Mixing and combustion in scramjet combustor with raised and relieved ramp

Abstract

A numerical study of wall-mounted parallel injector ramp has been conducted to investigate the mixing process of scramjet engine using unstructured grids. Two different ramp configurations have been studied, raised and relieved ramps. A three dimensional models for the two different rampconfigurations have been used with two different side sweep angles, 0 (unswept) and 5 degrees. Numerical results are obtained using an existing CFD code FLUENT with unstructured grids with a size approximately 300,000 nodes. Results are presented for both non-reacting and reacting flows. Results show that the unswept relieved ramp gives better mixing results than the unsewept raised ramp. Furthermore numerical results show that the swept ramps give better results than the two unswept configurations. introduction Considerable fundamental research has been conducted in response to the increased interests in the development of scramjet propulsion systems. A critical element in the design of the scramjet engine is detailed understanding of the complex flowfield present in different regions of the system over a range of operating conditions. Significant amount of numerical and experimental research have been directed towards injectors design that must produce rapid mixing and combustion of the fuel and air due to the short combustor residence time. In the past years various mixing enhancement schemes including perpendicular and parallel injections have been proposed. One of these schemes is the ramp injection. Critical issues regarding fuel injection and mixing in a scramjet combustor are discussed in detail in Refs. [1-16]. Stouffer et al. [17,18] investigated experimentally both the raised and relieved ramps. The methods that have been 1 Graduate Research Assistant, Department of Mechanical Engineering, Student Member AIAA, ASME. 2 Eminent Professor/Scholar, Department of Mechanical Engineering, Associate Fellow AIAA. 3 Professor and Chair,Mechanical Engineering Department. 4 Associate Professor, Mechanical Engineering Technology Dept, Member ASME, AIAA Copyright © 2000 by the American Institute of Aeronautics and Astronautics, Inc. All rights are reserved. (c)2000 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization. used to enhance the mixing process for the scramjet combustor are reviewed and summarized by Seiner et al. [19]. The main objective of this research is to study numerically the mixing process in scramjet combustor using unstructured grids. Two different configurations of wall-mounted ramps injectors, raised and relieved ramp injectors, have been investigated.