Calibration of wavemaker using sonic surface wave transducer and capacitance probe

T.R./Z

UNIVERSITY OF GLASGOW

DEPARTMENT. OF NAVAL ARCHIT.ECURE

EXPERIMENT TANK

Formal Contribution

11th INTERNATIONAL TOWING TANK CONFERENCE, 1966.

SUBJECT - SEAKEEPING

REPORT NO. 2.

CALIBRATION OF WAVEMAKER

SONIC SURFACE-WAVE TRANSDUCER

and

CAPACITANCE PROBE

BY

A. M FERGUSON

UNIVERSITT

OP GLSGOW

Department of Naval Architecture

Experiment Tank

REPORT NO. 2

CALIBRATION OF WAVMAfRT

USING

SONIC SuRFACE-WAVE TRANSDUCER

AN

CAPACITANCE PROBE

A. M. Ffz'guaon

a. 2/64

Calibration of Wavemaker. Introduction

The opportunity to carry out a full calibration of the waveinaking apparatus was taken during the period when the

"Sonic Surface-Wave Transducer" (on circulation by D.T.M.B.) was in use at Glasgow University Experiment Tank.

This memorandum describes the measurementstaken by both

the sonic probe and the capacitance probe. _{Records were}

also taken of the motion characteristics of the wavéniaker. Apparatus.

The wave profile was measured by (a) the D.T.M.B. Sonic Surface-Wave Transducer using the technique described in the instructions circulated with the probe.

(b) Capacitance probe. Three typeB of capacitance probes were tested.

(I A brass strip sheathed inperspex.

(2 A " dia. silver steel rod with plastic sheath.

(3

A 0021" dia. solid copper wire loop with plastic sheath.

All three probes recorded the same wave amplitude. Probe

No.3 was chosen. for the tests because of its superior ability to repeat a linear calibration.

The signals from both sonic and capacitance probes were recorded on a multi-channel. ultra violet recorder.

The waveform of theplunger was recorded by direct linkage to a Kemph and Remmers pen. recorder.

Procedure.

Both probes were mounted on the centre line of the carriage

at the forward end. _{The capacitance probe was èituated 3'O":}

behind the sonic probe.

The wavémaker was made to produce waves over the cOmplete

range of frequencies and crank se.tting8 available. Records

were taken simultaneously from the sonic and capacitance probes with the carriage stationary, about one third tank

length from the wavemaker. Check readings were taken at

and - tank length from the wavemaker but no attenuation

was evident.

The following tests were also carried out with forward carriage speed.

(a) With a wave length of 15' and over a range of X /L for

forward speeds of 5, 10 and 15'/sec.

(b) With

X/L

= 40 and ) _{5, 10 and 19 ft. for forward speeds}

of

_5,

IO, and 15 ft./sec.

It was found to be impracticable. to run the wire capacitance

probe beyond 4'/seo. Therefore those tests involving

forward carriage speed were conducted using the sonic

probe; only.

Calibrations of sonic and capacitance equipment were carried

out at least 4 times each test period. It was found beneficial

to clean the wire probe occasionally with a.s.oft cloth containing silicone jelly.

Results. Fig. 1. Fig. 2. Fig.

3..

Fig.

4.

(2) Wavemaker Calibration.

Control unit settings for wave height against .

Wave height against carriage speed for

= 5',

10'

and 19' with

AfL

= 40'

at zero speed.

Wave height against crank for X

15'

over range of

forward carriage speed.

Amplitude ratio against X

= wave amplitude plunger amplitude

Fig.

_5.

Wave profile comparison and waveform of plunger

motion. Conclusions.

The working range of the wavemaker is shown in Pig. I. The curves on this plotting are the means of results

obtained by both sonic and capacitance probes. The maximum

scatter was no more than

0.05"

about the mean line with

neither probe consistently reading high or low.

Fig. I. also shows that the constant speed drive motor

slows slightly as the crank radius is increased. This is

indicated by the slightly higher frequency dial setting required to 'maintain a constant wavelength as the crank radius is increased.

