Honors College Theses

Publication Date



Mechanical Engineering (B.S.)

Document Type and Release Option

Thesis (open access)

Faculty Mentor

Dr. Ilie


In the operation of a Scramjet engine, which operates at hypersonic velocities, one of the most important factors is mixing the fuel and air before the high velocity air stream through the engine blows the mixture out of the engine before it could burn. Because of the importance of rapidly mixing fuel and air within a Scramjet engine, there are multiple design elements used to increase mixing. One of which is called a flame holder cavity, which is usually located behind fuel injectors, and designed with an open (length to depth ratio is less than 10) geometry to promote recirculation of the fuel and air. Additional factors which may affect the mixing within the engine are the spacing between fuel injectors, the angle of the fuel injectors, and the blowing ratio of the fuel injectors which is the ratio of fluid entering through the fuel injectors to fluid entering the engines main inlet. These three factors based around the fuel injectors are studied utilizing multiple models of as base scramjet, with modified fuel injectors to test each of these variables. Utilizing the scramjet models prepared in Solidworks, Ansys CFX could then be used to test how the modifications preformed. These tests allow the optimal combination of fuel injector spacing, angle, and blowing ratio to be found.

Thesis Summary

An analysis was performed of the fuel air mixing performance of a scramjet engine, testing variations in the spacing between the fuel injectors, angle of the fuel injectors, and the blowing ratio. This analysis was performed using ANSYS CFX software.