Design and Analysis of a Methane Pump for 10 Ton Class Rocket Engine

Abstract

In rocket propulsion, weight has a vital role on efficiency and cost of the program. Since fuel, oxidiser and delivery system contribute a major share of the total weight; so it is desirable to design an efficient fuel delivery system as well as proper choice of fuel. Methane is being considered as the next generation rocket fuel for its certain advantages over liquid hydrogen and kerosene. Pump-fed system is a well-established preferable fuel delivery system as compared to pressure-fed system. To obtain a reduced size of pump it is necessary to run the device at high rpm (more than 10,000rpm). For this high speed it is not possible to run the pump with electric motor or generator. This leaves turbine as a suitable alternative for primemover. Hence pump-fed system is commonly known as turbo-pump system; as it consists of turbine and pump. Pump gives the necessary pressure rise to the fuel and oxidiser while turbine acts as the prime-mover. The present work is limited to design and analysis of the pump part alone. Although pump-fed system has been successfully designed for various propellants, but the research is limited and new for methane as working fluid. Centrifugal pump is preferred to other kind of pumps because of its compact size for a given head rise and a larger throttling range. A high speed impeller demands for high inlet pressure to meet the NPSH requirement to avoid cavitation. Increasing the storage pressure of propellant will demand for a thicker tank and hence higher structural mass, which is undesirable for high performance. Hence an inducer is necessary before impeller to raise the propellant pressure from storage value to required NPSH value at inlet of impeller. The impeller is followed by a volute and diffuser assembly which is intended to give a directional flow to the fluid and convert velocity head into pressure head. The focus of the work is to determine the throttling range, pressure distribution, velocity distribution and performance evaluation for the assembly.