CA1311373C - Vortex shedding flowmeter - Google Patents

Abstract

Abstract VORTEX SHEDDING FLOWMETER
This invention discloses a flowmeter comprising a vortex generator of an elongated bluff body disposed gene-rally perpendicular to the flow direction and a vortex detector of an elongated planar member disposed generally parallel to and downstream of the vortex generator of a plane generally parallel to the flow direction, wherein the vortex sensor is fixedly secured to the wall of flow pass-age at one extremity and coupled to the force receiving member of an impulse detector at the other extremity.

Description

~31 1373 VORTE~ SHEDDING FLOWMETER
This invention discloses a flowmeter comprising a vortex generator of an elongated bluff body disposed gene-rally perpendicular to the flow direction and a vortex detector of an elongated planar member disposed generally parallel to and downstream of the vortex generator on a plane generally parallel to the flow direction, wherein the vortex detector is fixedly secured to the wall of the flow passage at one extremity and coupled to the force receiving member of an impulse detector at the other extremity.
The volume flow is determined from the frequencies of vortex shedding and the mass flow is determined from the amplitude of the alternating lift forces on the vortex detector exerted by the vortices, which are obtained by processing and analyzing the electrical signals from the impulse detector, As an option, the vortex detector may include an electromagnet exerting a testing force of known magnitude in pulses or alternating modes, from which the proportionality relationship between the lift forces on the vortex detector and the amplitude of the impulse detector output is calibrated on a real time basis.
This invention sets forth the second generation vortex shedding flowmeter known as the Three-ln-One vortex flowmeter, that measures not only the volume flow rate but also the mass flow rate and the density of fluid, and has a sensitivity as good as or even better than the best of the turbine or paddle type flowmeters in measuring low fluid velocities and has a much greater turn-down ratio.
The existing vortex shedding flowmeters measure only the volume flow and are not capable of measuring low _ ~ ~elocity fluid flows. For example, the best of the oxi~t-ing vortex shedding ~lo~etors rails to measure air ~lo~
under th~ standard conditions lo~er than 20 to 25 faot per second and water flows lower than 1 to 2 ~eet per seeo~d.
It i8 ~ell known that the vortéx shedding phenomena oc¢ur in fluid flows of very lo~ velocities in a hi~hly regular and clear pattern ~uch a8 air flo~s o~ a few foet per second ~elocity and water flo~s of a fractio~ of a foot per second velocity.

10Tho primary ob~oct of the pros-nt in~entlon is to provldc a vortox sheddlng flowm~t~r capable o$ m-asurlug ~luid $10~B in ~id- ~angos, e.g., air flo~s as lo~ aJ 5 to 10 rOot porsecond a~d ~ator flo~s as lo~ as 0.1 to 0.3 rOet por s-cond.
Anoth~r ob~oct is to pro~id~ a vortox shodding ~lo~-metor that m-asured mass flo~ rat-s a~ ~oll as tho ~olu~-~lo~ rat-s.
A further ob~oct i8 to provld- a vortox shoddi~g flo~m-t-r that measurs~ rluid d-nslty.
20Yot anoth-r obJect is to provido a vortex shoddiug flowmotsr co~prising a vortex detoctor or an longatod planar ~omb~r ~lxedly ~-cured to the flo~ Pa~sa6- ~all at one extromity and connoctod to a l-~-r me~bor at th-other extromity, ~hich lo~or mombor i8 coupledto tho ~orce receiYing member of an impul~e dotector in a fl-xlbl-arra~gemont.
~ -t a ~urther obJ4ct i8 to provlde a ~ort-x ~h-dd-ing ~lonmot~r compri~inK a ~srt0x detector Or an elonga~-d planar memb~r socured to ths flo~ pa~sa~e wall at on~
extremity a~d connected to a lever memb-r at the oth-r L

~, extremity~ uhich l~er membcr includos a strain or motion detector contained th-roin or coupled there~ith.
Still another ob~ect i8 to provido a vortox shodd-ing ~lonmeter comprl~ing a vortex detector Or an ~lo~gat-d planar member fixedly socured to th- flo~ passa~o ~all at ono xtremity and floxibly connected to the ~orce r-c~l-lng ~omber o~ an impulse det-ctor.
Still a ~urthor Qb~-ct is to provide a vortox shodd-ing ~lonmoter comprising an el-ctromagn-t Y-rting impul~o~
,,, 10 Or kno~n magnitud- o~ tho ~ort-s detector, from ~hlch the proportionallty relationship b-tween the magnitud- o~ tho t forc-s ~oneratod by the ~ortlc~ and the amplitud- o~
tho tr~nsdu¢er putput 18 calibrat-d on a r-al tlm- basis.
Th-~- and other ob~ects to the pr-s-nt ln~ ntion ~ill b-com- clear as th- d-~¢ription thor-o~ proco-d-.
;~ Th~ prosont in~ontion may be describod ~ith a groat clarity and spocificlty by referrlngto the rollo~ing r rigures Figure l lllustratos an embodimont of the ~ort-s ; 20 generator-vortox d~t-etor eo~bination o~ the pro80nt ~ .
s~ ~ in~entlon that emplo~s a fore- tr~m~tter le--r ~lth ~
" ~ L ola~tie fulerum moa~s Figuro 2 illustratos a~ embodimont of the vortos '~:
generator-~ortex d~etor eombination of the prosont in en-tion employing a foree transmitter le~or ~ith a pi~oti~6 ulcrum mean~.
~igure 3 lllustrates an ombodl~o~t o~ the ~orto~
~ generator-vortex detector combi~atlon of tho pre~ent ,~ in-ention employing a ~lexible ~orce reeei~lng member qf th~ tran~ducer fixedly eonnoeted to the forc- tran~itter 131 1373 ~`

