cfx berlin - webinar · 2015. 7. 22. · cfx berlin software gmbh excellent simulation &...
TRANSCRIPT
![Page 1: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/1.jpg)
Dipl.-Ing. Jan Hesse
© CFX Berlin Software GmbH
Karl-Marx-Allee 90 A
10243 Berlin
[email protected] | www.cfx-berlin.de | www.twinmesh.com
Webinar: TwinMesh for Reliable CFD Analysis of Rotating
Positive Displacement Machines
14.07.2015
![Page 2: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/2.jpg)
Folie 2
TwinMesh is a novel software that automatically generates high
quality hexahedral grids for the rotary parts of positive displacement
machines (developed by CFX Berlin Software GmbH)
TwinMesh is complementary to ANSYS and allows the use of
physical models available in ANSYS CFX
![Page 3: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/3.jpg)
CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions
• CFX Berlin is a certified partner of
ANSYS, Inc. and provides numerical
simulation software and solutions for:
– Fluid mechanics + thermodynamics
– Electromagnetics
– Structural mechanics
– Coupled physics simulation
• CFX Berlin business areas:
– ANSYS & TwinMesh software, Hardware
– Engineering & simulation services
– Training & consulting
– Research & development
3
![Page 4: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/4.jpg)
Introduction
• Rotating positive displacement machines
– Available in the current version of TwinMesh 2015
TwinMesh 4
Lobe pumps
Internal gear pumps
Boerger
External gear pumps Gerotor pumps
Screw compressor
![Page 5: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/5.jpg)
Introduction What are the challenges?
• Complex geometries
– Interlocking rotors (often screwed)
– Size-changing working chambers with very small clearances between the lobes
and between rotors and casing
• Complex (transient) flow characteristics
– Cavitation (Multiphase)
– Non-newtonian fluid
– Compressibility
– Real-gas properties
– Turbulence
– Viscous heating, etc.
• These challenges lead to specific
meshing requirements for reliable CFD analysis
– Min. angle, volume change, aspect ratio
5
Rotor clearances
Axial
clearances
Size-changing
working chambers
TwinMesh
![Page 6: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/6.jpg)
Introduction Realization in a CFD simulation
• Time-depending change of the flow volume inside a lobe pump
– Realized with TwinMesh 2015 and ANSYS CFX
TwinMesh 6
![Page 7: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/7.jpg)
Methods for chamber modelling
TwinMesh 7
Overview
Methodes for chamber
modelling without
TwinMesh
Rotor clearances
Axial clearances
Size-changing
working chambers
![Page 8: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/8.jpg)
Methods for chamber modelling Immersed-Solid
• Advantages
– Fast – only one mesh for fluid and solid volumes
– Variable time step control
• Disadvantages
– Insufficient wall treatment
– Multiphase is not available
(e. g. Cavitation)
– Only incompressible fluids
– Possible numerical instabilities depending
on local pressure gradients (e. g. gap flow),
small time steps necessary
– Very large number of elements depending on
geometry especially for unstructured meshes
TwinMesh 8
Schwotzer, T.: „Simulation einer Drehkolbenpumpe
mit der Immersed-Solid-Methode“, Bachelorarbeit,
Technische Universität Berlin, 2009
![Page 9: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/9.jpg)
Methods for chamber modelling Mesh Deformation and Remeshing
• Advantages
– Automatic mesh generation (less manpower required)
– Fluid volume is represented by the mesh
– Full model support
(e.g. Multiphase with Cavitation,
turbulence model)
• Disadvantages
– Mesh-generation for almost each iteration
(increasing computation time)
– Element topology (Tetra) leads to very high
element numbers in gaps (increasing computation time)
– Mesh quality issues due to mesh deformation and
element topology when using remeshing
– Numerical errors due to frequent interpolation of calculation results between
different meshes
TwinMesh 9
![Page 10: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/10.jpg)
Methods for chamber modelling Manual Generation of Structured Hexahedral Meshes
• Idea
– Manual grid generation in ANSYS ICEM CFD Hexa
for many rotor positions per rotation
• Advantages
– Best mesh and numerical quality
– High resolution of gaps is possible
– Element topology allows manageable model size
– No interpolation errors since the grid topology
remains the same
• Disadvantages
– Extremely high manual effort: grid
generation for 2D-models would
need 4 weeks
block structured grid
TwinMesh 10
Fuchs, M.: „Numerische Simulation der instationären
Strömung in einer Drehkolbenpumpe“, Bachelorarbeit,
Technische Universität Berlin, 2010
![Page 11: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/11.jpg)
Methods for chamber modelling TwinMesh – an essential part of CFD
• TwinMesh was developed based on the manual approach by using structured
hexahedral meshes including the following specifics
– Fast mesh generation with less manual effort
reduce engineering working time
– Generation of high quality structural meshes for high quality CFD results
Check quality before simulation
Reliable simulation results in comparison with measurement data
– Provide templates to speedup the CFD workflow
ANSYS CFX Setup files for each type of machine (only change the mesh and the boundary
condition values to finish the setup)
Session file to transfer information from TwinMesh to the CFD setup
– TwinMesh meshes work with ANSYS CFD
Use of high quality numerical models
TwinMesh 11
![Page 12: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/12.jpg)
How does TwinMesh work?
