Experimental and Computational Analysis of Unidirectional Flow Through Stirling Engine Heater Head

A high efficiency Stirling Radioisotope Generator (SRG) is being developed for possible us e in long -duration space science missions. NASA’s advanced technology goals for next generation Stirling convertors include increasing the Carnot efficiency and percent of Carnot efficiency. To help achieve these goals, a multi dimensional Computational Fl uid Dynamics (CFD) code is being developed to numerically model unsteady fluid flow and heat transfer phenomena of the oscillating working gas inside Stirling convertor s. In the absence of transient pressure drop data for the zero mean oscillating multi -dimensional flows present in the Technology Demonstration Convertors on test at NASA Glenn Research Center, unidirectional flow pressure drop test data is used to compare against 2D and 3D computational solutions. This study focuses on tracking pressure dro p and mass flow rate data for unidirectional flow though a Stirling heater head using a commercial CFD code (CFD -ACE). The co mmercial CFD code uses a porous -media model which is dependent on permeability and the inertial coefficient present in the linear a nd nonlinear terms of the Darcy -Forchheimer equation. Permeability and inertial coefficient were calculated from unidirectional flow test data . CFD simulation s of the unidirectional flow test were validated using the porous -media model input parameters w hich increased simulation accuracy by 14% on average .