الفهرس 
VIBRATION ANALYSIS BACKGROUNDOnly 14 pages are availabe for public view
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Abstract
Pumping system is the most important water system supplying water for irrigation and removing subsurface water for drainage purposes. The need to match fluctuations in the flow rate demand, water levels, and control energy costs, arise the need to implement pumps of Variable Speed Drives (VSD). Pumps with variable speed drives improves operation and performance of pumping system and allows them to operate efficiently and hence save energy over the required range of field operation. Variation of speed may considerably lead to coinciding of stationary speed with the critical speed. For pumps with VSD applications, the excitation frequencies become variable and the likelihood of encountering a resonance condition within the continuous operating speed range is greatly increased. This thesis directed to develop a proper scheme to investigate and analyze the dynamic performance of a variable speed pump and its sensitivity to speed variation. The tests are carried out in the laboratory on a centrifugal pump unit of 5.0 kW power and 3000 rpm (50 Hz) rated speed with a variable speed drive. Tests are done at different operating speeds. Forced vibration measurements are taken at different operating speeds to determine vibration levels and exciting frequencies. Experimental modal testing is carried out at different condition to simulate the design and installation case. Operational deflection frequency response analysis is done to simulate the actual operating conditions. Finite element models are created to predict the dynamic characteristics of the pump unit. Firstly, the model is built to predict the natural frequencies and mode shapes for the internal rotating elements of the pump unit as a substructure. Then, the external casing of the pump unit is built. Finally, the whole pump unit including rotating elements and casings is modeled to simulate the design phase for free supporting condition. Finite element analysis of the internal parts of the iii pump unit was obtained and can be used to clarify what is going on inside the pump unit. Rotor dynamic analysis of the centrifugal pump rotor was conducted to calculate the critical speed of the rotor though out plotting Campbell diagram. Hydraulic tests are carried out at different operating speeds. Measurements of flow rate, total head, and electric power consumption are taken at every speed to obtain the full performance curve. The best efficiency point is determined at every speed.