Large-eddy simulation of the flow in a low-speed centrifugal compressor

2008 ◽  
Vol 56 (8) ◽  
pp. 1271-1280 ◽  
Author(s):  
K. M. Guleren ◽  
A. Turan ◽  
A. Pinarbasi
Keyword(s):  
Large Eddy Simulation ◽  
Centrifugal Compressor ◽  
Low Speed ◽  
Eddy Simulation ◽  
Large Eddy

Large eddy simulation of bed formation in subaqueous bedload

2020 ◽  
Author(s):  
Chenwei Zhao
Keyword(s):  
Large Eddy Simulation ◽  
Bedload Transport ◽  
Main Flow ◽  
Transport Rate ◽  
Surface Elevation ◽  
Computational Time ◽  
Low Speed ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Low Speed Streaks

<p>Large eddy simulation of incompressible turbulent flow over a loose bed of spherical particles are investigated in an open channel. Eulerian and Lagrangian point-particle methods is applied to solve the Navier-Stokes equations and particle motion respectively and the particle-flow interaction is also considered. A new method solving particle-particle collisions is utilized for the first time to reduce the computational time spending on calculating the pairwise distances between particles. A turbulent fluid condition from the experiment of Robert and Uhlman (2001) are chosen of which the corresponding sediment patterns are ‘ripple’. Flow over the formed bed is considered and it is found that double-averaged Reynolds stresses including shear stress and three normal stresses reach their peak values near the bed. However, affected by the movable bed, they decay quickly as the height increases. The flow direction slightly rises over the stoss-side of ripples and falls after the crest and the velocity magnitude of time-averaged flow accelerate and decelerate before and after the crest of ripples as well. Hence, recirculation zones and clockwise vorticity appear at the trough of the bed where kolk boil vortices like hairpins and elongated streamwise vortices is also evident. Coherent structures, in the form of high- and low-speed streaks near the bed are also affected by the bed formation. The near-bed low-speed streaks entrain into the main flow domain over the stoss-side of ripples and the high-speed fluid streaks from the main flow rush toward the bed over the leeside of ripples. The bedload transport rate is well represented by previous empirical formulas. The bed surface elevation changes from upstream to downstream with time and there is a difference in the direction of sediment transport which is obvious three-dimensionality. In addition, it is also found that the bed surface elevation shows a positive correlation with particle streamwise velocity and entrainment rate which means higher bed elevation leads to larger bedload transport rate.</p>

Large Eddy Simulation for a Deep Surge Cycle in a High-Speed Centrifugal Compressor With Vaned Diffuser

2015 ◽  
Vol 137 (10) ◽  
Author(s):  
Ibrahim Shahin ◽  
Mohamed Gadala ◽  
Mohamed Alqaradawi ◽  
Osama Badr
Keyword(s):  
High Pressure ◽  
Large Eddy Simulation ◽  
Centrifugal Compressor ◽  
Pressure Fluctuation ◽  
High Speed ◽  
Computational Study ◽  
Mean Flow ◽  
Vaned Diffuser ◽  
Eddy Simulation ◽  
Large Eddy

This paper presents a computational study for a high-speed centrifugal compressor stage with a design pressure ratio equal to 4, the stage consisting of a splittered unshrouded impeller and a wedged vaned diffuser. The aim of this paper is to investigate numerically the modifications of the flow structure during a surge cycle. The investigations are based on the results of unsteady three-dimensional, compressible flow simulations, using large eddy simulation (LES) model. Instantaneous and mean flow field analyses are presented in the impeller inducer and in the vaned diffuser region through one surge cycle time intervals. The computational data compare favorably with the measured data, from the literature, for the same compressor and operational point. The surge event phases are well detected inside the impeller and diffuser. The time-averaged loading on the impeller main blade is maximum near the trialing edge and near the tip. The amplitude of the unsteady pressure fluctuation is maximum for the flow reversal condition and reaches values up to 70% of the dynamic pressure. The diffuser vane exhibits high-pressure fluctuation from the vane leading edge to 50% of the chord length. High-pressure fluctuation is detected during the forward flow recovery condition as a result of the shock wave that moves toward the diffuser outlet.

Large eddy simulation of unsteady rotor-stator interaction in a centrifugal compressor

1997 ◽  
Author(s):  
Sorin Mitran ◽  
Doru Caraeni ◽  
Daniel Livescu ◽  
Daniel Livescu ◽  
Sorin Mitran ◽  
...  
Keyword(s):  
Large Eddy Simulation ◽  
Centrifugal Compressor ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Rotor Stator Interaction

Predictions of Turbulent Flow for the Impeller of a NASA Low-Speed Centrifugal Compressor

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
K. M. Guleren ◽  
I. Afgan ◽  
A. Turan
Keyword(s):  
Turbulent Flow ◽  
Centrifugal Compressor ◽  
Function Analysis ◽  
Wake Region ◽  
Spectra Analysis ◽  
Low Speed ◽  
Eddy Simulation ◽  
Boussinesq Hypothesis ◽  
Large Eddy ◽  
Stress Variations

The turbulent flow inside a low-speed centrifugal compressor at design condition is investigated using large-eddy simulation (LES) comprising of up to 26×106 computational volume cells. Unlike in the past, the current study’s special emphasis is placed on the turbulence field evolution inside the impeller. LES predictions suggest that the Boussinesq hypothesis does not seem to be valid, especially near the exit of the impeller where the blade unloading takes place. Reynolds stress variations show a tendency toward an “axisymmetric expansion” type of turbulence after the impeller exit for which the subgrid-scale stress contribution shows a monotonic decrease. Probability density function analysis for the leakage flow show that instantaneous velocities in the wake region are less intermittent as compared with those in the jet. Time spectra analysis display also another feature that the energy cascade proceeds at a higher rate and lasts longer in the wake region than in the tip jet region.

Assessing Wall-Modeled Large-Eddy Simulation for Low-Speed Flows with Heat Transfer

AIAA Journal ◽  
2021 ◽  
pp. 1-10
Author(s):  
Haosen H. A. Xu ◽  
Xiang I. A. Yang ◽  
Pedro M. Milani
Keyword(s):  
Heat Transfer ◽  
Large Eddy Simulation ◽  
Low Speed ◽  
Eddy Simulation ◽  
Large Eddy
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