TCFD - Comparison with CFX...TCFD –Comparison with CFX 1.3 Result: Total pressure difference - Stage 120.000 130.000 140.000 150.000 160.000 170.000 180.000 190.000 0,020 0,025 0,030

www.cfturbo.com© CFturbo® Software & Engineering GmbH Seite 1/10

Project

TCFD – Comparison with CFX1. Radial Pump: RP01

2. Radial Blower: RB01

Daegone Nam

Daniel Pöscha

CFturbo® GmbH

Unterer Kreuzweg 1

D- 01097 Dresden

Tel. 0351 40790479

December 2016

www.cfturbo.com© CFturbo® Software & Engineering GmbH Seite 2/10page 2

TCFD – Comparison with CFX

Radial Pump 01BM_RP01



1.1 Case settings: Basic

Physical settings (water)

Dynamic viscosity 0.001 [kg/m·s]

Density 998.2 [kg/m3]

Ref. Temperature 293 [K]

Ref. Pressure 101325 [Pa]

Operating conditions

Rotating speed 1470 [rpm]

Flow rate [m3/s]

P1 0.02222

P2 0.03333

P3 0.045

P4 0.05

P5 0.05556

P6 0.06111



INT6

INT1

INT4 INT3

INT2

INT5

All multiple interfaces in rotating domain have to be set as AMI-interface

Stage: INT1 – INT6Impeller: INT2 – INT3

1.1 Case settings: Interfaces

STAT

Co2-ROT

INT1-SIDE-2 INT3-SIDE-2

INT5-SIDE-1INT4-SIDE-1 INT2-SIDE-1

Co3-IMP

INT3-SIDE-1

INT2-SIDE-2

Co1-INPIPE

INT1-SIDE-1

INLET

Co4-VOL

INT4-SIDE-2

INT6-SIDE-1

OUTPIPE

INT6-SIDE-2

OULLET

INT5-SIDE-2

INT1



1.2 Mesh

2.9 M cells3 prism layers


TCFD Mesh Settings Value

Background mesh size 0.01

Co2_refinementSurfaces (SFP patch) 3 4

refinementSurfaces (rests) 1 4

No of Prism layers 3

<TCFD Mesh> <CFX Mesh>

TCFD

CFX-Mesh

Fluent-Mesh

OpenFOAM-Mesh

ICEM

fluentMeshToFoam

Geometry source: OpenFOAM mesh



1.2 Mesh

<TCFD Mesh> <CFX Mesh>



1.3 Result: Total pressure difference - Stage

120.000

130.000

140.000

150.000

160.000

170.000

180.000

190.000

0,020 0,025 0,030 0,035 0,040 0,045 0,050 0,055 0,060 0,065

Δp

tot,

Stag

e[P

a]

Flow rate [m3/s]

CFX

TCFD

TCFD_CFX-MESH

≈ 5.9 %

➢ All values area averaged



140.000

150.000

160.000

170.000

180.000

190.000

200.000

210.000

0,020 0,025 0,030 0,035 0,040 0,045 0,050 0,055 0,060 0,065

Δp

tot,

Imp

elle

r[P

a]

Flow rate [m3/s]

CFX

TCFD

TCFD_CFX-MESH

1.3 Result: Total pressure difference - Impeller

≈ 4.7 %




1.3 Result: Static pressure difference - Stage

120.000

130.000

140.000

150.000

160.000

170.000

180.000

190.000

200.000

210.000

0,020 0,025 0,030 0,035 0,040 0,045 0,050 0,055 0,060 0,065

Δp

stat

,Sta

ge[P

a]

Flow rate [m3/s]

CFX

TCFD

TCFD_CFX-MESH

≈ 1.3 %




1.3 Result: Efficiency - Stage

0,45

0,5

0,55

0,6

0,65

0,7

0,75

0,8

0,85

0,020 0,025 0,030 0,035 0,040 0,045 0,050 0,055 0,060 0,065

Effi

cien

cy [

-]

Flow rate [m3/s]

CFX

TCFD

TCFD_CFD-MESH

≈ 3.9 %




1.3 Result: Torque

0.045

0.050

0.055

0.060

0.065

0.070

0.075

0,020 0,025 0,030 0,035 0,040 0,045 0,050 0,055 0,060 0,065

Torq

ue

[N

·m]

Flow rate [m3/s]

CFX

TCFD

TCFD_CFX-MESH

≈ 2.0 %




[Pa][Pa]

Vflowrate: 0.05 [m3/s]

1.3 Result: Static pressure

<TCFD> <CFX>

✓ Treatment of pressure in paraview: pstat = p*density – p@INLET of TCFD + p@INLET of CFX



[Pa] [Pa]


Vflowrate: 0.05 [m3/s]

<TCFD> <CFX>

✓ Treatment of pressure in paraview: pstat = p*density – p@INLET of TCFD + p@INLET of CFX



1) AMI interface has to be used for rotating component with Multiple interfaces• mxp setting value: “0“ • Mixing plan interface for multiple interface causes error during the interation

2) TCFD overestimates the total pressure difference compared to result of CFX• Maximum gap in total pressure difference: ~ 6 %

3) The results from TCFD mesh and TCFD simulation with CFX mesh are almost overlapped

4) The cause of the difference with CFX result is not about MESH• 3 % – 6 % gap in result can be caused by difference of solver.

