Effect of Cooling Channel Aspect Ratio on Rocket Thermal Behavior

A tradeoff analysis is performed on a test case representative of the cooling system of 1MN thrust class oxygen/hydrogen liquid rocket engine. The aim of the analysis is to find the channel aspect ratio that maximizes the heat extracted from the hot gas, for a given coolant pressure drop and hot-gas side wall temperature. The analysis requires many cooling channel flow calculations that are performed by means of a simplified model, referred to as quasi-two-dimensional, and a three-dimensional conjugate heat transfer model based on numerical integration of the Navier-Stokes and Fourier's equations. Both models are able to describe, with different level of details, the whole cooling device composed by the coolant and the solid domain, which is exposed to the hot gas. The fast quasi-two-dimensional approach is used to select channel geometries showing the same pressure loss. Discussion is made on results obtained with the more accurate three-dimensional model. Results identify, for the selected test case, an ideal aspect ratio that optimizes cooling performance at large values of channel aspect ratio.