The conceptual design of Liquid rocket engine includes both performance and weight estimate considering mission requirements and constraints. In this study a design optimization strategy has been employed to obtain a suitable design for liquid rocket engine with gas generator cycles. Multi-objective optimization technique was used to maximize specific impulse and thrust to weight ratio by varying O/F and expansion ratio for a given chamber pressure. First the performance parameters are calculated followed by its mass estimation. In next step, FMINCON optimization technique is employed to get the best design. Two different mass estimation techniques are used in this study to find one which is more suitable for this purpose. First technique is based on an Empirical relation whereas second technique involves detailed calculation for every element with respect to a reference engine.
Results obtained show the compromise between the engine performance and thrust to weight requirements. The methodology developed in this article is beneficial in preliminary phase of system design to meet optimized performance and thrust to weight requirements.