Experimental Characterization of a Cavitating Pintle Valve with H2O2

conference paper

English

This paper is aimed at presenting the experimental activities performed by University of Padova and Moog-Bradford to characterize the behavior of a cavitating pintle valve when high concentration peroxide is selected as operating fluid. This work is related to the EU FP7 SPARTAN project, which is focused on developing a soft-landing demonstrator, based on throttleable hybrid rockets propulsion system. HTPB and 87.5% H2O2 are the selected propellants [1], [2]. Hybrid technology has been chosen for its intrinsic advantages: simplicity, reliability, safety, low costs, and throttleability. As an oxidizer, H2O2 has many qualities: high density and oxidizer to fuel ratio; storability and non-toxicity; possibility to decompose it through a catalyst. On the other hand, peroxide imposes safety regulations for handling and storage since it presents a corrosive capability, remarkable reactivity and possible instability, especially in high concentration. The SPARTAN mission profile requires continuous throttling of oxidizer mass flow rate, up to 10:1. For this purpose, Moog-Bradford has developed and optimized a fast response (<500ms full stroke) cavitating pintle valve. The valve features linear response as a function of stroke and allows for repeatable and accurate (1% FS) mass flow control. Optimization of pressure recovery (0.7 at full scale of 0.6 kg/s) has been obtained thanks to an extensive numerical investigation, conducted by Brno University of Technology, in synergy with preliminary experiments from Moog-Bradford, about the valve internal geometry. During the optimization phase, the valve has been tested with H2O to compare the experimental dependency of the mass flow rate from the pintle position with the theoretical prediction. An analytical model has been derived to predict the mass flow rate variation as a function of liquid density, since its value shifts from 998.2kg/m3 for water to 1378.5kg/m3 for 87.5% H2O2 at room temperature (20°C). Further tests have been needed in order to characterize the valve behavior with high concentration H2O2, assure its safe operativeness and validate the analytical model. The valve has been tested with H2O2 at 70% at the facility of the University of Padova, partner of the consortium. A dedicated test-bed has been designed and safety procedures and operations have been defined. The valve has been successfully tested at several pintle positions, and correlations with the theory have been derived. The paper describes the experimental tests performed with hydrogen peroxide and discusses the results obtained, and the comparison with the expected performance. Moreover a description of the valve and its concept is given.

hydrogen peroxide, h2o2, pintle, valve, cavitation, nozzle, Spartan, throttleable, rocket engine

FAENZA, M.; MORETTO, F.; TIJSTERMAN, R.; DVOŘÁK, P.; POPELA, R.; PETRONIO, D.; PAVARIN, D.

2014

30. 4. 2014

Space Propulsion Comitee/AAAF

Paris, France

978-85-86686-70-2

Space Propulsion Conference 2014 Proceedings

1

7

7

http://www.propulsion2014.com