2021 Vol. 36, No. 7

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Qualitative analysis and application validation of compound bowing design in turbine cascade with large turning angle
WANG Songtao, XUE Xingxu, ZHOU Xun, LUO Lei
2021, 36(7): 1345-1355. doi: 10.13224/j.cnki.jasp.20200411
Abstract PDF(2411KB) icon612 icon289
Abstract:
The influence of the compound bowing design was discussed based on theoretical analysis and verified by numerical simulations based on a highly-loaded linear turbine cascade with a large turning angle. The compound bowing design applied local positive bowing design near the endwall region on the suction surface of a negative bowed blade, so the blade presented negative bowed pressure surface and compound bowed suction surface. Generally, the study showed that the compound bowed suction surface could improve the flow field by adjusting the static pressure distribution on suction surface and the deflection of the cross flow. In detail, the negative bowed suction surface could suppress the development of the boundary layer and the shedding vortex near the mid-span, while the positive bowed suction surface could suppress the development of the boundary layer and the Corner Vortex near the endwall. Moreover, the positive bowed suction surface near the endwall could further suppress the passage vortex and the corner vortex by adjusting the deflection of the cross flow and reducing the interaction between the cross flow and boundary layer near the suction surface. As a result, it showed that the compound bowed cascade could lead to a loss coefficient reduction about 65.5% better than the negative bowed one in this study.
Research on transient load for transonic compressor based on dynamic boundaries
LI Shaobin, ZHANG Weiya, YANG Caiqiong, GUO Qiannan
2021, 36(7): 1367-1376. doi: 10.13224/j.cnki.jasp.20210801
Abstract PDF(4086KB) icon421 icon325
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Focusing on the transient state of aviation turbine engines components, a method based on dynamic boundaries and a two-way fluid-structure interaction(FSI) method were used to calculate the acceleration process of the transonic compressor NASA Rotor 67.The curve of the compressor transient process considering the blade deformation was calculated, and the influences of the aeroelastic deformation of the blade on the aerodynamic parameters during the acceleration process and the shock wave structure and evolution process in the flow field were studied.And the deformation distribution of the blade in acceleration process under unsteady aerodynamic load and centrifugal load was also studied.The results showed that: with the increase of the rotational speed, the influence of the blade deformation on the total pressure ratio parameter and the total temperature ratio parameter was more obvious.The structure and evolution of the shock wave in the flow path when considering blade deformation were slightly different with those without blade deformation in the acceleration process of the transonic compressor.The transient load caused the gradual increase of blade deformation during the acceleration process.The blade deformation was mainly concentrated in the upper half of the blade, and mainly caused by centrifugal load, which was dominated by bending deformation, and caused the torsion phenomenon at the leading edge of the tip to cause change of aerodynamic performance.
Control of blade end slot on shock wave/boundary layer interaction of transonic cascade corner
MA Jianci, ZHOU Ling, JI Lucheng
2021, 36(7): 1377-1387. doi: 10.13224/j.cnki.jasp.20200428
Abstract PDF(7240KB) icon415 icon198
Abstract:
A method of using the blade end slot for passive control of the corner separation in a transonic compressor cascade was proposed. Because of the pressure difference between the pressure and suction sides, the blade end slot enables one to induce jet flow into the corner region, thereby restraining the corner separation in transonic cascade. The effect and mechanism of the blade end slot on the performance of the compressor cascade at different incidence angles were investigated numerically. The results demonstrate that, at smaller incidence angle, high-speed jet flow through the blade end slot can destroy the ring vortex in corner region, thereby reducing the corner separation, improving the performance of the cascade; at larger incidence angle, the jet flow can no longer destroy the ring vortex, but still re-energized the low-momentum fluid in the corner region, suppressed the corner separation, and the operation range was extended. The blade end slot reduced the total pressure loss coefficient by 11.6% at 0° incidence angle, and the operation range were increased from 2° to 3°.
Unsteady aerodynamic interactions of contra rotating propeller
YAN Wenhui, TANG Sijia, WANG Fengming, WANG Xuechen, YANG Xiao
2021, 36(7): 1398-1405. doi: 10.13224/j.cnki.jasp.20210051
Abstract PDF(3057KB) icon618 icon279
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In order to optimize the aerodynamic performance of a contra rotating propeller and study the complex unsteady aerodynamic interactions between two propellers of the contra rotating propeller, the unsteady Reynolds-averaged Navier-Stokes (URANS) numerical simulation method and sliding mesh technique were implemented. The three-dimensional unsteady aerodynamic interaction of a 6×6 contra rotating propeller configurations was calculated, which indicated the variation of aerodynamic performance of the contra rotating propeller. Furthermore, the suggestions for optimizing the aerodynamic layout and operation control method were given. The simulation results showed that the fluctuation of the thrust coefficient and power coefficient of the overall contra rotating propeller was about 1.5% and the fluctuation of the propulsion efficiency was about 0.1% due to the unsteady aerodynamic interference at the cruise Mach number 0.38. There were 12 periodic fluctuations in both the front and aft propellers during one rotation. Because the aft propeller of contra rotating propeller can take advantage of the tangential slipstream energy of the front one, it had much higher propulsion efficiency than that of the front propeller, and the efficiency of the overall rotor can be improved too. In addition, according to the distribution of pressure coefficient and axial velocity, the intensity of unsteady aerodynamic interaction was relatively large at 70% of rotor radius.
