Surge Pressure Management in HTV Propulsion System

Abstract

One of the common challenges in operating a spacecraft propulsion system is to manage the water hammer effects resulting from activation of fast-acting isolation valves. In smaller system, these pressure transients are maintained within acceptable limits by careful selection of the propulsion elements. However, it becomes cost prohibitive to design and qualify all the affected components to withstand high surge pressures seen in larger propulsion systems, such as the one used in HTV (H-II Transfer Vehicle). HTV is an advanced space vehicle being developed by Japan Aerospace Exploration Agency (JAXA) to enhance cargo delivery capabilities of the fleet of vehicles visiting the International Space Station (ISS). This paper presents a comparison between thermal reprime demonstration test results and dynamic simulation of the flight-like system. An overview of the HTV propulsion system is provided and unique operational processes employed to enact thermal reprime capability represents a significant milestone in vehicle development and provides a novel approach to reducing surge pressure associated with manifold activation of on-orbit vehicles utilizing rapidresponse isolation valves.