Experimental and Numerical Analysis of Transpiration Cooling of a Rocket Engine Using Lamilloy (Trademark) Plates (PREPRINT)

摘要

Transpiration cooling of rocket engine thrust chamber walls has the potential for improving the performance of liquid rocket engines by reducing the required cooling flow. For the TR107 hydrocarbon booster engine, it is estimated that replacing the proposed chamber wall film cooling with transpiration cooling could result in an engine Isp increase of 2% to 3%, which provides the potential to increase the maximum booster delivery capability by 4000-5000 lbm. In the past, various transpiration cooling wall materials have been investigated with varying degrees of success. In this investigation we examined the use of Lamilloy * as the transpirant wall. Lamilloy is a cooling system with a 30+ year history in jet engine applications developed by Rolls- Royce LibertyWorks . This work represents the first evaluation of this technology for rocket engine applications in a representative hot-fire environment. Tests were performed in a sub-scale hot-fire chamber that produced heat fluxes of 4-15 Btu/in.2/s at chamber pressures of 370-670 psi. Gaseous oxygen/RP-1 propellants were fired at mixture ratios ranging from 1.2 to 1.8. Three off-the-shelf Lamilloy designs were tested with three different transpirants: gaseous nitrogen, water, and RP-1. Testing demonstrated that the hot-gas wall temperature decreased rapidly in the downstream direction due to the cumulative effect of the injected coolant. The tested Lamilloy specimens demonstrated the potential to be an effective material for use as a transpiration cooled wall. However, the specimens tested were designed for low pressure drop in gas turbine combustor applications thus did not provide the high pressure drop needed for rocket propulsion applications. The extensive database generated during this testing can be used to guide future Lamilloy transpiration cooling designs for specific rocket thrust chamber applicat.