CFD Computation of Water Injection on Lift and Drag of a Hydrofoil With Cavitation

2009 ◽  
Author(s):  
Mohammad J. Izadi ◽  
Pejman Hazegh Fetratjou
Keyword(s):  
Numerical Simulation ◽  
Drag Coefficient ◽  
Turbulence Model ◽  
Mass Flow ◽  
Bubble Dynamics ◽  
Turbulent Viscosity ◽  
Lift Coefficient ◽  
Water Injection ◽  
Cloud Cavitation ◽  
Lift And Drag

The occurrence of cavitation on hydrofoils can cause undesirable effects such as a decrease in lift, and an increase in drag. The goal of this research is to investigate the effect of water injection on the lift and drag coefficient of a hydrofoil. An unsteady uniform flow of water over a 3-D NACA hydrofoil is numerically simulated. For the numerical simulation of a cavitating flow, a bubble dynamics cavitation model is used to describe the generation and evaporation of the vapor phase. The RNG k-ε turbulence model is used as a turbulence model. A modification to the turbulent viscosity, which is necessary to simulate the cloud cavitation, is implemented. This simulation is implemented for various angles of attack and different injection velocities. Comparison between experimental data and the numerical simulation obtained here is done to validate the numerical results. The results presented show that, as the mass flow of the water injection increases, the lift coefficient decreases for all angles of attack but the rate of this decrease decreases for higher angles of attack. As the mass flow rate increases, the drag coefficient increases more for small angles of attack, and decreases for larger angles of attack, and the injection does not change the drag coefficient as much for large angles of attack. In general, water injection does not increase the lift and does not decrease the drag for all angles of attack.

CFD of Water Injection on Lift and Drag of a 2-D Hydrofoil With Cavitation

2009 ◽  
Author(s):  
Mohammad J. Izadi
Keyword(s):  
Numerical Simulation ◽  
Drag Coefficient ◽  
Turbulence Model ◽  
Mass Flow ◽  
Bubble Dynamics ◽  
Turbulent Viscosity ◽  
Lift Coefficient ◽  
Water Injection ◽  
Cloud Cavitation ◽  
Lift And Drag

Undesirable effects such as a decrease in lift and an increase in drag can be the result of the occurrence of cavitation on hydrofoils. The goal of this research is to investigate the effect of water injection on the lift and drag coefficient of a 2-D hydrofoil. An unsteady uniform flow of water over a NACA hydrofoil (2D) is numerically simulated. For the numerical simulation of a cavitating flow, a bubble dynamics cavitation model is used to describe the generation and evaporation of the vapor phase. The RNG k-ε turbulence model is used as a turbulence model. To simulate the cloud cavitation, a modification to the turbulent viscosity which is necessary, is implemented. This simulation is done for various angles of attack and different injection velocities. Comparison between experimental data and the numerical simulation obtained here is done to validate the numerical results. The results presented here show that, as the mass flow of the water injection increases, the lift coefficient decreases for all angles of attack but the rate of this decrease decreases for higher angles of attack. As the mass flow rate increases, the drag coefficient increases more for small angles of attack and decrease for larger angles of attack.

Numerical Analysis of Water Suction Effect on Lift and Drag Coefficient of a Hydrofoil With Cavitation

2009 ◽  
Author(s):  
Mohammad J. Izadi
Keyword(s):  
Drag Coefficient ◽  
Mass Flow ◽  
Static Pressure ◽  
Turbulent Viscosity ◽  
Lift Coefficient ◽  
Vapor Bubbles ◽  
Cloud Cavitation ◽  
Lift And Drag ◽  
Lift And Drag Coefficient ◽  
Unsteady Cavitating Flow

