基于一套高效通用的多层运动嵌套网格技术,建立了适合悬停状态倾转旋翼机旋翼/机翼气动干扰特性分析的高效混合计算流体力学(CFD)方法.在倾转旋翼/机翼贴体网格区采用可压雷诺平均Navier-Stokes(RANS)方程作为主控方程,过渡/背景网格区选用Euler方程,湍流模型选用Spalart-Allmaras模型.时间推进上采用双时间推进格式进行非定常求解,并在方法中运用了SPMD(Single Program Multiple Data)模式的并行加速技术.在此基础上,首先分别采用UH-60A直升机旋翼及XV-15倾转旋翼机旋翼作为数值算例,验证了CFD方法的有效性.然后着重对倾转旋翼/机翼的非定常干扰流场及气动力分布特征进行了数值研究,模拟得到与实际情况相符的“喷泉效应”干扰现象.计算结果表明,干扰作用使得倾转旋翼相对于孤立旋翼拉力数值减小了3%,但总的拉力系数损失达到了17%,证明悬停状态下气动干扰对飞行器气动性能有重要影响.
Based on the multi-layer moving-embedded grid technique,an efficient hybrid computational fluid dynamics (CFD) method is developed to analyze the aerodynamic interaction characteristics of the tiltrotor and wing in hover.A highly-efficient multi-layer moving-embedded grid technique is first established.Compressible Reynolds-averaged Navier-Stokes (RANS) equations with an Spalart-Allmaras turbulence model are employed in the tiltrotor/wing grid region,while Euler equations are chosen to simulate the transition/background region.In order to solve the unsteady flowfield of the tiltrotor/wing,a dual-time method is used.In the present study,the SMPD (Single Program Multiple Data) model parallel acceleration technology is adopted.On this basis,a UH-60A rotor and XV-15 tiltrotor are taken as numerical examples to verify the validity of the established method.Then the unsteady interaction flowfield of the tiltrotor/wing are investigated in detail,and the special "fountain effect" phenomenon is simulated.Due to the interaction effect,the thrust coefficient of the tiltrotor is slightly decreased by 3% than that of an isolated rotor,but the total thrust coefficient loss is about 17% as compared to the isolated rotor.It is demonstrated that the tiltrotor/wing interaction in hover has significant effect on the aerodynamic performance of the tiltrotor aircraft.