叶顶间隙对非定常激振力及下游静子振动影响

Effects of Tip-Clearance on Unsteady Exciting Force and Down-Stream Stator Vibration

关键词:  叶顶间隙  非定常流动  气动激振力  振动  快速傅里叶变换

Key words:  Tip-clearance  Unsteady flow  Aerodynamic exciting force  Vibration  Fast fourier transform

摘要:

压气机叶片叶顶间隙会产生泄漏流，对非定常流动及下游静子会产生一定影响。为研究不同叶顶间隙下非定常气流激振力以及静子叶片振动响应，对不同叶顶间隙下单级压气机的非定常流动进行计算。随后分析非定常结果的流动特性。再利用快速傅里叶变换对静子表面的非定常激振力进行频谱分析，并将按不同频率分阶的载荷加载到静叶上以求解振动响应。非定常结果表明随叶顶间隙增大，效率和压比与之呈线性递减关系，叶片表面时间平均的压力也随之降低。而激振力的频域结果表明，激振力主要频率与叶片通过频率接近，且一阶激振力效应最大。振动响应结果显示随叶顶间隙增加，振动幅值有所降低，但在20% ~ 40%叶高处有非线性现象，位移波谷有轻微下降。且前三阶响应结果接近静叶第3阶，第8阶和第17阶模态振型，频率相差为10%左右。

Abstract:

Tip clearance of compressor blade will produce leakage flow， which can have a certain impact on unsteady flow and downstream stator. In order to study the unsteady flow excitation force and the vibration response of stator blades under different blade tip-clearances， the unsteady flow of single - stage compressor under different blade clearance is calculated. The flow characteristics of the unsteady results are then analyzed. After that， the unsteady exciting force of the stator surface is analyzed by fast Fourier transform， and the load is applied to the stator by frequency to solve the vibration response. Unsteady flow results indicate that as the tip clearance increase， the efficiency and the pressure ratio are linearly decreasing. In addition， the time average pressure on the surface also decreases. The frequency domain of the excitation force shows that the main frequency of the excitation force is close to the frequency of the blade passing frequency， and the first-order exciting force effect is the largest. And the results of vibration response show that the amplitude of the vibration decreases with the increase of the blade tip-clearance， but at 20% ~ 40% leaf height， there is a nonlinear phenomenon， the displacement has a slight decline. The first three order response results are close to the modal shapes of 3rd， 8th and 17th order， and the frequency difference is about 10%.