Design and Characterization of an Altitude Chamber for Chemical Rocket Engines

Jacob M McCormick, Purdue University

Abstract

Over the course of a launch, a rocket experiences a broad range of atmospheric pressures, influencing the performance of the rocket nozzle. Aside from implementing a complex system to modulate the geometry of the rocket nozzle, it is nearly impossible to optimize the overall performance of the rocket engine for the entirety of the burn. It is therefore necessary for engineers to optimize the performance for a specific atmospheric pressure range. For this reason, facilities exist which are capable of testing propulsion systems at relevant operational conditions. This is accomplished by simulating the atmospheric pressure relevant to the altitude of interest in a closed volume, also known as an altitude chamber. This thesis focuses on the development of reduced pressure testing capabilities at Zucrow Laboratories. A two-stage ejector on loan from NASA Marshall is used in series with a supersonic diffuser to allow for the testing of up to100 lbf rocket engines at equivalent altitudes of up to 100,000 ft. The objective of this research is to implement a one-dimensional (1-D) model which accurately predicts the performance of the two-stage ejector in real time, informing the maximum thrust and simulated altitude capabilities within the altitude chamber located in room 134A of ZL3 during experimental testing. A new 1-D model was created which efficiently balances computational performance with prediction accuracy. The new model was validated using experimental data collected for a smaller single-stage ejector utilizing facility nitrogen as the suction fluid and facility air as the motive fluid. The validated model was then shown to accurately predict the performance of the single-stage ejector system during the testing of a small solid rocket motor (SRM) within the altitude chamber. The new 1-D model was then calibrated using experimental data from the twostage ejector on loan from NASA Marshall. It was shown that the new model is capable of predicting the performance of the two-stage ejector for varying rocket engine configurations. As a result, this new model was proven to be a viable predictive tool to inform the testing capabilities of the altitude facility at Zucrow Labs. In addition, a new rocket engine is designed for the characterization of a hybrid grain configuration within the altitude chamber at reduced pressure, which serves as a continuation of the atmospheric testing campaign performed in collaboration with the Jet Propulsion Laboratory (JPL).

Degree

M.Sc.

Advisors

Pourpoint, Purdue University.

Subject Area

Energy|Design|Atmospheric sciences

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