Cavitation is the formation of the vapor bubbles within a liquid where the flow dynamics, cause the local static pressure to drop below the vapor pressure. This phenomenon can cause undesirable effects on the hydrofoils such as a decrease in the lift and an increase in the drag. In the present study, the unsteady cavitating flow over a 3-D hydrofoil is numerically simulated. The purpose of this work is to investigate the effect of the upper surface suction in the cavitation area on the lift and drag coefficients of a hydrofoil. An unsteady uniform flow of water over a 3-D NACA hydrofoil is numerically simulated. The full cavitation model along with the RNG k-ε turbulence model is implemented. A modification to the turbulent viscosity, which is necessary to simulate the cloud cavitation, is implemented. The simulation is implemented for various angles of attack and various suction velocities. Comparison between some experimental data and the numerical simulation obtained here is done in order to validate the numerical results. The results obtained here show that, as the mass flow of the water suction increases, the drag coefficient is decreased for large angles of attack, but for small angles of attack it does not change as much. As the mass flow of the water suction increases, the lift coefficient is decreased for small angles of attack and for larger angles of attack the lift coefficient is increased.

Numerical Simulation of the Three Component Coefficients of Bridge

2012 ◽  
Vol 430-432 ◽  
pp. 2004-2007
Author(s):  
Yi Feng Huang ◽  
Ji Xin Yang
Keyword(s):  
Numerical Simulation ◽  
Wind Speed ◽  
Drag Coefficient ◽  
Turbulence Model ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Moment Coefficient ◽  
Pitch Moment ◽  
Airflow Field ◽  
Bridge Girder

Numerical simulation has been carried out on the airflow field of bridge girder at construction state and completed bridge state under different wind speed and different wind angle of attack. The k-ε two-equation turbulence model is used in the numerical simulation by FLUENT. Variation of the three component coefficients can be obtained. The results show that drag coefficient and lift coefficient gradually becomes smaller and tends to stabilize, while pitch moment coefficient shows the trend of first increased and then reduced as wind speed increases. Drag coefficient and pitch moment coefficient does not change much and lift coefficient gradually becomes smaller with the change of wind angle of attack.

Numerical Simulation of Flow Control on Marine Riser With Attached Splitter Plate

2010 ◽  
Author(s):  
Jiasong Wang ◽  
Hua Liu ◽  
Fei Gu ◽  
Pengliang Zhao
Keyword(s):  
Numerical Simulation ◽  
Flow Control ◽  
Drag Coefficient ◽  
Lift Coefficient ◽  
Splitter Plate ◽  
Hydrodynamic Characteristics ◽  
Control Effect ◽  
Long Time ◽  
Lift And Drag ◽  
Lift And Drag Coefficient

Attaching a splitter plate (SP) on the base of a riser wall is used to control the flow of risers and evaluated by using the CFD technique in this paper. A finite-volume total variation diminishing (TVD) approach for solving incompressible turbulent flow with renormalization group (RNG) turbulence model was used to simulate the hydrodynamic characteristics of the riser system with additional SP for the different aspect ratio of length to diameter L/D. It was shown that the present numerical method has high order of accuracy by comparing with the available experimental and numerical simulation data for typical circular cylinder flow. A riser system attached with SPs of L/D = 0.5∼2.0 for Reynolds number 1000, and 30000 respectively can obviously reduce the lift and drag coefficient and alter the vortex shedding frequency. The mean drag coefficient can be reduced up to 20% and 35% and the maximum lift coefficient can be reduced up to 94% and 97%, for Re = 1000 and 30000, respectively. The lift can be effectively suppressed after a relative long time. L/D = 0.5∼1.0 may be considered as more practical geometries considering the real conditions, which also have good flow control effect.

