A New Test Facility for Investigating the Interaction Between Swirl Flow and Wall Cooling Films in Combustors

Abstract

Swirl stabilization of flames is typically used in combustors of aero engines and gas turbines for power generation. In the near wall region of the combustor liner, the swirling flow interacts in a very particular way with wall cooling films. This interaction and its effect on the local wall cooling performance gave reason to design and commission a new atmospheric test rig for detailed aerodynamic and thermal studies. The new test rig includes three burners in a planar arrangement. Special emphasis was placed on the simulation of realistic operating conditions as Reynolds number and temperature ratio. The liner cooling and the formation of a starter cooling film can be independently controlled. The rectangular flow channel is equipped with large windows to allow for laser optical diagnostics like PIV and 3-component LDA. The thermal analyses are based on highly resolved temperature mappings of the cooled surface utilizing infrared thermography. First experimental results are presented in terms of static pressure distributions on the combustor liner and PIV contour plots of the swirl flow. The static pressure pattern corresponds well to the up wash and downwash regions of the swirl flow.

Impact of Swirl Flow on the Cooling Performance of an Effusion Cooled Combustor Liner

“…[14]. For that reason only the most important information conceming the test facility will be provided in this section.…”

“…As in the case of the pressure measurement technique a detailed description of the PIV setup can be found in Wurni et al [14]. Comments concerning the accuracy of the results are also given there.…”

“…To avoid out of plane uncertainties the light sheet thickness was set to 1 mm according to the velocities expected perpendicular to the measurement plane. The maximum deviation found in areas with high turbulence is 3.5% for the averaged velocity distribution [14]. Figure 2 gives an illustration of the basic measurement plane at midspan of the airspray nozzle without any cooling application.…”

“…This gives an indication, in which areas swirl flow wall interactions have to be expected and hence, the through flow behavior of the coolant is significantly affected. The pressure measurement instrumentation which was applied for this study is explained in detail in Wurm et al [14]. The bottom wall of the test section was replaced by an aluminum sheet with 96 pressure taps.…”

“…The contour plot shows the averaged axial velocity distribution downstream of the airspray nozzle exit (x/P = 0) for the 30 deg straight edge heat shield, which is illustrated as a white triangle. Velocity is normalized to an averaged velocity measured at the exit of the test section, where the flow field has recovered to a homogeneous block profile [14]. Pilot zone, main flows and the main recirculation zone are clearly visible.…”