experimental analysis of wet compression in axial

1

LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS

Experimental Analysis of Wet Compression in Axial Compressor Stage


Laboratory of Thermal TurbomachinesNational Technical University of Athens

I. Roumeliotis K. Mathioudakis

2



Experimental Analysis of Wet Compression in Axial Experimental Analysis of Wet Compression in Axial Compressor StageCompressor Stage

Experimental Set-Up

Effect of Water Injection on Compressor Stage Aerodynamic Performance

Effect on Stage Power Consumption

Conclusions

3



First Stage of an Axial Compressor

Impaction Pin Nozzles (Mee Industries )

Experimental Set - Up

4



Experimental Set - Up

Lagrangian Framework

Droplet Evaporation Model

Meridional Flow Solver (2D)

Bellmouth Configuration

elongationbellmouthtrajectories

ImpingmentInitial Injection Position

Selected Injection Position

0.6 m

5



Experimental Set-Up

1. The flow rate of water

2. The pressure at nozzle manifold

3. Compressor Rotational Speed

4. Power of the Shaft

5. Ambient Conditions (pt0,Tt0,war0)

6. Compressor Inlet Conditions (pt1, ps1, Tt1, war1)

7. Inlet Flow Rate (Venturi)

8. Compressor Exit Conditions (pt3, ps3)

9. Oil Thermal Losses

Test-Rig Measurements

Nozzles manifold

microphone

Venturi static tapsstator rotor

throttle exit

Ps3 wall taps

pt1,Tt1,war1

Pt3 rake

Mechanical measurements

Pe GB

pt0,Tt0,war0

6



Experimental Set-Up

•Pressure Measurement: Potential Plugging of Pressure Holes and Connections due to Droplets

•Temperature Measurement: Droplets impingement at Temperature Sensors tend to Mask the Flow Temperature

•Humidity Measurement: Influencing the Magnitudes used for calculating the Stage Performance Characteristics

•Unstable Operation Determination: Hot Wire use in Droplet Laden Flow is not Plausible

Measurements Considerations

7



Experimental Set-Up

Pressure Measurements

0200400600800

10001200140016001800

0 10 20 30 40time(sec)

ps3-

p am

b(Pa

)

air purging

air purging

correct value

•Increased Pressure Holes Diameter

•Purging System using Pressurized Air and Electronic Vanes

•Defining of Acquisition Time to 1 sec

8



•Bleeding Air from the Stage Inlet introducing a bent tube facing downstream

•Using Power of the Shaft for the measurement of consumed power

Experimental Set-Up

Compressor Measurements

9



Experimental Set-Up

•Unstable operation can be detected by acoustic measurements

•Use of a Hot-Wire for dry Measurements

•Microphones used for Droplet Laden Flows

Unstable Operation Determination

1.068

1.072

1.076

1.08

1.084

1.088

7 8 9 10 11 12 13

mcor

πC

,cor

6.E-01

7.E-01

8.E-01

9.E-01

1.E+00

7 8 9 10 11 12 13

mcor

RM

S

10



Experimental Analysis of Wet Compression in Axial Experimental Analysis of Wet Compression in Axial Compressor StageCompressor Stage

Experimental Set-Up


Effect on Compressor Power Consumption

Conclusions

11



0

0.2

0.4

0.6

0.8

1

1.2

1.4

0.8 0.9 1 1.1 1.2 1.3Φ/Φref

Ψ/Ψ

ref(

t-s,

13)

dry50bar140bar

•Manifold Pressure: 50bar•mwinj/mair=0.6÷0.85%

•MMD=20μm

•Manifold Pressure: 140bar•mwinj/mair=1.1÷1.5%

•MMD=12μm

•Assuming Incompressible Flow

s3 s1s-s,is 2

1 tip

p -pΨ =ρ ×U

Effect of Water Injection on Compressor Stage Effect of Water Injection on Compressor Stage Aerodynamic PerformanceAerodynamic PerformanceEffect on Pressure Rise Coefficient

12



0

0.2

0.4

0.6

0.8

1

1.2

1.4

0.8 0.9 1 1.1 1.2 1.3Φ/Φref

Ψ/Ψ

ref

(t-s

,13)

drywet

mwinj/mair=1.5%

Accoustic Pressure for wet Operation

0

0.2

0.4

0.6

0.8

1

RM

S/R

MS m

ax

Effect of Water Injection on Compressor Stage Effect of Water Injection on Compressor Stage Aerodynamic PerformanceAerodynamic PerformanceEffect on Pressure Rise Coefficient

13



Effect of Water Injection on Compressor Stage Effect of Water Injection on Compressor Stage Aerodynamic PerformanceAerodynamic Performance

0

0.2

0.4

0.6

0.8

1

0 0.5 1 1.5 2 2.5 3ω/ω,midspan(dry)

