Modeling of Compressible Flow with Friction and Heat Transfer using the Generalized Fluid System Simulation Program (GFSSP)

The present paper describes the verification and validation of a quasi one-dimensional pressure based finite volume algorithm, implemented in Generalized Fluid System Simulation Program (GFSSP), for predicting compressible flow with friction, heat transfer and area change. The numerical predictions were compared with two classical solutions of compressible flow, i.e. Fanno and Rayleigh flow. Fanno flow provides an analytical solution of compressible flow in a long slender pipe where incoming subsonic flow can be choked due to friction. On the other hand, Raleigh flow provides analytical solution of frictionless compressible flow with heat transfer where incoming subsonic flow can be choked at the outlet boundary with heat addition to the control volume. Non uniform grid distribution improves the accuracy of numerical prediction. A benchmark numerical solution of compressible flow in a converging-diverging nozzle with friction and heat transfer has been developed to verify GFSSP’s numerical predictions. The numerical predictions compare favorably in all cases. Introduction Most commercial network flow analysis codes lack the capability to simulate onedimensional flow in a rocket engine nozzle. Simulation of one-dimensional flow in rocket nozzle requires a numerical algorithm capable of modeling compressible flow with friction, heat transfer, variable cross-sectional area and chemical reaction. One of the primary requirements of compressible flow simulation is to accurately model the inertia force which is often neglected in many network flow analysis codes. NASA Marshall Space Flight Center has developed a general purpose finite volume based network flow analysis code: Generalized Fluid System Simulation Program (GFSSP) [1] which is widely used for the design of Main Propulsion System of Launch Vehicle and secondary flow analysis of turbopump. The purpose of the present paper is to verify and validate GFSSP’s numerical predictions with several benchmark solutions described in the following section. Problem Description: In this study, mainly two types of geometries are considered – (a) a straight pipe of constant diameter, and (b) a converging-diverging nozzle of linearly varying diameter.