Turbine Nozzle Guide Vane Exit Area Traversing in a Short Duration Light PistonTest Facility

摘要

Tests were performed in the RAE Isentropic Light Piston Cascade (ILPC) facilityto measure the total pressure loss of turbine nozzle guide vanes (NGV). A three-hole non-nulling probe has been used with a fast acting traverse which gives a full circumferential sweep over two blade wakes in approximately 500 to 700 ms. Two types of probes have been used: the first with high frequency response sensors mounted within 25 mm of the probe tip, and the second with low response sensors mounted 500 mm away from the probe tip using lengths of pneumatic tubing. It is shown that the first probe suffered significantly from probe aerodynamic perturbation due to vibration effects when the air stream was started up in the ILPC. It was found that analog filtering was required at around 250 Hz in order for the NGV wakes to be distinguished. The wakes extracted after filtering were found to be quite distinct even at one axial chord downstream of the NGV. The second probe was found to be relatively free of aerodynamic perturbations due to the damping nature of the long length of pneumatic tubing between probe tip and transducer. Results are presented for both probe types which indicate the wake decay between 0.2 and 1.0 axial chords downstream of NGV trailing edge. A full area traverse is also shown which indicates the areas of secondary flow downstream of the blade row.