lover.
Fi~ure 4 lllu6trates an ombediment of the vortoY
generator-~ortex detector combination of the prs~ent in~-n-tlon employing a rorco transmitt-r l-~or ~ith ~ fulcru~
moans di~pos-d at a mids~ctlon theroo~.
Figuro 5 illustrate~ a~ ombodiment o~ th- ~ort-s gonorator-~ort-~ detector comb1~atlon o~ tho present in--n-tion omploying a force tran~mitter lever combinod ~ith a motion detector.
Figure 6 lllustrate~ an embodiment of the vorteY
g-norator-~ortex detector combination o~ the present ln~eu-tion employing a forco transmitter le~er couplod to a torsion or torquo detoctor.
Figur- 7 illu6trate6 an o~bodiment o~ th- o~tos generator-~ortox detector combination of th- present in--n-tion includin~ an olectroma4net exorti~g impulsos o~ kno~n magnitude on the vortox detector for calibratlng the proportionality relation~hlp bet~een tho magnitudo o~ th-li$t ~orcss and the amplitude o~ th~ transducer output.
~ 20 Figur~ 8 lllu~tratos an ombodimont Or the ~ort-s ,~ ., gonerator-~orte~ d-toctor combi~ation including a n-slbl-Jolnt coupllng th- ~ortos dotoctor ~d the ~orco r-¢-l ~ g membex o~ tho tra~sdu¢or.
Figure 9 illustrate~ an embodimont o~ the vortes ` generator-~ort~x dotoctor comb~ation lncluding a fle~ibl-oint coup~in~ an o~tenelon of the ~ortox dot-ctor and the transducer.
Figuro 10 illustratos an embodlm0nt of the vortos ~i generator-~ortex detector combination including an elec~ro-~o 3 maBnet ~mpulse generator for calibratlon purpose .
"

,,, Figuro 11 illustrato~ a cross soction o~ an embodi-~" ment o~ the lmpulse detector of tho prosent in~ontlon.
;; Figure 12 illustrates a~other cro~ ~sctio~ o~ tho i- lmpulse dotoctor shown in Figure 11.
-it~ Figure 13 illu6trates a ~urther cro6s ~ection o~ the lmpulse detector shown in Figuro 11.
~i" ~
Figure 14 illu~trate yet anoth~r cress soctlon o~
the impul~e dotector shown in Figuro 11.
Figure 15 illu~trate~ another combination o~ tho Piezo electrlc oloments congruous with tho impul~o d-tector hown in Figur~ 1 1.
Figure 16 illustratos a ~urthor comblnation o~ tbie Piezo oloctric olemonts conBruous with the i~pu18~ d~t-ctor ,, ,~ sho~n in Figure 11.
Figure 17 illustrates a cross section o~ anoth-r ~- embodi~ent Or the lmpulse detector of the pre~e~t inYe~-tlon.r Figure 18 lllustratos anothor cros~ section o~ t~-impul~ detector sho~ in Figure 1?.
Figure l9 lllustrates a further cross s-ctioh o~
the impul~e detoctor shown in Figure 17.
x~ Figure 20 illustrates a cross ~oction o~ a pr-~-rr-d embodiment ~or ~ackaging the variou~ comblnatio~s o~ th-ortex generator and the vorteY dotector o~ the pro~ont in~ention i~to a rlo~meter ha~lng an integral struct~r-~
,,, ~
,1; Figure 21 illu~trates a perspecti~e vie~ o~ tho slee~e tu~ing employed in the co~tructlon of the flo~-meter shou~ ~ Figure 20.
Figur~ 22 illustrates a cut-out ~le~ of tho vorto~
."~
~ 30 deteGtor included ln the co~bination ~ho~n ln Figure 21.

~1 1373 !, ~he present inventlon te~chos the follo~ing ne~
principles which are superiox in structure6 and function6 and patentably dlfferent compared with the existing arta Flrstly, ln the pres~nt invention, the vortex detector i8 fixedly secured to the wa}l of floR pas~age, ~hich arrang--ment keeps the resonance frequency far abov~ the operating range Or the ~ortex ~hedding ~requencie~ and, consequently, it Pllo~s the use of a flex~ble coupling bet~ee~ the ~ortex detector and the ~orce roceiving member of the transduGor~
that provide~ a greater ~ensiti~ity in detecting lo~
intenslty vortices~ In existing art~ the rortex det-ctor is ~l~xibly secured to the wall of flow passage ~hilo lt i8 rigidly couplod to the force recei~lng ~ember of the trans-ducer, ~hich i8 precisely the reverse of the presont in~entlon. The fixed couplin~ of tho ~ortex detector to the force receiving member of the transducer practi¢od in ,, ~
~ the oxisting arts requires much greater threshhold force rs ~
that can be dotected by the transducer at the minim~m level a~ the ma~or portion of the ~orce is absorbed~by ~-~ 20 the ~ixed coupling and o~ly a small portion iB tran~itt-d to the tran~ducer, while the flexible coupling o~ tho ~; vortex detector to the force recei~ing member of tho transducer as taught by the present in~ention transmits most of the force to the transducor and~ consequently, the flexible coupling of the present in~ent1on enables it to detect vortice~ with i~tensities far bello~ the low~r limlt , t~t: measurable with the exi~ting arts Secondly, the p~o~ent invention makes it possible to employ a wing oi the optimum chord length as the ~ortex detector The ide~l 30 ~dth of the bluff body employed as the vortex generatQr 1 ~ 7~
~ 6 -.;.

. . .
equal to a quarter of the flow pa~sage di~meter. The wa~e length of the slnuating stream lines created by the ~ortices shed from the two side~ of the blu~f body i~ a~
alternating pattern 18 approximately equal to eig~t times the bluff body wldth. Consequently, the optimum chord length of the vortex detecting w$ng i~ equal to thre0 to four times the width of the bluff body, e.g~, the diameter of the flow Pas~age. In the existing arts, the vortes ~ensing ~ing fixedly connected to the transducor has to extend through a hole included in the rlOw pas~ago ~all.
The dlsturbance on the fluld ~lo~ and impracticPlity i~
~ manufacturing limit the ~ize of the hole through the w~ll 7 ~ of the flow paa~a~e to one half o~ ~he diameter Or th-low passage. There~ore~ the chord length Or the vortes senslng ~ing i~ limlted to one half of the optimum value i~ in the existing artE, ~hile the vortex sensing wing~o~
!;'~ the present inventlon installed through the flo~ Pa8sage opening has the optlmum chord length equal to the dla~eter of the flow passage. The doubling of the liftlng sur~aco area Or the ~ortex sensing wing in the present in~o~tion doubles the sensit~vity ~n detecting vortices. Thirdly~
the present i~ventio~ measures the volume flo~ ma8 flow and fluid density, while the eYisti~g arts mea~ure . "
only the volume flow. ~he vortex ~hedding frequency i8 `~` proportio~al to the fluid velocity, which relationship i8 u~ed in measuring the volume flow in the exieting arts a~
well as i~ the present invention. The amplltude `Df the ,,.
alternating llft forces exerted on the vortex sen6ing ~ing i8 proportional to the square of the ~luid velocity~ti~es the density of the fluid$ which combination 18 kno~n as ~ . .

