Experimental investigation of contraction ratio influence on scramjet inlet performance at mach 5.85

Date of Award


Degree Name

M.S. in Mechanical and Aerospace Engineering


Department of Mechanical and Aerospace Engineering.


Jose Camberos


The Scramjet Inlet Performance Experiment (SIPE) investigated the performance of a fully-rotated Busemann design. SIPE was conducted in the AFRL Mach 6 High Reynolds Number Facility at M=5.85. An assessment of starting characteristics (over a range of angles of attack) and total pressure probe blockage (at discrete angles of attack) preceded the performance analysis. The tested Busemann inlets, comprised entirely of internal contraction, had contraction ratios of 1.6, 2.0, and 2.6. SIPE used static pressure along the top dead streamline of each inlet (15 ports each), Schlieren imaging, and total pressure at the inlet throat (1 pitot probe) in the study. The critical internal contraction ratio and starting characteristics agreed well with literature; the CR=1.6 and CR=2.0 inlets self-started, but the CR=2.6 inlet never started. The fixed geometry of the pitot probe was found to affect inlet operability and flow behavior, which constrained cases for the performance analysis. Performance parameters quantified at the throat included total pressure recovery and adiabatic kinetic energy efficiency. Designs with low values of contraction ratio had the best starting behavior and performance. Although started conditions were achieved, the impracticality of a generic Busemann design with minimal contraction resulted in unsatisfactory performance characteristics. Regardless of design feasibility, confidence in captured flow physics of predictive methods for scramjet inlet analysis can be gained by using the results of this experiment.


Aerospace Engineering, Busemann inlet, scramjet inlet performance, hypersonic performance test, contraction ratio

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