Unlike usual turbopump inducers, the axial flow pump tested operates very stably at design flow rate without rotating cavitation nor cavitation surge. Flow visualization suggests that this is because the tip cavity smoothly extends into the flow passage without the interaction with the leading edge of the next blade. However, at low flow rate and low cavitation number, choked surge and rotating choke were observed. Their correlation with the performance curve under cavitation is discussed and their instantaneous flow fields are shown.

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In this paper investigation of two-dimensional wind-tunnel-wall interference is presented. The analysis is carried out using a traditional theoretical tunnel-wall corrections, a potential flow calculation by the vortex distribution method, and 2D Navier-Stokes simulations of the airfoil in the wind tunnel. The traditional theoretical tunnel-wall corrections are compared with the potential flow calculation. The agreement of the lift coefficients is satisfactory for the height-chord ratio larger than 2, and the moment coefficients are agree for the height-chord ratio larger than 4. The results of 2D Navier-Stokes simulations are compared with the small amount of low-speed experimental data available and the agreement is seen to be satisfactory, even for relatively small values of the height-chord ratio.

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In two-dimensional over-expanded supersonicjet, it is reported that the hysteresis phenomenon for the reflection type of shock wave in the jet is occurred under the quasi-steady flow in the recent studies. The transitional pressure ratio between the regular reflection and Mach reflection in the jet is affected by this phenomenon. However, the phenomenon in the over expanded axi-symmetric jet has not been investigated satisfactorily. The purpose of this study is to clarify the hysteresis phenomena for the reflection type of shock wave in the over-expanded axi-symmetric jet experimentally and to discuss the relationship between hysteresis phenomenon and rate of the change of pressure ratio with time. Furthermore, the effect of Mach number at the nozzle exit on hysteresis loop was investigated for two kinds of nozzle.

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The attachment of inducer upstream of main impeller is an effective method to improve the suction performance of turbopump. However, the various types of cavitation instabilities are known to occur even at the designed flow rate as well as in the partial flow rate range. In the present study, we have carried out the flow measurement and CFD analysis to clarify the inlet backflow structure of a 2-bladed flat plate helical inducer at a partial flow rate, where we observe a strong cavitation surge in low suction pressure conditions. It was mainly found that the inlet backflow appearing near the blade tip was associated with the leading edge separation vortex wrapped by the tip leakage flow, and that the flow re-attached immediately forming a separation bubble and the flow just downstream near the blade tip was increased by the radially toward 3-dimensional flow conveying the fluid from the inner region.

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Experimental investigation has been conducted for the rear stator cascade flow in the diagonal flow fan. Stage performance test and the internal flow survey by using five-hole probe was done for the axial-type stator flow , in which hub corner separation is especially focused on. In the design flow rate, a small corner separation region was observed in the hub corner, whereas quantitative growth of hub corner separation was made clear when the flow rate was reduced to 90% or 80% of design flow rate.

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The present paper deals with the effect of the surface roughness on the performance of centrifugal compressors and the applicability of the Computational Fluid Dynamics ( CFD) for the purpose of the quantitatively accurate prediction of the performance deterioration due to the surface roughness. A series of performance testing was conducted on the centrifugal compressor stages, whose wetted surfaces are intentionally roughened by shot-peening surface treatment. Corresponding CFD analyses were conducted. In these analyses the intensity and extent of the surface roughness were appropriately modeled based on the observations and measurements of the surface characteristics. Based on the above analyses and comparisons with experimental data, following conclusions were obtained. Reasonable quantitative agreements between experimental data and CFD analyses were obtained on centrifugal compressor stages. CFD analyses with wall roughness can be used to estimate the detrimental effect of the surface roughness.

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