t31 1373 the dynamlc pressure. In the present invention, th~ dyna-mic pressure is deter~ined by measuring the amplitude of the alter~ati~ t rorces on the vortex ~enslng wing~
~hich yields the mass flux a~d ~luid density ~hen it is divided by the fluid ~elocity and square thereof, re~pec-tively. The combination of the aforementioned novol a~d patentable principleR of the present i~vention brings forth revolutionarily ~ew and advanced flowmetQrs~ which may be a YorteY shedding volumetric ~lonmeter capable o~
measuring very low velocity flows as well as high velo¢ity flows or multifunctlon Yortex sheddlng flowmeters mea8uri~g the ~olume and mass rlows and the density of fluld tn a ~ide flow range~
In ~igure 1 there is illustrated a perspecti~e ~ie~
of an embodiment Or the vortex shedding rlonmeter of the prese~t invention, ~hich includes a vortex generato~, a vortex detector a~d a transducer. The vortex gonerato~
comprises a~ elongated bluff body 1 disposed ~ithin~the ,~
fluid stream generally perpendicular to the flo~ dl~ectlon~
which i8 rigldly secured to the ~all of the rlo~ pa88ag0 b~' at one or both extremit~e~ thereof- The vortex detoctor comprlses an elongated plana~ member 2 disposed gn~erall~
parallel to and do~nstream of the bluff body 1, ~herei~
the chord plane Or the elongated planar member or ~l~g se~or 2 i~ general}y parallel to the dlrectlon of tho lo~. The wing sensor 2 fi~edly ~ecured to tho ~all 3 o~
the ~lo~ pas~age at one extremity 4 i8 connected tO~a ~orce tra~mltter le~er 5 at the other extremity 6. The ~orco transmitter le~er 5 di~posed ~enerally parallel to t~e ~low d~rection a~d adJacent to the ~all 7 o~ the flow passage includes a fulcrum mean~8 di~po~ed at an extremity thereof opposite to the extremity connected to the wing senRor 2, which fulcru~ means couple~ the trans-mitter le~er 5 to the wall of the flo~ pa~sage in a pivotable arrangement over a minute angle about an axis ge~erally parallel to the longitud~nal axis of the bluff body 1. In thi~ partlcular embodimsnt, the fulcrum~means 8 compr1ses a flat elastic member disposed on a plane generally perpendicular to the chord plane of the ~ln~
sen~or and fixedly ~ecured to the transmitter member 5 at one extremity and to the wall 7 of the flo~ pas~a~e ~t the other extremity. The mldsection Or the transmittor lo~or 5 include8 a socket 9 engaged by a ball end 10 o~
the ~orce receivin~ member 11 extending from a thin fla~o con~tituting the closed end of the tran~ducer contalner vessel 12 that contalns the tra~sducer element, ~hich may be a stress detecting or ~train detect1ng element. The ball and socket ~olnt coupllng the force transmitter lever 5 and the force receiving member 11 may be ~ubsti-} ~
tuted ~ith other type~ of swivel or flex ~olnt commonly ~ practiced in the art of fl~xible coupllng.
:~ Tho ~ortices shed from the two slde~ Or the blu~
~ body ln an alternating pattorn create ~inuating stream-~$ ' ~ ~
lines trailing the bluf~ body xherein the ~ave l~n~th ot the si~uat~ng streamline~ i6 equal to the fluld v~loclty U divided by the frequency of the ~ortex shedding ~.
~ It is ~ell know~ that the frequency of the ~ortex shedd~
;~ in8 f iQ proportional to the fluid velo¢ity ~ Con80~
quently, the ~ave lsn~th of the sinuating streamline8 i8 ~0 generally a constant that i8 independent of the fluld , : _ 9 _ . :~
~r~

, ~elocity. The ~ing sensor 2 immersed in the sinuating stream lines experiences ~lternating llft forc~s cha~glng directlons at the same ~requency as that of the ~ortex ~hedding~ The alternating lift iorce~ on the ~ing sensor 2 or lateral deflections resulting therefrom are tra~mit-ted to the transducer elements containod in the transducer container ~essel 12 through the force tr~nsmitter le~or 5 and the rOrce recei~ing me~ber 11. ~he transducer elements ~, .
convert mecha~ical signal6 from the ~ing sensor 2 to electric~l ~ignal8, ~hich are processed and a~alized by ~.~
electronic analizer. The fluid ~elocity ~ is propor-tional to tho ~orkex shedding rrequency f in a ~lde ra~ge ~, , o~ fluid ~elocities including most industrial and do~eJtlc ~lo~ measuremont~. The proportionality relatlonsbip bet~een the fluid velocity and the ~ortex sheddln~ ~ro-, "
quoncy i8 detormined empiricall~ during flo~moter cali-br~tion. Tho vortex shedding flo~meter of the pre~ont inYention d~termine~ th~ ~luid ~elocity or ~olume ~lo~
rate ~rom the ~ortex ~hoddin~ ~requenc~ detectod by a~ali~-lng the olectric signals from tho tra~ducer~ ~hich~olcct-ric signals are generated by the alternating li~t ~rcos on the ~lng sensor 2. The amplitude o~ the alt-rnatlng lift force~ on the ~ing ~ens~r 2 i~ generally proportlonal to the square o~ the fluid ~eloclty times the fluid de~ty.
The amplitude of the e}ectric 8ignal8 ~rom the transduc-r may be a llnear or qua61-linear ~unction of the amplit~d-of the al~ernating llft force~ on the wing s0n~0r 2~
d0pending on the electro-mechanical characterlstlcs o~ tho coupling ~etween the wi~g 8en50r and the transducer~
,. ~j, .
~ 3O ~hich ~unctlon~l relationship i8 deter~ined empirlcally .,,,~, . ~
1 0 - ' ~ 13tl373 ~. i, during rlowmeter callbration. The vortex shedding ~lo~-meter Or the present i~eutio~ determi~es mass ~lo~ rato from the am~lltude Or the alternating li~t force~ o~ the ~ing sensor as the ma~ $10~ rate i8 proportional to the ~ dynamic pr~ssure d vided by the fluid ~elocity. The '~ dyn ml C pre~ure 1~ determined from the amplitudo o~ the ~lternatin~ lirt rorces on the ~lng sensor based on a~
empirical relationship determined during calibraticn o~
the flowmeter, ~hile the fluid ~elocity i8 determined ~rom the frequency of the alternating li~t $orces. 0~
course~ the ~ortes sheddin~ $10wmeter of the present ln~on-tion totormln0s the nuld d~nsity as the ratlo o$ th-~
~,/ dy~amic pressure to tho square Or the ~luld ~eloclty.
~he vortoz ~hedding no~meter of the present in~ontlon i may ~easuro ~olume flow, mass $10~ and fluid de~slt~
. ~ simultanoously, or any one or t~o o~ the threo $10~
ariables dependin~ on the functional and economic r-quiro-~: me~ts of the users.
~` ~ In Flgure 2 there i8 illu~tratod an ombodimont ha~in~ essentially the same eloments and constructlon~
s the ombodiment sho~n i~ Figure 1 ~ith ono e~ceptio~.
. The fulcru~ ~eans 13 o~ the rorce transmitter le~er 14 ¢omprlsos a pi~otal ~oint tkat allo~s rreo pl~otlng môvements about an axi~ generally parallel to th~ lor~itu-dinal aYis of the bluff body.
In Figure 3 there i8 illustrat~d an ombodi~ent : ha~ing essentially the 8 ame olements and con~truction~ ae~: the embodiment sho~n in Figure 2 ~ith one e~ception~
` The force recei~ing member t5 estending from one clo~d ond Or the tran~ducer contalner Yessel 16 compri~es ~

