Kwadwo Poku OwusuDepartment of Mechanical & Manufacturing Engineering

Supervisors: Dr. David C. S. Kuhn & Dr. Eric Bibeau

OutlineIcing and Icing MeasurementResearch ObjectivesResearch ObjectivesDesign ApproachE i t l d N i l P dExperimental and Numerical ProceduresResults and DiscussionConclusions

Icing and Icing MeasurementAtmospheric IcingEffects of Icing Effects of Icing Methods of Ice DetectionC i l I D t ti P b Commercial Ice Detection Probes

Atmospheric IcingIcing PrecipitationIcing from Sea Water SprayIcing from Sea Water SprayWet Snow AccumulationI l d I iIn‐cloud Icing

[Ahti 2005]

In‐cloud IcingRime Icing‐5°C to ‐12°C5Low Liquid Water

Content (LWC)Content (LWC)Feathery in appearance L d it Low density

In‐cloud Icing cont’dGlaze Icing0°C to ‐5°C0 C to 5 CHigh Liquid Water

C t t (LWC)Content (LWC)Clear in appearanceHigh density

Effect of Icing on Wind Turbines

Decrease of power due to modification in h d i f h bl dthe aerodynamics of the bladeIncreased fatigue of the components due to imbalance in the ice loadsChunks of ice thrown off from the blades can cause serious injuries to people and wildlife as well as damage to propertyg p p y

Methods of Ice Detection

Direct methods ‐ Detects property change caused by the accretion of ice. Such yproperties include mass and dielectric constantIndirect methods ‐ Based on detecting weather conditions that lead to icing such as weather conditions that lead to icing such as humidity or detecting the effect of icing such as reduction in power generatedsuc as educt o po e ge e ated

[ Homola et. al., 2005 ]

Commercial Ice Detection Probes

Labko Ice Detector 3210C

l i S i i Uses Ultrasonic Sensitive wire to detect icing

Control Rosemount Model 0871 LH1 Icing Sensor

Sensor part

Control unit

Uses Ultrasonic Vibrating Probe to Vibrating

probedetect Icing

p

Research ObjectivesDevelop an ice accretion measurement method suitable for use on meteorological towers based on the changes in capacitance and resistance between two electrically capacitance and resistance between two electrically charged cylindrical probes

Use theoretical models to study the changes in capacitance Use theoretical models to study the changes in capacitance with ice accretion, and validate these studies using “modelled” ice growth in a laboratory setting

Test the proposed method under simulated rime and glaze ice conditions in the icing wind tunnel

Design ApproachTrajectory of air

Conceptual Design Measure ice accretion

Trajectory of air

based on the changes in capacitance and resistance between resistance between two electrically charged cylindrical

Sensingelectric field

probes during an icing event

field

Supercooled water drops

Design Approach cont’dNumerical Design

Design icing probe using QuickField™ simulationsNumerically study the variation of capacitance with simple Numerically study the variation of capacitance with simple geometric “modelled” ice shape to define probe designValidate numerical results with experimental results based on acrylic model of icey

Experimental Design and ConstructionConstruct an ice accretion probe prototype with ancillary equipment and define the measurement method based on the numerical designand define the measurement method based on the numerical design

Experimental EvaluationTest the proposed method under simulated rime and glaze ice

di i i h i i i d lconditions in the icing wind tunnel

N i l d E i l Numerical and Experimental ProcedureProcedure

Numerical Electric Field Simulation: G i E tiGoverning Equations

ρεε −=⎟⎟⎠

⎞⎜⎜⎝

⎛∂∂

∂∂

+⎟⎠⎞

⎜⎝⎛

∂∂

∂∂

yU

xxU

x yx

constant dielectric == εε yx

(C/sq m)densitycharge=ρ

(V) potential electric =U

(C/sq.m)density chargeρ

Electric Field Boundary Conditions Cylinders are defined as floating conductors i.e. gequal but opposite potentialsU= 0 on the external boundaryboundaryDielectric constant of 3.1 for ice was usedCharges of ‐1C and +1C are specified

A typical computation domain

Acrylic Model of Ice

Acrylic cylinder sleeves Aluminum probe with acrylic sleeve

Icing Wind Tunnel

Inner duct of the wind icing tunnel

Probe Orientation

Wind and s

d

s

dsupercooled water drop direction

d

Wind and

d

d a dsupercooled water drop direction

Inline orientation Parallel orientation

Experimental Conditions

Temperature

( oC )

Type of icing

event

Liquid water

content,

Ambient

velocity (m/s)

Sensor

orientation

LWC, (g/m3) to ambient

air

‐2 (±2) Glaze 2.0

5 (±1)

1. Inline

P ll l

8 (± 1)

2. Parallel10 (± 1)

(± ) Ri 8

5 (±1)

