Unstable combustion processes for a single element Shear/Coax injector in a longitudinal combustor
Abstract
The combustion process within a single element dump combustor was studied using the Continuously Varying Resonance Combustor (CVRC) at Purdue University. Initial testing using hydrogen as the fuel resulted in unstable combustion that transitioned from one mode to another during a test. As a result of further analysis, it was hypothesized that the CVRC supports unstable combustion when the oxidizer post length is such that it acts as either a 1/4 wave or 3/4 wave resonator to the combustion chamber. A concurrent CFD simulation was used to show that at these oxidizer post lengths, the combustion process starts with a low head end chamber pressure and a high velocity coming out of the oxidizer post into the chamber. Excess fuel enters the chamber entrained in vortices and is burned prior to the arrival of an upstream running compression wave in the chamber. Once the upstream running chamber compression wave reaches the head end of the combustor, pressure waves propagate up the post and down the chamber and the cycle repeats itself. A series of tests were performed to test this hypothesis. Tests using different chamber lengths and fuels produced results that were consistent with the hypothesis.
Degree
M.S.A.A.
Advisors
Anderson, Purdue University.
Subject Area
Aerospace engineering
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