Rot

or B

lade

Spa

n

drywetmwinj/mair=2%


•Total Pressure Loss Coefficient:

tR1 tR22

1 1

p -pω=1/2×ρ ×W

S

2

tR + Wρ×2

p =p

Total Pressure Loss Coefficient Profile

14





•Local Total to Total Efficiency:

mwinj/mair=0.6%0

0.2

0.4

0.6

0.8

1

0.6 0.7 0.8 0.9 1 1.1 1.2ηt-t,Local/ηt-t,Local,midspan(dry)

Rot

or B

lade

Spa

n

drywet

( )u2 u1t-t,Local

t2 t1

1 V -Vp -p=

ρ ×Uη

Total to Total Efficiency Profile

15




0

0.2

0.4

0.6

0.8

1

0.2 0.4 0.6 0.8 1 1.2a3/a3,midspan(dry)

Stat

or B

lade

Spa

n

drywetmwinj/mair=1.3%

Stator Absolute Exit Angle Profile

16



Water Injection Effect on Compressor Stage OperationWater Injection Effect on Compressor Stage Operation

Experimental Set-Up


Effect on Compressor Power Consumption

Conclusions

17



0.95

0.96

0.97

0.98

0.99

1

1.01

1.02

0.8 0.9 1 1.1 1.2 1.3 1.4Φ/Φref

Cor

rect

ed c

onsu

med

pow

er

(Pco

mp,

cor/P

com

p,re

f)

mwinj / mair=1%

mwinj / mair=1.3%mwinj / mair=0.5%

mwinj / mair=0.7% dry

Effect on Compressor Power ConsumptionEffect on Compressor Power ConsumptionConsumed Power

•Consumed Power IncreaseDue to the increased mass flow

Due to other reasons

18



ΔPnet/P,dry = 1.044 x mwin/mair0

1

2

0 0.5 1 1.5 2mwin/mair(%)

ΔP n

et/P

,dry

(%)

O.P.1O.P.2O.P.3

ΔPnet/Pdry= 1.0839 x mwin/mair0

1

2

0 0.5 1 1.5 2mwin/mair(%)

ΔP n

et/P

,dry

(%)

50006000700080009000

Effect on Compressor Power ConsumptionEffect on Compressor Power ConsumptionNet Consumed Power Increase

•Consumed Power IncreaseDue to the increased mass flow

Due to other reasons

Operating Point 1

19



•The losses can be attributed to the centrifugation of the droplets by the Rotor

2net TIPΔP =K U winm⋅ ⋅

Compressor stage aerodynamic

efficiency is unchanged

Increase of net consumed power


0

0,5

1

1,5

2

0 0,5 1 1,5 2ΔPnet (measured)

45o

P los

ses

calc

ulat

ed (K

=0,3

8)

20



0

0.2

0.4

0.6

0.8

1

0 0.5 1 1.5 2mwin/mair(%)

K

•The losses can be attributed to the centrifugation of the droplets by the Rotor

2net TIPΔP =K U winm⋅ ⋅


0

0,5

1

1,5

2

0 0,5 1 1,5 2ΔPnet (measured)

45o

P los

ses

calc

ulat

ed (K

=0,3

8)

21



-2.5

-2

-1.5

-1

-0.5

00 0.5 1 1.5 2

mwin/mair(%)

(ηC

is,w

et-η

Cis, dr

y)/η

Cis, dr

y (%

)

50bar100bar140bar


•Isentropic Efficiency via Mechanical Measurements :

1

COMP in

t-t,13C,t-t,is / m

Δp /ρη = P

Efficiency Decrease

Effect on Compressor EfficiencyEffect on Compressor Efficiency

22



•Special Techniques should be used in order to obtain data from a Wet Compressor

•The pressure rise coefficient presented no significant deviation with water injection up to 2%

•Aerodynamic measurements indicate that the stage aerodynamic behavior will not be affected by the presence of droplets for water quantities up to 2%

•Water injection result to an increase of power consumption

•The net increase of the consumed power can be attributed to the centrifugation of the droplets by the rotor

•The increase of power consumption can be described by a single coefficient and the droplet size (from 12μm to 20μm) seems to have no significant effect

ConclusionsConclusions

23



•Further examination of the mechanism resulting to the increase of consumed power at higher rotating speed is needed

•Visual examination of droplet behavior at rotor and stator

•Quantification of the losses in correlation to water collection rate on rotor blades

•Examination of the method of injection on the losses due to water injection (e.g. angle of injection)

Future WorkFuture Work

24



•The work for this paper has been carried out in the frame of HERAKLITOS program. The program is co-funded by European Social Fund (75%) and National Resources (25%).

•The cooperation of Mee Industries and Mr T. Mee personally in purchasing the nozzle manifold is gratefully acknowledged

AcknowledgmentsAcknowledgments

experimental analysis of wet compression in axial

Documents