2021 Vol. 36, No. 9

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Bearing fault diagnosis based on ARCN model
LIANG Haitao, WANG Ligang, WANG Liang, ZHANG Qingfeng
2021, 36(9): 1793-1803. doi: 10.13224/j.cnki.jasp.20210186
Abstract FullText HTML PDF(1597KB) icon387 icon189
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The attention recurrent and capsule network （ARCN） diagnosis model was proposed by integrating the attention cycle mechanism and capsule network.Firstly，the bidirectional LSTM network was used to extract the time-series characteristic information to construct the primary capsule.Secondly，routing mechanism and attention cycle mechanism were used to construct adaptively digital capsule.The accuracy，robustness，stability and convergence error of ARCN model in bearing fault identification were verified by bearing experiment data of Western Reserve University.The accuracy of ARCN model was 1.2% higher than that of Caps model.The convergence error of the ARCN model reached 0.2.Based on the experimental simulation platform，the vibration signals of normal，inner ring fault，outer ring fault and rolling element fault were collected.The results showed that the misdiagnosis probability of each kind of fault was less than 1% of the total samples under ARCN model.
Test technique for dynamic characteristic of rotor axial force on aero-engine
YUAN Xue, ZHANG Yansong, QIU Daming, CHEN Zhonggang
2021, 36(9): 1804-1810. doi: 10.13224/j.cnki.jasp.20210140
Abstract FullText HTML PDF(2371KB) icon670 icon185
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Taking the axial force of thrust bearing on aero-engine as research object，and based on the measurement principle of stress ring method，a new testing technique applicable to dynamic characteristic of rotor axial force was developed.A stress ring transducer with fan-shaped fulcrum structure was designed on the basis of clamped beam model.The rationality of the special stress ring structure was validated by theoretical analysis and finite element simulation； and the measuring sensitivity and static characteristic index of stress ring transducer were quantified and represented.The trial run results of the aero-engine showed that non-negligible dynamic alternating load existed in rotor axial force，and its peak value accounted for 6%-29% of steady-state value.The results of frequency domain analysis indicated that the vibration source of axial force dynamic alternating quantity consisted of the fundamental frequency of rotating speed and the 2 times frequency of rotating speed，as well as 34，68 Hz.The phase analysis reveals that time domain waveform of stress ring circumference measuring points has phase synchronization change due to the dynamic alternating load caused by 34 Hz and 68 Hz，which met the manifestation of axial vibration，while the fundamental frequency and the 2 times frequency of rotating speed could have precessional motion changes along the stress ring circumference，meeting the manifestation of rotor imbalance failure.
Vibration localization suppression mechanism of mistuned bladed-disk by aperiodic piezoelectric damping
ZHANG Fengling, NIE Jinlong, LI Lin, TIAN Jing, WANG Zhi
2021, 36(9): 1811-1825. doi: 10.13224/j.cnki.jasp.20210133
Abstract FullText HTML PDF(4782KB) icon328 icon184
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An aperiodic piezoelectric damping technology was introduced into the mistuned bladed-disk structure to form an electromechanical coupling system.The dynamic equations of the electromechanical coupling system were derived，and the vibration localization suppression effect of the aperiodic piezoelectric system on the mistuned bladed-disk was theoretically analyzed.Two models of aperiodic piezoelectric system were constructed：the aperiodic piezoelectric shunting model and the aperiodic piezoelectric network model.The results show that，the aperiodic piezoelectric system，which is connected according to the dimensions of energy concentration， has a better effect on the vibration localization suppression effect compared with the dual-periodic piezoelectric network system.In the construction of the aperiodic piezoelectric network system，the resistance is no longer the key factor，and the energy distribution in the whole bladed-disk structure is changed mainly through the circuit form，in which the inductor is very important as an energy storage element.Through the reasonable design of circuit form of the aperiodic piezoelectric network，the vibration localization suppression effect better than the aperiodic piezoelectric shunting system and the dual-periodic piezoelectric network system can be obtained.