Fig. 2 and ₃ show the ability of the sonic probe to record

the wave amplitude with a forward carriage speed.

Fig. ₄ confirms the linear theory of waves that all the

points of A (wave amplitude/plunger amplitude) should'iie. on a unique curve.

Fig. ₅ shOws samples of wave profiles recorded by both

systems with the carriagestationary. It will be noted

that both give the same amplitude but the sonic probe .ind.icatea a steeper wave slope than that obtained by the

capacitance probe. Fig. ₅ also shows a sample of the

plunger motion waveform which as can be seen, closely

resembles a sine wave. It can be concluded that with a

stationary probe similar results can be obtained using

either the sonic or capacitance measuring equipment. It

is also evident that the sonic probe is reliable for wave amplitude measurement with forward speed over the range covered during these experiments.

Appendix.

The wavemaker at Glasgow University Experiment Tank consiSts of a hollow steel wedge plunger with a convex face, driven' through a Scotch Yoke and variable speed gearbox by a

U

ft

ft

UI...

_______UuUlaI IU!

iUuIIIUIk

UP.4

_______IUUUIIUU RUT

_____UIUP'dU

I

__&!

!

±

'9

-

i

.i I

-'-.

UUUUU..'1

L I L

UU!

lURUUU

iii.ppuuuiu

uuu....0

..U.U.UU.UU....UU

uI

III

J----D :3

111111

'I....

OUhIjIIlIITml

::

EE!IIIdE!iI

..

IOiIpiiII1spiIIIIIi1uu1ui

U U

_. UI

U

...uEI..u.rl.E.uaIurn...uIIuuI!!..ii

k

I'....

_i

U_u

1F

I

1._Il

I

g

uiuuuUuuuuuuuuu

suuuuIIuuuuIuuuuUUmsuuuueuuueuuIuu

.#IIU

-1111

III

uuu.a..uuu.uuuauuuua.0

IUuUUUUUIIUuUIUUUIUIU*UIUUUUUI

-...!

....!

_a.

__!UI!IU*UUUUUIUIS9UUIUUIIUUIUU

thi,IUIIIuu.i

-I!U1U1511P

)LJ:

p

I-U

U-U

UI.

UUU1UW4II1U11UU1

-- _suu

.u..rrn1

..auuua.

uuuuuucaII

IiuuluuS

uiuuu.u.uau.

-..Uuuuuu

UUU UU11

uIIIuUUu

iuiuuniiuuiiuuuiiuu

uu U

UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU..U..UU

..u.u.uu.u...uu...i.i..uu....i

IIIIIIIIIHIIIIIIIIHIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIHIIIIII

URUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUN.U.UUUUU...L...

HIIIIIIIIIIPIIIIIIIIIIIIIIIIIOIIIIIII!IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

UUUUUUUIlUUUUUUUUUUUUUUUUUUUUU !UUUUUUUUUUUUUUUUUUUUUU.S

.UUUUUIIUUUUUUUU'U Nu :uU.uu..I,u....uuUuu.U....u...

UUUUUuUUuuuuUUUUUUUuUUUU.U...U.uI...U...UU...I ...U.UuUr uuuu

UUUUUUUUUUUUIIUUUUUUUU'U!UUUUUUUUUUIUUUUUUUUUUUUUUUI iuuuciuuuu

oiiiuinnhiiiiuuuiinu;n;iiiiiioiiiiioiiiiuoiniuiii iuIIuInhIIIIIuIII

--.

