HEAT TRANSFER AND PRESSURE DROP MEASUREMENTS IN LOW ASPECT RATIO CHANNELS WITH CIRCULAR PINS AND STRIP FINS

Abstract

The heat transfer study of a rectangular duct has become important as it can replicate the channel geometry of the turbine blade or vane in a real engine. The low aspect ratio channel represents trailing edge channel of the vane where the internal features inside it are installed to not only strengthen the blade structure, but also promote higher turbulence in order to enhance heat transfer. With its ease of manufacturing, the circular pin is one of the most popular features introduced in this field of study. In addition, the strip fins are brought to compare with the circular pin. The strip fins provide relatively high area ratio with less area reduction on the end wall. The tests were conducted at Turbomachinery Laboratory, Texas A&M University. The laboratory was capable of generating the range of Reynolds number from 20,000 to 80,000. The experiment was conducted to study heat transfer and pressure loss of seven different designs, including smooth channel (area ratio of unity), three area ratios from a circular pin shape, and the other three area ratios from a strip fin shape. The aspect ratio and spanwise space setups were varying from test by test. All the design configurations in this experiment were in staggered arrays as they gave us higher heat transfer than the in-line design.