On-line detection method of flameout in turbofan engine
WANG Yudong
2021, 36(7): 1406-1416. doi: 10.13224/j.cnki.jasp.20200432
Abstract PDF(3679KB) icon602 icon163
Abstract:
The on-board measured parameters including high pressure rotor speed, low pressure rotor speed and engine inlet total pressure were used to establish the flameout on-line detection method based on the corrected change rates of these physical speeds. According to engine states modulations in the whole envelop and engine tests, the amplitude of change rates of high and low pressure rotor speeds in flame out process was 1.5-5.0 times that in deceleration and surge process, the amplitude of change rate of high pressure rotor speed in high pressure shaft fracture process was 6.0-10.0 times that in flameout process, and the amplitude of change rate of low pressure rotor speed in low speed pressure shaft frac-ture process was 2.0-3.5 times that in flameout process. With these properties, the detection method could clearly distinguish flameout process from other transient processes such as deceleration, surge and shaft fracture. Being verified in engine tests, the detection time was 0-0.3s, the detection rate of this method was 100%, and no false or missed detection had been found.
Method on helicopter BVI noise reduction based onmiss-distance control
ZHANG Wei, WANG Fei, ZHAO Qijun
2021, 36(7): 1417-1425. doi: 10.13224/j.cnki.jasp.20200433
Abstract PDF(5084KB) icon451 icon180
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A method for calculating the miss-distance of helicopter rotor was proposed. For the calculation of miss-distance, rotor inflow and tip-path-plane angle were required firstly. The rotor coupled N-S(Navier-Stokes )/free-wake model and rotor trim model of high accuracy and high efficiency were developed respectively. The method was validated using several numerical examples in both hover and forward flight. Applying the developed method, the effect mechanism of longitudinal forces and flight parameters on miss-distance was analyzed. Further, the ground noise radiated from the helicopter rotor was calculated. It demonstrated that the maximum ground noise was reduced by 4dB through the longitudinal forces and acceleration. At the same time, the relationship between miss-distance and flight parameters was studied and some instructive conclusions for low-noise flight were obtained.
Influence of corrugation position on aerodynamic performance of dragonfly gliding airfoils
XU Na, ZHOU Shuaizhi, MOU Xiaolei
2021, 36(7): 1434-1442. doi: 10.13224/j.cnki.jasp.20210039
Abstract PDF(4654KB) icon350 icon129
Abstract:
The aerodynamic performance of airfoil can be optimized by changing the corrugation structure of insect wings, which can benefit the aerodynamic design of micro air vehicles. The gliding aerodynamic performances of three dragonfly-mimic airfoils, with corrugation located at the leading edge, trailing edge and middle position, were studied respectively by using computational fluid dynamics (CFD) method. The gliding angle of attack rose from 0° to 20°, and Reynolds number ranged from 700 to 2300. The results showed that the airfoil with the corrugation located at the trailing edge had the largest lift coefficient and lift-drag ratio at different angles of attack and Reynolds numbers, presenting the best gliding aerodynamic performance; when gliding at the angle of attack of 10° at Reynolds number of 1500, the time-averaged lift coefficient of the airfoil with the corrugation at the trailing edge was 58% and 82% larger than that of the airfoil with the corrugation at the leading edge and middle position, and the lift-drag ratio increased by 49% and 33%, respectively; the vortices in the corrugated trailing edge made the leading edge vortex more concentrated and closer to the wing surface, and delayed the shedding of the leading edge vortex.
Reaction kinetic model of n-propylcyclohexane based on HyChem method
WANG Guangcai, WANG Qianpeng, DING Mengyuan, WANG Juan
2021, 36(7): 1452-1461. doi: 10.13224/j.cnki.jasp.20200417
Abstract PDF(3953KB) icon425 icon126
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The kinetic model of n-propylcyclohexane was studied by using the Hybrid Chemistry (HyChem) modeling method. The pyrolysis of the large fuel molecule to form small products was modeled by the seven-step lumped reaction, while the oxidation of the small products was described by the detailed reaction model USC Mech Ⅱ. The HyChem kinetic model of n-propylcyclohexane consisting of 112 species and 791 elementary reactions was constructed by coupling the two sub-mechanisms, and the experimental data of the flow reactor pyrolysis, ignition delay time and laminar flame speed were used to conduct the model validation. The results showed that this reaction mechanism can accurately predict the product distribution during the pyrolysis of n-propylcyclohexane, and it also had good performance in the prediction of the global combustion parameters, the calculation relative error of ignition delay time was 29.7%, and the calculation relative error of laminar flame speed was 11.1%.
