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为提高旋翼非定常气动弹性载荷的分析精度,在刚性旋翼计算流体力学(CFD)方法中引入计算结构动力学(CSD)方法,建立了一套适合于新型桨尖旋翼气动弹性载荷分析的CFD/CSD耦合方法。旋翼流场分析采用NavierStokes/Euler方程作为控制方程,围绕旋翼生成运动嵌套网格。在流场求解中,采用双时间法推进,通量计算采用Jameson中心格式,并采用B-L(Baldwin-Lomax)湍流模型。基于Hamilton变分原理和中等变形梁理论开展桨叶弹性运动变形分析,并发展了一套具有任意转角梁单元的新方法以提高新型桨尖旋翼的动力学分析精度。采用基于代数变换方法的网格变形策略,建立了一套CFD/CSD松耦合方法,桨叶运动变形和旋翼气动力信息通过流固交接面传递。首先分别对CSD和CFD模块进行了验证,然后计算了UH-60A旋翼在高速前飞状态下的气动弹性载荷,并与试验值进行了对比,最后重点对旋翼桨尖形状进行了参数分析。计算结果表明,相比于升力线理论和刚性旋翼CFD方法,CFD/CSD耦合方法可以显著提高旋翼非定常气动弹性载荷的分析精度,并能更准确地反映新型桨尖旋翼的气动弹性耦合效应;同时采用后掠桨尖在桨叶前行侧30°~90°方位角范围可以显著降低激波强度,有利于改善旋翼的气动特性。
In order to improve the analytical precision of rotor unsteady aerodynamic elastic loads, a computational structural dynamics (CSD) method is introduced into the rigid rotor computational fluid dynamics (CFD) method and a set of CFD / CSD coupling method. Rotor flow field analysis using NavierStokes / Euler equations as the governing equations around the rotor to generate a motion nested grid. In the solution of the flow field, a dual-time method is used. The flux calculation uses the Jameson center format and the B-L (Baldwin-Lomax) turbulence model. Based on the Hamilton variational principle and the medium deformation beam theory, the elastic deformation of the blade is analyzed. A new method with arbitrary angle beam elements is developed to improve the dynamic analysis accuracy of the new type of blade rotor. A mesh deformation method based on algebraic transformation was used to establish a CFD / CSD loose coupling method. The blade motion deformation and rotor aerodynamic information were transmitted through the fluid-solid interface. First of all, the CSD and CFD modules were verified respectively. Then the aerodynamic elastic load of the UH-60A rotor at high-speed forward flight was calculated and compared with the experimental values. Finally, the rotor tip shape was analyzed emphatically. The calculated results show that the CFD / CSD coupling method can significantly improve the analytical accuracy of unsteady aerodynamic elastic loads and can more accurately reflect the aerodynamic elastic coupling effect of the rotor blades than the lift-line theory and the rigid rotor CFD method. At the same time, using the swept tip in the azimuth range of 30 ° ~ 90 ° in front of the blade can significantly reduce the shock intensity and improve the aerodynamic characteristics of the rotor.