英文文献Investigation into pressure pulsations in a centrifugal pump using numerical methods supported by industrial testsR.Spence and J.Amaral-Teixeira ABSTRACT The operation of centrifugal pumps can generate instabilities and pressure pulsations that may be detrimental to the integrity and performance of the pump. In the present study a numerical investigation of the time variation of pressure within a complete pump was undertaken. A range of parameters and three flow rates were investigated and the pulsations were extracted at 15 different locations covering important pump locations experiencing the largest pulsation levels. It was also note that monitoring pulsations at the top dead centre of the pump volute casing would provide a better indication of internal pump pulsations than monitoring at the discharge.1、 Introduction Centrifugal pumps have been developed and refined over many years. In practice the design of both the impeller and volute are complex, with numerous geometrical parameters being required to identify a design that will form a hydraulically efficient pump. Even with tried designs it is well known that the operation of rotodynamic pump can result in the generation of the design process used; the final decision regarding the suitability of any significantly new pump design is usually made following physical testing. These tests are often expensive in term of time and resources, for example due to the manufacturing of pattern equipment, the prototype pump itself as well as the assembly and the use of test facilities. Gradually, pump manufacturers are turning to computational techniques to study design features.Typically these investigations are conducted with a view to reducing, or eliminating the number of tests conducted and to highlight any undesirable design characteristics at an early stage. Although commercial CFD packages have been used to predict time dependent pressure pulsations, computational facilities seem to have limited most of that work to simulating the volute and impeller interactions only, without the suction inlet branch and leakage flow paths being considered. The current work aims to improve the quality and scope of previous work related to pressure pulsations by performing simulations involving the complete hydraulic pump geometry.The numerical model incorporates all of the major flow paths in a pump encompassing the suction inlet, impeller, leakage pathways and the volute casing. The work focuses on a reduced scale version of a high energy impeller in a double entry, single stage pump arrangement. The understanding of pressure pulsations by pump manufacturers seems surprisingly limited. No official standards exist for safe levels of pressure pulsations in pumps; the only industry adopted guideline is a guarantee of less than 3% variation in the pump outlet pressure. Yet, it is not known whether a limitation of 3% variation in the discharge corresponds to a safe limit at other locations within a pump. Therefore a detailed assessment of preesure pulsations in both the impeller and volute has been performed to guarantee for other critical parts of the pump. The analysis covers three flow rates over a flow range extending from the pump duty condition (1.00oQn) to a common pump minimum operating point of 25% of the duty condition (0.25oQn)The analyses presented here are part of a large parametric study investigating the effect of internal geometry on pressure pulsations within the pump. Due to the constrains involved in such a large study, one additional aim of this work was to show that a reasonable estimate of pressure pulsations and trends in pressure pulsations can be achieved, for differing pump geometries, in a reasonable time frame by numerical means.2、 Experimental Investigation Some experimental results were available to one of the authors from industrial tests performed to examine pressure pulsations in a reduced scale contract pump. This experimental work performed a number of years before the numerical analyses. The pump received fluid from a closed system, such that the pump was situated with a bend 3.5 diameters upstream and a second bend 4 diameters downstream. Directly following the upstream bend, flow straighteners were fitten in order to reduce the flow effects caused by the bend on the inflow to the pump. Ten Z type Kistler pressure tappings were mounted on the pump. Pressure tappings were used to collect data at various stationary locations around the pump. Holes were drilled at specific locations around the pump and tubes were used to connect the pressure transducers to each location. The path distance from the tapping point to the transducer was kept as short as possible (10-15omm) to ensure that any resonant frequencies caused by the path distance are above the measured range.One Z type Entran pressure transducer was utilized in the experimental tests. This transducer was mounted in the impeller shroud 15omm behind the suctio