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The key fluidic component of a pneumatic pulse jet pump is a reverse flow diverter (RFD), which consists of a driving nozzle and diffuser, with a suction gap separating the two. Because the suction gap is open to the storage tank, the mass flow through a RFD is not constant, and it is difficult to determine its pumping capacity in the reverse flow mode. For symmetrical RFDs, we experimentally investigated the effects of the driving nozzle exit diameterd0, suction gap lengthdc, liquid viscosity μ, and pipeline load impedance on the RFDs’ performance in the reverse flow mode. A dimensionless performance curve insensitive tod0,dc, μ, and the pipeline load impedance was found based on these experimental data. The output flows of RFDs with suction factors higher than 0.9 could be determined using this dimensionless performance curve. [ABSTRACT FROM AUTHOR]

Comparing to pumps with moving parts water-jet pumps have a lower efficiency and surface roughness is an important factor for these types of pumps. The aim of this simulation study is to numerically determine how the scaling-up, downscaling and change in the absolute and relative roughness would impact on the energy efficiency of the pumps, using a commercial computational fluid dynamics (CFD) solver ANSYS FLUENT. In order to select the turbulence model that produces the predictions closest to the actual data from four turbulence models, a preliminary study was conducted on a full-scale jet pump. Using the transition SST model, which gives the best results among all the models, the effects of scale and roughness on the performance of the pumps were investigated in the scale range from 1/4 to 20/1. The optimum efficiencies for different area ratios over a wide range were determined according to the scale and size of roughness. It was seen that the efficiency increases significantly up to a given scale size at a constant absolute roughness, while it is generally independent of the scale size at constant relative roughness. The relative efficiency for the area ratio 5.92 reduces to 60% at the relative roughness value of 0.05. Moreover, CFD appears to be the most appropriate tool for model studies of jet pumps. [ABSTRACT FROM AUTHOR]

Pneumatic pulse jet pumps are air-powered, low-maintenance devices useful for delivering hazardous liquids. A key component in these pumps is the reverse-flow diverter (RFD), consisting of a nozzle and a diffuser. Despite several decades of practical application, no clear guidelines exist for RFD design during the reverse-flow portion of the pumping cycle. We experimentally investigated the effects of diffuser entrance/nozzle exit area ratio, suction gap length, and diffuser divergence angle on RFD flow and pressure. The results were used to derive two dimensionless performance coefficients (ξM = 0.50ϕ0.38 and q = A + B · exp[-Euout/(C · Eu0)] + D · exp[-Euout/(E · Eu0)]) and to develop a series of design guidelines for RFDs in reverse-flow mode. [ABSTRACT FROM PUBLISHER]