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Xu R.,Shenyang Aerospace University | Zhang N.,Shenyang Aerospace University | Niu L.,Shenyang Aerospace University | Yang M.,Shenyang Liming Aerospace Engine Group Co.
Applied Mechanics and Materials | Year: 2012

In order to study heat transfer process in APU compartment of passenger plane and to perform structure thermal analysis, temperature field of APU compartment has been calculated by numerical computation. The computation model of flow and heat transfer process in APU compartment are setup by commercial CFD software Fluent, Realizable k-ε turbulent model and S2S thermal radiation model are used, and the flow field, temperature and heat flow information are acquired. Radiation heat transfer is the major heat transfer process in APU compartment; APU fireproofing cover and heat insulation hood of exhaust pipe function work as radiation heat shielding screens; and cooling air in the APU fireproofing cover plays an important part in decreasing the temperature of the fireproofing cover; the injection cooling air in the exhaust pipe reduced the wall temperature effectively. The results provide reference to optimization design. © (2012) Trans Tech Publications, Switzerland.

Zhang J.,Shenyang Liming Aerospace Engine Group Co. | Wang Y.,Sino Aerospace Power Shenayng Precision Technology Co.
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2016

It is necessary to perform surface fine grain treatment on investment casting K417G alloy low pressure turbine blade, however, excessive corrosion can be easily observed in the alloy during grain degree inspection. Effects of FeCl3, CuSO4 corrosion agent on surface and properties of the K417G alloy blade were analyzed. The results reveal that with CuSO4 containing corrosion agent, carbide at grain boundary of the alloy can be flaked to lead to damage the grain boundary. Stress rupture testing at 950℃ and 235 MPa reveals that effects of corrosion on stress rupture of the alloy can be ignored for 5 min, while it is deteriorated sharply for 20 min. With FeCl3 containing corrosion agent, the flake of carbide at grain boundary of the alloy blade is absent. The stress rupture testing at 950℃ and 235 MPa reveals that effects of corrosion on stress rupture of the alloy blade can be ignored for 5 min and 20 min, while it is decreased greatly for 40 min, which is attributed to the increase of shrinkage porosity in dendrite of the alloy with increasing in corrosion time. The FeCl3 containing corrosion agent was adopted to inspect the grain degree of the turbine blade. © 2016, Journal Office of Special Casting and Nonferrous Alloys. All right reserved.

Hong Z.,Beihang University | Hong Z.,Shenyang Liming Aerospace Engine Group Co. | Gao G.,Shenyang Liming Aerospace Engine Group Co. | Jing X.,Beihang University | Sun X.,Beihang University
Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica | Year: 2015

A grid-less time domain method for predicting trailing edge noise radiated from a two-dimensional flat plate is established in the present study, which is based on the discrete vortex method and vortex sound theory. The trailing edge noise is calculated in a decoupling manner. Firstly, the shear layer shed from the plate trailing edge is simulated through a discrete vortex method, and the key parameters of the vortices are obtained, including the strengths, positions and velocities. Then, a sound radiation model of the vortices in the free space is deduced in the frame of the vortex sound theory. Besides, to account for the influence of the plate surface, a time domain boundary element method is introduced. After that, the sound pressure distribution and the far field directivity radiated from the trailing edge vortices are analyzed. The present results indicate that the vortex clouds rolled up by point vortices are typically dipole sources, and the scattering effect from the plate surface can not only enhance the sound pressure level but also lead the maximum sound pressure to propagate in the vertical direction to the surface. This grid-less model depicted here simulates the flow and sound field simultaneously, which can help to improve the basic understanding on the trailing edge noise radiation and provide a reliable method for noise investigation with engineering importance as well. © 2015, Press of Chinese Journal of Aeronautics. All right reserved.

Wang X.,Aerospace Research Institute of Materials And Processing Technology | Li S.Q.,Aerospace Research Institute of Materials And Processing Technology | Yang Q.,Shenyang Liming Aerospace Engine Group Co. | Teng B.Q.,Shenyang Aerospace engine Design Institute | And 3 more authors.
Materials Science Forum | Year: 2015

Single shot peening (SSP) with cast-iron shot and double shot peening (DSP) with cast-iron shot and ceramic shot were applied to investigate the relationship between surface integrity status and the fatigue property of titanium alloy TC4 on the notched specimens (stress concentration coefficient Kt=1.7). Surface roughness, residual stress profile and fatigue curve of the notched specimens were tested using scanning profilometer, XRD residual stress tester and rotating-bending fatigue testing machine, respectively. The results showed that surface roughness decreased 18.3% from Ra 1.09 μm post SSP to Ra 0.89 μm after DSP. Moreover, the position of the maximum value of residual stress migrated out close to the surface and the value of surface residual stress raised 12.6% to -800MPa from SSP. Additionally, the fatigue limit of the notched specimens pose SSP increased 64.7% to 467MPa from 283 MPa of AM, furthermore, edged up by 8% from 432MPa on unpeened smooth samples. It may be concluded that the double shot peening on titanium alloy has, therefore, eliminated the weakness of fatigue property caused by stress concentration. © (2015) Trans Tech Publications, Switzerland.

Hong Z.,Beihang University | Hong Z.,Shenyang Liming Aerospace Engine Group Co. | Dai X.,Beihang University | Zhou N.,Shenyang Liming Aerospace Engine Group Co. | And 2 more authors.
Journal of Sound and Vibration | Year: 2014

When a Helmholtz resonator is exposed to grazing flow, an unstable shear layer at the opening can cause the occurrence of acoustic resonance under appropriate conditions. In this paper, in order to suppress the flow-induced resonance, the effects of inside acoustic liners placed on the side wall or the bottom of a Helmholtz resonator are investigated. Based on the one-dimensional sound propagation theory, the time domain impedance model of a Helmholtz resonator with inside acoustic liner is derived, and then combined with a discrete vortex model the resonant behavior of the resonator under grazing flow is simulated. Besides, an experiment is conducted to validate the present model, showing significant reduction of the peak sound pressure level achieved by the use of the side-wall liners. And the simulation results match reasonably well with the experimental data. The present results reveal that the inside acoustic liner can not only absorb the resonant sound pressure, but also suppress the fluctuation motion of the shear layer over the opening of the resonator. In all, the impact of the acoustic liners is to dampen the instability of the flow-acoustic coupled system. This demonstrates that it is a convenient and effective method for suppressing Helmholtz resonance by using inside acoustic liner. © 2014 Elsevier Ltd.

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