1

Improving Durability of Turbine Components

Through Trenched

Film Cooling and Contoured Endwalls

Principal Investigator:

Prof. David G. Bogard

University of Texas at AustinGraduate research assistant: Todd Davidson

Co-Principal Investigator:

Prof. Karen A. Thole

Pennsylvania State UniversityGraduate research assistant: TBD

Background image: [Hamed, A., Tabakoff, W., and Wenglarz, R., 2006]

UTSR Peer Review Workshop

October 20, 2010

2

Project Objectives

a. Evaluate the degradation of performance for trench and

crater film cooling configurations when subjected to

active deposition of contaminants. This will be done on

simulated vane and endwall models.

b. Design improved trench or crater film cooling

configurations that mitigate the degradation effects of

deposition of contaminants.

c. Determine the overall cooling effectiveness (including

conjugate heat transfer effects) with and without thermal

barrier coatings for the vane and endwall.

3

Project Objectives, continued

d. Develop the knowledge needed to design film cooling

configurations on contoured endwalls.

e. Perform detailed velocity and thermal field

measurements along the vane, endwall, and

downstream wake, with and without film cooling, to

provide benchmarks to evaluate CFD simulations.

f. Develop improved cooling designs specifically for the

vane-endwall junction including mitigation of deposition

effects.

Simulated vane test facility at UT

• Simulated Three Vane –Two Passage Linear Cascade

• Liquid nitrogen cooled secondary flow during overall effectiveness measurements

• Constant heat flux boundary condition on near adiabatic airfoil for heat transfer coefficient measurement

• Surface temperatures measured using FLIR P20 and P25 IR cameras

4

Internal cooling configuration

U

Turbulence rods

Test vaneBypass flow

Bypass flow

Adjustable outer wall

U-bend

cooling

channel

Radial

cooling

channel

U

Turbulence rods

Test vaneBypass

flow

Bypass

flow

Adjustable

outer wall

Technical Approach: use matched Biot number models to obtain overall effectiveness which includes internal cooling effects

5

Experimental model needs to match Bi and hf /hi

if

icaw

hk

t

h

TTq

11,"

0

i

fci

w

h

hBi

TT

TT

1

1Overall effectiveness:

Heat transfer through

the wall:

A baseline was established by measuring with

internal cooling only.

6

Suction sidePressure side

Variation in was found to correlate with variation

in external heat transfer coefficient.

From Dees’ dissertation (2010)

Comparison of and contours with film cooling

shows redistribution of localized cooling by coolant

jets

TT

TT

ec

aw

,

7

x/d

Region of

measurements

TT

TT

ic

w

,

From Dees’ dissertation (2010)

This study will evaluate trench and crater film cooling

configurations

z/d

z/d

z/d

Configuration 6

Configuration 4

Configuration 5

z/d

z/d

z/d

Configuration 6

Configuration 4

Configuration 54

5

z/d

z/d

z/d

Configuration 6

Configuration 4

Configuration 5

z/d

z/d

z/d

Configuration 6

Configuration 4

Configuration 54

5

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0 0.5 1 1.5 2

M

1 Trench4 Crater5 Crater6 Crater19 Baseline

All configurations have a trench

depth s = 0.5d .

1

4

5

6

19Trench Craters

z/dz/d

Configurations(From Dorrington et al. 2007)

Thermal field measurements will be an important part

of this study to show coolant jet details and conjugate

heat transfer effects

Conducting wall

Adiabatic wall

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6

y/d

q

z/d = 0

z/d = -0.12

z/d = 0.12

z/d = -0.24

z/d = 0.24

z/d = -.48

z/d = 0.48

z/d = -0.71

z/d = 0.71

z/d = 1.07

z/d = -1.07

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

-0.1 0 0.1 0.2 0.3 0.4 0.5 0.6

y/d

q

z/d = .0

z/d = -0.24

z/d = 0.24

z/d = -0.48

z/d = 0.48

z/d = -0.71

z/d = 0.71

z/d = -1.07

z/d = 1.07

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I = 0.75, x/d = 5

From Dees’ dissertation (2010)

Note thermal boundary layer

development

The objective of our studies is to understand the effect of

deposition on non-axisymmetric contoured endwalls

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Contoured endwall

Passage

vortex

Horseshoe

vortex

Langston [1980]

Passage

cross-flow

Do deposits adversely affect heat transfer and

film cooling with contoured endwalls?

