THE IMPACT OF CENTRE BODY ALIGNMENT TO FLOW THROUGH AN ANNULAR DIFFUSER

Cold air-flow testing was completed over a range of inlet Reynolds numbers of 0.8-3.5 x 10(5) on several annular diffuser designs to quantify the variation in first order statistics due to misalignment. The procedure involved in attaching the outer duct wall caused a maximum 5% axis shift with respect to the outlet diameter at the diffuser outlet relative to the centre body axis and translated to an approximate inlet variation in height of 2%. This shift was sufficient to distort the flow whereby the quadrant with the greater area at the annular diffuser inlet corresponded to higher total pressure at the outlet. Results showed that static pressure coefficient never varied by more than 3.8% and the outlet velocity uniformity coefficient stayed within 2.4% from reference configurations; however, total pressure coefficient had a larger variation in some cases greater than 10%.