Analysis of Vortex-Induced Vibration of Riser using Spalart-Almaras Model

2014 ◽  
Vol 69 (7) ◽  
Author(s):  
Jaswar Koto ◽  
Abdul Khair Junaidi
Keyword(s):  
Reynolds Number ◽  
Drag Coefficient ◽  
Vortex Shedding ◽  
Lift Coefficient ◽  
Offshore Structures ◽  
The Other ◽  
Main Concern ◽  
Vortex Induced Vibration ◽  
Simulation Results ◽  
Lift And Drag

Vortex-induced vibration is natural phenomena where an object is exposed to moving fluid caused vibration of the object. Vortex-induced vibration occurred due to vortex shedding behind the object. One of the offshore structures that experience this vortex-induced vibration is riser. The riser experience vortex-induced vibration due to vortex shedding caused by external load which is sea current. The effect of this vortex shedding to the riser is fatigue damage. Vortex-induced vibration of riser becomes the main concern in oil and gas industry since there will be a lots of money to be invested for the installation and maintenance of the riser. The previous studies of this vortex-induced vibration have been conducted by experimental method and Computational Fluid Dynamics (CFD) method in order to predict the vortex shedding behaviour behind the riser body for the determination of way to improve the riser design. This thesis represented the analysis of vortex induced vibration of rigid riser in two-dimensional. The analysis is conducted using Computational Fluid Dynamic (CFD) simulations at Reynolds number at 40, 200, 1000, and 1500. The simulations were performed using Spalart-Allmaras turbulent model to solve the transport equation of turbulent viscosity. The simulations results at Reynolds number 40 and 200 is compared with the other studies for the validation of the simulation, then further simulations were conducted at Reynolds number of 1000 and 1500. The coefficient of lift and drag were obtained from the simulations. The comparison of lift and drag coefficient between the simulation results in this study and experiment results from the other studies showed good agreement. Besides that, the in-line vibration and cross-flow vibration at different Reynolds number were also investigated. The drag coefficient obtained from the simulation results remain unchanged as the Reynolds number increased from 200 to 1500. The lift coefficient obtained from the simulations increased as the Reynolds number increased from 40 to 1500.

Stability Analysis of a Light Aircraft Configuration Using Computational Fluid Dynamics

2012 ◽  
Vol 225 ◽  
pp. 391-396 ◽  
Author(s):  
Mohammed Mahdi ◽  
Yasser A. Elhassan
Keyword(s):  
Numerical Simulation ◽  
Stokes Equations ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Rate Of Change ◽  
Navier Stokes ◽  
Rolling Moment ◽  
Moment Coefficient ◽  
Stability Derivatives ◽  
Lift And Drag

This work aims to simulate and study the flow field around SAFAT-01 aircraft using numerical solution based on solving Reynolds Averaged Navier-Stokes equations coupled with K-ω SST turbulent model. The aerodynamics behavior of SAFAT-01 aircraft developed at SAFAT aviation complex were calculated at different angles of attack and side slip angles. The x,y and z forces and moments were calculated at flight speed 50m/s and at sea level condition. Lift and drag curves for different angles of attack were plotted. The maximum lift coefficient for SAFAT-01 was 1.67 which occurred at angle of attack 16° and Maximum lift to drag ratio (L/D) was 14 which occurred at α=3°, and the zero lift drag coefficient was 0.0342. Also the yawing moment coefficient was plotted for different side slip angles as well as rolling moment. The longitudinal stability derivatives with respect to angle of attack, speed variation (u), rate of pitch (q) and time rate of change of angle of attack were calculated using obtained CFD results. Concerning lateral stability only side slips derivatives were calculated. To validate this numerical simulation USAF Digital DATCOM is used to analyze this aircraft; a comparison between predicted results for this aircraft and Digital DATCOM indicated that this numerical simulation has high ability for predicting the aerodynamics characteristics.

Numerical Simulation Analysis of Car Overtaking on SST Turbulence Model

2014 ◽  
Vol 628 ◽  
pp. 270-274
Author(s):  
Yi Bin He ◽  
Qi Zhi Shen
Keyword(s):  
Numerical Simulation ◽  
Numerical Experiment ◽  
Drag Coefficient ◽  
Turbulence Model ◽  
Simulation Analysis ◽  
Turbulence Models ◽  
Force Coefficient ◽  
Side Force ◽  
Sst Turbulence Model ◽  
Side Force Coefficient

Thebased SST (shear strain transport) turbulence model combines the advantages of and turbulence models and performs well in numerical experiment. In the paper, the SST turbulence model is applied to model vehicle overtaking process with numerical simulation technology. The change graph of drag coefficient and side force coefficient are gained. Analysis of the phenomena is presented at the end.

