Experimental and numerical investigation of the transient characteristics and volute casing wall pressure fluctuations of a single-blade pump

2018 ◽  
Vol 233 (2) ◽  
pp. 280-291 ◽  
Author(s):  
Steffen Melzer ◽  
Tim Müller ◽  
Stephan Schepeler ◽  
Tobias Kalkkuhl ◽  
Romuald Skoda
Keyword(s):  
Flow Field ◽  
Boundary Conditions ◽  
Numerical Simulations ◽  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Pressure Amplitude ◽  
Centrifugal Pumps ◽  
Transient Pressure ◽  
Time Step ◽  
Wall Pressure Fluctuations

In contrast to conventional multiblade centrifugal pumps, single-blade pumps are characterized by a significant fluctuation of head and highly transient and circumferentially nonuniform flow field even in the best-efficiency point. For a contribution to a better understanding of the flow field and an improvement of numerical methods, a combined experimental and numerical study is performed with special emphasis on the analysis of the transient pressure field. In an open test rig, piezoresistive pressure sensors are utilized for the measurement of transient in- and outflow conditions and the volute casing wall pressure fluctuations. The quality of the numerical simulations is ensured by a careful adoption of the real geometry details in the simulation model, a grid study and a time step study. While the power curve is well reproduced by the numerical simulations, the time-averaged head is systematically overpredicted, probably due to underestimation of losses. Transient pressure boundary conditions for the numerical simulation show a better prediction of the measured pressure amplitude than constant boundary conditions, whereas the time-averaged head prediction is not improved. For a more accurate prediction of the transient flow field and the time-averaged characteristics, the utilization of scale-resolving turbulence models is assumed to be indispensable.

Effects of convex transverse curvature on wall-bounded turbulence. Part 2. The pressure fluctuations

1994 ◽  
Vol 272 ◽  
pp. 383-406 ◽  
Author(s):  
João C. Neves ◽  
Parviz Moin
Keyword(s):  
Numerical Simulations ◽  
Pressure Fluctuations ◽  
Direct Numerical Simulations ◽  
Wall Pressure ◽  
Wave Number ◽  
Radius Of Curvature ◽  
Number Range ◽  
Transverse Curvature ◽  
Wall Pressure Fluctuations ◽  
Taylor’S Hypothesis

The effects of convex transverse curvature on the wall pressure fluctuations were studied through direct numerical simulations. The flow regime of interest is characterized by large ratio of the shear-layer thickness to the radius of curvature (γ = δ/a) and by small a+, the radius of curvature in wall units. Two direct numerical simulations of a model problem approximating axial flow boundary layers on long cylinders were performed for γ = 5 (a+ ≈ 43) and γ = 11 (a+ ≈ 21). The space-time characteristics of the wall pressure fluctuations of the plane channel flow simulation of Kim, Moin & Moser (1987), which were studied by Choi & Moin (1990) are used to assess the effects of curvature.As the curvature increases the root-mean-square (r.m.s.) pressure fluctuations decrease and the ratio of the streamwise to spanwise lengthscales of the wall pressure fluctuations increases. Fractional contributions from various layers in the flow to the wall r.m.s. pressure fluctuations are marginally affected by the curvature. Curvature-dependent timescales and lengthscales are identified that collapse the high-frequency range of the wall pressure temporal spectra and the high wave-number range of the wall pressure streamwise spectra of flows with different curvatures. Taylor's hypothesis holds for the wall pressure fluctuations with a lower convection velocity than in the planar case.

The Quantification of Internal Noise Levels and Wall Pressure Spectra in Industrial Gas Pipelines

1991 ◽  
Author(s):  
M. P. Norton ◽  
A. Pruiti
Keyword(s):  
Prediction Models ◽  
Transmission Loss ◽  
Pressure Fluctuations ◽  
Internal Noise ◽  
Wall Pressure ◽  
Gas Pipelines ◽  
Noise Levels ◽  
Empirical Prediction ◽  
Wall Pressure Fluctuations ◽  
Semi Empirical

Abstract This paper addresses the issue of quantifying the internal noise levels/wall pressure fluctuations in industrial gas pipelines. This quantification of internal noise levels/wall pressure fluctuations allows for external noise radiation from pipelines to be specified in absolute levels via appropriate noise prediction models. Semi-empirical prediction models based upon (i) estimated vibration levels and radiation ratios, (ii) semi-empirical transmission loss models, and (iii) statistical energy analysis models have already been reported on by Norton and Pruiti 1,3 and are not reported on here.

Prediction of Elbow Flow Dynamics Using Correlated Wall Pressure Data

2018 ◽  
Author(s):  
André Baramili ◽  
Ludovic Chatellier ◽  
Laurent David ◽  
Loïc Ancian
Keyword(s):  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Partial Least Square ◽  
Flow Dynamics ◽  
Least Square ◽  
Partial Least Square Regression ◽  
Multiple Time ◽  
Duct Flow ◽  
Flow Induced Vibration ◽  
Wall Pressure Fluctuations

The present study focuses on the analysis of the flow-induced vibration phenomenon typically encountered on piping systems containing an elbow. The correlation between the turbulent flow through the elbow and the dynamic forcing it yields on the piping walls was assessed experimentally. A closed water loop containing a transparent elbow was designed in order to develop fully turbulent duct flow condition. Particle Image Velocimetry (PIV) was applied in the transparent zone in order to provide unsteady data on the flow dynamics through the elbow; simultaneously, wall pressure fluctuations were measured on and around the elbow. Several flow configurations were tested in order to obtain a large coupled database linking the flow features to the resulting dynamic excitation on the walls. Finally, Partial Least Square Regression (PLSR) was applied in order to harvest the correlated information contained in multiple pressure signals at multiple time-delays and build a relationship capable of estimating the temporal evolution of the velocity field using a set of measured wall pressure signals.

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