Development study on precooler for atrex engine

A review of the development of a precooler for the air-turboramjet expander cycle engine (ATREX) is given. Three types of precooler for the ATREX engine ground test model were designed, manufactured and tested under the sea level static condition. The results suggested two problems affecting the precooler performance such as heat transfer rate and air flow pressure drop. One is non-uniformity of the air flow through the tube banks. The other problem is frost formation on the heat transfer surfaces. Concerning the non-uniformity, the shell configuration was modified based on the analysis by CFD calculation. To improve the precooler performance under frosting condition, the new method to add a condensableg as into the air flow was proposed and.examined by experiments on a subscale heat exchanger model. Addition of a small quantity. of ethanol can be effectively restrain the decline of the precooler performance due to frost formation.