scholarly journals Detached eddy simulation of unsteady cavitation and pressure fluctuation around 3-D NACA66 hydrofoil

2015 ◽  
Vol 19 (4) ◽  
pp. 1231-1234 ◽  
Author(s):  
De-Sheng Zhang ◽  
Hai-Yu Wang ◽  
Lin-Lin Geng ◽  
Wei-Dong Shi
Keyword(s):  
Turbulence Model ◽  
Pressure Fluctuation ◽  
Cavitating Flow ◽  
Numerical Results ◽  
Detached Eddy Simulation ◽  
Cavitation Model ◽  
Cloud Cavitation ◽  
Sheet Cavitation ◽  
Eddy Simulation ◽  
Unsteady Cavitating Flow

The unsteady cavitating flow and pressure fluctuation around the 3-D NACA66 hydrofoil were simulated and validated based on detached eddy simulation turbulence model and a homogeneous cavitation model. Numerical results show that detached eddy simulation can predict the evolution of cavity inception, sheet cavitation growth, cloud cavitation shedding, and breakup, as well as the pressure fluctuation on the surface of hydrofoil. The sheet cavitation growth, detachment, cloud cavitation shedding are responsible for the features of the pressure fluctuation.

scholarly journals DES of the turbulent flow around a circular cylinder of finite height

2016 ◽  
Vol 13 (2) ◽  
pp. 179-188 ◽  
Author(s):  
Aly Hassan Elbatran
Keyword(s):  
Circular Cylinder ◽  
Turbulent Flow ◽  
Turbulence Model ◽  
Model Comparison ◽  
Research Work ◽  
Flow Characteristics ◽  
Numerical Results ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Finite Height

The current research work investigates numerically the turbulent flow field characteristics around three dimensional circular cylinder of finite height at Reynolds number of 43000 using Detached Eddy Simulation (DES) turbulence model. Comparison of the numerical results with the experiment data has been taken place. The results reveals that the DES turbulence model is superior for predicting the flow past the circular cylinder of finite height at this Re. The numerical results of this study show the great potential of the presented DES for investigating the complicated flow structure in this case. DES is very accurate for predicting the flow characteristics in many sophisticated cases and can reduce the computational efforts during the simulation process in comparison with Large Eddy Simulation (LES) turbulence mathematical model. 

Scale Effects on the Cavitation Development in Fluid Machinery

2011 ◽  
Author(s):  
Weiping Yu ◽  
Xianwu Luo ◽  
Yao Zhang ◽  
Bin Ji ◽  
Hongyuan Xu
Keyword(s):  
Turbulence Model ◽  
High Speed ◽  
Scale Effects ◽  
Design Procedure ◽  
Leading Edge ◽  
Characteristic Size ◽  
Cavitation Model ◽  
Fluid Machinery ◽  
Cloud Cavitation ◽  
Sheet Cavitation

The prediction of cavitation in a design procedure is very important for fluid machinery. However, the behaviors of cavitation development in the flow passage are believed to be much different due to scale effects, when the characteristic size varies greatly for fluid machines such as pumps, turbines and propellers. In order to understand the differences in cavitation development, the evolution of cavity pattern in two hydro foils were recorded by high-speed video apparatus. Both foils have the same section profile, and their chord lengths are 70mm and 14mm respectively. For comparison, the cavitating flows around two foils were numerically simulated using a cavitation model based on Rayleigh-Plesset equation and SST k-ω turbulence model. The experiments depicted that for both hydro foils, there was attached sheet cavitation near the leading edge, which separated from the rear part of the cavity and collapsed near the foil trailing edge. There was clear cloud cavitation in the case of the mini foil. The results also indicated that the numerical simulation captured the cavitation evolution for the ordinary foil quite well compared with the experiments, but could hardly predict the cloud cavitation for the mini foil. Thus, it is believed that both the cavitation model and the turbulence model should be carefully treated for the scale effect on cavitation development in fluid machinery.

Hybrid RANS–LES Modeling for Unsteady Cavitating Flow Simulation

2012 ◽  
Vol 152-154 ◽  
pp. 1187-1190 ◽  
Author(s):  
Guo Hua Gao ◽  
Jing Zhao ◽  
Fei Ma ◽  
Wei Dong Luo
Keyword(s):  
Flow Simulation ◽  
Cavitating Flow ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Experiment Validation ◽  
The One ◽  
Water Tunnel Experiment ◽  
Des Model ◽  
Better Than ◽  
Unsteady Cavitating Flow

A typical hybrid RANS-LES approach, DES (Detached Eddy Simulation), was introduced into cavitating flow simulation in this paper. The applicability of two DES models, including one equation DES model and SST k-ω DES model, and standard k-ε model was analyzed through experimental data of a water tunnel experiment. Validation results illustrate that the precision of DES method depends on the RANS model used and the length scale used to distinguish LES zone and RANS zone. The SST k-ω DES method can well predict cavitating flow. The averaged results gained through this model are better than those of standard k-ε or one equation DES model. By comparison, the one equation DES model shows little advantage than standard k-ε model to simulate cavitating flow.

