The centrifugal pump performance depends to great extent upon the flow pattern in the impeller passages. When the pump operates at small flow rates, the problem of circulation due to vortex formation in the impeller passages is found. A new method is introduced to control and reduce the size of generated vortices in the impeller passages. Slots are opened in the impeller vanes to allow fluid to flow from the pressure side to the suction side of the vane. The bleeding fluid could reduce the size of the vortices. It is found to depend mainly upon the length and the position of the slot. In the present work, the flow field is solved in the radial impeller passages using the stream function and the primitive variable approaches, to solve the flow equations. The flow pattern is used to compare the vortex size and the pump head for both cases with and without slotted impeller vanes at different slot sizes and at different positions. The slot position that produces the highest pump head, the slot length has been changed until the smallest vortex size is achieved. The numerical solution is introduced in a code program form, which is written in the Microsoft Visual C++ 6 language. Finally the optimum position and length of the slot is obtained at Rs/R2 = 0.4981, and with L /(R2-R1)= 0.2291. The model has been validated by comparison to a published experimental result of the same pump (for the same research program).
In the present paper, the effect of change the blade configurations of the centrifugal pump impeller on its performance has been investigated. The pump under investigation has been designed and manufactured to be able to change its blades configurations in a way that the performance of the pump could be measured. The blades configurations have been tested for conventional blades, as well as split to two and three parts. The split blades were tested for clockwise and anti-clockwise shifting. The experimental test rig has been carried out and the pump performances, (speed-head-flow rate-power and efficiency) have been measured for conventional impeller blades configuration, as well as for eight iterations of different impeller configurations according to the blades arrangement for different rotational speed ranged from 700 to 1450 rpm. The main blade configuration parameters are the splitting angle (forward or backward) and splitting diameter. The results showed that, for the same pump rotational speed, the pump head, efficiency and design flow rate, may increase or decrease by 12 to 16 %, compared to the basic impeller configuration. 1-Introduction Centrifugal pumps are widely used because of their design simplicity, high efficiency, wide range of capacity, head, smooth flow rate, and ease of operation and maintenance. The development of centrifugal pumps was very rapid due to its relatively inexpensive manufacturing and its ability to handle voluminous amounts of fluid.
Torque converter is an enclosed hydrodynamic turbomachine, used in vehicles for smooth transmission of power and speed change from the engine to the transmission and torque multiplication. Torque converter consists of three major components: a pump that is connected to the engine shaft, a turbine connected to the transmission shaft, and a stator connected to transmission housing through a one-way clutch. Stator blades provide a guiding for the fluid flow. Stator is a main factor in controlling the torque ratio, pressure distribution and coupling point speed ratio. In this paper, the effects of the stator blade shape on overall performance have been investigated numerically at different speed ratios, using commercial software, ANSYS-CFX. Two torque converters with two different stator blade shapes are used for this study. The first stator has a large round nose, while the second stator is a thinner blade stator. At high speed ratio there is more blockage to flow of large inlet radius stator. Results showed that torque converter with thin blade resulted in an increase of torque ratio at fixed turbine and maximum efficiency. The bending of the thin blade caused a blockage to fluid flow.
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