Performance enhancement of centrifugal pumps through axial clearance reduction: An experimental investigation

It is a well-known fact that the disk friction phenomena due to axial clearance has a significant impact on centrifugal pumps performance. Enhancing the efficiency of centrifugal pumps is crucial, as these pumps are widely used in industries and contribute significantly to energy consumption, offering substantial potential for energy savings and cost reduction. In the present work, the disk friction due to the axial clearance between the impeller and the back cover plate was examined experimentally for three commercial centrifugal pumps with specific speeds, = 19, 34 and 54 rpm at various flow rates. Hydraulic performance parameters were obtained for two different cases: one with original axial clearance and other with minimum axial clearance at rated/design (1450 rpm) and off-design (1000 rpm) conditions. In both conditions, pumps with minimum clearance provides the higher overall efficiency compare to the original clearance. At design conditions, = 34 rpm, the result shows higher performance improvement compared to = 54 rpm with efficiency rise of 5.20%. Although, the highest efficiency of 84.48% was obtained for = 54 rpm at maximum flow rate. Similarly, significant rise in parameters were observed for = 34 followed by = 19 and = 54 rpm at off-design conditions. Change in experimental disk friction head loss due to clearance reduction were compared to provide a clearer image about performance enhancement.