Tutorial: Gerotor Pump Modeling using FLUENT
Introduction
To perform a CFD simulation for a Gerotor inside Fluent, the deform ing fluid volume is identified as the region sandwiched between the Gerotor gears. This fluid region is known as Gerotor core in this tutorial and entire fluid volume is decompod into moving and deforming volumes. For the 2.5D approach, the Gerotor core region needs to be meshed with wedge elements, while for the pure hex mesh approach the Gerotor core region needs to be meshed with structured hex mesh with certain requirements. The requirements will be discusd in more details later on. While the wedge elements for the 2.5D approach can be generated easily, the structured hex mesh, on the other hand, can be tedious to generate manually becau of the requirements that it needs to satisfy.
A Structured Hexahedral mesh is generated by decomposing the Gerotor core in Design Modeler and then meshing in ANSYS Mesher. This will be done in Workbench.
For the mesh motion later on in Fluent, a UDF is ud for the pure hex mesh approach. In order for the UDF to move the mesh properly, the gerotor has to be oriented in certain ways. To be more specific, the inner gear has to be rotating about z axis, and the origin of the rotors has to be on the z coordinate.
It is generally easy to satisfy this orientation by rotating and translating the model. In this tutorial, the geometry satisfies this condition and no rotation and translation is needed.
In this tutorial you will learn how to:
Decomposition of Gerotor core geometry in Design Modeler.
Generating a Structured Mesh for the Gerotor core as required by the UDF for mesh motion.
Generating a Tetrahedral Mesh in ANSYS Meshing for the Gerotor ports.
Setup the ca in Fluent using the UDF.
七夕约会Prerequisites
This application document assumes that you are familiar with the menu structure in FLUENT, and that you have worked on some introductory tutorials. Some of the basic steps in the tup and solution procedures will not be shown explicitly. You should be familiar with the basic knowledge of dynamic mesh model and UDFs. This tutorial also assumes some familiarity with Design Modeler and ANSYS Meshing Platform.
Place the files in working directory
(gerotor-tutorial-core.stp, gerotor-tutorial-ports.stp, , ,
, gerotor.c, gerotor_vane_smoothing.c )
Preprocessing
神州五号1. Decomposition/meshing procedure for the Gerotor core:
a.Launch WB and add FLUENT Analysis System.
b.Double click Geometry Cell.
Select units as m.
黄河刀鱼c.Geometry Decomposition:
i.Import the Geometry - gerotor-tutorial-core.stp -> Generate ( add frozen )
ii.On z-x Plane Draw a Rectangular sketch covering extents of core ction
iii.On z-x Plane Draw another sketch. A line of arbitrary length aligned with z-axis.
iv.Revolve about z-axis by 2 degrees, Add Frozen.
贴对联的左右顺序v.Create a pattern with 90 bodies about z-axis
d.Create Boolean to interct the Core and the Pattern Solids.
e.Rename all new Solid to Core.
Suppress all the bodies outside the core volume that were created by the boolean operation and add them to a new part.
Rename all other bodies to Core. This is required to have common Fluid Zone in FLUENT for the entire Core.
Select all Core named bodies and create New Part. U Ctrl or Shift for multiple lection, RMB and Form New Part.
f.Merge multiple faces on each block.
This is required in order to generate a Mapped face mesh. Select the two surfaces and Tools -> Merge , Say yes for Merge Boundary edges.
Create Named Selection for Top and Bottom face as the will form an interface in
FLUENT with the Port mesh.
g.Meshing:
i.Refresh the Mesh Cell.
留言信箱ii.Right click and Edit Mesh Cell. This will open ANSYS Meshing Platform. It is assumed here that ur is familiar with using ANSYS Mesher.
iii.Right Click Mesh and Show -> Sweepable Bodies. All Bodies should get highlighted in Green color indicating that Surface and Geometry clean up is done
correctly. If any of the bodies is not en sweepable, go back to Design modeler
and check if any split faces are left unmerged on Inner Gear and Outer Gear
surfaces.
iv.Right Click Geometry and Inrt Virtual Topology. This will repair the remaining surfaces and edge
s that were left splitted in Design Modeler.
步履维艰v.Once all bodies are en to be mappable, Right click Mesh and preview Surface mesh.
vi.Inrt Edge sizings on the Inner Gear, Outer Gear Edges, The Core
z- direction and the Core Gap. This will help in controlling the mesh size, quality
and refinement required.
家乡的变化作文Inner and Outer Gear Edges:
Core Gap:
Core Thickness:
vii.Select all Surfaces and Inrt Mapped Face Mesh in the Mesh.
viii.Generate Mesh and Export as 美美的幸福生活
Note that the radial mesh lines for the gerotor core go through exactly the z axis due to the way the core is decompod. This is the requirement for the structured hex mesh. If the radial mesh lines do not go through the z axis, the mesh will get skewed after rotation inside Fluent.
