Design and Analysis of a Fuel Injector of a Liquid Rocket Engine

Abstract

the performance and stability of liquid rocket engines is determined to a large degree by atomization, mixing and combustion process. Control over these processes is exerted through the design of the injector. Injectors in Liquid Rocket Engines (LREs) are called upon to perform many functions. They must first of all mix the propellants to provide suitable performance in the shortest possible length. Suitable atomization and mixing must be followed, so that the size and weight of pressure vessels can be minimized. The injector implementation in Liquid Rockets determines the percentage of the theoretical performance of the nozzle that can be achieved. A poor injector performance causes unburnt propellant to leave the engine, giving unpleasant and poor efficiency. Injectors can be as simple as a number of small diameter holes arranged in carefully constructed patterns through which the fuel and oxidiser travel. The speed of the flow is determined by the square root of the pressure drop across the injectors, the shape of the hole and other details such as the density of the propellant. The performance of an injector can be improved by either using a superior propellant combustion, increasing the mass flow rate or by reducing the size & increasing the number of orifices on the injector plate. In the current project, the last method is applied. The first two methods are not applied due to exceptionally high cost of superior propellants & because the feed system is pressure feed and not pump feed.