Numerical method of flow and heat transfer characteristics of brush seals
LI Hao, SUN Dan, ZHAO Huan, ZHANG Guochen, FENG Yuzhong
2021, 36(9): 1826-1838. doi: 10.13224/j.cnki.jasp.20200446
Abstract FullText HTML PDF(2435KB) icon473 icon171
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Numerical methods for the flow and heat transfer characteristics of brush seals were studied，and the porous media，steady-state solid and transient fluid-solid-heat coupling models of brush seals were established respectively.An experimental device for leakage flow characteristics of brush seals was designed and built.On the basis of verifying the accuracy of the numerical method by experiment，the differences of three numerical methods were compared and analyzed，the flow and heat transfer characteristics of brush seals were studied.The sealing and heat transfer mechanism of brush seals was revealed.The research results showed that：under the working conditions，the error between the leakage calculated by brush seals porous media，steady-state solid and transient fluid-solid-heat coupling model and the experimental values was 9.8%-17.1%，8.1%-10%，6.92%-9.01%，respectively.The calculation speed of brush seals porous media model was faster，but experiment was required for correction of the porosity；the turbulence model had great influence on the flow and heat transfer characteristics of steady-state solid model；the transient fluid-solid-heat coupling model considered the interaction among flow，bristle and frictional heat，and the calculation accuracy was high，but the calculation time was longer.At the same pressure ratio，the temperature of bristle pack gradually increased from upstream to downstream，and the highest temperature of bristle pack increased with the increase of pressure ratio.The main reason for sealing of brush seals was attributable to the throttle effect of air flow through brush wire gap resulting in energy dissipation of leakage air flow，and the convective heat transfer between the leakage gas flow and the brush wire surface was the main form of friction heat dissipation of brush seals.
Dynamic performance of radial magnetic-gas bearing system
WU Yan, XIE Zhenyu, CHEN Licheng, HAO Jiansheng
2021, 36(9): 1839-1850. doi: 10.13224/j.cnki.jasp.20200494
Abstract FullText HTML PDF(2076KB) icon429 icon125
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In order to explore whether the damage caused by rotor drop can be reduced in case of the failure of magnetic bearing，the herringbone groove radial dynamic pressure gas bearing was introduced into the magnetic bearing rotor system，and the influence of the magnetic-gas bearing on the dynamic performance of the system and the support characteristics of the dynamic pressure gas bearing were studied.The finite difference method and small disturbance method were used to solve the film thickness equation and Reynolds equation，and the static and dynamic characteristics of the dynamic pressure gas bearing were studied.The electromagnetic force of the magnetic bearing was analyzed.The incomplete differential PID （proportion integration differentiation） control strategy of the magnetic bearing was used.The theoretical and test modal analysis of the system was performed.The high-speed rotation test of the system was completed.The bearing capacity of dynamic pressure gas bearing under different eccentricity and rotating speed was tested.Results showed that introduction of dynamic pressure gas bearings can improve the dynamic performance of the system.At the moment when the high-speed rotor dropped due to the failure of the magnetic bearing，the eccentricity was close to 1.The two radial dynamic pressure gas bearings can produce larger bearing capacity and reduce the drop caused by the rotor damage.
Experiment of oil droplet impacting on aluminium alloy surface
MA Xingyu, CHEN Bo, ZHOU Chao
2021, 36(9): 1851-1860. doi: 10.13224/j.cnki.jasp.20200495
Abstract FullText HTML PDF(1954KB) icon363 icon179
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The lubrication oil film on the surface of mechanical parts under spray or drip lubrication condition was influenced by the deposited film resulted from the impact of oil droplet with part surface.To understand the complex lubrication phenomena,it is necessary to study the impact behavior of oil droplet with metal solid substrate and the spreading process of deposited film.Therefore,an experimental apparatus was built to investigate the impact outcome of single oil droplet with aluminum alloy surface.High-speed photography was used to capture the oil droplet dynamical morphology and the spreading process of the subsequent film.The oil droplet deformation and the histories of spreading and recoiling of the film were analyzed qualitatively,and the effects of experimental condition and oil viscosity were discussed quantitatively.The experimental results showed that the deposited film spread outwards quickly, recoiled inwards very slowly, and reached eventually steady state.The whole film retraction and oscillation were not observed in the recoiling process.At lower impact angle,the slight slip between oil droplet and surface was found in the initial spreading stage, and due to the effects of gravity and spreading energy,finally,the film disintegrated without ejection of secondary oil droplets.The front spread factor increased with increasing impact velocity and decreasing impact angle,and the back spread factor increased with the increase of impact velocity and impact angle.The effect of oil droplet diameter on the front and back spread factors was insignificant.