Prediction of hoop mode burst speed of disk considering local stress effect
QUAN Changbiao, MI Dong, LIU Yang, LIAO Mingfu, HU Qingqing
2021, 36(7): 1489-1498. doi: 10.13224/j.cnki.jasp.20200421
Abstract PDF(4367KB) icon467 icon175
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Prediction result of burst speed of a aeroengine disk is usually slight larger than testing result when using the average stress method. The error tends to be much larger especially for the disk with a bolt hole. The average stress method was modified taking consideration of the effect of local stress.A correction factor was implanted to distinguish weight effect of the average hoop stress from that of the local stress of critical position at disk burst speed. Tensile test of standard cylinder and notched specimens of GH4169 and burst speed measurement test of two simulated disks were carried out. Notch strength ratio related to correction factor was calculated. Then the relationship between correction factor and notch strength ratio was obtained. Burst speed of a disk was predicted using these two methods and the burst speed measurement test was conducted. It concluded that the predicted result was larger than test data when using the average stress method with the error of 9.4%. When local stress was taken into consideration, the result was closely approximated to test data with the error of 2.67%. The prediction method of hoop mode burst speed of a disk considering local stress effect was of remarkable engineering practical worth value to its' simple formality and the reliable results.
High temperature behaviors of three coatings on nickel-based superalloy DSM11
LI Yanming, CHI Qingxin, LIU Huan, TONG Wenwei, ZHAO Shiwei, GAO Zhikun
2021, 36(7): 1499-1508. doi: 10.13224/j.cnki.jasp.20200448
Abstract PDF(7580KB) icon606 icon207
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Three coatings (Al-Si coating, Al coating and Co-Al coating) were prepared on the surface of nickel-based superalloy DSM11. The hot corrosion behaviors in the salt of 5%NaCl+95%Na2SO4 (mass fraction) at 900℃ and the fatigue property at 800℃ were investigated. The coatings after corrosion for 200h at 900℃, Al-Si and Co-Al coatings had excellent hot corrosion resistance to further hot corrosion because of a continuous and dense Al2O3 protective layer on the surface. Al coating had poorer hot corrosion resistance for a mixed oxidation layer in the corrosion area, which could not prevent hot corrosion. After fatigue test of the coatings at 800℃, the alloy samples were prone to rapid fracture that a lot of micro cracks appeared on the surface of Al coating. Co-Al and Al coatings showed better high-temperature fatigue performance. In order to select the most suitable protective coating of nickel-based superalloy, service environment and integrated performance should be fully considered.
High-efficiency and accurate dynamical modeling and evaluation method for complex irregular casing
WEI Jing, ZHOU Renhongyi, ZHANG Aiqiang, JIANG Dong
2021, 36(7): 1520-1532. doi: 10.13224/j.cnki.jasp.20200365
Abstract PDF(9093KB) icon406 icon135
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In order to solve the problem of difficult dynamic calculation and post-processing caused by complex irregular casing of large number of model elements and high order of the original matrix, a high-precision dynamic modeling and evaluation method for complex irregular casing based on experimental modal analysis-large-scale finite element-substructure condensation was proposed. Taking the main casing of a helicopter as the research object, the original finite element model of the special-shaped component was established and the validity of the model was verified through modal experiments. By analyzing the retained models of each mode of the substructure, the larger vibration energy space was selected as the condensed node, and then a condensation model with a greatly reduced number of degrees of freedom was obtained. The consistency of each mode before and after the condensation was verified by comparison. A method for measuring the model condensation error based on the correlation coefficient of the sequence was proposed. Finally, by taking the interface displacement compatibility condition into consideration, the substructure coupling was carried out; in addition, the inherent characteristics and computational efficiency of the overall model were compared. The research results showed that the dynamic characteristics of the condensation matrix were very close to the original matrix of the finite element, both the natural frequency and the mode error were less than 4%, the calculation time was shorter and the storage space was less occupied, greatly improving the calculation efficiency.
Optimization and test verification of rocket sled motion calculation algorithm
XIA Youcai, SUN Qihui, XIAO Jun, GENG Qiang, XU Jinxin, MA Jun
2021, 36(7): 1564-1568. doi: 10.13224/j.cnki.jasp.20200462
Abstract PDF(1407KB) icon579 icon138
Abstract:
The dynamic analysis of rocket sled test system was carried out, and the calculation method of rocket sled motion was studied. Based on the conventional algorithm, the calculation method of some parameter was improved, and a new parameter energy dissipation resistance was introduced to obtain the optimization algorithm. Comparing the results of four double-track sled tests with different speeds with the calculation results of the conventional algorithm and the optimized algorithm, it was found that: the minimum error of the conventional algorithm calculation result was 7.67%, the maximum error was 37.91%, and the minimum error of the optimized algorithm calculation result was 0.48%, and the maximum error was 5.0%; comparing the results of four different speed monorail sled tests with the calculation results of the conventional algorithm and the optimized algorithm, it was found that: the minimum error of the conventional algorithm calculation result was 11.78%, and the maximum error was 43.64%, and the calculation result of the optimized algorithm had a minimum error of 0.11% and a maximum error of 5.31%. The results showed that the optimization algorithm of rocket sled calculation can effectively improve the accuracy of calculation results compared with conventional algorithms, and the calculation results have certain engineering guiding significance for rocket sled test design.

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