Feasibility Demonstration of Electric Pump-Fed Systems Powered by Green Propellants

Kurzfassung

This document presents the work performed in the frame of the ASCenSIon project towards the feasibility demonstration of electric pump feeding, providing a comprehensive overview of the activities conducted to advance the technology’s maturity level. The suggested pressurization system is proposed in combination with green propellants as an alternative to the current state of the art pressure-fed systems powered by MMH/NTO. The premise is grounded on the advancements in battery and manufacturing technologies, advancements that could position electric pump feeding as a competitive alternative to pressure feds in the small to medium thrust level (from hundreds to a few kN thrust). Specifically, the study focuses on the 400 N level, with a particular emphasis on exploring the use of hydrogen peroxide and ethanol as baseline green propellant combination. Studying the feasibility of a technology involves providing a clear understanding of its development potential and associated challenges. The technical feasibility is addressed during the study by identifying requirements, potentialities, challenges and engineering constraints. To assess this potential, a dedicated set of tools was developed based on global sensitivity and Monte Carlo analyses. The aim is to enhance the agility of early-stage electric pump-fed studies by effectively identifying the key design drivers and based on that, delivering a competitive system specification. This information is essential to perform well-informed tradeoffs with respect to the state of the art, i.e., pressure-fed systems, way easier to assess due to their higher maturity. Likewise, the study also identified the challenges that could hinder technology development. At component level, a detailed discussion on the design of ultra-low specific speed centrifugal and positive displacement pumps is presented. Regarding the experimental domain, a major challenge stems from the absence of hardware dedicated to the experimental validation of electric pump-fed systems at the thrust level under consideration. To counter this, a test bench has been developed, incorporating a positive displacement pump to explore the capabilities of these pumps for space propulsion applications. Several tests have been conducted in this context to characterize their dynamics. Additionally, a first centrifugal pump model specifically tailored for the 400 N thrust level has been additively manufactured, likely standing as one of the few examples at this scale. From the cost and operational perspective, an assessment of the ArianeGroup former LunaNova kick stage (now OPALS) is presented. Coupled with mission feasibility studies, in particular a delta-v analysis for new kick stages CONOPS and a MDO multi-orbit multi-injection study, this assessment led to the identification of orbital transfer vehicles as a promising application for the proposed propulsion system. After detailing the different studies, the conclusions derived from the different activities are drawn. Overall, the integration of electric pump feeding and green propellants is deemed a feasible alternative for the low to medium thrust level, potentially challenging the pressure-fed hydrazine-based solutions currently in use. An electric pump-fed propulsion system powered by green propellants would mark a significant leap towards sustainability within the space industry, representing a practical pathway for transitioning to the use of less hazardous propellants in the analyzed scenarios. Yet, considerable efforts and resources remain necessary to develop the required system components, in particular pumps, tailored for these thrust levels. Finally, a roadmap outlining further actions is provided.