~3t t37~

elastic flat bar fixedly connected to th~ force trans~lttor le~er 17 at the extremity thereof. The ~arious types o~
~ ~ulcrum mean~ and ~oints coupiing the force transmitter ; . le~er a~d the iorce receiving member illustrated in Figures 1-3 may be u~ed in other combination6 not ~ho~n i~
the illustrated embodiment~.
- In Fi~ure 4 there i8 illustrated an embodimont o~
,; th~ vortex shodding flowmeter of the present invoation similar to the embodiment shown in Figure 2 with one exception being that the rulcrum moans 18 o~ the force transmittor lo~r 19 i8 disposed intermediate the t~o ~;~ extremltie~ o~ the force transmitter le~er respectively ~; con~ected to the wing ~ensor 20 and the transducer pack 21.
~ij,~ i Tho ~peclflc type of tho ~oint bet~eon the force tra~a~it-ter le~er and the force receiving member and the type of~
the tulcrum means may be one of those described ln co~-unction ~ith Figures 1-3 or other typos commonly employ~d a8 a for¢e tra~smitting ~oints in the practice o~ art.
In Figure 5 thtsre i8 lllustrateid aD embodiment Q~
the ~ortex shedding ~lo~mettetr o~ the present invention~
~ hich employ~ the comblnation Or the wing 6en#0r 22 a~td :
ii the transmitter le~er 23 supported in a rree-pl~ot~t~
arrangeme~t. One extremlty 24 of the wlng sensor i8 ~lmplY
aupported by the ~rall o~ the flo~ pas#agO wherein the ~ g ttaO~t~Or i8 all~t~od to pi~ot frt~tely about an axi~ goncrtill~
parallol to thé rlo~ tdirection~ ~hllo tho othor eYtro~lty, . ~ 25 18 connected to the tra~tamitter le~or 23 includ-ing a ~ree-pi~oting ~ulcrum means 26 d1sposed at the mld-section thereoI. The extremity of the trans~tter i~ 30 lever 23 opposlte to that connected to the wing sensor 22 t~ 12 -t3t 137~ 1 includes a motion detecting target 27. The motion detectr 28 detects the osclllatory mo~ement~ of the target 27 created by the alternating lift force~ on the wing son~Qr 22. The wing sensor o~ the embodiment6 Rho~ni in Figure~ 1-4 is fixedly supported at o~e extremity and, consequently, the wing sensor-transmitter le~r comblnation has a hlgh resonance frequency due to the fixed support o~ the ~ing sensor.T-he resonance frequency,which i8 far above the vorte~ shedding frequency range, i8 blocked out by tho electronic filter included 1n the electronic procossor that a~alizes the signal~ rrom the tra~sducer. The ~dng aensor o~ the embodiment shown ln Figure 5 ha~ zero or ~ ~ery lo~ resonance frequency because lt has zero el~a~t1c stlffness and, consequently, zero or very low resonance ~:i rrequency does not inter~ere ~ith the vortex sheddlng . , frequencies.
In Figure 6 there is ~llustrated a~ embodiment o~
; ~ the vortex shedding flonmeter of the present in~entio~
hich has elements and con~tructions simllar to the embodl-~- ~ 20 ment sho~ in Figure 3. The ~orce transmitter le~er 2~
; i : include~ a pivoting ~ulcrum means 30 dispos0d at an extremity opposlte to that secured to the ~ing ~ensor 31.
An a~gled ~oroe recei~lng member 32 extendlng rrom a t~
la~ge 33 constituting the closed end of the transdu¢e~
container ves~el 34 is connécted to the force transmltter ver 29. Tho maximum 8en8iti~ity ca~ be obtain~d by . dispo~ing the flange 33 included in the container Yes~el ~ 34 on A plane generally including the pi~otlng axi8 35 o~
-~ ~ the pivotlng fulcrum means 30.
I~ Figure 7 there i8 illustrated an embodlment or `~- 131 1373 ~, h' ~' , the vortex shedding flo~meter of the present invention that ~cludes meii~ns for calibrating the measurement of the " , ~; amplitude of the alternating lift ~orces on the ~ing s~nsor on an intermittent or real time basi~ The vortex ~heddi~g phenomena are intrinsic to the fluid ~low and, consequently~
~^ the determinatio~ o~ the fluid velocity $rom the vortex shedding frequency doe~ not include any implicit sourc~
s; Or error. 0~ the other hand, ~hile the amplitude of the alternating ll~t iorce8 created by the vortex ~heddi~g phenomena are intrinsic to the fluid flo~, the measurement ~; thereof includes a sourc~ o~ potential error that ari~e~
from the change~ in the electro-mechanical charateri~tic~
Or the coupling between the wing sensor iand the tra~sducor.
I~ other word~, the relationship betwee~ the amplitude o~ -the lift rorces o~ the wing sensor and the amplltude or ~i ~ the transducer out~ut can change as the mecha~ical characteristics of the wing aensor and the ~echaDlcal coupling to the transducer change due to agin8~ wear a~d other ef$ects. The electromiagnet 36 eYerts lateral ~orco~
of kno~ mag~iitude on the ~ing sen~or in intermittent ~r continuou~ pulses as the ferromagnetic element 38 aiii~-d to the combinat~o~ ~ the wing ~ensor 37 and the tran~-mitter le~er 39 i~ attracted b the core 40 of the ele~ro-ma~net 36 that i~ terminated at a clo~o proxlmity to th~, ~erromagnetic element 38 in a lateral relatio~ship the~-~
~` bet~een. The electronic data processor takes the ratio of the magnitude of the lateral force on the wing sonsor ~' ~ t exert~d b~ the electromagnet 36 to the amplitude of the ;
~ transducer output generated by the lateral force, wherein ~,, 3 that ratio i8 then multiplied to the amplitude oi the transducer output generated by the ~ortices in measurl~-R the true a~plitude o~ the alternating lift forces on the wing sensor 37. As a con~equence, the embodiment of the ~ortox shedding flonmeter of the present invention shown in Figure 7 acc~rately determines mass flo~ rates from the amplitude of the transducer output~. The spesi~ic design~ of the ful-crum means 41 and the coupllng b~t~een tha force tran~mitter lerer 43 and the ~orce receiving member 44 may employ o~e o~
the ~arlou~ type~ ~hown in Figures 1-6.
"
In Figure 8 there i8 illu~trated an embodiment Or the vortex ~heddlng flo~meter of the pre~ent invention, ~hich ;~ employs the flexible or swivel ~oin~ coupling the ~in~
sensor and the transducer without using a force tra~itter ,.. .
lever. One extremity o~ the wing sensor 45 18 risedly s-cur-ed to the ~all o~ the rlo~ passage, ~hile the other e~treJ-ity is coupled to the force receiving me~ber 46 exte~dln~
from the closed end of the transducer container vessel 47 by a ball and socket cou~ling 48. The ball and socket co~pl~n~
48 includes a ball ~oint affixed to the ~ing sensor 45~ that engages a socket included in the force receiring membor 46, hich extends ~rom a thin flango constltuting the clos~d.end o~ tho tran~ducer container re~sol 47. The ball and ~ock~t coupling sho~n in the partlcular embodiment may be replac-d ~ith other types Or pivoting or flexible couplings. The flexlble Joint 48 couplin~ t~e ~ing sen~or 45 and tho ~orcc receiving membor 46 pro~ideR a superior ~ensiti~lty i~ d te-cting lo~ lntensity vortices, as the alternating lift-~orc-~on the ~ing sensor of even very small magnltude tend to ,.~.
~ create ~ignificant flexural ~ove~ents at the flexible Jol~t " . .
and, cons~quently, transmit6 the alternating lift forc-~ to 131 1373`