1IINIIHIIII1IIIHIIeII:II:IIIHIIIII 1IHOIllhIOIIIO

"ln"oo"

UUUUUUUUUUUUIUUUUUUUI1UUUUUUUUUUUUUI UUUUUUIUUUUUUUUU "I IUUUUUCJUUUUUUU

IIIIIIIIIIIIIiIIIIIIIIIIlIuIIlIIIIUhIIIIIIIIHhIIIIIIIIIIIItIIIIHhIIIIIUUIIflhI

UUUUUUUUUIIUUUUUUUUUUUUUUUUUUIIUUUSUUNUUUUUUUUI IUU...U..UU

HHIHIIIIIIIHIIIIIIIIIIIHHHIHIHIIIIIIHII1IIIIHIIIILIIIIIIIIIIIIIIIHIIII

IllIflIHIHhIIIIIIIIIIHHhIIIIIIIHHI'IIIIIIHnIoPiIIIIIIIIIIIr!I!PIHIII

UUUUUUUUUIiUUUUUUUUUUUUUUUUUUUUUUIIUUUSUUUUUI UUUUUUI IUC2UWUUUU

UUUUUUUIIUUUUUUSUUUUUUUUUUUIIISUUUIUUUUUUUI

IUUUI

UUU

UUUUUUUUUIISUUUUUUUUUUUUUUUUUIIUUUUUUUUUUUUUUUI IUUUUWUI IUUU

UUU

IHIflhIIlIIIIIIIIIIIIIIIIUIflUhlIIIflhIIUIIUIUhIIIIIIIliI 1111111111

UUUUUUUUUUUIIUUUUUUUUUUUUUUUUUUUUUUUIIUUUUUUUUUU$UUUUUUWI I..U.L.I IUU

U

iiiiiiuiuii iuiiiuiniuiiiiinuiiinui uI:::uuIIuIuIuIuI IIUI?l i.u...:::

UUUUIUUUI UIUIUI...UUUUUUUUUUUUUI UUUUUUIUUUUUUR1IUU

I UUUUUUUUU

1011111111 IIHIIPHIII!IIIIIIIOIHIIIIIIIIIIIIIIIIIIIIP IllIIlIihII.iiiii

U....U.UUUI U UU USUUUU UUUUUUUURUI UUUUUUUUUUIUUUU1IIUUUUUUHUUUUU

....UUUUUUUU UUUUUSUUUUUUUUUUUUUUUIIUUUUUUUUUUUUUUUUUUrI IUUUUUI IUUUUUUUUUU

IflhIIilhIIIIIIIIII1IIIIIIIIIIflhIIIIIIIIIIHhIHIHhIIIIIuIIIIMIII IllIHhlIHhl

HhhhhhhIHhIIIIhhhhhhhhhIhhhhhhhhIhhIIhhHhhhhhUIhhhhhIFIII IIPIII IlIhhhhhhhhhl

UUUUUUUUUUIIUUIUUUUUUUUUUIUUUUIIUUUUUUUUUUUUUUUUUUP1 II IULI IUUIUUUUUUU

IIOIII1OIIIiIIllHHIllIHIHNIII1IIIIIIllllHIHIIIIIlIIII Iii 'ihiOiiiiii

11111111111 hhhlhIhhhhhhhhhHhIhIhIhhI' hhhhhhhIhIhIL]hhIhlIi1 Ihi IHhlIhhuIlI

I IIIHI1III IIIhIIhhhhhhhIhhIIhIhhhIH hhIIIIhhIhhIIhIhhII '.I I!1II III 111111111

.uu.u....I... UUUUUUUIUUIUIUUUI II L!I

IUUUUUUUU

.U...UU..I UUUUUUUUUUUUUUUUIIUUUUUUUUUUUUUUUU ii iii' ii iuuuuusu

UUUUUUUUUIIUUUUUUUUUUUUUUUUUUUUUUUUIIUUUUUUUUUUUUUUII.I U.lIr1 IUURUUUUUU

UUUUUUUUUUUUUUUUIIUUUUUUUUUUUUUUUUWI IMI

riii IUUUUUUUUU

UUUUUIUUUUUUUUUUUU UUUI i!i IIUIUUUUUUUUUUU

IllIllIllIllI IIlIlIlllIlllIIIIIIllIu..ii.un..uiuul.iuuai

ii

i.!:::::::::::::::

