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为增强基于任意角度压缩感知(CS)叶尖定时信号(BTT)重构的稳定性,采用小生境微种群遗传算法提出了基于小条件数的高稳定性传感器安装布置方法。研究发现:任意角度CS的恢复矩阵条件数越小,不同信噪比下同步和非同步振动信号重构误差越趋于稳定在较低范围,优化后发现条件数为1的排布方案下,相邻传感器角度间隔趋向于均布2m取K的形式。利用条件数为1的矩阵冗余特性,设计了高可靠性的传感器排布方案,数值试验和有限元仿真验证表明叶尖定时系统在失效一个传感器的情况下仍可稳定得到准确的重构结果。在信噪比为5 dB时,冗余排布相比参考排布的主倍频幅值重构误差降低4.4%以上,验证了采用最小条件数排布的任意角度CS信号辨识方法在噪声及传感器失效情况下仍可保证BTT测量结果的有效性和可靠性。 相似文献
173.
为了使高级波束成形中的函数波束成形、压缩感知波束成形、正交波束成形在旋转声源定位中获得广泛应用,对3种高级波束成形在旋转声源定位中的应用进行了研究,从声源空间分辨率,动态范围以及声源功率积分上与传统旋转波束成形和DAMAS(deconvolution approach for the mapping of acoustic sources)反卷积作对比。仿真与实验结果表明:3种高级波束成形均可以应用到旋转声源定位中,并且均能显著提升旋转声源空间分辨率和动态范围以及拥有较高的计算效率。函数波束成形在低频段的空间分辨率低于DAMAS并且容易产生较高的声源功率积分误差。压缩感知波束成形整体性能与DAMAS相近,并且在低频段的空间分辨率比DAMAS有优势。正交波束成形在低频段容易产生声源定位位置误差,抗干扰能力较弱,并且声源功率积分整体低于DAMAS。 相似文献
174.
《中国航空学报》2021,34(7):85-113
Gas turbines have been used extensively for aircraft and marine propulsions as well as land-based power generation because of their high thermal efficiency and large power to weight ratios. To further increase the thermal efficiency, numerous prior researches on gas turbine blade internal cooling have been intensively carried out, majorly under stationary conditions. However, the stationary studies neglect the effects of Coriolis and buoyancy forces, which should change the velocity, turbulence and temperature distribution under rotating conditions. To elucidate the rotational effects on gas turbine internal cooling, the extensive results collected from recent investigations are discussed, which include the rotation and buoyancy effects on the rib turbulated cooling, pin fin cooling, jet impingement cooling, dimple/protrusion cooling, latticework cooling as well as swirl cooling. The rotational effects on the friction factors and the most employed experimental and numerical methods are also presented. Moreover, recommendations for future research are outlined. Therefore, this review article provides extensive literature information for the design of the next-generation high-efficiency internal cooling for rotating turbine blades. 相似文献
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Nonlinear vibration response characteristics of a dual-rotor-bearing system with squeeze film damper
《中国航空学报》2021,34(10):128-147
Rolling bearing and Squeeze Film Damper (SFD) are used in rotor support structures, and most researches on the nonlinear rotor-bearing system are focused on the simple rotor-bearing systems. This work emphasizes the comparative analysis of the influence of SFD on the nonlinear dynamic behavior of the dual-rotor system supported by rolling bearings. Firstly, a reduced dynamic model is established by combining the Finite Element (FE) method and the free-interface method of component mode synthesis. The proposed model is verified by comparing the natural characteristics obtained from an FE model with those from the experiment. Then, the steady-state vibration responses of the system with or without SFD are solved by the numerical integration method. The influences of the ball bearing clearance, unbalance, centralizing spring stiffness and oil film clearance of SFD on the nonlinear steady-state vibration responses of the dual-rotor system are analyzed. Results show that SFD can effectively suppress the amplitude jump of the dual rotor system sustaining two rotors unbalance excitations. As the ball bearing clearance or unbalance increases, the amplitude jump phenomenon becomes more obvious, the resonance hysteresis phenomenon strengthens or weakens, the resonant peaks shift to the left or the right, respectively. SFD with unreasonable parameters will aggravate the system vibration, the smaller the oil film clearance, the better the damping performance of the SFD, the larger the centralizing spring stiffness is, the larger resonance amplitudes are. 相似文献
177.
《中国航空学报》2021,34(9):37-46
SiCp/Al composites are difficult-to-cut materials. In recent years, electrical arc discharge machining has been developed to improve the machinability of these materials. However, there is a big challenge to build a satisfactory heat transfer model of SiCp/Al composites in the arc machining. This is not only because of the material property difference between the reinforcement and matrix material but also because of the micro-dimension SiC reinforcements. This paper established a new heat conduction simulation model considering the SiC particle-Al matrix interface and the phase change effects in a single-pulsed arc discharge of SiCp/Al composites. A novel SiC particle-Al matrix cell geometric model was designed firstly. Then, the temperature distribution at a different depth from the workpiece surface was analyzed, the influence of sic volume fraction on temperature field was studied, and the contribution of the interface thermal resistance and latent heat were explained. To demonstrate the validity of the new numerical model, comparisons and verifications were employed. Finally, the method of improving the model was proposed and the machining mechanism of arc discharge of SiCp/Al matrix materials was discussed. It was found that high temperature is prone to concentrate on the surface layers of the workpiece especially when the SiC fraction is high, also, the temperature fluctuates respectively at the evaporation point of aluminum and SiC, and the SiC-Al resistance has less influence on temperature distribution compared to latent heat, etc. The model build in this work improves the simulation accuracy observably compared to the previous model, and the simulation work will help to acquire a detailed mechanism of material removal of SiCp/Al composites in the arc discharge machining. 相似文献
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高超声速再入钝头体表面热流计算 总被引:1,自引:0,他引:1
采用边界层外缘无黏流场数值求解三维可压缩定常Euler方程,将所得物面压力分布作为边界层外缘条件,用于边界层内跟踪流线的轴对称比拟工程算法,计算高超声速有攻角再入钝头体的表面热流。某钝双锥算例结果表明:算得的表面热流与实验数据吻合很好。该方法较纯工程算法提高了精度,较数值求解整个流场Navi-er-Stokes方程节省计算时间,对准确计算全轨道飞行复杂形状高超声速飞行器表面的热流分布有一定价值,适宜高超声速飞行器方案设计阶段气动热环境预测的需要。 相似文献