OH radical concentration measurements in high-pressure combustion cell
The concentration of OH connected to the heat release in a high-pressure combustion chamber simulating conditions in a rocket combustor
is carried out using a 355 nm-pumped OPO for excitation and an ICCD camera fitted with UV bandpass filters for detection. This work was
primarily carried out by Aravind Vaidyanathan,
concluding with the award of his PhD in 2008.
References
Abstract
In flow species concentration measurements in reacting flows at high pressures, based on nonintrusive
methods, have been acquired so far for isolated conditions in a range of experimental devices and
by using a variety of methods. Furthermore, extensive assessments of theuncertainties associated
with the measurement techniques are lacking. In general, these methods have been based on calibrations
determined from assumptions that were not sufficiently quantified to provide a detailed range of
the uncertainties associated with these measurements. This work quantifies the uncertainties
associated with OH measurement in an oxygen-hydrogen system produced by a shear, coaxial injector
typical of those used in rocket engines. Planar OH distributions are obtained for a range of
pressures from 10 to 53 bar, providing instantaneous and averaged distribution in a unified
study, using the same experimental setup and maintaining the rest of the parameters the same.
The uncertainty of 18 different parameters was evaluated and the overall root mean square error
was found as 21.9, 22.8, 22.5, and 22.9% at 10, 27, 37, and 53 bar, respectively.
Abstract
to 60 bar chamber pressure which has been designed to allow validation of CFD results over a wide
range of realistic rocket combustor conditions. In this study gaseous hydrogen-oxygen combustion
was studied at an oxygen/fuel mass ratio of 3.79 and a speed ratio of 0.4 at 37 bar and 103.5 m/s
hydrogen exit speed, giving a mass flux of 0.58 g/s. Using thermocouples in the combustion chamber
wall, the heat flux was assessed using conventional 1D as well as 3D calculations. It was found
that the 3D technique, which accounts for non-uniformities in the wall lateral direction,
generated a 35% higher heat flux estimate than the conventional 1D approach.
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