离心式叶轮三维反问题设计和数值计算

为解决离心式叶轮传统设计方法主要依赖于设计者经验以及设计周期较长等问题，采用三维反问题设计方法，根据给定的流场进行叶轮形状的设计，从而提高设计过程对叶轮性能的控制能力.三维反问题设计方法基于无黏有势流假设，将三维速度场分解为周向平均速度和周期速度进行求解，实现了在二维轴面流道上叶片形状和流场的三维计算.三维叶片形状根据速度在叶片表面满足滑移条件计算得到，同时获得该叶轮形状下其内部三维流场的计算结果.采用自编三维反问题设计程序进行了离心式叶轮的设计计算，并利用三维定常湍流数值计算技术对设计结果进行了流场模拟和性能评价，流场的模拟结果与设计方法计算结果定性吻合，验证了设计方法的有效性.研究结果表明：将三维反问题设计方法和三维湍流数值计算技术结合可有效缩短设计周期，提高设计质量，并可用于各种叶轮机械的设计.

Three-dimensional inverse design and fluid flow numerical simulation for centrifugal impeller

In order to solve the problems of traditional design methods, which are mainly rely on experience of a designer and the design cycle is often too long, a three dimensional (3D) inverse design method was used to design the impeller according to given flow field conditions. The method has a better control ability of design outcomes during the design procedure. Based on the inviscid and potential flow assumption, a 3D velocity field in centrifugal impeller is decomposed into an averaged circumfe rential flow and a periodic one; subsequently they are solved numerically in the two dimensional meri dional plane and the blade to blade surface to approximately obtain the 3D fluid flow field. 3D geometry of a blade is established according to the slip boundary condition on the surface of the blade, the flow field in the designed impeller is obtainable simultaneously as well. A centrifugal impeller was designed by a 3D inverse design code developed by the authors, also a 3D steady, turbulent fluid flow in the impeller was simulated by using a CFD code to examine the flow field and evaluate the impeller performance. The viscous fluid flow simulated and inviscid one obtained in the design are in qualitative agreement, confirming the validity of the 3D inverse design method. The results indicate that combination of the inverse design method and the turbulent flow simulation technique can shorten design cycle and improve design quality effectively. This design strategy may be applicable to impeller design of the rest type of fluid machine.