The flow-field generated by inclined ramp tabs in a rocket nozzle exhaust

Gourlay, Christopher M (1988). The flow-field generated by inclined ramp tabs in a rocket nozzle exhaust PhD Thesis, School of Engineering, The University of Queensland.

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Author Gourlay, Christopher M
Thesis Title The flow-field generated by inclined ramp tabs in a rocket nozzle exhaust
School, Centre or Institute School of Engineering
Institution The University of Queensland
Publication date 1988-01-01
Thesis type PhD Thesis
Supervisor Dr. John Simmons
Total pages 215
Language eng
Subjects 09 Engineering
Formatted abstract
Thrust vector control of rocket-propelled vehicles controlled by tabs in the rocket nozzle exhaust has been investigated. Literature relating to thrust vector control, the fluid dynamic aspects of the problem and the numerical solution of three-dimensional supersonic flow-fields has been reviewed. From the literature it was found prohibitive to predict the flow-field by a full three-dimensional approach owing to the complicated nature of the flow produced by a discrete number of tabs in a rocket nozzle exhaust. Therefore simplified one- and two dimensional mathematical models of the flow-field were developed. The configurations studied involved partial, symmetric and asymmetric insertion of three tapered ramp tabs into the efflux of a supersonic exhaust nozzle.

A free-piston shock tunnel was used to generate suitable conditions to simulate rocket nozzle exhaust flow. The maximum duration of useful test flow of the shock tunnel under different operating conditions was investigated theoretically. Experiments were conducted in this regime. Reduction in test time caused by the phenomenon of reflected and transmitted shock wave bifurcation was investigated. The shock tunnel was modified in an attempt to increase the duration of useful test flow by the technique of boundary layer suction. This technique was expected to reduce the contamination of the test gas by cold driver gas. Results showed that the bifurcation was not significantly reduced but that the contamination of the test gas would be lessened. It was recommended that the problem be investigated further.

Experimental data from a shock tunnel model of the rocket control tabs was compared with predictions of the mathematical models of the flow-field. Results were obtained by use of colour schlieren photography, and pressure measurements on the model of the rocket tabs. The photographs show the existence of a Mach disc and a Mach reflection pattem in the region enclosed by the tabs. Experiments were conducted over a wide range of conditions with variation of symmetry of the tab arrangement, tab size, tab inclination, test gas and flow conditions to determine the location of the Mach disc. Variations in the tab pressure were investigated in both the stream- and cross-stream direction. The pressure measurements showed that the Mach disc produced much larger tab forces than would have otherwise been expected. An attempt was made at measuring the heat transfer rate to the tabs. The experimental results were useful in the development of the mathematical models.

Predictions of the mathematical models for the shock locations, tab pressures and tab forces were in reasonable agreement for symmetric insertion cases. An estimate was made of the pressure distributions on the tabs in an asymmetric situation. The one-dimensional model gave good predictions of the flow using a calibration from independent data.
Keyword Rocket engines -- Thrust.
Tabs (Airplanes)
Rockets (Aeronautics) -- Nozzles.
Additional Notes Other Title: Inclined ramp tabs in a rocket exhaust. Pages out of sequence, original contains page 20 and 20A

Document type: Thesis
Collection: UQ Theses (RHD) - UQ staff and students only
Citation counts: Google Scholar Search Google Scholar
Created: Fri, 26 Jun 2015, 20:38:07 EST by Lucy Russell on behalf of Scholarly Communication and Digitisation Service