IhhhhhhhhhhuuIhhhhhihhihIihIhhhihhhhIhhIllhhhhhhhihhIIhIhhhhI

h!1I!IthIhhhIIIIhhI

I1IilIHhIHhII

IIIIIIIlIIHIIIIIIOIIOIIIIIIIIII IIIIIIIIIIiOhIIIIhIiiiiiooiiiiiiii

IhIIIhIhIIIh[HIhIl!IIHIhhhI1IhIHhhIhlIlhhhhhIhflIliUhhI1hhhIhlHHIIhUhhhII

hhhIhIhhhI hhhlhIhhIhhhIhIIhhhIhlhhIPIhhlhhIhIhhhhIhIhhhIhIhhIHhIhIhhIhhIhhhIhI

INS 7 6

5

C

- -- JU

--

I_____

- -

U

__.

._ -

_I

iinin

II

irgiI-IipIg:

_.I

i

II--I

II

I _I

I

-

I

F'

i_.F-.

I

I

I

S

I.

L

I

4

EEI.

IT

11

__pu!. I

IW.' I

1T-L---

L----;TI

Ii

_{ill_i}

111

16

EIiEuL

:I

U

U..

U..

... _.

-I

.

U.

II

u.

_.0

I

U.

_II

U

__I

U U UU

111________________

ulaiiii

-

liii-

-

iii

II=HhlII

-.

IIIIU

U

III

TIi*ui

OIl

Ill

UUI

H-- I

U

-

--ED

OR.AN

I

Il-u

II1I1IT

uuuuumsuuuuuuuuuuuu

IIhjIIIIlIIUIIIl

iIIIIIIBIIhiiiiuiuiiuiuniiniiuiiiunii

IIIIIIITAUUIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

iiuiiiiiuuuiuiim

.u...u...u...m...u...0

.ui

£.a....

IiglIIIlIIIlH..

,...IIIIUIJIIII$IIUIIIlflUIIIIIlflhIIIIIIHI

RB..

I

HHIIIUU

IiI"h

"'-iniiuiuiuiiiiiuuiiuuuuuuniu

.

r

auuRBrn

UURURURRRBRUBU1

u.miiIII

urn

uuuuuuuuumuwauusuuuuuu

BBRUR.R.UR.RRBURBBBUBF!4U

BR...

UURRRBRBRUIUU

.1IIIL

---t---H I

arnuiirnu

IIIIIIHHHIHIIHIIIH

011

UIIU!!IIIIIIIIHhIIHII

UmSR.URBrnURU.RBUBRBSR.

I

..m

.I

Ill'

I - f f f -f I

uurnpuuuj.:.:..

ii

I

-

*1

H

-H- H

UIHIIIUIIIUIU

I:

1t-n

HHIIUIIIINIII

_{uIIuIIIIIuIIIu,}

111110

1H1I11IJ'4Nh1i111IOIN1I1IIiIi111i1U1Iflh1Liiniiiiuiiii

uuRaRusuuuuuuIuuuuuuuauuuuBuuuumRaaRBuuuuuaauuuauuRuuuauuuuuRsuluuuuRuRI

UIIIIIIIftI1II

IIIIIUIIIIIIUIIIIIIII1IIIIUIIIIIHIUIIIIIUIUIIIIIIII

...c3R..R.RB.$..U.

'PaRBuBUuuuRBRaR.RUUUuR.UURBURBRR.URBSRBRu.uRuR..uu..

B

muIIInuImIIIIuiiiii

mmmmmmjIll'Jff

II

Pill

.u--RB...0

..rn.rn.m..mwm.a...jIiiiOhIIrl0fhlhl110fhl11

uRurnu.RRR...

HIIHNIIIflIHIIIIHIIIII

.RBBIIU*Nu..R1I.UIIBUIjIIIIIIIJHII1

rn..m...s.u....JUflIflhIPr999Pjfl9UhIIuIIflhlflhIflIflU

.RR.BRRBUURrnLmI9flHrn9ffl

IIIiiifliNIHIIOHhIIIflHhII

IIIIIilIHIIIUIIIIIIdII...

U.

