Aerodynamic Study ofAerodynamic Study ofGo-kart Nose ConesGo-kart Nose Cones

ME450 Introduction to Computer ME450 Introduction to Computer Aided EngineeringAided Engineering

Becker, JoeBecker, Joe

Professor H. U. AkayProfessor H. U. Akay

May 1, 2000May 1, 2000

Example of Enduro Type Go-kartExample of Enduro Type Go-kart Driver lays on his\her backDriver lays on his\her back Race on road courses such Race on road courses such

as Mid-Ohioas Mid-Ohio Speeds are in excess of 80 Speeds are in excess of 80

mph (35.76 m/s)mph (35.76 m/s)

Project ObjectiveProject Objective

Use Finite Element Code (ANSYS: CFD Use Finite Element Code (ANSYS: CFD component FLOTRAN) for the followingcomponent FLOTRAN) for the following– Comparison of two nose cone shapes to Comparison of two nose cone shapes to

determine which is more aerodynamicdetermine which is more aerodynamic– Comparison of two meshing techniquesComparison of two meshing techniques

» Mapped Mesh (Structured Mesh)Mapped Mesh (Structured Mesh)

» Free MeshFree Mesh

Theory: AssumptionsTheory: Assumptions

Steady StateSteady State Newtonian FluidNewtonian Fluid No-slip at Fluid\Solid No-slip at Fluid\Solid

InterfaceInterface TurbulentTurbulent IncompressibleIncompressible IsothermalIsothermal

Property Value Units

Density 1.205 kg/m3

Dynamic Viscosity 1.81E-05 Ns/m2

Characteristic Length 2.44 mFree Stream Velocity 35.76 m/s

Reynolds Number 5.80E+06

Model Setup: Basic GeometryModel Setup: Basic Geometry

Figure 1: Shape 1 in Flow Field

Figure 2: Shape 2 in Flow Field

Basic Geometry ComparisonBasic Geometry Comparison

Similarities Differences

Kart Length 8' (2.43 m) Upper surface of kart between leading

Inlet Length 10' (3.05 m) edge and 32" (0.813 m) from leading edge

Outlet Length 10' (3.05 m) Upper surface of flow field between leading

Min. Flow Height 9' (2.74 m) edge and 12.7' (3.861 m) from leading edge

ANSYS ProcedureANSYS Procedure

Define Keypoints and Create LinesDefine Keypoints and Create Lines Make Areas from Line LoopsMake Areas from Line Loops Mesh AreasMesh Areas Set Boundary ConditionsSet Boundary Conditions Set Solver ParametersSet Solver Parameters Solve FLOTRANSolve FLOTRAN

Shape 1: AreasShape 1: Areas

Shape 2: AreasShape 2: Areas

Mapped MeshesMapped Meshes

Shape 1 Mapped Mesh

Shape 2 Mapped Mesh

Free MeshesFree Meshes

Shape 1 Free Mesh

Shape 2 Free Mesh

Boundary ConditionsBoundary Conditions

All Boundary Conditions were applied to All Boundary Conditions were applied to lineslines

Velocity of 0 m/s applied to ground and all Velocity of 0 m/s applied to ground and all surfaces of kartsurfaces of kart

Velocity of 35.76 m/s in x-direction applied Velocity of 35.76 m/s in x-direction applied to the upper free stream surfaceto the upper free stream surface

Relative Pressure of 0 Pa applied to “outlet”Relative Pressure of 0 Pa applied to “outlet”

FLOTRAN ParametersFLOTRAN Parameters

Steady-state with turbulent solverSteady-state with turbulent solver Fluid properties set to air in standard SIFluid properties set to air in standard SI Solver set to perform 250 iterationsSolver set to perform 250 iterations

ResultsResults

Shape 1 Velocity (m/s)Shape 1 Velocity (m/s)

Shape 2 Velocity (m/s)Shape 2 Velocity (m/s)

Shape 1 Pressure (Pa)Shape 1 Pressure (Pa)

Shape 2 Pressure (Pa)Shape 2 Pressure (Pa)

Shape 1 Turbulent KE (J)Shape 1 Turbulent KE (J)

Shape 2 Turbulent KE (J)Shape 2 Turbulent KE (J)

Shape 1 Free Mesh ResultsShape 1 Free Mesh Results

Shape 1 Velocity (m/s) Shape 1 Pressure (Pa)

Shape 1 Turbulent KE (J)

Shape 2 Free Mesh ResultsShape 2 Free Mesh Results

Shape 2 Velocity (m/s) Shape 2 Pressure (Pa)

Shape 2 Turbulent KE (J)

ConclusionConclusion

Shape 1 is better than Shape 2Shape 1 is better than Shape 2 A mapped mesh is slightly better than a free A mapped mesh is slightly better than a free

meshmesh Results are only as good as the mesh that Results are only as good as the mesh that

they arise fromthey arise from

I AM DONE!I AM DONE!