Experience With the Development of an Euler Code for Rotor Rows

An Euler code for the transonic flow through an axial flow rotor has been developed. The method of solution is an implicit time marching scheme and approximate factorization has been used to minimize the computations. Although the basic methods have been well publicized in the external aerodynamics literature, several modifications were found to be crucial in order to apply the methods to internal flows. the internal flow calculations appear to be much more susceptible to instabilities than the external flow calculations. A boundary-fitted coordinate system is used which is an adaptation of one due to Ives. The calculation of the metrics of the transformation proves to be extremely important and a revision of the numerical viscosity treatment enlarges and enhances the domain where converged solutions can be obtained. In particular, it was found that the metrics must be discretized in the same spatial fashion as the governing partial differential equation in order to avoid introducing source-like terms which would quickly destroy the solution. Results are presented for the two-dimensional case of flows through a cascade with inlet Mach numbers up to 0.76 and with outlet conditions prescribed and with a Kutta condition applied.