I li( )‐10 (±2) Rime 0.8 1. Inline

2. Parallel

8 ( ± 1)

10 (±1)

Schematic of the Probe and Ancillary E i tEquipment

L d iHioki 3522‐50

Lead wires35 5

Capacitance meter

Computer

RS232 cable

Aluminum

Insulator

Computer

Insulator

Results and Discussion

Variation of Capacitance with C DiCenter‐to‐center Distance

4.8

3 8

4.3

(pF)

3.3

3.8

Cap

acita

nce

(

2.3

2.8

1 87 2 37 2 87 3 37 3 871.87 2.37 2.87 3.37 3.87

Center -to-center distance,s (cm)

Numerical

Electric Field Distribution

(s=1.87 cm)

Numerical

Capacitance Variation with Electrode Di t

4.6s

Diameter

4 2

4.4

(pF)

Dd

Impinging water drops

4.0

4.2

Cap

acita

nce

(

3 6

3.8

C

3.60.89 0.99 1.09 1.19 1.29

Diameter of electrode, D (cm) Numerical

Capacitance Variation with Ice Thi k

4.9

Thicknesst

4 7

4.8

(pF)

inline orientation

parallel orientation Inline orientation

4.6

4.7

Cap

acita

nce (

tt

4 4

4.5

tt

P ll l i i4.40 0.2 0.4 0.6 0.8 1 1.2

Thickness of modelled ice (cm)

Parallel orientation

Numerical

Capacitance Variation with Size of A li Sl

5.5

Acrylic Sleeves

4.5

5.0

(pF)

acrylic inline case

acrylic parallel case

numerical parallel case

3.5

4.0

Cap

acita

nce numerical parallel case

2 5

3.0

2.51.27 1.37 1.47 1.57 1.67

Outer diameter of acrylic (cm) Numerical

18

Icing Rates for Rime Ice

12141618

rete

d (g

)

5m/s inline

8 m/s inline

10 m/s inline 10

12

14

cret

ed (m

m) 5 m/s inline

8 m/s inline10 m/s inline

Temperature ‐10oCLWC 0.8 g/m3

468

10

Mas

s of

ice

acc 5 m/s parallel

8 m/s parallel

10 m/s parallel 4

6

8

knes

s of i

ce a

cc 5 m/s parallel8 m/s parallel10 m/s parallel

02

0 2 4 6 8 10 12 14 16 18 20

M

Exposure time (minutes)

0

2

0 2 4 6 8 10 12 14 16 18 20Th

ick

E pos re time (min tes)Exposure time (minutes) Exposure time (minutes)

Mass Thickness

Standard error bars on the 5 m/s parallel case for both cases

Experimental

35 14

Icing Rates for Glaze Ice

25

30

35

cret

ed (g

)

5 m/s inline8 m/s inline10 m/s inline

8

10

12

14

ccre

ted

(mm

) 5 m/s inline8 m/s inline10 m/s inline5 / ll l

Temperature ‐2oCLWC 2 g/m3

10

15

20

Mas

s of i

ce a

cc 5 m/s parallel8 m/s parallel10 m/s parallel

4

6

8

knes

s of

ice

ac 5 m/s parallel8 m/s parallel10 m/s parallel

0

5

0 2 4 6 8 10 12 14 16 18 20

M

Exposure time (minutes)

0

2

0 2 4 6 8 10 12 14 16 18 20Th

ick

Exposure Time (minutes)p ( ) Exposure Time (minutes)

Mass Thickness

Standard error bars on the 5 m/s parallel case for both cases

Experimental

Variation of Capacitance with Exposure Ti

5.325m/s inline

13.525 / i li

TimeTemperature ‐10oC Temperature ‐2oC

4.52

4.72

4.92

5.12

ance

(pF)

5m/s inline

8 m/s inline

10 m/s inline

5 m/s parallel8 52

9.52

10.52

11.52

12.52

nce (

pF)

5m/s inline

8 m/s inline

10 m/s inline

5 m/s parallel

Temperature 10 CLWC 0.8 g/m3

Temperature 2 CLWC 2 g/m3

3.72

3.92

4.12

4.32

Cap

acita 8 m/s parallel

10 m/s parallel

4 52

5.52

6.52

7.52

8.52

Cap

acita

n 8 m/s parallel

10 m/s parallel

3.520 2 4 6 8 10 12 14 16 18 20

Exposure time (minutes)

3.52

4.52

0 2 4 6 8 10 12 14 16 18 20

Exposure time (minutes)

Rime ice Glaze ice

Experimental

Variation of Capacitance with Mass and Thi k f Ri i

5.325 m/s inline

12

5.325 m/s inline

Thickness for Rime iceTemperature ‐10oC

4.52

4.72

4.92

5.12

tanc

e (pF

)