111I111UI!IIIiIIflAIlIIlIIIlIIIiiiiliiilii

011111

IIKIIIIIIIII1101111IIIIIIIIIHIINNIIPIIIHI00111111IOIIIHI

B....

URBBBUPBU

L

RU...

URRRRUBBRUUUUBRRRBBUUBU

B.

llllHIIHhIIllHlNlluhI11H

1111

11111

IIlIIilHIIllIIIIIUhlIIIIIIIIflhIIII

IIDIu1InuDIIINhIIuIINBIB.B.IRUUUB.

urn...u.uuu....BBURU.uuuURR

niIIlIIIIIIlHhIlHhIIIHIlluhIIlII

HLIII!I

lfflhIIIIIIIII

uuuuuuu

rn

i I

BUURUURRUUR.BBIURU

J

Ifililulil

IVI1J:

1111111

I I

...

"i!IIlIIIIIAhIIOIIOI

IIlIflI9I

unuuiui

RVVURBUILIPI

IUIIIIIII

11

TT

I

IIIUIIIIIIUIIIII!AIIIIIIIIIIIUIIIHhIHHhIIIIIII

l9IB

11111111

II

I1I11

-

KIIIIHIIIIIIIIIUIIIIVA$IIlllHIIIIIIIUNhIliIUhIIIIlII

1111111111

I I

IIIIIIlIRIIlIIlIIrIflhllIIIUIIIIiflhIIUhIIIIIIIIII

RBRR

4jTBUl

BUUUUBUBBRUBU

flu

Ru I

IIIIIIIIIIIIiiiiiIIIIIUhIIIuIuuuIHIIIIiIIIIflhII

IJUBB

BBURUBB

I1FBR*I

UIBR.RBBUBRBUWABURBBRUUBRRUUUBBBBBR.BUUUU

I RBRRBBR

PIrRUBI

RUURuRBBBBBURu4BR.UuRuUUUUUURuRRRuURRRU

IIUU11tiIIul

<

i

HIIIIHIUIIIEMIHUIIIIIIIIIIII1UNUIIIIIHMIUII

I

IIUIIIHI

bUllill

0 uIU3LIJA 3CAM

flITIflfl

>1

o

.

u....

i Lt.J.m.mu...

lu uuu uuu.u. .uu.uuua.uuuu. .u.u...u...u.a.uu.u..uuuuuu....

...uuu.uamuuaauu.uuuuuus.uuus..uuuuuuuuuuuuuauumauuuuuuuuuuu

....0

uu ..u.... u..is U. s....uul....

a... mu ma.. ...m uaauaauu

u.uuauuusuiuusuauuuuaumuumuua.auumuuuuuuuuumuuamuuuu

auuuuuuuuuaauu

..auau...u..auuauuauuuU.u....uuuuum.u.auauuu.u..uu..uu....

...uuuuua.uuuuauuuuaauuuuuuuwuuuuuuuuuuauu.u.umuu

u...u.a....uu..u.ua...

ti

uuuuusuaauuaumuauauauuuuuuuuauuuumuuuuuuuuuuuuuuuuuuauaauumauuu

N..m.uuma.m....a..u.

.a...auu..u...u..usa.aa

uuuuuUaauauuUaUaUUUuUUUUaaUUUUUUaUUuUUu*UaRUaUUUarIuUUUUaUUUUuUUu

...au...ua..u....aa.aaa..u..aaE...ua.u.u.,;u...uu..

.u...ia.a..uuma uau.a..au. .upuauua au...0

ia

a.a.'uau.a.mam

I II

...uuu...muuuuuuuuauwuaaauuuaaauarii mauau.*iuuauuuaauu

...u...ua.u....u..u.u..uu...

uuuuuuuuuuuuuuaa

a _____

...uIr

--..u...u..u..a.

_____

uumuuuuauiri Fuuk ...a..

...uuiu.uai auu

-..uuusuau...asu

....

...

'.u.wJ i...

uuuuasuuauauuauuuuuu' .,...M..U.UUUU...

