scholarly journals Large-Eddy Simulation of Unsteady Flow in a Mixed-Flow Pump

2003 ◽  
Vol 9 (5) ◽  
pp. 345-351 ◽  
Author(s):  
Chisachi Kato ◽  
Hiroshi Mukai ◽  
Akira Manabe
Keyword(s):  
Large Eddy Simulation ◽  
Unsteady Flow ◽  
Mixed Flow ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Flow Pump

Large Eddy Simulation of Unsteady Flow in a Mixed Flow Pump Guide Vane

2013 ◽  
Vol 444-445 ◽  
pp. 555-560 ◽  
Author(s):  
Yi Bin Li ◽  
Ren Nian Li ◽  
Xiu Yong Wang
Keyword(s):  
Large Eddy Simulation ◽  
Unsteady Flow ◽  
Pressure Fluctuation ◽  
Guide Vane ◽  
Suction Surface ◽  
Mixed Flow ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Small Flow ◽  
Flow Pump

In order to investigate the characteristics of unsteady flow in a mixed flow pump guide vane under the small flow conditions, several indicator points in a mixed flow pump guide vane was set, the three-dimensional unsteady turbulence numerical value of the mixed flow pump which is in the whole flow field will be calculated by means of the large eddy simulation (LES), sub-grid scale model and sliding mesh technology. The experimental results suggest that the large eddy simulation can estimate the positive slope characteristic of head & capacity curve. And the calculation results show that the pressure fluctuation coefficients of the middle section in guide vane inlet will decrease firstly and then increase. In guide vane outlet, the pressure fluctuation coefficients of section will be approximately axially symmetrical distribution. The pressure fluctuation minimum of section in guide vane inlet is above the middle location of the guide vane suction surface, and the pressure fluctuation minimum of section in which located the middle and outlet of guide vane. When it is under the small flow operating condition, the eddy scale of guide vane is larger, and the pressure fluctuation of the channel in guide vane being cyclical fluctuations obviously which leads to the area of eddy expanding to the whole channel from the suction side. The middle of the guide vane suction surface of the minimum amplitude pressure fluctuation to which the vortex core of eddy scale whose direction of fluids rotation is the same to impeller in the guide vane adhere.

Large-Eddy Simulation of a Mixed-Flow Pump at Off-Design Conditions

2015 ◽  
Vol 137 (10) ◽  
Author(s):  
Antonio Posa ◽  
Antonio Lippolis ◽  
Elias Balaras
Keyword(s):  
Large Eddy Simulation ◽  
Flow Rate ◽  
Design Flow ◽  
Immersed Boundary ◽  
Mixed Flow ◽  
Eddy Simulation ◽  
Image Velocimetry ◽  
Large Eddy ◽  
The One ◽  
Flow Pump

The flow through turbopumps is characterized by highly unsteady phenomena at part load conditions, involving large separation and generation of vortical structures. This behavior is strongly dependent on the interaction between rotating and steady parts, which is significantly modified, compared to the one at the design flow rate. Therefore, at off-design conditions, eddy-resolving computations are more suitable to analyze the complex physics occurring inside turbomachinery channels. In this work the large eddy simulation (LES), coupled with an immersed-boundary (IB) method, is utilized to study a mixed-flow pump at a reduced flow rate, equivalent to 40% of the nominal one. The present approach has been already validated in a previous study, where a satisfactory agreement with two-dimensional (2D) particle image velocimetry (PIV) experiments has been shown at design conditions. In this paper a comparison with the LES results at the optimal flow rate is also proposed, in order to understand the important modifications of the flow occurring at part loads.

scholarly journals Large-Eddy Simulation of Unsteady Flow in a Mixed-Flow Pump

2003 ◽  
Vol 9 (5) ◽  
pp. 345-351 ◽  
Author(s):  
Chisachi Kato ◽  
Hiroshi Mukai ◽  
Akira Manabe
Keyword(s):  
Large Eddy Simulation ◽  
Flow Rate ◽  
Tangential Velocity ◽  
Low Flow ◽  
Flow Rate Ratio ◽  
Mixed Flow ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Specific Speed ◽  
Flow Pump

This article describes the large-eddy simulation (LES) of the internal flows of a high–specific-speed, mixed-flow pump at low flow-rate ratios over which measured head-flow characteristics exhibit weak instability. In order to deal with a moving boundary interface in the flow field, a form of the finite-element method in which overset grids are applied from multiple dynamic frames of reference has been developed. The method is implemented as a parallel program by applying a domain-decomposition programming model.The predicted pump heads reproduce the instability and agree fairly well with their measured equivalents, although the predicted stall takes place at a flow-rate ratio that is a few percentage points lower than the measurements. The phase-averaged distributions of the meridional- and tangential velocity components at the impeller's inlet and exit cross sections were also compared with those measured by laser-Doppler velocimetry. Reasonably good agreements have been obtained between the computed and measured profiles. The developed LES program thus seems to be a promising design tool for a high–specific-speed, mixed-flow pump, particularly for off-design evaluations.

Prediction of Pressure Fluctuation on a Vehicle by Large Eddy Simulation

2015 ◽  
Author(s):  
Yoshinobu Yamade ◽  
Chisachi Kato ◽  
Akiyoshi Iida ◽  
Shinobu Yoshimura ◽  
Keiichiro Iida
Keyword(s):  
Structural Analysis ◽  
Large Eddy Simulation ◽  
Unsteady Flow ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Sound Fields ◽  
Eddy Simulation ◽  
Acoustical Analysis ◽  
Wide Range ◽  
Large Eddy

The objective of this study is to predict accurately interior aeroacoustics noise of a car for a wide range of frequency between 100 Hz and 4 kHz. One-way coupled simulations of computational fluid dynamics (CFD), structural analysis and acoustical analysis were performed to predict interior aeroacoustics noise. We predicted pressure fluctuations on the outer surfaces of a test car by computing unsteady flow around the car as the first step. Secondary, the predicted pressure fluctuations were fed to the subsequent structural analysis to predict vibration accelerations on the inner surfaces of the test car. Finally, acoustical analysis was performed to predict sound fields in the test car by giving vibration accelerations computed by the structural analysis as the boundary conditions. In this paper, we focus on the unsteady flow computations, which is the first step of the coupled simulations. Large Eddy Simulation (LES) was performed to predict the pressure fluctuations on the outer surfaces of the test car. We used the computational mesh composed of approximately 5 billion hexahedral grids with a spatial resolution of 1.5 mm in the streamwise and spanwise directions to resolve the dynamics of the small vortices in the turbulence boundary layer. Predicted and measured pressure fluctuation at several sampling points on the surface of the test car were compared and they matched well in a wide range of frequency up to 2 kHz.

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