Spinning-Scroll Pump for Cryogenic Feed System

The proposed innovation is the world's first cryogenic spinning scroll pump (CSSP) capable of pumping liquid methane or oxygen at flows of 8-10 lbm/s. The primary goal is to develop a versatile proof of concept CSSP, capable of pumping liquid or two-phase methane or oxygen at a wide range of speeds (i.e. 1,000-8,000 RPM) and a wide range of differential pressures while maintaining high-reliability and a compact size. The pump will be configurable, to allow multiple pumps to be placed in series for high-pressure multi-stage operation. During Phase I, Air Squared successfully designed, fabricated and tested a prototype CSSP on liquid nitrogen.For Cryogenic pumping, state of the art (SOA), consists of two vastly different technology options. Centrifugal turbopumps and positive displacement pumps. Turbopumps utilize an impeller-inducer combination that relies on high impeller speeds to create a differential pressure. While the high-speed operation makes turbopumps compact, it also limits bearing life, differential pressure, and they can't handle two-phase flow. Positive displacement pumps can handle larger pressure differentials and don't have issues with two-phase flow. However, they can't achieve speeds over 3,000 RPM without bulky and high-load bearings making them less desirable for aerospace applications.The CSSP offers the best of both options. As a positive displacement pump, it can achieve high-pressures with minimal reduction in flow and pump saturated liquids at low net-positive suction heads. Due to the spinning motion of the pump, various centrifugal loads are eliminated allowing speeds over 8,000 RPM possible and making the design compact and lightweight. Additionally, the spinning motion of the scrolls eliminates the need for a counterbalance common in orbiting scroll designs. This further reduces weight by eliminating counterweights and eases bearing loads. Air Squared believes the proposed CSSP is a perfect fit in support of Methane In-space Propulsion.