Keywords

Hypersonic, Scramjets, Ramjets, Variable-geometry

Abstract

The influence of compressibility on supersonic reacting flows is explored by varying the area expansion ratio in a supersonic cavity combustor using a moving wall. In principle, this design allows on-the-fly adjustment of the combustor aft wall expansion ratio to accommodate variable inlet conditions and fueling rates. The variable back pressure broadens the operability envelope and ensures greater pressure rise recovery compared with a constant geometry combustor. The results demonstrate that modulating area expansion alters the combustor pressure distribution and can influence cavity flame dynamics. At sufficiently high equivalence ratios and compression levels, the back pressure induced by the moving wall interacts with the cavity flame by increasing the flame angle. The greater burning surface correlates with a noticeable increase in pressure along the moving wall, and the flame angle is verified by chemiluminescence imaging. Furthermore, this methodology demonstrates the capability to reliably transition between ram and scram modes and to re-establish supersonic flow throughout the isolator and combustor by actively providing aft wall relief under conditions that would otherwise lead to thermal choking in the combustor.

Completion Date

2026

Semester

Spring

Committee Chair

Ahmed, Kareem

Degree

Doctor of Philosophy (Ph.D.)

College

College of Engineering and Computer Science

Department

Mechanical and Aerospace Engineering

Format

PDF

Document Type

Dissertation

Identifier

DP0053243

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