Numerical Simulation of Cavity Shedding from a Three-Dimensional Twisted Hydrofoil and Induced Pressure Fluctuation by Large-Eddy Simulation

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Xianwu Luo ◽  
Bin Ji ◽  
Xiaoxing Peng ◽  
Hongyuan Xu ◽  
Michihiro Nishi
Keyword(s):  
Large Eddy Simulation ◽  
Pressure Fluctuation ◽  
Three Dimensional ◽  
Cavitating Flow ◽  
Numerical Results ◽  
Central Plane ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Cavity Shedding ◽  
Twisted Hydrofoil

Simulation of cavity shedding around a three-dimensional twisted hydrofoil has been conducted by large eddy simulation coupling with a mass transfer cavitation model based on the Rayleigh-Plesset equation. From comparison of the numerical results with experimental observations, e.g., cavity shedding evolution, it is validated that the unsteady cavitating flow around a twisted hydrofoil is reasonably simulated by the proposed method. Numerical results clearly reproduce the cavity shedding process, such as cavity development, breaking-off and collapsing in the downstream. Regarding vapor shedding in the cavitating flow around three-dimensional foils, it is primarily attributed to the effect of the re-entrant flow consisting of a re-entrant jet and a pair of side-entrant jets. Formation of the re-entrant jet in the rear part of an attached cavity is affected by collapse of the last shedding vapor. Numerical results also show that the cavity shedding causes the surface pressure fluctuation of the hydrofoil and the force vibration. Accompanying the cavity evolution, the wave of pressure fluctuation propagates in two directions, namely, from the leading edge of the foil to the trailing edge and from the central plane to the side of the hydrofoil along the span. It is seen that the large pressure fluctuation occurs at the central part of the hydrofoil, where the flow incidence is larger.

Large eddy simulation of turbulent cavitating flow in a Venturi-type section with special emphasis on LES errors and pressure fluctuation analyses

2021 ◽  
Vol 35 (26) ◽  
pp. 2150440
Author(s):  
Linfeng Deng ◽  
Yun Long ◽  
Bin Ji ◽  
Xinping Long
Keyword(s):  
Large Eddy Simulation ◽  
Pressure Fluctuation ◽  
Cavitating Flow ◽  
Numerical Results ◽  
Fluctuation Analysis ◽  
Simulation Accuracy ◽  
Modified Model ◽  
Eddy Simulation ◽  
Large Eddy ◽  
The Relationship

In this study, large eddy simulation (LES) coupled with the homogeneous cavitation model is used to simulate the turbulent cavitating flow in the venturi with special emphasis on LES errors and pressure fluctuation analysis. The numerical results accurately predict the quasi-periodic behavior and frequency characteristics of the cavitation by comparing them with the experimental observations. The modified one-dimensional model is utilized here to figure out the relationship between cavitation and pressure fluctuation. A good coincidence between the predicted and monitored pressure is obtained to validate the consideration of the geometric and flow factors in the modified model. Further analysis indicated that the cavity volume acceleration is the main source of cavitation excited pressure fluctuation. Moreover, LES Verification and Validation (V&V) are involved to quantify the errors and uncertainties of the numerical results. It is found that the large magnitude of the errors often emerges in the region where the re-entrant jet and shedding cavity occurs, which demonstrates the influence of cavitation on the simulation accuracy. The modeling error has a larger magnitude than the numerical error and both often show opposite signs. To better understand the influence of cavitation on LES V&V, the interaction between cavitation and vortex is also discussed further.

Investigation of Aerator Flow Pressure Fluctuation Using Detached Eddy Simulation with VOF Method

2022 ◽  
Vol 148 (1) ◽  
Author(s):  
Zhengwen Li ◽  
Zhaowei Liu ◽  
Haoran Wang ◽  
Yongcan Chen ◽  
Ling Li ◽  
...  
Keyword(s):  
Pressure Fluctuation ◽  
Vof Method ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Flow Pressure

Modeling of unsteady structure of sheet/cloud cavitation around a two-dimensional stationary hydrofoil

