Reduced Load Fan Performance Testing for Input Power Determination

The ASME Performance Test Code, PTC 11 Fans, is currently undergoing revision. While there are several changes being made, there are also new additions, the most notable of which is a method to measure input power at reduced fan loads. This information is often required to validate a power guarantee; a condition that presents a unique challenge because fan operation needs to be established at a specific flow and pressure rise that can be corrected to guarantee inlet conditions using the fan laws of similarity. Part 1 of this paper outlines a testing procedure to achieve results close to the specified condition. There is a very low probability that any particular test can be performed at the guarantee condition so several tests within acceptable bounds of the specified point are necessary. Part 2 of this paper discusses a multipoint, distance-weighted interpolation method for determining the final result.