A Methodology to Compare the Performance of Low Pressure Fan Test Rigs Using Non-dimensional Fan Characteristics

Current international standards and testing procedures are inadequate for measuring the performance of low pressure fans. Methods of generating pressure differences, techniques for measuring electrical power, standardisation of electrical voltage and frequency, and the treatment of the uncertainty of measured data are amongst the unresolved problems. Even if factors such as these are standardized, it is not practicable to build identical test rigs in different countries and existing rigs do not give identical results. This paper outlines a technique whereby the performance of different test rigs can be compared. Under the same physical conditions, in different test rigs, a specific fan should have the same performance characteristic. Such a characteristic may be represented in a non-dimensional form and can be obtained from each test rig being compared. Differences between measured characteristics indicate differences in performances of the rigs. A mathematical model fitted to each characteristic may then be used statistically to identify differences between rigs. In the example presented, if all differences between two particular rigs were attributable to pressure measurements, a variation of 5·8 Pa was identified, indicating a very sensitive methodology applicable to both low and high pressure fans. It is recommended that this procedure is adopted internationally for the comparison of fan test rigs.