In order to understand flow characteristics inside a positive displacement pump, every point in the flow field must be carefully observed. Such observations are difficult, expensive and usually time consuming to achieve with physical testing. During tests one can observe flow characteristics only at the locations where the instrument device is attached, not the whole flow domain. This thesis mainly focuses on the evaluation of design and performance characteristics of a positive displacement triplex diaphragm pump. For this purpose not only numerical investigations but also experimental studies were conducted using a positive displacement pump which is supplied by the pump manufacturer and is available in the fluid mechanics laboratory of Middle East Technical University. The effect of valve characteristics on the pump efficiency such as valve spring stiffness, valve displacement, mass of the check valves, and diaphragm shape are investigated in this thesis by using CFD (Computational Fluid Dynamics) technique. The pump performance is analyzed in terms of its volumetric and hydraulic efficiencies. The effect of the valve closure delay is also discussed. After the CFD and experimental results of the current pump model are compared and it is seen that they are in close agreement with each other, parametric studies are performed in computer environment. From analysis results it is observed that using stiffer springs reduces valve closing time and tend to decrease flow reversal effects. Secondly, using heavier check valves increases valve closing and opening times and also increases the stresses on the components of the pump with the increased pressure drop through discharge valve. As a result of this condition, hydraulic and volumetric efficiency reduce. Thirdly, with the longer valve displacement arrangement, more time is required for opening and closing of the check valves therefore efficiency of the pump reduces.

The purpose of the diploma thesis is to establish on survey of swirl pump from previous years and his optimization via which is suggested the second degree of synchronous pump whereas they should work together like a total artificial heart. Hydraulic and constructional proposal is solved. Conception is realized experimentally also with help of CFD calculation, results are compared with each other.

Due to the increasing demand, nonclog type sewage pumps are designed and manufactured in large amounts all over the world. However, a methodology on the design of these special duty pumps is not encountered in the literature. Therefore, the manufacturers tend to develop their own empirical methodologies. In this thesis, a nonclog pump is designed and constructed on the basis of suitable approaches of known centrifugal pump design methods. In this frame, a nonclog type submersible pump that is capable of handling solids, up to a diameter of 80 mm is aimed to be designed. The designed pump delivers 100 l/s flow rate against a head of 24 m. The rotational speed of the pump is 1000 rpm. Design procedure and the important points that differ nonclog pump design from standard centrifugal pump designs are given. In addition, hydraulic characteristics of two nonclog pumps, one of which is the pump designed in this study, are investigated by means of computational fluid dynamics (CFD) code. The designed pump is manufactured and tested in Layne Bowler Pump Company Inc. The test result indicates that design point is reached with a deviation in the limits of the related standard. Wire to water total best efficiency obtained by the test is 60%. Close agreement between results of actual test and numerical experimentation performed by CFD code shows that CFD analysis is a quite useful tool in predicting the hydraulic characteristics of nonclog pumps. Moreover, the pump is tested at 750 rpm and the test results are found to be in good agreement with the similitude anaysis results.

The demand on high efficiency pumps leads the manufacturers to develop new design and manufacturing techniques for rotodynamic pumps. Computational Fluid Dynamics (CFD) software are started to be used during the design periods for this reason in order to validate the designs before the pumps are produced. However the integration process of CFD software into the design procedure should be made carefully in order to improve the designs. In this thesis, the CFD software is aimed to be integrated into the pump design procedure. In this frame, a vertical turbine type mixed flow pump is aimed to be designed and design improvements are intended to be made by applying numerical experimentations on the pump. The pump that is designed in this study can deliver 115 l/s flow rate against the head of 16 mWC in 2900 rpm. The effects of various parameters in the design are investigated by the help of CFD software during the design and best performance characteristics of the pump are aimed to be reached. The pump that is designed in this study is manufactured and tested in Layne Bowler Pumps Company Inc. The design point of the pump is reached within the tolerance limits given in the related standard. In addition, the results of actual test and numerical experimentation are compared and found to be in agreement with each other. The integration of CFD code to the design procedure is found quite useful by means of shortening design periods, lowering manufacturing and testing costs. In deed the effects of the design parameters are understood better by applying numerical experimentations to the designed pump.

In this thesis a vertical turbine mixed flow pump that has a flow rate of 40 l/s and 16 mwc head at 2900 rpm is designed. Effect of design parameters are investigated and flow inside the pump is analyzed with the help of numerical experimentations. The designed pump is manufactured and tested in Layne Bowler Pumps Company and completed in T&Uuml / BiTAK - TEYDEB project. Pump is designed in the tolerance limits that are defined in the standard TS EN ISO 9906. Numerical experimentation results for performance charecteristics show the same trend with the test results. In addition, axial thrust measurements are done on the designed pump with using load cells. Effect of balancing holes and balancing ring are investigated. Balancing holes are drilled at various diameters at the back side of the impellers and its effect is analyzed on the pump performance characteristics. Test results are compared with different approaches.

The diploma thesis deals with the issue of artificial hearts and ventricular assist devices. The theoretical part describes the heart and its function. Blood is characterized in terms of rheological behavior and the possible criteria for hemolysis are discussed. The following section describes the most commonly used ventricular assist devices, with emphasis on the use of the regenerative pump, including its components. In the practical part, an experimental analysis of two pumps (COV 43 and COV 23) is performed. Furthermore, non-dimensional characteristics of the pumps are constructed using the laws of similarity. In the computational part, the CFD analysis of the regenerative pump is performed by means of stationary and transient calculation. The results are compared with the experimental findings and based on the results, the impeller of regenerative pump was modified.