Recognize the Cold Flow Perturbation Sources in a Dump Combustor With Taper Exit

This paper reports on experimental investigation of the flow field inside a low aspect ratio dump combustor with tapered exit. The length of the combustor studied was less than the reattachment length for the separated flow. The flow field behavior in the combustor is evaluated from pressure and velocity measurement at varying flow Reynolds number. The pressure measurement inside the combustor at different locations was performed by the piezo-resistive pressure sensors. The velocity measurement inside the combustor was carried out by a hot wire probe. The rms (root mean square) velocity and turbulence intensity distributions are found to be axisymmetric due to the geometry of the combustor. The variation in pressure and velocity with locations and Reynolds number was studied. The velocity variation near the surface of the combustor (r/R = 0.66) was showing the opposite behaviour upto x/h = 4.837 than the radial locations (r/R = 0.0, 0.33) due to presence of recirculation and high separation of shear layer by deceased in the strength of the potential core. The pressure and velocity measurement studies support that the presence of the strong recirculation and high turbulence inside the combustor. The power spectral studies of the pressure and velocity fluctuations also suggested the presence of strong recirculation, acoustic modes and turbulence behaviour inside the combustor. The velocity distributions were corroborated by comparing the frequency spectrum with the wall pressure distributions and the results were found to be in very good qualitative agreement with each other.