8 m/s inline10 m/s inline5 m/s parallel8 m/s parallel 4.52

4.72

4.92

5.12

tanc

e (p

F)

8 m/s inline10 m/s inline5 m/s parallel8 m/s parallel

Temperature 10 C LWC 0.8 g/m3

3.72

3.92

4.12

4.32

Cap

acit 10 m/s parallel

3.72

3.92

4.12

4.32

Cap

acit

10 m/s parallel

3.520 2 4 6 8 10 12 14 16

Mass of ice accreted (g)

3.520 2 4 6 8 10 12 14 16

Thickness of ice accreted (mm)

Mass Thi kMass Thickness

Experimental

Variation of Capacitance with Mass and Thi k f Gl i

11 2

12.525 m/s inline

12.52

Thickness for Glaze iceTemperature ‐2oC

8.52

9.52

10.52

11.52

ance

(pF)

5 m/s inline8 m/s inline10 m/s inline5 m/s parallel8 m/s parallel

8.52

9.52

10.52

11.52

ance

(pF)

5 m/s inline8 m/s inline10 m/s inline5 m/s parallel8 m/s parallel

Temperature 2 CLWC 2 g/m3

4.52

5.52

6.52

7.52

Cap

acit 8 m/s parallel

10 m/s parallel

4.52

5.52

6.52

7.52

Cap

acita 8 m/s parallel

10 m/s parallel

3.520 5 10 15 20 25 30 35

Mass of ice accreted (g)

3.520 2 4 6 8 10 12 14 16

Thickness of ice accreted (mm)

M Thi k Mass Thickness

Experimental

Sensitivity of Probe to Ice Accretion‐Ri i Rime ice

0 12

0.14

/g)

5 m/s inline0 25

0.30

pF/m

m)

0.06

0.08

0.10

0.12

nce

per

Mas

s (p

F/ 5 m/s inline8 m/s inline10 m/s inline5 m/s parallel8 m/s parallel

0.15

0.20

0.25

per T

hick

ness

(p 5 m/s inline

8 m/s inline10 m/s inline5 m/s parallel

0.00

0.02

0.04

0 2 4 6 8 10 12 14 16 18 20

Cap

acita

n 8 m/s parallel10 m/s parallel

0.00

0.05

0.10

0 2 4 6 8 10 12 14 16 18 20

Cap

acita

nce 8 m/s parallel

10 m/s parallel

0 2 4 6 8 10 12 14 16 18 20

Exposure time (Minutes)

0 2 4 6 8 10 12 14 16 18 20

Exposure time (minutes)

Mass Thickness

Experimental, Temperature -10oCLWC 0.8 g/m3

Sensitivity of Probe to Ice Accretion‐Gl i Glaze ice

0.400.45

pF/g

)

5 m/s inline 1.47

1.68

/mm

)

0.200.250.300.35

ance

per

Mas

s (p 5 m/s inline8 m/s inline10 m/s inline5 m/s parallel8 / ll l 0 63

0.84

1.05

1.26

r T

hick

ness

(pF

/

5 m/s inline8 m/s inline10 m/s inline5 m/s parallel

0.000.050.100.15

0 2 4 6 8 10 12 14 16 18 20

Cap

acit

a 8 m/s parallel10 m/s parallel

0.00

0.21

0.42

0.63

0 2 4 6 8 10 12 14 16 18 20

Cap

acit

ance

per 8 m/s parallel

10 m/s parallel

Mass Thickness

0 2 4 6 8 10 12 14 16 18 20

Exposure time (minutes)

0 2 4 6 8 10 12 14 16 18 20

Exposure time (minutes)

Mass Thickness Experimental, Temperature -2oCLWC 2.0 g/m3

Resistance Variation with Exposure Resistance Variation with Exposure Time

30

35

40

20

25

30

istan

ce (M

Ω)

5 m/s rime ice8 m/s rime ice5 / l i

5

10

15Res

i 5 m/s glaze ice8 m/s glaze ice

00 2 4 6 8 10 12 14 16 18 20

Exposure time (minutes)

Experimental

O ti l P b C fi tiOptimal Probe Configuration

Length of cylinder (cm) 15

Number of cylinders 2

8Center‐to‐center, s (cm) 1.87

Diameter d (cm) 1.27Diameter, d (cm)

Orientation to supercooled

water dropsParallel

ConclusionsA method based on capacitance and resistance can be use to detect icing as well as distinguishing b t th t t f i l d i ibetween the two types of in‐cloud icingThe sensitivity of the prototype probe depends on factors such as center to center distance size of factors such as center‐to‐center distance, size of probe cylinders and location of the ice depositsThe sensitivity of the prototype probe to ice The sensitivity of the prototype probe to ice accretion is high in the first few minutes of exposureThe icing rates increased with wind speedThe icing rates increased with wind speed

Questions ?