Drag and lift measurements of solid sports balls in still air

2017 ◽  
Vol 232 (3) ◽  
pp. 255-263 ◽  
Author(s):  
Jeff R Kensrud ◽  
Lloyd V Smith
Keyword(s):  
Surface Roughness ◽  
Wind Tunnel ◽  
Drag Coefficient ◽  
Rough Surface ◽  
Lift Coefficient ◽  
Laboratory Setting ◽  
Air Drag ◽  
High Speeds ◽  
Drag And Lift ◽  
Lift And Drag

The following article considers lift and drag measurements of solid sports balls propelled through still air in a laboratory setting. The balls traveled at speeds ranging from 26 to 134 m/s with spin rates up to 3900 r/min. Light gates measured the speed and location of the balls at two locations from which lift and drag values were determined. Ball roughness varied from polished to rough surface protrusions, that is, seams as high as 1.5 mm. Lift and drag were observed to depend on speed, spin rate, surface roughness, and seam orientation. A drag crisis was observed on smooth balls as well as non-rotating seamed balls with seam heights less than 0.9 mm. The drag coefficient of approximately 0.42 was nearly constant with speed for spinning seamed balls with seam height greater than 0.9 mm. The still air drag coefficient of smooth balls was comparable to wind tunnel drag at low speeds ( Re < 2 × 105) and higher than wind tunnel results at high speeds ( Re > 2 × 105). The lift and drag coefficients of spinning balls increased with increasing spin rate. The lift coefficient of baseballs was not sensitive to ball orientation or seam height.

Effects of surface flow visualisation on aerodynamic loads at low Reynolds number

2015 ◽  
Vol 119 (1215) ◽  
pp. 663-672
Author(s):  
L. W. Traub ◽  
R. Waghela ◽  
E. M. Botero
Keyword(s):  
Drag Coefficient ◽  
Lift Coefficient ◽  
Time History ◽  
Surface Flow ◽  
Flow Visualisation ◽  
Distribution Method ◽  
History Of ◽  
Low Reynolds ◽  
Lift And Drag ◽  
Lift And Drag Coefficient

AbstractIn this article, the effect of on-surface flow visualisation (SVF) techniques on measured loads over an airfoil are explored. Titanium dioxide based mixture effects on the lift and drag coefficient are experimentally quantified at low Reynolds numbers by recording the time history as the patterns evolve and freeze. With statistical comparison based on Student’s t-distribution method, it was determined that the effect on the drag coefficient was minimal but the lift coefficient was slightly attenuated. Additionally, it was observed that at high angles-of-attack the temporal history of the flow as the wind tunnel ramps up may alter the steady-state flow field in the presence of a SFV mixture.

Numerical Simulation of Channel Flows by a One-Equation Turbulence Model

1997 ◽  
Vol 119 (4) ◽  
pp. 885-892 ◽  
Author(s):  
V. I. Vasiliev ◽  
D. V. Volkov ◽  
S. A. Zaitsev ◽  
D. A. Lyubimov
Keyword(s):  
Numerical Simulation ◽  
Turbulent Flows ◽  
Turbine Blade ◽  
Turbulence Model ◽  
Turbulent Viscosity ◽  
Numerical Data ◽  
Equation Model ◽  
Channel Flows ◽  
Parabolic Flows

A one-equation model for turbulent viscosity, previously developed and tested for parabolic flows, is implemented in elliptic cases. The incompressible 2-D and axisymmetric flows in channel with back step as well as the incompressible and compressible 2-D flows in turbine blade cascades are calculated. The CFD procedures, developed for both incompressible and compressible turbulent flows simulation, are described. The results of calculations are compared with known experimental and numerical data.

Sign in / Sign up

Export Citation Format

Share Document