Effects of tip clearance and impeller geometry on the performance of semi-open ceramic centrifugal fan impellers at elevated temperatures

Centrifugal fans are being widely used in many industrial applications. However, when handling gases with temperatures exceeding 800 °C, the use of centrifugal fan impellers are of particular interest since the conventional steel impellers would not be operated at such elevated temperatures. In the present experimental study, three semi-open centrifugal fan impellers have been designed and fabricated using ceramic materials to provide high resistance to temperature. Experiments have been conducted to investigate the performance characteristics of these impellers and the deteriorations in their performance due to varying tip clearance. Factors have been determined to estimate the tip clearance losses. Results showed that the simple impeller geometries of ceramic materials were less sensitive to the varying tip clearance. In addition, the gas temperature has been found to have almost no influence on the performance degradation due to the tip leakage flow.