Comprehensive Data Reduction for N2O/HDPE Hybrid Rocket Motor Performance Evaluation

Kamps Kamps,Sakurai Sakurai,Saito Saito,Nagata Nagata

doi:10.3390/aerospace6040045

Abstract

Static firing tests of a hybrid rocket motor using liquid nitrous oxide (N2O) as the oxidizer and high-density polyethylene (HPDE) as the fuel are analyzed using a novel approach to data reduction that allows histories for fuel mass consumption, nozzle throat erosion, characteristic exhaust velocity (c*) efficiency, and nozzle throat wall temperature to be determined experimentally. This is done by firing a motor under the same conditions six times, varying only the burn time. Results show that fuel mass consumption was nearly perfectly repeatable, whereas the magnitude and timing of nozzle throat erosion was not. Correlations of the fuel regression rate result in oxidizer port mass flux exponents of 0.62 and 0.76. There is a transient time in the c* efficiency histories of around 2.5 s, after which c* efficiency remains relatively constant, even in the case of excessive nozzle throat erosion. Although nozzle erosion was not repeatable, the erosion onset factors were similar between tests, and greater than values in previous research in which oxygen was used as the oxidizer. Lastly, nozzle erosion rates exceed 0.15 mm/s for chamber pressures of 4 to 5 MPa.

Highlights

Hybrid rockets are currently the focus of countless aerospace propulsion projects worldwide.Possibly the most prominent example is Virgin Galactic Ltd.’s hybrid rocket-powered spaceplane,“SpaceShipTwo”, which is projected to begin commercial operations this year (FY2019) [1]
The objective of this research is to further develop the experimental methodology introduced by Kamps et al so that the analysis of tests conducted under the propellant combination of Nitrous oxide (N2 O)/high-density polyethylene (HDPE) yields results for the histories of fuel consumption, nozzle erosion, and characteristic exhaust velocity efficiency regardless of the oxidizer-to-fuel-mass ratio
The propellant combination of nitrous oxide (N2 O) and high-density polyethylene (HDPE) shows promise for use in hybrid rocket apogee kick motors for the attributes of storability, non-toxicity, and stable burning with minimal combustion oscillations

Summary

Introduction

Hybrid rockets are currently the focus of countless aerospace propulsion projects worldwide.Possibly the most prominent example is Virgin Galactic Ltd.’s hybrid rocket-powered spaceplane,“SpaceShipTwo”, which is projected to begin commercial operations this year (FY2019) [1]. Hybrid rockets are currently the focus of countless aerospace propulsion projects worldwide. One potential use for the current state-of-the-art hybrid rockets is as apogee kick motors, which will alleviate satellite operators from relying solely on piggy-backing on larger satellite buses to destinations beyond geostationary transfer orbit (GTO), reducing launch wait times, and increasing freedom of movement to desired orbital placements. Kuo and Chiaverini summarize the advantages of hybrid rockets for upper-stage use as having high specific impulse, throttling capability, safe manufacturing, and low cost [4] Jens et al reported extensively on the concept of a hybrid rocket-powered apogee kick motor for placing CubeSats into deep space [5,6,7]. A key aspect of their proposed design is the storage of gaseous oxygen at very high pressures—roughly 50 MPa—to keep the storage volume at a minimum

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Conclusion