Essay: Turbomachines

Turbomachines requires high quality mesh. Because of the complex geometry it is not easy to get this type of high quality mesh, also the time required for carrying out dynamic analysis of such mesh is very high. So in order to be able to carry out large number of analysis it is very necessary to do create such mesh which will decrease the time required for carrying out analysis.
Ansys recommends high quality Hexahedral mesh which provides better accuracy with less processing power required .
Such Hexahedral mesh can be generated by using Ansys Turbogrid
Preparing model for meshing
After creating model in CATIA file is saved as IGS and this file is imported in Ansys design modular.Mesh is generated in turbogrid. For Turbogrid to create Topology and subsequently Mesh it requires following curves and domains to defined and flowpaths
Hub.curve
Shroud.curve
Inlet
Outlet
Flowpaths
In design modular various parts of component is merged to get a single solid, which is required for preparing the mesh.Thus cleaning of component is done so that the mesh can be prepared and the quality of mesh can be maintained
In design modular editing is done. In design modular to save time and processing power, analysis will be carried out on one rotor blade and then symmetry will be applied.After that merge of the faces and edges is done.Hub and shroud is sliced and also some surface extension is done.After that plane is created.On the plane sketch projection of the blade is taken.
So after doing this we get two files Hub.curve ,shroud.curve.After that inlet and outlet are defined.
After defining Hub,shroud,inlet and outlet flow path is defined using function flow path in bladeEditor menu.After doing so points are exported using exportpoint function.Now model is ready for meshing in Turbogrid.
When the model is imported to Turbogrid , Turbogrid creates topology using the predefined curves.
In turbogrid some design modification can also be done like if the tip of the blade isn’t smooth in shape than we can choose cut-off or square option in bladeset.Also Hub and shroud clearance can be given. Doing proper editing topology is created.
In mesh data option different inputs can be given like mesh reinfinement (Fine, course, medium), number of nodes etc. After doing so mesh is created.
After performing CFD analysis of variable geometry turbine can conclude that turbine’s performance range can be increased by changing angle of stator blades, turbo lag can also be reduced by the same as varying power requirements are served by different angles of stator blades. Hence the purpose of variable geometry turbine is satisfied