Search Results

As the need for super high speed components (pumps, motors, etc) continue to grow rapidly, so does the need to make measurements at speeds higher than ever before. Bearings are a major component in any rotating system. With continually increasing speeds, bearing failure modes take new unconventional forms that often are not understood. Such measurements are impossible if bearings fail to perform. This paper will address the dynamic modes a bearing passes through and the potential failure modes associated with each. A review of the state of the art of current failure modes will be given, and then a hypothesis on some new failure modes associated with particular speeds will be discussion. The paper will also describe an apparatus that was designed especially to study these phenomena. Range of speed studied is 0- 60,000 rpm. Preliminary measurements indicated that this range breaks into three different zones: low (0-15,000 rpm), moderate (15,000-25,000 rpm) and high (25,000- 60,000 rpm).

Enhancing the performance of centrifugal pumps requires a thorough understanding of the internal flow. Flow simulation inside the pump can help understand the rotatory motion induced by the impellers, as well as the flow instabilities. The flow inside a centrifugal pump is three dimensional, disturbed and accompanied by tributary flow structures. When a centrifugal pump operates under low flow rates, a secondary flow known as recirculation starts to begin. The separation of flow occurs which creates vortices and decreases local pressure which induces cavitation. This phenomenon of recirculation will rise the Net Positive Suction Head Required (NPSHR). This work aims to improve the pump efficiency under low flow rates by adding multiple cylindrical disks at the pump inlet section to suppress the flow recirculation. In this study, a numerical simulation is carried out to investigate the influence on the pump internal flow by adding multi cylindrical disks.

This paper presents an experimental investigation of flow field instabilities in a centrifugal pump impeller at low flow rates. The measurements of pump hydraulic performance and flow field in the impeller passages were made with a hydraulic test rig. Analysis of Q-ΔP-η data and flow structures in the impeller passages were performed. In the present work, the effect of various flowrates on centrifugal pump impeller performance was analyzed based on pump measured parameters. The impeller’s geometry was modified, with positioning the curved spacer at the impeller suction side. This research investigates the effect of each inlet curved spacer model on pump performance improvement. The hydraulic performance and cavitation performance of the pump have been tested experimentally. The flow field inside a centrifugal pump is known to be fully turbulent, three dimensional and unsteady with recirculation flows and separation at its inlet and exit.

Cooling fans have many applications in industrial and electronic fields that remove heat away from the system. The process of designing a new cooling fan with optimal performance and reduced acoustic sources can be fairly lengthy and expensive. The use of CFD with support of mesh morphing, along with the development of optimization techniques, can improve the acoustic’s performance of the fan model. This paper presents a new promising method which will support the design process of a new cooling fan with improved performance and less acoustic surface power generation. The CFD analysis is focused on reducing the acoustic surface power of a given cooling fan’s blade using the surface dipole acoustic power as the objective function, which leads to an optimized prototype design for a better performance. The Mesh Morpher Optimizer (MMO) in ANSYS Fluent is used in combination with a Simplex model of the broadband acoustic modeling.

A study has been conducted on a small engine cooling system in order to find a way to reduce common overheating problems at idle conditions and high engine speeds with restricted airflow. The system flow rates, pressure, and temperature characteristics were monitored at different positions in the system while engine speed was varied. The results show that by adjusting the flow rates according to certain variables, the overall effectiveness of the system is increased and overheating problems can be eliminated. The findings also show that this adjustment can be accomplished by incorporating a controllable electric water pump into the design. Dynamometer testing has also been conducted to show that, in addition to controlling flow rates, the use of the electric pump also possesses the potential of increasing the power output of the engine.

A cooling fan is an essential device of the engine cooling system which is used to remove the heat generated inside the engine from the system. An essential element for successful fan designs is to evaluate the pressure over the fan blade since it can generate annoying noices, which have a negative impact on the fan’s performance and on the environment. Reducing the acoustic surface power will assist in building improved designs that comply with standards and regulations in achieving a more quiet environment. The usage of computational fluid dynamics (CFD), with support of mesh morphing, can provide simulation study for optimizing the shape of a fan blade to reduce the aeroacoustic effects. The investigation process will assist in examining and analyzing the acoustic performance of the prototype, impact of different parameters, and make a solid judgement about the model performance for improvement and optimization.

Designing a centrifugal pump impeller comes with challenges due to multiple parameters that affect the pump efficiency. A high velocity gradient exists in the flow between the impeller shroud and sidewall of the pump casing due to one surface stationary and the other moving at a high velocity. The internal rotating flow in the impeller shroud-sidewall gap is a major problem that leads to a decrease in pump performance. This study presents a design modification of the gap between the impeller shroud and the pump casing sidewall using an idler disk located in between, which rotates freely during pump operation. In this paper, a numerical analysis was performed to investigate the idler disk's effect on the pump performance for different volumetric flow rate values and idler disk geometries. ANSYS-2019-R1 was used (FLUENT solver) to carry out the computational fluid dynamics (CFD) analysis for evaluating the performance of the baseline and modified designs in a centrifugal pump.

This paper presents methods of rapid prototyping design and manufacturing used in the development of a centrifugal pump impeller with curved spacer (CS). In this research subtractive and additive rapid manufacturing methods were applied to create complex curved spacer profiles for testing as part of geometry optimization process for a high speed and high flow rate centrifugal pump impeller. Seven models for the curved spacer were designed and each model was integrated with the bare impeller separately for simulation analysis. One design was selected for manufacturing with applying subtractive and additive processes. In subtractive manufacturing method, the raw material was removed from a solid shaft by a cutting process under digital control from a computer file. The complexity of the modified impeller spacer profiles required the use of expensive CNC machining with five axis capability.