Experimental investigations concerning cavitation in radial flow pump for three different leading edge profiles of the vane were carried out in an open circuit system. The operating condition of the radial flow pump under cavitating case was understood by measurement of noise and vibration along with the pump parameters for various speeds and flow rates. The outcome of the experimental results revealed that the noise and vibration were better predictors of inception and development of cavitation. Further observation inferred from critical net positive suction head (NPSH) curve of 3% head drop and critical NPSH value of noise and vibration are presented.

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Globe valves are one of the oldest valve types used for throttling applications for all sizes due to better controllability and range. One of the major limitations associated with the use of globe valves in liquid application is cavitation. It takes place both in part open and in fully open conditions due to varied reasons. There are different designs of globe valves available but for control valve applications, cage and plug designs are widely employed. Cage and plug design consists of body, valve cage, plug and an actuating mechanism. Actuating mechanism is connected to the valve plug (moving part), through valve shaft. There are many investigations reported about the flow visualization and numerical simulation of normal type globe valves. But study on valves with cage and plug design are not tried in detail. The objective of the present work is to provide a comprehensive study of flow through a globe valve with cage and plug design with emphasis on cavitation. Cavitation reduction is achieved by breaking the flow in the form of more than one liquid jets, there by increasing the turbulence in the valve flow path. This ensures the local static pressure not going below vapour pressure. Experimental studies were done in the water test facility with an operating pressure of 1.6 MPa and flow rate of 0.05 m 3 /s. In the study, total area of opening of the valve and the valve stroke were kept constant.

Background: Electric Submersible Pumps (ESPs) are widely used in agricultural fields, petroleum, and various other industries. These pumps are mostly driven at a constant speed since an A.C. motor is normally used as the drive. However, ESPs can also be operated at various speeds by employing a Variable Frequency Drive (VFD). Several patents have been published in ESP. Normally these pumps are started with the discharge valve at its closed position in order to control the starting current. When the ESP runs at its shut-off position, it will develop a higher head and an increase in fluctuating pressure. In order to evaluate the effects of pressure fluctuation, its characteristics must be investigated. Objective: Experimentally investigate the characteristics of pressure pulsation which are generated at each stage of a multistage ESP during shut-off condition at various speeds. Methods: An ESP with five stages was selected for conducting experiments. A VFD was used for operating the ESP at five speed settings from 80 to 120 % of its rated speed. Piezoresistive transducer was placed at the delivery side of the pump to acquire the signals of unsteady pressure. The pump was operated at closed valve condition at each speed, and unsteady pressure signals due to pressure pulsation were captured. Results: Obtained results have indicated the presence of fundamental frequency pertaining to vane passing frequency and harmonics of higher frequencies. Conclusion: Study of pressure fluctuations at shut-off will help to analyze the failures of ESP due to vibration which occur when the pump runs at closed valve position for a prolonged length of time and stability of these pumps at lower flow rates.

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