Fluidic Jet Turbulence Generators for Deflagration to Detonation Transition in Pulsed Detonation Combustors

<p>The goal of this study is to establish the dominant flow structure required to effectively accelerate the turbulent deflagration flame front to detonation velocity in the shortest possible distance while using a single Jet in Cross Flow (JICF). Jets in crossflow, depending on orientation and momentum ratio, can induce two types of flow structures that propagate downstream; vortex filaments and turbulent eddies. Vortex flow structures are coherent rotating columns that can persist for a considerable distance before diffusing. Turbulent eddies are characterized as random fluctuations in flow velocity or small pockets of rotation. The test rig used for this study consists of a valveless pulse detonation combustor operating at near-ambient conditions supplying air at a rate of (0.05-0.1)kg/s and equivalence ratios of 1.0 to 1.3 using Ethylene fuel. Experimental studies comprised of four phases of testing : full obstacle configurations, single orifice, fluidic jet, and hybrid. Overall, the initial fluidic tests reveal the primary effect is an increase in peak pressure (13%-120%) and a decrease in the ion detonation time by up to 19% favoring upward facing jets while velocity displayed no discernable change from the baseline. A study was also conducted with physical transition geometry comparing both valve and valveless configurations. Findings indicate frequent obstacles leading the DDT section both improves flame acceleration and mitigate the backflow due to a porous thrust surface with insufficient supply pressures and furthermore verifies excessive obstacles are detrimental towards later flame acceleration and transition to detonation.</p>

Name thesis:degree_name

Master of Science in Aerospace Engineering

Level thesis:degree_level

Thesis - Open Access

Discipline thesis:degree_discipline

Aerospace Engineering

Year

2016

Author dc:creator

• Lowe, Jarrett E.

• fluidic jets
• turbulence
• deflagration
• detonation
• combustors
• Aerodynamics and Fluid Mechanics

Repository record dc:identifier

https://commons.erau.edu/edt/224

OAI identifier oai:identifier

oai:commons.erau.edu:edt-1223