VOLUME MESH OF TURBOCHARGER USING ANSA

OBJECTIVE:

To eliminate the topological errors that are acquired in the given a Turbo Charger CAD model and perform surface and volumetric meshes with different mesh lengths for different components and to do the required actions for those meshes.

Before going to do the operations, we have had to know the basic concept of Turbo Charger.

TURBOCHARGER:

A Turbocharger is in the form of forced induction which forces the air into the Internal Combustion Engine. It increases the amount of air entering the engine to create more power. A turbocharger has the compressor powered by a turbine. The turbine is driven by the exhaust gas from the engine. It does not use a direct mechanical drive. This helps to improve the performance of the turbocharger. It is generally called as Turbo (or) Gas Compressor. It increases the power output of the equipped engine by more than 30% to 40% compared to the normal engines.

PROCEDURE:

(1) Cleaning-up the Model:

The given model file is opened and it will be shown as a wireframe model. The shadow mode is ON to view in 3D model and it will be shown as,

Then we have to clear the errors which are acquired during the designing. It can be seen that there was some glitching on the surface of the model, which is due to imperfect designing, that is, the presence of unwanted components in the inner parts of the model. With this surface glitch, there were some of the errors on the surfaces too. These errors are identified by single cons on the surfaces. We have to Check ON in visualizing the CONS to identify where the single CONS are in the Process Parameters on the Quality Criteria.

Here the error freed component is,

(2) Assigning PIDs:

Then the next phase is to assigning the Property IDs (PIDs). This is used to differentiate each component with different names and colors and to perform different meshes too. The bulb in the selected PID is glow based on whether the selected PID is visible or not. For the invisible inner components, the bulb will not glow. Latterly, the Compress option is used to view only the visible components in the model. This option generally simplifies the model by not showing the invisible components. The most important to know about the compressor option is, once compression is done, we cannot retrieve those components in the model.

(3)Is 2D Mesh is Essential?:

Then after creating the PIDs, we have to combine those components, that is, to make it the same control volume. So we have to delete the closed surfaces in between the faces the components to stick them to make as to share the same control volume. This action is first implemented to compressor blades and then to go on the other components.In this , we have to do a Volume Mesh for the model. But before doing a Volume Mesh, we must know that, the model must be undergo Surface Mesh before going to Volume Mesh.So we need to do a Surface Mesh here.

The Surface Mesh (or) 2D Mesh of 3mm mesh length for all the components on the surface of the turbocharger is performed, which is known as Uniform Mesh, not in the inner part only on the surface.

(4)Rectifying Problems In 2D Mesh because of Property Mesh:

The next thing is to discuss is there is no problem that will arise when we mesh the full component in one single mesh length. But when we mesh the different components with different mesh length the problem will occur. It can be seen that meshing is not done on one surface which is due to software confusion on which part has to mesh with which mesh length. The meshing of different components with different mesh lengths is done by using the Properties Dialog box. Selecting the required PID which have to mesh, right-click on it, and select show only option and perform mesh on a given mesh length. This is known as Property Mesh.

The various different mesh lengths for various components to be meshed is displayed here.

And the corresponding individual meshes are,

The thing behind this is, initially the mesh for various components is done quietly, The problem arises when we combine the particular component with the other component of different mesh parameters. Here the problem has arisen between the shaft rotor and the turbine impeller which are of different mesh lengths. This problem is rectified by the repeat the mesh operation on the unmeshed component.

And it can be seen that, in this case, in the surface of contact, the mesh size will increase gradually for those components.

Then the other thing is, in order to share the same control volume, there should be no overlapping and interference. In this, the overlapping of the shaft rotor and the compressor casing is found and it is rectified using Project option and deleting the unwanted surfaces and extrusions. In this operation, we have to connect the meshed surfaces which are unconnected before. Because of doing this, the software got confused and cancel the mesh and we have to re-mesh on those unmeshed surfaces.

After done this, it can be seen that in the meshing operation of compressor casing which has mesh length of 5 mm and the shaft rotor which has a mesh length of 1 mm, there was a sudden decrease in the interface of the casing and the shaft. It is not considered as the error in meshing, but in terms of visualizing, we should consider that. It is rectified by introducing random hot points around the interface and patching those marked hot points. This should be done on the inner side of the casing too. It is shown as,

(5)Volume Mesh:

Then after this, Volumetric Mesh has to be done. The Volume Mesh is differ from Surface Mesh may be regular or irregular which is used to compute the internal stresses and forces in an object throughout the entire volume of the object. Here, we have a two objects, compressor and turbine and these two objects should have a seperate Volumes to mesh. So we need to create a seperate Volumes for both Compressor and Turbine. For that, we need to cover those surface to make them as a individual entire volume. So, we covered the inlets and outlets of both Compressor and the Turbine by creating the new surface and alloting a new PIDs too.

Next, to do the Volume Mesh, V-Mesh option is clicked. Then, we have to define the Volumes to be Meshed, by clicking the Define option in the Volume. A small dialog box to which of the parts are to be worked is selected here. Here, I choosed whole model and the number of Volumes of the components are generated in the next dialog box. Select the Volumes that need to be Mesh by Viewing by isolate them and remove the unwanted volumes. Here, we need to Mesh the two Volumes, Compressor Volume and Tubine Volume. So. select the Volumes which suits those and remove the remaining. Then in the next step the various types of Volume Meshes is shown in the Unstructured Mesh Section, from which a required type of Volume Mesh is selected. Here, we need to do a Mesh for CFD Analysis, so we choose Mesh option \'Tetre CFD\'.Then selcect the whole component and press the middle click button on the mouse to perform Volume Mesh.

(6)Detailed View Of Volume Mesh:

After Volumetric Mesh is done, let examine the meshing by removing some parts in Meshing. In this, we can see that in the boundaries of components such as turbine impeller, compressor two stage blades, compressor casing there was the coarse mesh and in the surfaces away from these boundaries, we have very fine meshing. This is because, in those boundaries and interfaces the internal stresses of the fluids are more when compared to the places where away from the interfaces. So in those places, meshing is very coarse and dense.In our meshed component, it is shown in various places. They are,

OUTPUT:

The file regarding the Volume Mesh of this Turbo Charger Model is dropped here:

https://drive.google.com/open?id=1s4-nSTP5jvAA6WL0IPforhjiVsI3ztId