interference angle iteration algorithm based on initial iterative value setting and secant method could meet the requirement of real-time simulation of turboprop engine control system.
Turbofan engine gas path performance monitoring based on improved square root unscented Kalman filter
HU Yu, YANG Yue-cheng, ZHANG Shi-ying, SUN Zhen-sheng, ZHU Jie-tang
2014, 29(2): 441-450. doi: 10.13224/j.cnki.jasp.2014.02.025
Abstract PDF(1220KB) icon1659 icon943
Abstract:
An improved spherical simplex square root unscented Kalman filter (ISRUKF) algorithm based on Gaussian process regression (GPR) was investigated to specifically address unknown or inaccurate models problems, resulting in bad or even divergent filtering results in turbofan engine performance monitoring. The transition and measurement GPR models of turbofan engine dynamic systems were established, and used as a substitute for nonlinear model in unscented Kalman filter (UKF). Meantime, the spherical simplex sampling was exploited to decrease the computational complexity, while square root of measurement residuals covariance matrixes was used instead of variance matrixes during recursive arithmetic process to improve the calculation efficiency and numerical stability in ISRUKF algorithm. Using the GPR, the models were firstly trained and verified, thus overcoming dependency on the previous engine models with the abilities of adaptive noise adjustment and high precision. The gradual and rapid deterioration process of different turbofan engine gas path components were then testified and compared by the extended Kalman filter (EKF), SRUKF and ISRUKF. The results show that the precision of ISRUKF has reached 99.9%, demonstrating the effectiveness of the ISRUKF for health parameters monitoring of turbofan engine gas path.
Rapid prototype real-time simulation of turbo-fan engine sensor fault diagnosis
ZHAO Cheng-wei, YE Zhi-feng, WANG Ji-qiang, YIN Bin-bin
2014, 29(2): 451-457. doi: 10.13224/j.cnki.jasp.2014.02.026
Abstract PDF(954KB) icon1876 icon1001
Abstract:
Centered on NI (National Instruments) CompactRIO, a real-time simulation platform with rapid prototyping was built to validate the fault diagnosis approaches for turbo-fan engine sensors rapidly and efficiently. Based on a bank of Kalman filters, an turbo-fan engine sensor fault diagnostics system was developed in LabVIEW environments. Extensive experiments were conducted for the fault detection, isolation and restructuring of individual sensor faults, at both steady state and dynamic conditions. The accuracy of the proposed algorithm was thus verified. Experimental results showed that Kalman filter algorithm could ensure safe operation of engine control system even in the case of sensor failures, the best accuracy of diagnosis reached 1.4%, and the effectiveness of this rapid prototype real-time platform for sensor fault diagnosis was also shown. Consequently, the developed platform could be taken as the foundation for semi-physical tests.
Control strategy for compound coaxial helicopter under conversion mode
WANG Qiang, CHEN Ming, XU Guan-feng
2014, 29(2): 458-466. doi: 10.13224/j.cnki.jasp.2014.02.027
Abstract PDF(1088KB) icon1579 icon926
Abstract:
According to the characteristics of the compound coaxial helicopter,the general aerodynamic forces and moments of rotors,wing,fuselage,stabilator,vertical stabilizers (containing the rudder) and propeller were modeled and a trimming equation set was established accordingly.In view of the controlling redundancy problem,a control strategy was studied for the compound coaxial helicopter under conversion mode,using the linear transition method and minimal power optimization transition method.A sample compound coaxial helicopter was taken as an example to demonstrate the effectiveness of the method.Then the trimming values,the attitude angles and the power of these two methods were compared.The result shows that both the two methods can solve the controlling redundancy problem,while the trimming values and the attitude angles are reasonable and the linear transition method is better in the smooth change of the control values,the difficulty level of the controlling system and the flight quality.
Numerical simulation of viscous flows with adaptively refined Cartesian grid
HAN Yu-qi, GAO Ge
2014, 29(2): 467-474. doi: 10.13224/j.cnki.jasp.2014.02.028
Abstract PDF(1034KB) icon1435 icon906
Abstract:
Quadtree-based Cartesian grid was automatically generated from specified geometry.Adaptive refinements were performed according to geometric parameters and solution of flow field.An altered CCST (curvature corrected symmetry technique) approach was proposed to apply solid wall boundary conditions.Driven flows in a square cavity and flows around NACA0012 airfoil were simulated and compared with the result of published structured grid and stretched Cartesian grid.The results show that solid wall boundary condition are accurately applied by current altered CCST approach,while incompressible/compressible subsonic,transonic and supersonic viscous flows are adequately simulated with adaptively refined Cartesian grid.
Numerical simulation of airfoil flows with a turbulence model
GAO Lin, JIANG Li-jun, CUI Shu-xin, GAO Ge
2014, 29(2): 475-480. doi: 10.13224/j.cnki.jasp.2014.02.029
Abstract PDF(849KB) icon2932 icon1046
Abstract:
Turbulent flows over AS240 and NACA4412 airfoil were simulated numerically using a two-equation turbulence model named k-ξ model. The predictions of velocity profiles and the pressure coefficient of airfoil AS240 at 8°/19° attack angle and NACA4412 at 13.87° attack angle were calculated. The results were compared with those using k-ε and k-ω models,as well as experimental data. It indicates that the new k-ξ model offers more realistic prediction than the other two models. The main finding shows that the new k-ξ model is good at predicting separated flows around airfoils, and it captures the flow feature of pressure-induced separation adequately. All calculations are implemented as per openFOAM 1.7.1(open source field operation and manipulation).

Copyright © 《Journal of Aerospace Power》 All Rights Reserved.

Supported by: Beijing Renhe Information Technology Co., Ltd.