Term of Award

Summer 2022

Degree Name

Master of Science, Mechanical Engineering

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Mechanical Engineering

Committee Chair

Marcel Ilie

Committee Member 1

Mosfequr Rahman

Committee Member 2

Prakashbhai Bhoi

Abstract

In recent years the development of rocket engines has been mainly focused on improving the engine cycle and creating new fuels. Rocket nozzle design has not been changed since the late 1960s. Recent needs for reliable and reusable rockets, as well as advancements in additive manufacturing, have brought new interest into the aerospike nozzle concept. This nozzle is a type of altitude adjusting nozzle that is up to 90% more efficient than bell nozzles at low altitudes and spends up to 30% less fuel. Since the nozzle body is submerged in the hot exhaust gasses it is difficult to keep the rocket body at a reasonable temperature. The purpose of this research is to investigate techniques commonly used on bell nozzle geometries and determine their effectiveness on the aerospike nozzle geometry. The techniques investigated are film cooling and transpiration cooling. The aerospike engine used for the analysis was simulated via ANSYS Fluent 2020 R2 and validated from experimental results. The simulation utilized the k-ε turbulence model and the eddy-dissipation combustion model to accurately simulate the combustion of the H2/O2 rocket engine. The film cooling study investigated the effects of inlet geometry and the coolant blowing ratio, while the transpiration study investigated the effects of the coolant inlet pressure. The film cooling inlet angle was varied from 15° to 30°, the inlet size varied from 1mm to 3mm, and the blowing ratio was varied from 0.25 to 2. The transpiration cooling inlet pressure was varied from 10,000 Pa to 100,000 Pa. The film cooling study results showed that the inclination of the coolant inlet, coolant inlet size, and blowing ratio all positively affected the film cooling efficiency, but subsequently reduced the overall nozzle efficiency. The larger angle and blowing ratios were strong enough to distort the exhaust flow and completely divert it from the nozzle wall. The transpiration cooling results showed that the low and high inlet pressures had a low efficiency while the inlet pressure near 50,000 Pa had the highest efficiency. Since the transpiration cooling allows for the flow to exit at all points along the nozzle wall and create a film it showed the lowest wall temperatures with the least reduction in efficiency. Overall, the results showed that film cooling and transpiration cooling, while commonly used on bell nozzles, are able to similarly cool the aerospike nozzle.

OCLC Number

1362895700

Research Data and Supplementary Material

No

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