Analysis on thermoelasto-hydrodynamic lubrication characteristics of tilting pad thrust bearings under heavy load
FENG Xinkai, YANG Lihua
2021, 36(9): 1861-1870. doi: 10.13224/j.cnki.jasp.20200514
Abstract FullText HTML PDF(2226KB) icon483 icon205
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A thermoelasto-hydrodynamic （TEHD） model of tilting pad thrust bearings was established and solved by Newton-Raphson iterative method.The influences of elastic deformation，thermal deformation and load on the static and dynamic characteristics of oil film were studied.Results showed that the elastic deformation reduced the dynamic pressure effect of the oil film，while the thermal deformation enhanced the dynamic pressure effect of the oil film.With the increase of external load，the influence of thermal deformation on the static and dynamic characteristics of the bearing decreased and the influence of elastic deformation became more significant.Besides，the influence of elastic deformation was more sensitive under heavy load.Considering the significant influences of bearings material compressive resistance and high temperature resistance on the static and dynamic characteristics of tilting pad thrust bearings，study on the stability and safety of thrust bearings can help to optimize thrust bearings design.
Tooth surface 6σ robust optimization desgin under installation error of spiral bevel gear
CHEN Peng, DONG Hongtao, WANG Sanmin, LI Fei, HE Qianjin, LI Yizhi
2021, 36(9): 1871-1879. doi: 10.13224/j.cnki.jasp.20200506
Abstract FullText HTML PDF(1396KB) icon428 icon187
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Due to the installation error in the transmission of aviation spiral bevel gears，its uncertainty had a great impact on the noise and robustness of the gear transmission.Monte Carlo simulation was used to describe the sampling method and the multi-island genetic algorithm for spiral bevel gears.The design of the second-order contact parameters was combined with the local synthesis method and the 6σ analysis method to form a robust optimization design method.And a robust optimization design not sensitive to installation errors was developed.The results showed that，under a given working condition， the robustness of the uncertainty of installation error in gear transmission can be improved to more than 99.9% by reasonably presetting the value and tolerance of second-order contact parameters，the sensitivity of contact mark and transmission error can be effectively reduced by more than 30%，and the contact performance of spiral bevel gear transmission can thus be improved.The feasibility of the robust design method for spiral bevel gears based on the 6σ robust optimization design technique in the article was verified.
Research for online detection of aerodynamic instability while aero-engine test
PENG Shenghong, LIU Zhiyou, ZHANG Zhilin, ZHONG Ming, TIAN Yingwei, CHENG Xi
2021, 36(9): 1880-1886. doi: 10.13224/j.cnki.jasp.20210106
Abstract FullText HTML PDF(1153KB) icon491 icon110
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Based on the technological problem for lack of effective safety monitoring measures,the research for online detection of engine aerodynamic instability during aero-engine test was carried out.By analyzing engine instability characteristic data, the aerodynamic instability identification algorithm was designed based on time-frequency and wavelet analysis,and the online detection system of engine aerodynamic instability with one's own domestic intellectual property right was was developed.Result showed that the system can accurately and timely detect the engine aerodynamic instability characteristic signal, including excellent features such as,identification system response time was less 50 ms,and the project practicability was high.The research demonstrated the ability of online early warning to the engine test aerodynamic instability.
