Design and Analysis of LOX Pump for 10 Tonne Thrush LCH4-LOX Cryogenic Engine

Abstract

In order to achieve the nation’s space lift goals, ISRO (Indian Space Research Organisation) is planning to improve its orbital transfer vehicle capabilities, which demands improvements in the Cryogenic engines. For inter planetary missionslike Mars, Scientists are planning for the reusable rocket engines which would be capable of landing on the surface of mars and can extract methane from its atmosphere. Since, to travel such a long distance there must be an abundant fuel supply to the rocket engines and hence presence of methane on the mars atmosphere in the large quantity can be utilized effectively. Hence there is a requirement of designing and analysis of LOX turbo-pump forL(CH4-O2) cryogenic engine.In current research of rocket propulsion, weight plays an essentialrole on efficiency and economy of the program. Since fuel-oxidizer system contributes a major share of the total weight, hence it is desirable to design an efficient fuel delivery system as well as proper choice of fuel andoxidizer. In the current work the approach is to design and analyses all components of liquid oxygen turbo-pump such as inducer, impeller, volute and diffuser. To obtain a compact size of turbo-pump it is necessary to run it at higher speed of 15000 rpm or more. For such higher speed it is not possible to run the pump with electrical motor or generator. This leads the turbine as an only alternative for the prime mover. Therefore, pump-fed system is commonly known as turbo-pump system as it consists of pumpand turbine. Pump gives the necessary pressure rise to the fuel and oxidizer while turbine acts as a prime mover. Generally, in pressure-fed system, increasing the storage pressure of propellant will demand for thicker tank and hence higher structural mass, which is undesirable for high performance. Hence, Cryogenic pump-fed systems are preferred over other kinds of pump because of their compact size for any particular head rise and significant throttling range. Since, pump-fed system has been effectively designed for various propellants, but the research is completely new for methane and oxygen as working fluid and oxidising agent. This works provides the detailed hydrodynamic design of pump, aero-thermodynamic design of inducer and impeller. LOX turbo-pump system consists of pump impeller with cavitating inducer upstream. A high speed impeller generally requires a high inlet pressure to overcome the NPSH requirement to avoid cavitation. Increasing the storage pressure of propellant will demand for thicker tank and hence higher structural mass, which is undesirable for high performance. The impeller is followed by the volute and diffuser assembly which is proposed to give a directional flow to the fluid and convert velocity head into pressure head. The current approach deals with the CFD analysis of turbo-pump assembly using Ansys CFX-pre to analyse the part loading capacity, efficiency, throttling range, pressure distribution, velocity distribution and performance evaluation of individual components and for complete assembly.