## MESHING OF TURBOCHARGER USING ANSA

OBJECTIVE:

To surface mesh and then conduct volumetric mesh for CFD application over the turbocharger model using different element size for different PIDs using ANSA v17.1.0 and observe the geometric change.

WHAT IS A MESH?

A mesh is a network that is formed of cells and points. It can have almost any shape in any size and is used to solve Partial Differential Equations. Each cell of the mesh represents an individual solution of the equation which, when combined for the whole network, results in a solution for the entire mesh.

PURPOSE OF MESHING?

Solving the entire object without dividing it into smaller pieces can be impossible because of the complexity that is within the object. Holes, corners and angles can make it extremely difficult for solvers to obtain a solution. Hence meshing is preferred.

WHAT IS A SURFACE MESH?

A surface mesh is a discrete representation of the geometry of the individual regions that will be used for the volume mesh generation.It i smade up of faces and vertices.

WHAT IS A VOLUMETRIC MESH?

Volumetric meshes are a polygonal representation of the interior volume of an object. Unlike polygon meshes which represent only the surface as polygons, volumetric meshes also discretize the interior structure of the object.

STEPS TAKEN:

STEP1: IMPORTING THE PRESSURE VALVE MODEL

The 1st step is to import the turbocharger model into ANSA v17.1.0.

STEP2: GEOMETRY CLEANUP

PURPOSE OF GEOMETRY CLEANUP?

With the geometry cleanup process we are making the model geometrically continuous, that is all the gaps in between them are closed and thereby a geometry connectivity is created. Since meshing is a process of dividing the entire geometry into smaller pieces by forming a continuous group of cells over the geometry i.e., like a wire net over an object. Hence, we require geometry cleanups for fine meshing of the component.

Here, from the above image after opening the model and enabling the TOPO module then the SHADOW mode and then making a GEOMETRY CHECK we came to know that our geometry has errorswhich means that there is a gap between surfaces which is highlighted  using a red coloured line known as SINGLE CONS and overlapping of two different surfaces which need to be cleaned up to form a continuous surface.

• From the above image we are cleaning the geometry by deleting the pink coloured over lapping surface in the turbo casing.

• From the above image we are cleaning the geometry of impeller casing using the command: hotpoints-parameter to create a hot point at a distance of 0.5 , then by using the command:Faces-New-Coons we are patching up the surface.

• From the above image we are cleaning the geometry over the turbo casing inlet by using the command: faces-new-fitted.

• From the above image we are cleaning up the geometry of the turbo casing outlet by by dividing and deleting the extending surface from the outlet surface using the command: CONS-project

• From the above image we are cleaning up the geometry of the turbo casing by using the command: faces-Intersect then selecting the two surfaces to be intersected followed by deleting the unwanted surfaces.

STEP3: ASSIGNING PID

• Using the command: Faces-setPID  we are setting up the individual PIDs.

STEP4: CREATING A SINGLE VOLUME

• Here we are intersecting the stage 1 blade, stage 2 blade and rotor staft to create a single volume.
• To perform the above mentioned process we are using the command:faces-topo to isolate the intersection surface and then delete the isolated surface.

STEP5: ASSIGNING LENGTH TO THE PIDs

Stage1 blade = 1mm
Rotor shaft = 1mm
Impeller = 2mm
Turbo casing = 5mm
Inlet casing = 5mm
Compressor casing = 5mm

•  To assign node length we should switch from TOPO mode to MESH mode.
• As per above mentioned node lengths we are going to assign individual node lengths for each individual PIDs using command: perimeter-length by dragging cursor over individual PIDs

STEP6: SURFACE MESHING

• After MESHING using the command: Mesh generetion-free with the element type as tria and enabling the reconstruct mode we see that the meshed part of  rotor shaft is automatically unmeshed which is due to the intersection of shaft with impeller and other PIDs with different node length.
• The above mentioned problem can be overcome by deleting the overlapping surface followed by projecting the boundary over the shaft using command: CONS-project in the TOPO mode followed by once again assigning the node length to the shaft with enabling the meshed macros mode and once again meshing the entire geometry.

STEP7: VOLUME MESHING

• To create a volume mesh we should cover inlet, outlet for turbo casing and compressor casing to create a closed volume using the command: faces-new-fitted in TOPO module
• Followed by we should assign PIDs for the newly created surfaces and then mesh them

• Switching from surface mesh moed to volumetric mesh mode.

• After detecting the volumes from the geometry select the required volumes and delete the unwanted ones.
• Now performing volumetric mesh using the command: unstructered mesh-tetra CFD in the v-mesh module.

• After volume mesh when disecting the turbocharger using NOT command we see that inside the turbocharger there is a perfect creation of volume which is created inside and around the blades and shaft in the turbocharger.

RESULT:

CONCLUSION:

From the above result we came to a conclusion that

• 924576 tria elements (2D-element) have been bonded to form a surface mesh over the geometry.
• 9895054 tetra elements (3D-element) have been bonded to form a volume mesh inside the geometry

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