![Page 13: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/13.jpg)
TwinMesh Seven steps from CAD to Mesh
• TwinMesh is a novel software, developed by CFX Berlin Software
GmbH which generates high-quality hexahedral meshes for the
rotating parts of axis parallel rotary positive displacement machines.
Split of the simulation
domains into steady
and rotating parts
Grid generation for the rotors
with TwinMesh and for the
Steady parts with ANSYS ICEM
CFD or ANSYS Meshing
Rotor 1 Rotor 2
Stator
Numerical calculation
with ANSYS CFD
Simulation Workflow
TwinMesh 13
![Page 14: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/14.jpg)
TwinMesh 1. Geometry import
• File format (2D cross section of the machine)
– IGES
– CSV-File with point coordinates
TwinMesh 14
![Page 15: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/15.jpg)
TwinMesh 2. Boundary definition
• Boundary types
– Rotor curvature
– Casing curvature
– Additional curvature for interface creation
TwinMesh 15
![Page 16: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/16.jpg)
TwinMesh 3. Geometric characteristics
• Options
– Type of machine
– Number of lobes
– Rotorposition
– Rotor curvature modifications
– Screwing
– Meshes per pitch angle
– …
TwinMesh 16
![Page 17: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/17.jpg)
TwinMesh 4. Interface generation
• Automatic contact definition for the rotor meshes
– Interfaces between the rotor meshes are
automatically generated depending on
rotor curvature
TwinMesh 17
Rotor 1 Rotor 2
Stator
![Page 18: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/18.jpg)
TwinMesh 5. Mesh properties
• Definition of node distribution
– On curves
– In radial and axial direction
– Inflation layer
TwinMesh 18
![Page 19: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/19.jpg)
TwinMesh 6. Mesh generation and quality check
• Automatic mesh generation for each rotation angle
– Smoothing algorithm depending on orthogonality and volume change
– Different methods of mesh connection at the rotor-rotor-interface available
(non-conforming or 1to1)
– Visual and quantitative quality check tools available
TwinMesh 19
Mesh quality
Mesh
![Page 20: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/20.jpg)
TwinMesh 7. Mesh export
• Export
– Mesh export to ANSYS CFX (format .cfx5) for the first rotor position
– Export of mesh displacement coordinates for each rotor position
– Including ANSYS CFX Session File for easy setup in ANSYS CFX
TwinMesh 20
![Page 21: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/21.jpg)
TwinMesh Mesh movement
• Mesh movement of a lobe pump – with the “OuterFix”-type strategy
TwinMesh 21
![Page 22: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/22.jpg)
TwinMesh Mesh movement
• Mesh movement of an external gear pump – with the “InnerFix”-type strategy
TwinMesh 22
![Page 23: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/23.jpg)
TwinMesh Mesh movement
• Mesh movement of a gerotor pump – with the “InnerFix”-type strategy
TwinMesh 23
![Page 24: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/24.jpg)
TwinMesh Mesh movement
• Mesh movement of a screw compressor – with the “Mixed”-type strategy
TwinMesh 24
![Page 25: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/25.jpg)
CFD simulation examples for
rotating pd machines
![Page 26: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/26.jpg)
Simulation examples External Gear Pump
• Flow characteristics
– High pressure gradients
– Full cavitation model Vapour cavitation and aeration
– SST- Turbulence model
• Boundary conditions
– Inlet
1 bar (abs)
– Outlet
11 bar (abs)
– Rotational speed
500 rev/min
TwinMesh 26
• Output
– Time dependent information Pressure pulsation
Flow velocities
Cavitation behavior
– Average information
(also transient available) Mass flow
Torque on rotors
Temperature
![Page 27: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/27.jpg)