Timing optimization for intake and exhaust of an aircraft piston engine
CUI Huasheng, LI Binshi, ZHAO Zhenfeng, FENG Yishuo
2021, 36(9): 1887-1893. doi: 10.13224/j.cnki.jasp.20200503
Abstract FullText HTML PDF(1260KB) icon554 icon106
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A genetic algorithm optimization method based on simulation was used to study the valve timing optimization of a certain type of spark-ignited aircraft piston engine.By coupling engine performance model and modeFrontier software，the intake and exhaust timing，intake and exhaust duration were optimized to achieve better engine performance.The analysis results showed that the engine power increased by 7.3% and the fuel consumption rate reduced by 2.5% under cruising condition.The optimized intake and exhaust timing can also improve engine performance under 100% throttle opening，which can reduce taxiing distance of the aircraft equipped with the engine.
Transonic flow characteristics of supercritical airfoil in heavy gas medium
ZHA Jun, ZENG Kaichun, KOU Xiping, YANG Xinghua, ZHANG Huizhuo
2021, 36(9): 1894-1905. doi: 10.13224/j.cnki.jasp.20200490
Abstract FullText HTML PDF(3009KB) icon396 icon148
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The Peng-Robinson non-ideal gas state equation was used to simulate the thermodynamic characteristics of the heavy gas medium，and to form a closed flow model for heavy gas medium by combining with the Reynolds average Navier-Stokes equations.The LU-SGS （lower-upper symmetric Gauss-Seidel） implicit time-marching scheme and the finite volume method were used to simulate the flow over a supercritical airfoil in air and heavy gas medium respectively.Numerical results showed that the lift and drag of supercritical airfoil increased，the surface negative pressure in supersonic region increased，the displacement thickness of boundary layer decreased，the shock wave moved backward，the skin friction increased significantly，and the trailing edge flow separation delayed under transonic conditions.This study provides a basic support for the subsequent research on flutter characteristics of aircrafts in heavy gas medium and the development of correction methods.
Numerical investigation on thrust reverse flow field of podded engines on blended wing body
QIU Aoxiang, SANG Weimin, XIE Ruixuan
2021, 36(9): 1906-1916. doi: 10.13224/j.cnki.jasp.20200508
Abstract FullText HTML PDF(2952KB) icon447 icon124
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Reverse thrust is an efficient deceleration braking method to shorten the taxiing distance.Based on RANS （Reynolds averaged Navier-Stokes） method，SST （shear stress transport） turbulence model and inlet/exhaust boundary conditions were used to simulate the flow field around the thrust reverser.The variation law of aerodynamic load under the influence of the thrust reverser was explored，the drag increasing effect of the thrust reverser under different engine power was evaluated，and the distortion characteristics of the inlet flow field were preliminarily analyzed.The results showed that the thrust reverser flow can significantly affect the distribution of aerodynamic load，and the surface pressure in front of the engine increased gradually.Behind the thrust reverser flow belt，the surface pressure decreased sharply，and the influence weakened along spanwise direction.In a certain range，the larger axial deflection angle of the thrust reverser flow indicated the stronger influence of thrust reverser flow on the distribution of aerodynamic load，and the better drag increasing effect.The distortion characteristics of the inlet flow field would be affected by the changes of the axial deflection angle of reverse flow and the Mach number of freestream.
Analysis of n-dodecane spray jet by proper orthogonal decomposition
QIN Wenjin, XU Lihui, LU Dengbiao, LIU Hao
2021, 36(9): 1917-1923. doi: 10.13224/j.cnki.jasp.20200500
Abstract FullText HTML PDF(1180KB) icon350 icon191
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Large eddy simulation was used to calculate the cold spray phenomenon of single component alternative fuel n-dodecane for aviation kerosene，and to explore the coupling phenomenon of multiple physical fields in spray jets.The process of fuel breaking，evaporation and oil-gas mixing was analyzed from the macro level，and it was found that the flow field vortices played an important role in the process.The data base of mass fraction field and vorticity field of n-dodecane jet flow was processed by the proper orthogonal decomposition，and the relationship between them was explored from the micro level.The results showed that there was a significant spatial distribution correlation between the n-dodecane mass fraction field spray structure and the jet flow vorticity field vortex structure，reflecting that the evolution of two structures had important correlation characteristics.The turbulence fluctuation resulted in the change of the vortex scale，which affected the breakup and evaporation of the fuel，and finally changed the distribution morphologies of different scale structures of spray.
