Published on: August 27, 2019 By: Valcor Aerospace Comparison of Surge Pressure Mitigation Devices For Use in Propellant Feedlines During A Priming Event Vitor Cardoso 1 , Richard Kelly 2 , Yuri Gerasimov 3 Valcor Engineering Corporation, Springfield, NJ, 07081 Abstract The priming of a liquid propellant feed system can create surge pressures that can be damaging to the system. In the past, spacecraft have used flow restrictions such as orifices and venturis. The addition of such restrictions can cause significant pressure loss during thruster firings. This paper will discuss a new approach, which will be to install a flow limiter in the propellant line. Such a device would sense an abnormally high flow, and close so that the orifice size is reduced. This would limit the flow velocity, thus reducing the pressure surge. It would then return to its full open position during nominal flow, thus not producing any excess pressure drop during normal operation. This paper presents a trade study that compares four devices: an orifice, a venturi, a flow fuse, and a flow fuse with a dashpot (slow closing). It will be shown that the use of a flow fuse with a dashpot is the best option. Introduction High pressure spikes typically occur within propellant feedlines during a priming event1. Such an event occurs when a pyro valve, or latch valve opens, allowing liquid propellant to fill the downstream lines, which are at vacuum conditions. These spikes are the result of high velocity propellant flowing into a dead-ended line (closed valve). The impact of the column of liquid propellant hitting the closed valve creates a compression wave, also referred to as “Water Hammer”. This priming event is a well known phenomenon that has been much studied and analyzed. Pressure spikes may lead to detonation of the propellant. As a rule of thumb, pressure spikes should not exceed the proof pressure rating of both the pressurization lines and the flow control components. A possible solution is to install a fixed flow restriction in the line, which will decrease the liquid impact velocity, thus reducing the water hammer. The drawback to this approach is that the system will suffer from a pressure loss during normal flow usage. This paper presents a trade study of four devices: an orifice, a venturi, a flow fuse, and a flow fuse with a dashpot (slow closing). A flow fuse will sense an abnormally high flow, and close a poppet so that the orifice size is reduced. This would limit the flow velocity, thus reducing the pressure surge. The poppet would then return to its full open position during nominal flow, thus not producing any excess pressure drop during normal operation. A literature...