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311.
《中国航空学报》2023,36(5):187-201
The adaptive feedback control of stability with circumferential inlet distortion has been experimentally investigated in a low-speed, axial compressor. The flat-baffles with different span heights are used to simulate different distorted inflow cases. Compared with auto-correlation and root-mean-square analysis, cross-correlation analysis used to predict early stall warning does not depend on the distortion position. Hence, the cross-correlation coefficient was used to monitor the stable status of the compressor and provide the feedback signal in the active control strategy when suffering from different distortions. Based on the stall margin improvement of tip air injection obtained under different distorted inflow cases and the sensitivity analysis of cross-correlation coefficients to injected momentum ratios, tip air injection was adopted as the actuator for adaptive feedback control. The digital signal processing controller was designed and applied to achieve adaptive feedback control in distorted inflow conditions. The results show that the adaptive feedback control of air injection nearly achieves the same stall margin improvement as steady air injection under different distortion intensities with a reduced injection mass flow. Thus, the proposed adaptive feedback control method is ideal for the engine operation with circumferential distorted inflow, which frequently occurs in flight. 相似文献
312.
《中国航空学报》2023,36(7):412-419
The ionic-wind-powered Micro Air Vehicles (MAVs) can achieve a higher thrust-to-weight ratio than other MAVs. However, this kind of MAV has not yet achieved controlled flight because of the unstable thrust produced by the ionic wind and the dynamic instability related to the small size. In this paper, a passive attitude stabilization method of the ionic-wind-powered MAV using air dampers is introduced. The key factors that influence the performance of the air dampers, including the layout, position, and area of the air dampers, are theoretically studied. The appropriate optimal position of the air dampers is also obtained by Monte Carlo stochastic simulations. Then the proposed passive attitude stabilization method is applied to the ionic-wind-powered MAVs of different wingspan (2 cm and 6.3 cm). Finally, the experimental results show that using the proposed method, attitude stabilization is achieved for the first time for the ionic-wind-powered MAV. Moreover, the altitude control of an ionic-wind-powered MAV with a wingspan of 6.3 cm is also demonstrated. 相似文献
313.
Honeycomb seals are a crucial component to restrict the leakage flow and improve system stability for the turbomachines and aero-engines. In this work, the leakage and rotordynamic performance of honeycomb seals with the Swirl-Reverse Ring(SRR) is predicted by employing the approach of Computational Fluid Dynamics(CFD) and the multifrequency whirling model theory.Numerical results show that the positive preswirl flow and circumferential velocity can be effectively weakened for the honeycomb seal... 相似文献
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针对典型跨声速压气机转子,采用非定常数值模拟方法研究了叶片掠设计和机匣处理的组合作用对压气机转子性能的综合影响。分别探讨了转子前掠、后掠和掠叶片与机匣处理组合等形式对转子峰值效率和稳定工作裕度的影响效果和内在机制。研究发现,前掠转子与机匣处理组合能够以较小的效率损失(-0.56%)为代价获得最佳的扩稳效果;在前掠转子与机匣处理组合作用下,对间隙泄漏流的动量激励和叶顶低能堵塞流体的有效消除是组合机匣处理扩稳的本质原因。结果表明,采取前掠转子和机匣处理的组合形式,可以弥补前掠转子设计损失转子最大负荷的不足,同时以较少的效率损失代价充分发挥了机匣处理的扩稳潜力。 相似文献