Effect of fuel nozzle position on pollutant generation performance of combustor
LIU Aiguo, LI Haoran, CHEN Xuanren, YU Haoyang, MAO Xiaodong, HU Jian
2021, 36(9): 1924-1931. doi: 10.13224/j.cnki.jasp.20200507
Abstract FullText HTML PDF(1251KB) icon367 icon98
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A dry-type low emission （DLE） micro gas turbine combustor with medium and low calorific value biomass gas was studied.The experimental test and numerical simulation of pollutant generation characteristics at different positions of fuel nozzle were carried out.The influences of nozzle position on fuel air mixing uniformity and NOx generation characteristics were obtained.The results showed that：adjusting the fuel distribution ratio and the position of the fuel nozzle can affect the emission characteristics of the combustion chamber，and there was a fuel distribution ratio that made the NOx emission the lowest；the uniformity of the fuel and air mixture was the main factor affecting the NOx generation；NOx was mainly produced in the duty combustion area，and the NOx mass concentration can be reduced to 7.6 mg/m3 by adjusting the fuel distribution ratio and the position of the fuel nozzle.
Effect of lean blowout performance of trapped vortex combustor of the afterburner
TAN Yunchuan, ZHONG Huagui, SUN Ruili, SUN Haitao
2021, 36(9): 1932-1941. doi: 10.13224/j.cnki.jasp.20210121
Abstract FullText HTML PDF(2426KB) icon412 icon142
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Three different schemes of cavity structure were designed to study the lean blowout （LBO） performance by test research method.Aviation kerosene was employed as fuel.In all operating conditions，the inlet pressure ratio of out and inner bypass varied from 0.97-1.07 and the mainstream Mach number ranged from 0.13-0.20.It was revealed that the fuel air ratio of lean blowout increased with the increasing inlet pressure ratio of out and inner bypass.LBO also increased with the increasing mainstream Mach number，and when the mainstream Mach number was larger，the increase was larger.In upper region of the vortex，the axial average of absolute velocity decreased，and the positon of the main vortex center was closer to the after wall of the cavity within a certain range，and the lean blowout performance of trapped vortex combustor of the afterburner was excellent.
Numerical simulation of internal flow field in gas generator of fire extinguishing bomb
LI Yunfeng, DENG Kangqing, LU Ruihua, QIN Peiwen, GUO Chunliang, YAN Lifan, HUANG Changlong
2021, 36(9): 1942-1950. doi: 10.13224/j.cnki.jasp.20200385
Abstract FullText HTML PDF(1703KB) icon472 icon219
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In order to improve the fire-fighting performance and optimize the structure design of fire extinguishing bombs，Fluent was used to simulate the flow field in the gas generator of fire extinguishing bombs，and the flow field distribution in the bomb was adjusted by changing the opening of the gas generator and the parameters of the propellant.The calculation results showed that when the first hole distance was equal to 15 times the gas generator exhaust hole diameter，there were 5 pressure peaks of similar size and higher value on the near wall surface of the fire extinguishing bomb shell，and the pressure distribution was most conducive to the rupture of the prefabricated hole slot of the fire extinguishing bomb shell；the stronger symmetry of the exhaust holes on the gas generator in the fire extinguishing bomb indicated more uniform pressure distribution in the generator.The experimental verification showed that the pressure-time curve obtained by the simulation was in good agreement with the measured data，indicating that the model is suitable for simulation of the internal flow field of the fire extinguishing bomb.
