A Simplified Method for 3-D Potential Flow in Turbomachinery Using Vortex Sheet Boundary Conditions

Abstract

Within the framework of inviscid flow theory, the character of three-dimensional flow in turbomachinery blade row is discussed. One of the important differences between 3-D and 2-D flow in turbomachinery is the discontinuity of velocity at the two sides of trailing edge and across downstream boundary. The inconsistency of the traditional periodicity conditions for downstream boundary and of the axisymmetric assumption for outlet flow with the three-dimensionality of turbomachinery flow is discussed also. For 3-D potential flow, the vortex sheet boundary conditions (VSBC) for downstream boundary and a fully 3-D condition for outlet flow are presented. A simplified method is developed by implementation of VSBC on a fixed vortex boundary in order to predict the fully 3-D flow in blade passage as well as downstream of blade row. In the present investigation two calculations are carried out. In one calculation the traditional boundary conditions are imposed while in another one the VSBC are used to demonstrate the capability of the newly develped boundary conditions. The agreement between some calculated results and the theoretical analysis is very well.

3D Mean-Stream-Line Method: A New Engineering Approach to the Inverse Problem of 3D Cascade

“…has been developed further by several investigators. The major developments are: the analytical solution of MSLM (Cai, 1966 and1984), the accuracy analysis of MSLM (Cai, 1981), the introduction of periodicity and high order terms of the Taylor series to solve the hybrid problem (Novak & Haymann-Haber, 1983) and the solution of the full inverse problem (Cai, 1987).…”