Simulation results External Gear Pump
• 2D-Simulation result with mesh movement and vapour fraction
TwinMesh 27
![Page 28: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/28.jpg)
Simulation examples External Gear Pump
• Possible simulation study
– Change of the profile gap size
TwinMesh 28
Inceasing massflow with
decreasing profile gap
Chamber pressure
Vapour volume Mass flow
High pressure
peak in
disconnected
flow volume
![Page 29: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/29.jpg)
Simulation examples Gerotor pump
• Simulation domain
TwinMesh 29
Case without axial gaps
![Page 30: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/30.jpg)
Simulation examples Gerotor pump
• Simulation results for case
with axial gap flow
– Time dependent information
Pressure pulsation
Flow velocities
Cavitation behavior
– Average information
(also transient available)
Mass flow
Torque on rotors
Temperature
• Possible simulation study
– Change geometry to minimize the
pressure peak
Folie 30 TwinMesh
![Page 31: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/31.jpg)
Simulation examples Screw compressor
• Flow characteristics
– Highly screwed rotors
– Including axial gap
– Compressible fluids
– High flow velocities
• General analyses
– Torque, power and massflow
TwinMesh 31
Torque Massflow
Rotation angle [°] Rotation angle [°]
Massfl
ow
[kg
/s]
To
rqu
e [
Nm
]
Outlet
Periodic flow Initial phase Periodic flow Initial phase
![Page 32: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/32.jpg)
Simulation examples Screw compressor
• Consideration of heat conduction in rotor solid
– Temperature
TwinMesh 32
![Page 33: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/33.jpg)
Simulation examples Screw compressor
• Possible simulation study
– Different types of discharge port geometry
TwinMesh 33
Ab
so
lute
Pre
ssure
[P
a]
Rotation angle (male) [°]
Type 2
Type 1
Type 3
Type 1 Type 2 Type 3
![Page 34: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/34.jpg)
Simulation examples Lobe pumps
• Flow characteristics
– Incompressible fluids with cavitation (multiphase)
– Non-newtonian fluids even with high viscosity
TwinMesh 34
![Page 35: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/35.jpg)
Summary
Why TwinMesh?
Fast: TwinMesh provides an automated workflow for structured mesh
generation and CFD analysis setup of pd machines
Reliable: TwinMesh delivers high quality numerical grids, avoids
interpolation errors and allows the use of the full range of physics
available in ANSYS CFD
Efficient: TwinMesh HexMeshes allow for reasonable transient CFD
model size
Folie 35
![Page 36: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/36.jpg)
TwinMesh enables developers of rotary pd machines to:
Increase product durability, performance and efficiency
– E.g. prevention of damage by cavitation or pressure pulsation
– E.g. optimization of flow and pressure and thermal behavior
Reduce development and manufacturing costs by use of virtual
prototyping
Drive real innovation and optimization by better understanding of the
machine behavior in detail
– E.g. clearance losses, pulsation, temperature gradients and heat transfer
Folie 36 TwinMesh
![Page 37: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/37.jpg)
Outlook
Software developing goes forward to include more functionality to
handle almost all positive displacement machine types.
Planned extensions in future releases of TwinMesh:
TwinMesh 37
Eccentric screw pump Scroll compressor Screw spindle pump
![Page 38: CFX Berlin - Webinar · 2015. 7. 22. · CFX Berlin Software GmbH Excellent Simulation & Engineering Solutions CFX Berlin is a certified partner of ANSYS, Inc. and provides numerical](https://reader031.vdocuments.us/reader031/viewer/2022012003/60aefe455513901048207ac4/html5/thumbnails/38.jpg)
Summary
is your partner for:
TwinMesh™ Software
ANSYS Simulation Software
Training & Support
Consulting & Development
Folie 38