2015 ◽  
Vol 231 (3) ◽  
pp. 455-469 ◽  
Author(s):  
Feng Hong ◽  
Jianping Yuan ◽  
Banglun Zhou ◽  
Zhong Li
Keyword(s):  
Volume Fraction ◽  
Cavitating Flow ◽  
Wake Flow ◽  
Two Dimensional ◽  
Cavitating Flows ◽  
Cavitation Model ◽  
Ansys Fluent ◽  
Cloud Cavitation ◽  
Lift And Drag ◽  
Multi Phase

Compared to non-cavitating flow, cavitating flow is much complex owing to the numerical difficulties caused by cavity generation and collapse. In the present work, cavitating flow around a two-dimensional Clark-Y hydrofoil is studied numerically with particular emphasis on understanding the cavitation structures and the shedding dynamics. A cavitation model, coupled with the mixture multi-phase approach, and the modified shear stress transport k-ω turbulence model has been developed and implemented in this study to calculate the pressure, velocity, and vapor volume fraction of the hydrofoil. The cavitation model has been implemented in ANSYS FLUENT platform. The hydrofoil has a fixed angle of attack of α = 8° with a Reynolds number of Re = 7.5 × 105. Simulations have been carried out for various cavitation numbers ranging from non-cavitating flows to the cloud cavitation regime. In particular, we compared the lift and drag coefficients, the cavitation dynamics, and the time-averaged velocity with available experimental data. The comparisons between the numerical and experimental results show that the present numerical method is capable to predict the formation, breakup, shedding, and collapse of the sheet/cloud cavity. The periodical formation, shedding, and collapse of sheet/cloud cavity lead to substantial increase in turbulent velocity fluctuations in the cavitation regimes around the hydrofoil and in the wake flow.

Influence of wall roughness on the static performance and pressure fluctuation characteristics of a double-suction centrifugal pump

2018 ◽  
Vol 232 (7) ◽  
pp. 826-840 ◽  
Author(s):  
Zhifeng Yao ◽  
Min Yang ◽  
Ruofu Xiao ◽  
Fujun Wang
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Design Flow ◽  
Experimental Investigations ◽  
Wall Roughness ◽  
Detached Eddy Simulation ◽  
Centrifugal Pumps ◽  
Eddy Simulation ◽  
Static Performance

The unsteady flow field and pressure fluctuations in double-suction centrifugal pumps are greatly affected by the wall roughness of internal surfaces. To determine the wall roughness effect, numerical and experimental investigations were carried out. Three impeller schemes for different wall roughness were solved using detached eddy simulation, and the performance and pressure fluctuations resolved by detached eddy simulation were compared with the experimental data. The results show that the effects of wall roughness on the static performance of a pump are remarkable. The head and efficiency of the tested double-suction centrifugal pump are raised by 2.53% and 6.60% respectively as the wall roughness is reduced by means of sand blasting and coating treatments. The detached eddy simulation method has been proven to be accurate for the prediction of the head and efficiency of the double-suction centrifugal pump with roughness effects. The influence of the roughness on pressure fluctuation is greatly dependent on the location relative to the volute tongue region. For locations close to the volute tongue, the peak-to-peak value of the pressure fluctuations of a wall roughness of Ra = 0.10 mm may be 23.27% larger than the case where Ra = 0.02 mm at design flow rate.

Numerical Simulation and Vorticity Analysis of Cavitating Flow Around a Marine Propeller Behind the Hull

2019 ◽  
Author(s):  
Yun Long ◽  
Chengzao Han ◽  
Bin Ji ◽  
Xinping Long ◽  
Zhirong Zhang
Keyword(s):  
Experimental Data ◽  
Pressure Fluctuations ◽  
Relative Vorticity ◽  
Cavitating Flow ◽  
Numerical Results ◽  
Tip Vortex ◽  
Marine Propeller ◽  
Thrust Coefficient ◽  
Sheet Cavitation ◽  
Vorticity Transport

Abstract In this paper, the unsteady cavitating turbulent flow around a marine propeller behind the hull is simulated by the k-ω SST turbulence model coupled with the Zwart cavitation model. Three systematic refined structured meshes around the hull and propeller have been generated to study the predicted cavitation patterns and pressure fluctuations. Numerical results indicate that the predicted transient cavitating flow behind the hull wake, including sheet cavitation and tip vortex cavitation, shows quasi-periodic feature and agrees fairly well with the available experimental data. The deviations of pressure fluctuations between experimental data and numerical results are much small. With mesh refining, the cavitation region and the magnitudes of the calculated pressure fluctuations increase, while the differences between two adjacent sets of grids become smaller. In addition, the uncertainty of the thrust coefficient obtained by Factor of Safety method is significantly small. Further, the interaction between the cavitation and the vortex by the relative vorticity transport equation is illustrated. Results show that the magnitude of stretching term is obviously larger than the other three terms, and the dilatation term and the baroclinic term both have an important influence on the generation of vortices.

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