Development Model of a Gas Pressure Regulator for Spacecraft Propulsion : Design Enhancement and Testing

Abstract: This thesis treats the testing, analysis, and continued development of a mechanical pressure regulator prototype, intended for use in spacecraft propulsion systems. Herein referred to as the Adapted Mechanical Pressure Regulator (APR), the regulator is an adaptation made by the Swedish space system developer OHB Sweden AB (OSE) of an existing patented design originally intended for use outside of the space industry. The intended aim of the development project is to produce two variants of the APR, one intended for use in chemical propulsion systems, using helium (He) as its mainflow medium; and one intended for use in electric propulsion systems, using xenon (Xe) as its main flow medium. The APR was subjected to a suite of flow and pressure tests using nitrogen (N2) and helium (He) to assess its current performance range. By iteratively modifying the regulating mechanism, followed by subsequent testing, the regulating performance of the xenon variant was brought within the requirements outlined by OSE, whereas the helium variant requires further analysis. Following the establishment of an updated mathematical model to describe the regulator’s performance, as well as a radiation assessment of the various nonmetallic components, a revised design incorporating the temporary adjustments to the mechanism was proposed. Due to limitations in time and availability of manufacturers, testing of the proposed design was not included in this thesis. Astructural Finite Element Analysis (FEA) was performed on the newly proposed design, and a test was developed to assess the permeability properties of elastomers with respect to gasses in order to improve the leak rate of the regulator. A number of other suggested design changes, not already included in the revised design, was proposed in order to improve the behaviour of both variants of the APR. This was done with the intent of ensuring that it one day may qualify for flight inspace.