Development of nanosecond-gated laser induced breakdown spectroscopy for fuel mole fraction measurements in supersonic combustion
type: CreativeWork
description: Hypersonic air-breathing propulsion systems such as supersonic combusting ramjets or scramjets are of great interest due to the high flight velocities and increased specific impulse offered over solid or liquid fuel rockets. Scramjets operate on the same Brayton cycle as typical jet turbine engines; however, there is no rotating compressor. Rather, the scramjet takes advantage of the high dynamic pressure of incoming air and all shockwaves formed by the vehicle forebody or engine inlet geometry compressing the incoming air. Ramjets and scramjets operate on the same principal, but there is one key difference. In a ramjet, the air is decelerated to subsonic speeds in the combustor, while in a scramjet the core flow remains supersonic. Both engines require an external or secondary propulsion system to accelerate the engine to the appropriate speed prior to operation. A dual mode scramjet is a design which allows for operation in both ram-mode and scram-mode and allows for scramjet operation with a lower required takeover velocity from the secondary propulsion system. Efficient and robust scramjet takeover is one of the most important aspects of scramjet development. Scramjet takeover refers to the transition from the secondary propulsion system to scramjet propulsion. An important aspect of this takeover is the ignition of the scramjet combustor. Scramjet engines operating at hypersonic velocities undergo autoignition, which occurs when the total temperature of the compressed flow is high enough to directly ignite the injected fuel. For dual-mode scramjets, the total temperature at takeover velocity is insufficient to ignite the injected fuel. In such engines, an ignition device is necessary. In order to understand the ignition process and ignition probability in a scramjet combustor, an accurate understanding of fuel and air mixing and the ignition transient process is required. A model scramjet combustor presents a challenging environment for measurements as the supe…
abstract: Hypersonic air-breathing propulsion systems such as supersonic combusting ramjets or scramjets are of great interest due to the high flight velocities and increased specific impulse offered over solid or liquid fuel rockets. Scramjets operate on the same Brayton cycle as typical jet turbine engines; however, there is no rotating compressor. Rather, the scramjet takes advantage of the high dynamic pressure of incoming air and all shockwaves formed by the vehicle forebody or engine inlet geometry compressing the incoming air. Ramjets and scramjets operate on the same principal, but there is one key difference. In a ramjet, the air is decelerated to subsonic speeds in the combustor, while in a scramjet the core flow remains supersonic. Both engines require an external or secondary propulsion system to accelerate the engine to the appropriate speed prior to operation. A dual mode scramjet is a design which allows for operation in both ram-mode and scram-mode and allows for scramjet operation with a lower required takeover velocity from the secondary propulsion system. Efficient and robust scramjet takeover is one of the most important aspects of scramjet development. Scramjet takeover refers to the transition from the secondary propulsion system to scramjet propulsion. An important aspect of this takeover is the ignition of the scramjet combustor. Scramjet engines operating at hypersonic velocities undergo autoignition, which occurs when the total temperature of the compressed flow is high enough to directly ignite the injected fuel. For dual-mode scramjets, the total temperature at takeover velocity is insufficient to ignite the injected fuel. In such engines, an ignition device is necessary. In order to understand the ignition process and ignition probability in a scramjet combustor, an accurate understanding of fuel and air mixing and the ignition transient process is required. A model scramjet combustor presents a challenging environment for measurements as the supe…
author: McGann, Brendan
language: en
keywords: LIBS, combustion
date published: 2022-01-12T21:45:41Z
date modified: 2026-07-22T22:24:52Z
provider: University of Illinois - Urbana-Champaign
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Illinois at Urbana-Champaign

PropertyValue
property ID: Handle
value: http://hdl.handle.net/2142/113033