the force receiving member 46. The fixed connoction o~ one eYtremity o~ the wing se~sor 45 to the ~all of the flo~
passage provides a high re~onance frequency of the ~i~g sensor existing far abo~e the ~ortex shedding frequenc~
range. The vortex ~hedding flonmeter sho~n in Figur~ ~ op-r~
ates on the 8ame principles as those described in CQ~U~-tion with Figure 1.
In Figure 9 there is illustrated an embodim~nt o~ the .,~,, ~ ortex shedding flowmeter o~ the present inYention sl~ilar :
to the embodiment sho~ in Figure 8 with one e~ception. ?he ins 8e~80r 49 fiYedly secured to the w~ll of the flo~ Pus~-age at ono extremity lncludes a~ angled extension 50 este~d-ing ~rom the other extremity to~ards the ~ortex ge~erat~g blu~f body 51 i~ a dlrection generally parallel to the ~o~
direction. The extremity of the angled extensio~ 50 1e ~QUP-~
:led to the ~orce recei~ing member 52 exte~ding from th- ~
transducer container ~essel 53 by a fle~ible Joint 54 8u¢h a~ a ball and socket ~oin~ a~ sho~n in the particular o~bo-di~ent or an elastic bar Joint as Rho~n in Figure 10~ I~
, . ,.~
; 20 order to detect the frequency and intensity o~ the ~ortic~e by means ef the ~lter~ating lift forces on the ~ing se~or 49, tho ~ing s~nsor 49 mu~t be located do~nstrea~ o~ t.h~
bluff body 51 out~lde the ~ako o~ the dead ~lo~ zono.
~: embodiment sho~n in Figure 9 makes lt po~iblo to di~po~
the ~i~g een80r 49 at a desired do~stream locatlon ~hilo keepi~g tho tran~ducer pack located in the midsoctio~ o~
the flowmeter. It should be mentioned that, in aJl ea4Qdi~
ment s~ch a~ the one ~ho~n in Eigure 8, it ma~r be d-~lrable to di~ e the ~ing sensor in a parallel a~d slightl~r 0~8-t 30 relations*p ~ith re~pect to the bluff body in order to a~oid the wake of the dead flow zone.
In F$gure 10 there i8 illustrated an embodiment of t~e vortex shedding flowmeter o~ the present in~ention that includes an electromagnet 55 for the same calibration pur-pose a~ that described in conJunction with Figure 7. The ferromagnetic eleme~ 56 af~ixed to the combination o~ the wing 6ensor 57 and the angled cxte~io~ 58 iQ attracted to the coro 59 of the electromagnet 55 when it l~ e~-rglzed ~ith a pulse o~ electric currents o~ kno~n amount. In this particular embodi~ent, the ~tremity o~ the angled ext-neion 58 J~ co~n-cted to the force receiving member 60 of a flatt-o~od ol~ctlc bar construction extending ~rom the transducer container ~eeeel 61. The flexible Joint coupling the angled exten~lon to the transducer pack may be a free-flesin~ Joint euch a~ a b~ll a~d socket ~oint instead of the elastic bar coupling shown l~ the partlcular embodiment. The ~ortex sheeding flowmeter sho~n in Figure 10 operate6 on the s~me principles as those described in conJunction ~ith Figure 7.
In Figure 11 there i8 illustrated A cross section o~
a preferr~d embodiment of the tra~sducer pack that i8 ideal ~or the flow~eter embodiments 6ho~n in Figures 1-10. Th-transducer pack includes the container ~essel 62 ~ith a clo~ed e~d co~pris~ng a thln fla~ge 63 ha~inB a relniorcing rlb 64 dl~posed thereacros~ on a plane gen~rally par~llel to th0 fl~ direction. Tho $orce rec~ g mo~bor 65 osto~d8 $rom the rlb 64 and i6 couplcd to the ~l~8 80n80r dlreotl~
or ~ia the $orce tra~6mltter le~er or the angled eYtension by a flexible ~oint 66. Th~ tran~ducer container ~essel 62 contains a pair of P18Zo olectric discs 67 and 68, a~d a palr oi cQ~ductor di8c~ 69 and 70 re~pectively in contact ; - 17 -~ith the t~o Piezo electric di8c8 and i~sulated electri¢ally from one another by a dielectric di8c 71, which elements of a coaxial a~embly are under a pressurized contact ~ith the thin fla~ge 63 as the as6embly iB compres~ed by a plug 72 threadedly engaging the ope~ end of the container ~ el 62.
A pair or the conductlng ~ires 73 and 74 respecti~ exten-ding from the t~o conductor discs 69 a~d 70 a~d routod thro-ugh a hole l~cluded in the plug 72 transmit electric signals generated by Piezo electric disc6 67 and 68 to an eloctronic slgnal analizer. Th0 Piezo electric discs packaged lnto a cyllndrical stack are i~olated ~rom the cyliadrical ~all o~
the container Yessel 62 by an annular ~oid ~pace 75 ther--bet~een, ~hlch arr~ngement not only electrically isolato~
the stac~ of the traa~ducer elements fro~ the contai~er ~essel 62 but also enhances stre~s transmission from the .! force recei~ing member 65 to tho tran~ducer element~ acro~s the thin flange 63. ~he alternating li~t forces o~ tho ~ng 6ensor creates torque`or pi~oting mo~emeats on the forc-recel~ing member 65 about an axis generall~ colnciding ~lth `~ ~ 20 the line o~ intersection between the thin ~lange 63 ~nd th-rolnforc~ng rib 64~ It should be under~tood that the w - o~
:~ the Piezo electric discs packaged as sho~n i~ Figuro 1t i8 ~erely one or many tranaducer arran~ements compatible ~ith tho flo~metor embodimonts ~hown in ~igures 1-10. For oxam -plo~ ~trai~ gauge8 a~fixed to the rib 64 with a slzabl~
hight or to the thin flange may be employed in placo o~ tho . ~
Piezo electric discs.
In Figure 1~ there i8 illustrated another cross sec-tion o~ the tra~sducer pack Rho~n i~ ~igure 11, which cross ~e¢tion i8 taken along plane 12 12 as ~ho~ in Figure 11.
_ 18 -~31 1373 . .
P' The rib 64 disposed across and built on the thln fla~ge 63 ,, pre~ents the sagging of the thin flange 63 under the pre~s-ure loading eYerted by the threaded plug 72 without hlndor-ing the pi~oting movements of minute magnitude Or the force recei~ing member 65 about ani axi8 generally coinciding ~ith 1` the line of intersection betueen the thin flange 63 and the rlb 64. It i~ important to lino up th~ plane includ~ng the rib 64 ~ith the chord plane of the wing sensor disposed pa-rallel to the flou direction.
I~ Figure 13 there i~ illustrated a further cro~B
section of the tra~i~ducer pack Rhown in Figure ~ hic~
cross ~èction 1B taken along plaine 13-13 a8 shown in Fl6ure The Piezo électrlc disc 67 compriae~ t~o opposltely polarized Piezo electric element6 76 and 77 disposed i~ a geomotrically s~mmetric arrangement about the plane luolud-. ing the rib 64. One side of each of the two Piezo electrlc elementB 76 and 77 i~ ln phy&ical and electrical conta~
~. with the conductor disc 69, ~hile the other sides are groun-,~ ded to the thin fla~ge 63 Or met~llic construction.
In Figure 14 there i~ illustrated yet another ¢ro-s section of the transducer pack ~ho~n ~ Figure 11, whiCh cro~fi ~ection 1~ taken along plane 14-14 as sho~n in Figure 11. The Piezo electric disc 68 comprise~ a single Piezo electric element disposed symmetrically about the plane ... .
including the rib 64. One side o~ the Piezo electric dl~c ~;~ 68 i8 in physical and electrical contact ~ith the conductor ~'~ disc 70, ~hile the other side is grounded to the metalllc plug 72-~: The mechanical vlbrations of the flowmeter compon-nt~
generate electromoti~ force~ of oppoPite sign6 from tho two ,., t~ 9 ~f ~