Mechanism of high frequency combustion instability control by pulsed discharge plasma in rocket engine
ZHOU Siyin, NIE Wansheng, BAO Heng
2021, 36(9): 1951-1961. doi: 10.13224/j.cnki.jasp.20210250
Abstract FullText HTML PDF(1916KB) icon380 icon176
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To explore the effect of plasma on high frequency combustion instability of rocket engine，a control scheme of pulsed quasi-direct current discharge plasmas was provided.The effects of pulsed discharge plasmas on average parameters and dynamic characteristics of combustor flow field were all numerically studied.Results showed that compared with the steady actuating way，the average temperature and pressure both decreased under the pulsed actuating way，yet the effect of plasma on the whole combustor can be ignored.Similar to that of steady actuating way，the plasma could depress the high frequency pressure oscillation within a certain time.However，the depression effect of pulsed discharge plasma was better than steady actuating way when suitable actuating parameters were adopted.According to the power spectral density plots，the characteristic dominant frequencies of combustor pressure oscillation were mainly determined by both the combustor intrinsic acoustic frequencies and the actuating frequencies for the pulsed actuating way.The power spectral density amplitude of dominant frequency decreased as the actuating frequency increased.The coupling charateristics of combustor pressure and heat release was not altered by the plasma.However，through decreasing the heat release rate，the pressure oscillating amplitude can be reduced，indicating that the pulsed discharge plasma can be used for depressing high frequency combustion instability.A pulsed actuating scheme with an actuating frequency of 50 kHz and a duty cycle of 20% can achieve the best control effect among the studied conditions.
Analysis of Mars exploration mission based on gas-dynamic-mirror fusion thruster
SONG Jun, ZHANG Chen, YANG Wenjie, ZENG Qiusun, CHEN Zhibin
2021, 36(9): 1962-1973. doi: 10.13224/j.cnki.jasp.20200510
Abstract FullText HTML PDF(1663KB) icon368 icon126
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The gas-dynamic-mirror based fusion concept was expanded into space propulsion applications to analyze the range of specific impulse and thrust under different plasma density and hydrogen propellant mass flow rates.The theoretical calculation showed that the highest specific impulse can be above 10 000 s，and thrust up to dozens of Newton.On this basis，the fusion thruster based on the gas dynamic mirror was further used to simulate the Mars exploration mission.Assuming the initial mass of the thruster was 100 t，the simulation results showed that the residual mass increased from 88.59 to 98.24 t when the mission flight time varied from 282.42 to 639.76 d.The analysis showed that the fusion space thruster based on the gas dynamic mirror can well meet the requirements of future manned and cargo Mars missions by adjusting the specific impulse and thrust，making it an option for the development of high-performance space thrusters in the future.
Curing characteristics of phenolic and epoxy transition layer and properties of composites
YANG Xiao, LI Yong, HUAN Dajun, LIU Hongquan, LI Lisha, CHEN Xiaodong
2021, 36(9): 1974-1985. doi: 10.13224/j.cnki.jasp.20200498
Abstract FullText HTML PDF(2382KB) icon520 icon107
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In order to meet the requirements of structural and functional integration of composite shell of solid rocket motor，the formula，process and performance of the transition layer of the two resins were studied.The performance characteristics of the transition layer content distribution in the system of phenolic resin B30，epoxy resin TDE-85 and curing agent methylhexahydrophthalic anhydride （MHHPA） were mainly studied.The digital display rotary viscometer and digital display constant temperature water bath were used to measure the viscosity of the resin，and differential scanning calorimetry （DSC） was used for thermal analysis of the resin with gradient content.The kinetic parameters of the mechanism of multiphase reaction system were solved.The curing process and properties of the resin with transition layer were verified.The properties of the resin with transition layer were compared with those of the resin without transition layer.The results showed that：in the transition layer system，B30 and curing agent MHHPA reacted first，followed by B30 self-curing；the mechanical properties of epoxy resin TDE-85 and phenolic resin B30 met the performance requirements of structural layer and functional layer；compared with the resin without transition layer，the ablation resistance of the resin with transition layer had little change，but the bending strength increased by 67.8%，and the tensile strength increased by 56.1%；compared with the composite without transition layer，the interlaminar shear strength of the composite with transition layer increased by 94.9%，but the ablation resistance changed little.In conclusion，the transition layer can meet the structural and functional integration requirements of composite shell of solid rocket motor.
