A 2D NUMERICAL AND EXPERIMENTAL INVESTIGATION ON THE PRESSURE FLUCTUATIONS INSIDE A DOUBLE VOLUTE CENTRIFUGAL PUMP AT THREE DIFFERENT RADIAL GAPS

Pressure fluctuations in centrifugal pumps are one of the most traumatic issues that exist as a result of the interaction between the rotor "impeller" and stator "volute". The experiments that were carried out on the double volute pump model in Saudi Arabia have proved that the radial gap "clearance" between the impeller and the tongue of the volute plays a major role in increasing and decreasing that vibrations that are generated due to the pressure fluctuations. Unsteady 2D simulations were carried out on the model to study the pressure fluctuations especially at the critical locations such as around the impeller , the cutwater, and the volute tongue. The results show that the sliding mesh technique is a very useful procedure for simulating these kinds of simulations. The results also show that the peak of the pressure fluctuations occurs at the first blade passing frequency for the 3 gaps "2, 3.6, 7"mm. Numerical static pressure was captured accurately for each gap but the amplitude of the pressure fluctuations were overestimated due to the inaccurate nature of the 2D simulations. The highest gap "7 mm" is the best solution for the vibrations and noise reduction due to the decrease in the pressure fluctuations without affecting the performance of the pump greatly. The performance curves are discussed.