~; 131 1373 .: .

, oppositely polarized halves 76 and 77 o~ the fir6t Piezo electric disc 67, which cancel on~ anoth~r, while the torque or pivoting motion of the force rece~ing member 65 result-ing from the alternating li~t forces on the ~ing sensor generat~s elect~omotive forces Or the ~ame ~igns from the t~o oppo~ltely polarized hal~ss of the Pieæo electric di~c 67, which add u~ to become ~lectric signals repreRenting tho vortex 6hedding phe~omena. If the t~o halves of the fir~t P~ezo electrlc disc 67 are accurately symmetric in g-ometr~
, and perfectly anti~ymmetric in polarlzatlon, then the rlrst Piezo electrlc di~c 67 would pick up vortex ~ignal8 o~ly and no noises from the mech~ical ~lbration. In reallty~
,~
uch a per~ection can ~ot be accomplished and the fir~t Piezo electrlc di~c 67 picks up mostly ~ortex signals and a small amou~t of the noiso as~ociated with mec~anic~l ~lb~
ration~. The vortex shedding pbenomena generate electro~o~
. "" :
tive ~orces of opposite sign~ from the two identically pola-rized halves of the second Piezo electric disc 68~ ~hick ~
cancel o~e another, while the mechanlcal ~ibrations ~e~-rs-20 te electromotive ~orces of the same sig~s irom the t~o hal~es of the Piezo electric disc 68, ~hich add up to b-como j! ~ , -~ ~ the noise ~lgnals. There~ore, the second Piezo olectric dl~c picks up mostly noi8e8 and little vortex signal. ~h~ el~o-tromoti~e rorces from the two Piezo olectr$c di8c8 are ~o~-binod iu such a ~ay that the ~oises are canceled and ~o pure rorteY sign~ls are obtained and, the~, a~allzed by a~
; electronic ~ignal a~alizer to obtain the frequenc~ ~nd aoP-:s' ;-:
~ litude of the alternating lift forces on the ~ing se~or~
, ;~ from ~hich the volume fIow and~or mass flow a~d/or ~luid - ~ 30 density are determined.
~ 20 -In Figure 15 there i8 illustrated another combina-tion o~ the two Piezo electric discs packaged in the ~ame arrangement as that shown in Figure 11. The CrQ88 ~ec~io~
(a) equivalent to the cross 6action sho~n in Figure 13 sho~s tho rlrst Piozo electric disc 78 disposed asym~tri-:. cally about the pla~e including the reinforcing rib o~ the;.
thin flange, ~hlch may be a circular disc ha~ing only o~e hal~ 79 thereo~ i8 polarized. Th~ cross section (b) equl-~alent to the cross section shown in Figure 14 shows the second Piezo electric disc 80 disposed symmetrically about the pla~e including the reiniorcing rib, whlch may be a ¢ircular di~c haYing only one half thereo$ 18 pol~liz~
cd as sho~n or ono ~ith the same polarization for both hal~e~. The $lrst Piezo electric disc 78 picks up ~ort~
8ignal~ R8 ~ell a~ the ~ibration nolses, ~hile the second ~, P~ezo electric disc 80 picks up mostly Ylbration nolses.
The ~ignals $rom the two Piezo electric discs 78 and 80 are combined in ~uch a ~ay that the Ylbration noisos ar-ca~cellod and pure ~ortex signal~ are obtai~ed.
I~ Eigure 16 there i8 illustrated a ~urther ~o~na-i-~l.:,, ~ tlon of the t~o Plezo electric dlsc~ 81 anid 82 packag-a l~
, j the ~amie arra~i~ement as that sho~ni i~ Figure 11. Both Piezo electric di~cs have t~o oppo~itoly polarized hal~-~
disposed s~mmietrically about the plane l~clud~ng tho , ~ ~ .
` rei~forcing rib~ The t~o Piezo electric dl8c8 faco o~
anothor in a~i electrlcally antlsymmietrlc arra~gement a~ut the plane iucludinig a dielectric dl~c correspondi~g ts t~-S~ element 71 sho~n ini Figure 11. ~he t~o Piezo electric iBC~ 81 and 82 generate electro-motl~e forces of op~o~lt-8ig~i~ afisociated ~ith the ~ortex sheddi~ig only. The ~, h' j:
" ', ~i di~erential electro moti~ef ~orces between the t~fffffffo Piezo s ~, ., oloctrlc discs 81 and 82 are analized b obtain tho frequen-cy ant amplituto o~ the alternating lift force8 on tho ~lng sensor.
~.
- In Fi6ure 17 there i8 illu~tratod a cross ~effction o~ ~othefr e~bodim~nt of the tra~fducefr pack b~Yl~ th~f - same elements and cof~structions as that 6hown i~ Figuro 11ith one e~ception. The t~ffffo Piezo electric disc~ 83 and 84 are ~foparated from one another by a conducting di~ffc 85 split i~to t~o hal~es insfffulated elefctrlcally ~om o~e another. The ~ires 86 and 87 re~fpecti~ely ostending ~'''from ,, ",~
~ the t~ffO hal~efe o~ the ¢onductlng discs 8f5 transmit eIectri-f~ cal E~ffig~al~ff 6efnerated by ~o hal~fffes or the comblnatio~ o~
f,~
the t~o Pi~zo eloctric di~cs to a~ ~lectronic ~lgnal ~r~; analizor.
,i, ,~, In Flgure 18 there i~ illustratod another cross sectio~ o~ tho tran~ducer pack sho~n in Fi~ure 17~ ~hich cros~ ~ction is taken along plane 18-lô as sho~n in Figure 17. The iirst Piezo electric di~c 83 lnclud-o t-o hal~es of the same polarization andj consequo~tl~ can be a single Piezo electri¢ elemo~t.
In Figure 19 there i8 illustrated a rurther croo~
sectio~ o~ the tra~ducer pack sho~n ~ Figure 17, ~hlCh cross 8ection i~ ~ken along plane 19-19 as sho~n ln F$gure 17. Th~ second Plezo electric di8c 84 ha~ing t~o ~ hal~es o~ the ~ame polarizatlon ca~ be a~ undi~idod ~glo d',,';, Piezo e}octrlc dl~c. The t~o Piezo electric di~cs 83 and 1'1 "
; ~ ~! 84 are disposed in an electrically symm~tric ~a¢e to ~ace `~ arrangement a¢ro6s the conducti~g disc 18 di~ided into 30 t~o hal~s~ ln-ulated from one another. The differe~tial ~` 131 1373 ~j ,~, ~....
~,j, ,. . . . .
electro motl~e rorces betueen the t~o hal~es of the conduct-ing disc 85 are analized by an electronic slgnal analizer in obtaining the $requency and the amplitude Or the alt~r-nati~g lift forces on the wing se~or.
In Figure 20 there is illu~trated a cros~ 6ectio~
~, an embodiment of an in-line ~ortex shedding flo~meter ~, of the present in~ention, which sho~s the structural ~, arrangement incorporating the principle~ and element~
de~crlbed in con~unction with Figure~ 1-10. The flo~mot0r ~: 10 body 85 lnclude~ a bore 86 that receives a slee~e tubl~g : 87 ln a clo~e tolerance that pro~ido~ the flo~ pa~g-.,*
88. The ~lee~e tubing 87 l~ secured to the flonm~ter body by ~eldi~g~ 89 and 90. The ~ortex generat~ng U ~f~
body 91 l~ ~ecured to the sleeve tub~ng 87 by ~eldings applied to the t~o extremities thereof- One cxtremity 92 of the ~ing sonsor 93 i8 rixedly secured to tho sleev-tubing 87 by wel~ing, while the other extremity 94 i8 - connoctod to the ~orce tran~mitter le~or 95 by ~eldi~g.
- The ~orce tra~smitter le~er 95 i8 disposed in an elongated cutout included ln the wall of the slee~e tubing 87~ The pln 96 exte~di~g throu~ ~ hole in the ~all Or the ~lo*
meter body engages a hole lncluded ln the transmitter le~er 95~ ~hich comblnation pro~ides pi~oting fulcrum.
h~ transdu¢er co~t~in~r ~e8~el 97 188ecu~ed to the ~lo~
meter body ~herein the ball end Or the ~orce recei~i~6 momber 98 eYtending through the ~all ~ the ~lo~otor bsd~
; e~ga8es the ~ocket lncluded in the tran~mitter l-~er 9~, which comblnation provideR the rleYible Jolnt coupli~g th0 transmitter lever 95 to the force receivl~g membor 98 The core 99 ol the c~llbratlon lectro~a4net l0C eYtend~