Adjoint-based aerodynamic design optimization of transonic turbine cascades considering different constraints
LI Jiaxing, LUO Jiaqi, CAO Zhiyuan
2021, 36(9): 1986-1998. doi: 10.13224/j.cnki.jasp.20200468
Abstract FullText HTML PDF(1905KB) icon495 icon205
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A simplified method based on non-reflecting boundary theory for determining the inlet and outlet boundary conditions of adjoint equations was introduced，by which the aerodynamic design optimization of turbomachinery blade considering different constraints was investigated.The results showed that the simplified adjoint equations strongly coupling with flow under inlet and outlet boundary conditions were sufficiently accurate and applicable in different constrained optimization design.After outlet specific entropy design optimization without constraints，the outlet specific entropy decreased by 0.253%，with varied passage area and outlet flow angle.Considering the constraints of outlet flow angle and passage area separately and the constraints from both of them，the outlet specific entropy after optimization decreased by 0.176%，0.227% and 0.164%，respectively.The aerodynamic performance of the optimized blades was significantly improved，while the optimization constraints were maintained.Moreover，the results demonstrated that changing the curvature of blade profile weakened the shock wave effectively.When the curvature of front portions decreased，the flow velocity decelerated and the outlet flow angle increased，meanwhile when the curvature of front portions changed slightly，the outlet flow angle was constrained better.
Impacts of non-axisymmetric stagger angle on performance of compressor rotor blade
ZHUANG Haowan, TENG Jinfang, MA Yuchen, ZHU Mingmin, QIANG Xiaoqing
2021, 36(9): 1999-2011. doi: 10.13224/j.cnki.jasp.20200489
Abstract FullText HTML PDF(2450KB) icon560 icon154
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In order to provide a reference for engineering design and manufacture of high pressure compressor blades at all operating conditions，steady and unsteady numerical simulations on multiple single-passage and eight-passage cases were conducted，and the impacts of non-axisymmetric stagger angle distribution on compressor performance were investigated at the design and off-design operating points.The results showed that the performance parameters of non-axisymmetric stagger angle cases were all lower than those of the uniform stagger angle cases，and the scatter range of the mass flow rate was wider at the near choking point.Non-axisymmetric stagger angle distribution made the pressure coefficients on the blade surface vary more greatly，which led to obvious decrease of the rotor efficiency.In the typical case with a small average deviation and a large standard deviation of the non-axisymmetric stagger angle distribution，because a blade among the passages greatly deviated from the stagger angle of the original blade，flow separation occurred within the range of 48%-82% blade span at the large flow rate condition，which decreased the outlet flow angle and efficiency.At the near stall point，compared with the original case，the corner separation at the hub of the typical case increased obviously.The diffusion factor at 10% blade span was 0.72% higher than the original high-loading design，which led to a decrease in the stall margin.
Optimal control of thrust for turboprop with engine and propeller integration during takeoff
TIAN Feilong, DING Hongshuai, ZHENG Hongliang, ZHAN Luoji
2021, 36(9): 2012-2016. doi: 10.13224/j.cnki.jasp.20210804
Abstract FullText HTML PDF(940KB) icon517 icon137
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An engine and propeller integrated control architecture was proposed for turboprop engine rapid response during takeoff.Throttle lever was used to schedule the fuel control loop and pitch control loop for fast system response.A optimal control strategy for thrust was developed at the very beginning of the takeoff in order to maximize thrust according to the property of propeller.Air speed was selected to schedule the maximum effective power to improve thrust response during takeoff.The simulated result showed that the thrust increased by 2.59% in average during takeoff，and the time accelerated to takeoff was less than 2.5 s by the proposed optimal takeoff thrust control strategy and integrated control architecture.The system dynamic response was enhanced effectively by the designed method.

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