| Changes on the physical size of a rocket engine can force the flow time and the chemical reactions characteristic time to change by orders of magnitude. Therefore, the length of an engine greatly affects the chemical composition at the exit plane. In order to determine scale effects on flow properties of rocket engines, four engines were chosen to be studied: a 500,000-pound, a 16,000-pound, a 1,200-pound, and a five-pound thrust engine. The rocket nozzle analysis program TDK was used to analyze each engine model. This was done using simulation of the largest two engines, first at full-scale and then at sizes roughly comparable to the smaller two. The exit plane properties of the flow from each engine were studied to determine the scale effects on these engines. As expected, the chemical composition was found to vary from the larger to the smaller scale engines due to dissociation and recombination effects. |
