Analyzing drag and lift performance in ATV models using CFD.
Project Title : Analyzing drag and lift performance in ATV models using CFD
Objectives :
1)To perform CFD analysis on four different alterations in ATV model.
2)To study Velocity and pressure contours.
3)To study flow trajectories.
4)To find drag and lift forces.
5)To compute drag and lift coefficients.
Introduction:
All Terrain vehicle(ATV) is an vehicle capable of drive on any road or offroad terrain in any condition.these vehicles are generally 4WD.For this project lets consider general model of ATV that runs in Baja Event.It is true that BAJA ATVs have lower top speed (<60Kmph),So drag forces are very less as compared to other resistances acting on vehicle.but since these atvs operate on low power engine and considering the format of event reducing small amount drag force is also beneficiary.
Case Setup:
For CFD analysis take normal air conditions and relative air velocity be 60 kmph.for simplicity neglecting effect of sub components like tire,suspension and transmission and other small components.consider following four cases for CFD analysis.
1)ATV without front upper panel and straight back panels.
2)ATV without front upper panel and curved back panel.
3)ATV with front upper panel and curved back panel.
4)ATV with front upper panel and flat curved back panel.
Procedure :
1)Cleaning light parts to make models suitable for CFD analysis.
2)Defining boundary conditions for CFD.
3)Adjusting meshing to increase accuracy.
4)Solving model.
5)Postprocessing.
Results:
CASE-1.
Velocity Contour (SV)-
Velocity Contour (TV)-
Pressure Contour (SV) -
Pressure Contour (TV) -
Flow Trajectory-
Goal Convergence-
Drag force-
Lift force-
Goal values-
negative value of lift force beacause it is acting downwards.
CASE-2.
Velocity Contour (SV) -
Velocity Contour (TV)-
Pressure Contour (SV) -
Pressure Contour (TV) -
Flow Trajectory -
Goal Convergence -
Drag force -
Lift force -
Goal values -
CASE-3.
Velocity Contour (SV)-
Velocity Contour (TV) -
Pressure Contour (SV) -
Pressure Contour (TV) -
Flow Trajectory -
Goal Convergence -
Drag force-
Lift force-
Goal values-
CASE-4.
Velocity Contour (SV) -
Velocity Contour(TV) -
Pressure Contour (SV)-
Pressure Contour (TV) -
Flow Trajectory -
Goal Convergence -
Drag force -
Lift force-
Goal Values -
Calculation of Drag and lift coeffient -
frontal area =1.2 sq.m
Coefficient of drag is computed by using following formula -
`Cd=(2*Fd)/(ϱ*A*V*V)`
Coefficient of lift is calculated by similar formula by repacing drag force by lift force.
Conclusion -
From results it can be verified that as flow seperation point moves away from body drag resistance decreases.