..u..n.u....u..ii

..quruii.uu...am..a..aaaIL..ii..uuiu.a.u. aufi

uuuuauw:u.

uuuuuuauuuauu

....

uaaausua

uauauausauuuu

.:u::III:::w3ItrIdIIiUIII t1th

Utm. mUOIutmWj

.uuu. i..uisa

m..mamai I:1I

r.

::

iuu

IIwggmwAr...

.u...uuu..uu.I

..m

_gg...uaria..

uuuuuuuaamuaiiu, ,.rni..n..i...amaaa.

...samUUUtIUIJ..1i..1..IIUUUUmuU.U.URUR.uuUARP4WUUUP'4.UflUm.j IUU!E3U

...u...a...u..U.U..us.u..U..r/,1usumIaR.m.aUa!1 uaa.u.a.

usa

IUUstu

uuuuuuuuuuus.Us.uUU..uuus.

H-t

HQ isaauv

. ISURU

.u...u.asa

uuuuuuuuuuuuuuuauuuauuuus

...aa..0 ivaipas

auuuuuuuuuaauuuuuuuuusmuuuuuuuuuu

.m....uauu.

H

"

..uu..a.uu....sausas..uU uss.s.r

muuuuuuuUauuURuuumuuuusu.aadauuuUUUU*aUUUUUUUUUU5lUURu

I

i.*.a

..us....ua..us.auUUaUgIU.iUuVIPUUaUauIRUu..UURs..uUURUuU.U..Ui aa.zw'u

uuuusuuuuuuuuuuauuuu

.aas4u.ausa.tmaaas.muumuuu.us.us.amsuuus

...ua...U.a.aU.U..URrr4aURsUUauUuU.Us...UsusRaUR.UuUR.U.UUaUUUURU

1

.u.usuu.au.usususus.s.WI'Au.usUU.UURUUusUaUURa..uUR..UUUUsuUURRURUUU.

....m...us...U.tm.U,ZiA2m5.U.us..URU.U.UU...URUUU.U...U.Uus.UUusURUURUUu

.uus.uuuaU95JIr$Vi4sUUUUU.uUUUUUuURIUUUUUUUa*usuUUUUUuUUsUauURURuuRU

muuuusuuuuusu

us.

...auaassuuusuusuuussuss..u....musuuuu

uuumuuuuumuua

....a..u..u.1p4k.r/a.as.s.us.u...a.uU..a..mU..u.usUU.ssu...UasaaUaR.UU

UUUUUUURU

uuuuuuusuuuuuuuuwausumusuusuusuum....

usuuuusus.w4uuau,,a

.uUUUusUURi.aU,A..F .R.URUUaus.uUUa*UaUUUUusuUu..uuU!jU.UUU5tm

aauuauuuwauuuuw/Aa*W'

..auua.,4.auua.s..RiuU.auuUUUUUsuuUUUuUURuUUUU....UUU.uSUUUUas.uUUURs.UUUuU

uusuuuau.auur/auusw ..UUR.a.s...a.Uuusasa.uaR.au.usuUUsuUuuu..uUus.U.Uuuaa

....r...u.ia....juuus..us..m.amu.usa.s.fl11h.ua.a.u.uuu.saus....

...,,U..s..1.RU.lUUUuuuuuUu.UUus.U.UuUUR..Uu5U5UUUU.URUs.uURU.uUUUUU5UUUU

uuuuu'iuuuuuuauu. a....asa..u..uI.uas.uuusuuua.aa*.uusUUU....uU..uUaassIUuaUuu

uuuus.asuusu...0 uuuuuauusususauss.uUaUUUuUUUusU*Us.UR.URUs.U.UU5s.IUUuUU

...uusuu.s.uus..us.ussu.UauUURURUUuUUmUUUuusBURUUuuUuUUUuURUUUUUURURUaU

I

.usu..us...us.us..uU..URa....UU.usUU.URUUUR..UU..u.UUuuuUUuUUURUIUUUUUu

..uu...uusu....uus.su..auuRUuuu.UURUUURUUUUUSSUUUUUUUUUUUUUSSRUIUNMUUUUIUUURU