Heater #1

#2

A novel heater design was developed for contoured endwalls

to allow it to conform to the surface

3.32Cax

(28.6″)

Heat flux

plates

Removable for

flat or contoured

endwall tests

Axial chord

(Cax=8.6″)

1.0Cax

Z/CaxHeight contours

(relative to flat endwall)

Contoured endwall

heater design

Heater

dividing

line

Oil flow visualization for the contoured endwall did not show

a scoured region caused by the passage vortex

Flat Contoured

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Passage

vortex effect Blade 3

Blade 6

Blade 3

Blade 6

Langston [1980]

Saddle point

region

Counter

vortex effect

Passage

vortexSaddle

pointCounter

vortex

Endwall contouring reduced heat transfer by 25% in the

region of high heat transfer near the pressure side

Flat endwall

heat transfer

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Blade 4

Blade 6Blade 6

Blade 4

air

ax

k

hCNu

Heat transfer augmentation

with endwall contouring

flat

flatcontour

h

hhh

Δ

Increased augmentation

occurs in low heat transfer

areas

Coolant does not sweep across the passage as well for the

contoured endwall, compared to the flat endwall

Flat

Mideal=1.0

Flat

Mideal=2.0

Holes at 0°

Holes at 0°

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Contoured

Mideal=1.0

Contoured

Mideal=2.0

kMM

PP

PP

U

UM

kkidealideal

endwall,sin,tot

endwall,splenjideal,jjideal

ρ

ρ

ρ

ρ

j=coolant

k=individual hole

PSU will investigate the effects of deposition on film-cooling

with endwall contouring

Flat Endwall Contoured Endwall

Experiments by

[Lynch et al., 2010]

Pack-B Endwall Contour

CFD

M=1.0 CFD

Baseline

Experiment

M=1.0

Baseline

Experiment

M=1.0

Baseline

Experiment

M=2.0

Baseline

Experiment

M=2.0

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Phase UT Deliverables Penn State Deliverables

Phase I Planning and

Project Coordination

• Agreed upon plan for frequency and mode for communication

• Agreed upon test plan for initial phases of work

Phase II - Deposition

with No Film-Cooling

•Identify where vane deposits occur

• Vane heat transfer with deposits

• Measurements of aero-thermal BL

• Conducting contoured endwall model

•Identify where endwall deposits occur

• Contoured endwall heat transfer with

deposits

• Measurements of aero-thermal BL

Phase III - Deposition

with Trenched Film-

Cooling on Vane and

Contoured Endwall

• and with trenched holes on

vane

•Evaluation of new trench / TBC

design for vane

• and for film-cooling on a contoured

endwall

•Evaluation of trenched film-cooling on

contoured endwall

Phase IV - Optimized

Hole/Trench on Vane

and Contoured Endwall

• Effectiveness measurements for an

optimized hole shape / trench for

vane

• Results from numerous hole shape

/ trench hole designs for the vane

• Effectiveness measurements for the

optimal hole shape / trench for

contoured endwall

•Measurements of aero-thermal

boundary layers

Phase V - Mating of

Optimized Hole/Trench

on Contoured Endwall

• Measurements of aero-thermal BL’s

for hole shape / trench on vane

• Measurements in vane wake with

optimal hole shape / trench

• Evaluation of mating between vane and

contoured endwall with overall

effectiveness measurements using

optimized hole shape / trench

Phases and Deliverables for the project

17Background image: [Hamed, A., Tabakoff, W., and Wenglarz, R., 2006]

Questions?