THE INFLUENCE OF INLET CONTRACTION ON VANE AERODYNAMIC LOSSES AND SECONDARY FLOWS WITH VARIABLE TURBULENCE AND REYNOLDS NUMBER

摘要

Exit survey measurements comparing exit losses for a constant inlet height cascade and a contracting inlet cascade have been acquired in a low speed wind tunnel facility. The measurements were taken for both a low and a high turbulence level across a four to one range in chord Reynolds number (500,000, 1,000,000, and 2,000,000). The high intensity turbulence has been generated using a simulated aero-combustor for both cascades. Exit survey measurements have been acquired for the two cascades using a five-hole cone probe at stations representing an exit location of V* axial chord downstream from the trailing edge plane. Measurements detail total pressure loss, turning angle, and secondary velocities. At the low turbulence condition, the contracting inlet cascade shows a significant reduction in losses compared with the constant height inlet cascade. The contracting inlet cascade also features an aft loaded vane profile which may have some impact on the development of secondary flows. The constant cross-section cascade uses a fully loaded vane profile. The difference in losses between the two cascades is also significant at the high turbulence condition. However, at the high turbulence condition, the losses for the contracting inlet cascade are greater than the constant cross-section cascade. These increased losses are believed to be due to the more aggressive turbulence of the contracting inlet case. The contracting inlet effectively moves the vane leading edge plane forward into the exit of the combustor where the vane passage is subjected to more aggressive turbulence levels.