Effects of Injector Design on the Performance of a Small Liquid-Fueled Rocket Engine
Alternative Title
Abstract
The injector is an essential part in any bipropellant rocket engine, and its efficiency can greatly affect an engine’s performance. Much work has been done to study the performance of various injector designs, primarily focusing on liquid-on-liquid injectors, such as those used in the Saturn- V’s F-1 engine, and as a result there is a large amount of readily available information for designers to draw upon when developing new engines. However, when liquid oxidizers (such as liquid oxygen, nitric acid, nitrogen tetroxide, etc.) are not available, a gas-on-liquid injector is often the most feasible design, yet this type of injector has far less documentation.
As a continuation of research from the previous year, this study will utilize a small-scale rocket engine, fueled by a mixture of gaseous oxygen and liquid ethanol, to compare the performance of various gas-liquid injector designs including double-impinging, tripleimpinging, and spray-type injectors. The injectors’ effects on the performance of the engine will be quantitively assessed by using sensors to measure the engine’s thrust and chamber pressure during test firings. The injectors’ performance will also be qualitatively assessed by observing their mixing characteristics and spray patterns with the use of high-speed cameras, and Schlieren imaging. A primary focus of this study is on improving the availability of useful information for amateur rocket designers, who may not have access to high-end machining capabilities. As a result, the injectors must be relatively simple to manufacture with the equipment found in most machine shops (manually operated vertical mills, lathes, etc.) so that the designs used in this study can be adapted for use on other small-scale rocket engines.