ENGINE CYCLE ANALYSIS AND CONFIGURATION STUDIES FOR A NUCLEAR THERMAL ROCKET (NTR) ENGINE

A nuclear thermal rocket (NTR) engine is an attractive spacecraft propulsion system due to its high thrust and specific impulse. Although, the majority of the required technologies were developed in the 1950s-1970s itself, interest in NTR propulsion has renewed in the past two decades for enabling manned and cargo interplanetary missions. This paper presents engine cycle and configuration studies for development of an NTR engine in ISRO. In order to reduce development efforts for conventional subsystems, turbopumps for two operational cryogenic engines of ISRO, referred to here as Engine A and Engine B, are considered in configuring the NTR engine. The methodology for cycle analysis is presented. Results from the cycle analyses are used to obtain engine subsystem specifications, and thereby help in finalizing an engine configuration, considering the given constraints. The selected configuration works on a closed engine cycle, which is a modification of the conventional expander cycle. The engine generates 23 kN thrust with specific impulse of 865 s, and is suitable for technology demonstration and robotic space missions. Sensitivity studies are then carried out on the selected configuration. Based on these studies, sensitive/critical engine parameters are identified, and their impact on the engine cycle, along with feasibility limits is determined.