1.4 Summary



Radial Blower 01BM_RB01



2.1 Case settings

Physical settings (Air)

Dynamic viscosity 1.831e-05 [kg/m·s]

Ref. Density 1.19 [kg/m3]

Ref. Temperature 293.15 [K]

Ref. Pressure 100000 [Pa]

Compressible Yes

Operating conditions

Rotating speed 82500 [rpm]

Flow rate [m3/s]

P1 0.015

P2 0.016

P3 0.017

P4 0.018

P5 0.020

Flow-In

Flow-Out

StatorImpeller



2.1 Case settings

INT1: MixingplaneINT2 : Mixingplane

INT3: AMI

INLET: Volumeflow

OUTLET: Fixied pressure

Pressure settings

Max/Min pressure ± 1,000,000 [Pa]

Outlet pressure 110,000 [Pa]

Initial pressure 100,000 [Pa]

Relaxation factors

Pressure 0.3

Velocity 0.7

Temp. & Turb. 0.1

Density 0.1

Mesh settings

Background mesh size

0.003 (Co1 & Co4)0.0016 (Co3)0.0014 (Co2)

refinementsurface(Diffusor wall)

2 4

Blade cap gap 0.00015 [m]

No. of layers 3



2.2 Mesh




2.3 Result: Total pressure difference - Stage

5000

5500

6000

6500

7000

7500

8000

8500

9000

9500

10000

14 15 16 17 18 19 20 21

Δp

tot,

Sta

ge[P

a]

Flow rate [l/s]

CFX

TCFD

≈ 1.8 %




5000

5500

6000

6500

7000

7500

8000

8500

9000

9500

10000

14 15 16 17 18 19 20 21

Δp

tot,

Imp

[Pa]

Vflowrate [l/s]

CFX

TCFD

2.3 Result: Total pressure difference - Impeller

≈ 1.5 %




5000

5500

6000

6500

7000

7500

8000

8500

9000

14 15 16 17 18 19 20 21

Δp

stat

, Sta

ge[P

a]

Flow rate [l/s]

CFX

TCFD

2.3 Result: Static pressure difference - Stage

≈ 4.2 %




0,50

0,55

0,60

0,65

0,70

0,75

0,80

14 15 16 17 18 19 20 21

ηtt

, Sta

ge[-

]

Flow rate [l/s]

CFX

TCFD

2.3 Result: Efficiency - Stage

≈ 1.0%




2.3 Result: Torque

0,0160

0,0170

0,0180

0,0190

0,0200

0,0210

0,0220

0,0230

0,0240

14 15 16 17 18 19 20 21

Tq[N

·m]

Flow rate [l/s]

CFX

TCFD

≈ 3.7%





X-normal cross-section (x=0) Vflowrate: 0.017 m3/s

[Pa] [Pa]

<TCFD> <CFX>

✓ Treatment of pressure in paraview: pstat = p – p@INLET of TCFD + p@INLET of CFX




Z-normal cross-section (z=0.015) Vflowrate: 0.017 m3/s

[Pa] [Pa]<TCFD> <CFX>




<TCFD> <CFX>


[Pa] [Pa]

Vflowrate: 0.017 m3/s




1) Recent version of TCFD supports the Mesh at the clearance• Refinement factors are changed automatically by specifying the length of gap

2) Compressible settings • Pressure setting for outlet should be higher than surroundings• Recommended relaxation factors for fan case:

3) TCFD overestimates the pressure difference and torque compared to result of CFX.• Gap in total pressure difference: 1.5% - 1.8 %

4) TCFD simulation with CFX mesh was not possible • due to the different size of INT2 in each side (different diameter of outlet of

impeller and inlet of diffusor)• Mis-match of each side of interface patch causes high fluctuation of variables

2.4 Summary

p_relaxation 0.2/0.3

U_relaxation 0.5/0.7

Rho_relaxation 0.01/0.1

Turb. & T_relax 0.01/0.1

TCFD - Comparison with CFX...TCFD –Comparison with CFX 1.3 Result: Total pressure difference - Stage 120.000 130.000 140.000 150.000 160.000 170.000 180.000 190.000 0,020 0,025 0,030

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