through hole~ ln the flowmeter body a~d the tra~smitter lever 95 and 18 terminated ad~acent to the ferromagnoti~
h' ~
element 101 afiixed to the wing sen~or 93. The particular arra~gement of the electromagnet 100 and acces~ories thereof ~re roasible when t~e flo~meter body 85 i~ made ,,, of a nonferro-ma~netlc material such a~ the 300 serios , ,, 8tainle8~ steel- The members extending through holes ln the ~lo~meter body may be secured to the flonmeter bo~y : in leak-proo~ manner~ by mechanical rastening means such as ~elding~ or threaded fastening~. A vortex shedding ~: flonmeter mea~uring only t~e volume flo~ ~ould ~ot requiro ~' the calibration electroma8net 100 and ~¢cessories thereor.
, It is quite cloar that the structural deeign sho~n ln '~ Fi~ure 20 can be easily modified to incorporate ~n e~bodl-, ment sho~n ln Figure 8~ 9 or 10. It should be understood Zl'~ that the combinatio~ of the slee~e tub1ng 87, the ~i~g ~ ,,, ~ , sen~or 93 and the force transmitter l~ver 95 may be ca~t or formed i~to a single integral a~sembly lnetoad o~ the ~eld con~ected assembly~ The pi~otlng iulcrum acd the ~:,ii.:,...
s~i~el ~oint bot~een the force transmitter l~er 95 a~d ~s the ~orce recoi~ing member 98 may be ~elded to con~ert them to a~ elastic fulcrum and ela~tlc ~oint, rospectl~ely~
as such ~eld~ can be made by a~ ~elding tool ln~erted lnto ~: the $lo~ passago 88.
Figur0 21 there i~ illu~trat~d a perspectl~ i ie~ of the slee~e tublng 87 that lncludes tho blu~r body 91~ the ~ing sen~or 9~ and the ~orco transmitter le~or 95 ~:~ disposed in an elongated cutout 102 in the ~all o~ the slee~e tubi~g 87~ ~hich combinat~on i~ ready to be ins-rt-h~ 30 ed into th~ bore 86 included in th~ flo~meter body 8~.
~ ,~
~ 24 -~he holes 103, 104 and 105 included in the transmitter lever 95 are for receiving the fulcrum pin 96, the force recelvlng member 98 and the core 99 of the calibration electromagnet 100, respectively~ It is readily recognized that the Parti-cular design of the structural arrangement makes it posslble to incorporate a wing fiensor of any chord length.
In Figure 22 there i8 illustrated a cutout vie~ sho~-ing the ~ing sensor 93 hypothetically Reparated from tho force transmitter lever 95. The ferromagnetic element 101 10 weld-connected to the wing sen60r 93 has a groove 106 receiv-ing the extremity o~ the core 99 of the calibration eloctro-mag~et 100 in a spaced relatlonship. As an option, a pair of slits 107 and 108 may be included in the ~all Or the sloe~e ..
tublng 87, ~hich are disposed ad~acent to the two opposlte sides o~ the ~ing sen60r 93. Such slits of varying lontths are u~ed to ad~ust ~he resonance frequency of the wing sensor 93. For example, a ~ortex shedding f~owmeter measuring llquld flo~s can have a resonance froquency much lower than that of ,:
a ~ortex shedd~ng flowmeter measuring ga6 flo~s. The ~orteY
20 sheddlng ~lowmeter desiened ~or measurlng gas ~lo-8 can bo readily converted to that measurlng liquld ~lo-8 by incorpo-rating the slits 107 and 108 o~ deslred length.
While tho principles of th0 presont in~entlon havo !I.t~
.~ no~ been made clear by the lllu~trated embodiments, thoro ,~
ill be immod~ately ob~lous ~odlfications o~ the structur~
arr~n~ement~, proportions~ elements and materlals, ~hic~ ~re particularly adapted ~o the s~ecific working en~lron~enta and operatlng conditlons in the practice of the ln~entl ~ithout departing from those princlples.

Claims (25)

1. An apparatus for measuring fluid flow compris-ing in combination:
a) a body including a flow passage extending from one extremity to the other extremity of the body;
b) a vortex generator of an elongated cylindrical shape disposed across a first cross section of the flow passage; and c) a vortex detector comprising a planar member disposed across a second cross section of the flow passage on a plane generally parallel to the central axis of the flow passage in a generally parallel arrangement with respect to the vortex generator wherein one extremity of the planar member is secured to the wall of the flow passage, a lever member including a fulcrum means disposed generally parallel to the central axis of the flow passage with one extremity connected to the other extremity of the planar member opposite to said one extremity secured to the wall of the flow passage, and a transducer means including a force receiving member connected to the lever member;
wherein said transducer means provides signals related to the frequencies of vortex shedding from the vortex genera-tor as a measure of fluid flow through the flow passage.

2. The combination as set forth is Claim 1 wherein said transducer means provides signals related to the amplitudes of alternating lift forces on the planar member as a measure of mass flow rate of fluid moving through the flow passage.

3. The combination as set forth in Claim 2 wherein the ratio of the amplitude to the frequency of the alternat-ing lift forces on the planar member is used as a measure of the density of fluid moving through the flow passage.

4. The combination as set forth in Claim 1 wherein the force receiving member is connected to the lever member by a free-flexing joint.

5. The combination as set forth in Claim 1 wherein the force receiving member is connected to the lever member by an elastically flexible joint.

6. The combination as set forth in Claim 1 wherein the transducer means includes at least one Piezo electric element under a pressurized contact with a thin flange from which the force receiving member extends.

7. The combination as set forth in Claim 2 wherein said combination includes an electromagnet intermittently exerting a lateral force of known magnitude on the combi-nation of the planar member and the lever member, from which the ratio of the amplitude of signals from the transducer means to the magnitude of the forces of the planar member is determined for calibration purpose.

8. An apparatus for measuring fluid flow comprising in combination :
a) a body including a flow passage extending from one extremity to the other extremity of the body;
b) a vortex generator of an elongated cylindrical shape disposed across a first cross section of the flow passage; and c) a vortex detector comprising a planar member disposed across a second cross section of the flow passage generally parallel to the vortex generator on a plane generally parallel to the central axis of the flow passage wherein one extremity of the planar member is secured to the wall of the flow passage, and a trans-ducer means including a force receiving member connected to the other extremity of the planar member opposite to said one extremity;
wherein said transducer means provides signals related to the frequencies of vortex shedding from the vortex generator as a measure of fluid flow through the flow passage.

9. The combination as set forth in Claim 8 wherein said transducer means provides signals related to the amplitudes of alternating lift forces on the planar member as a measure of mass flow rate of fluid moving through to flow passage.

10. The combination as set forth in Claim 9 wherein the ratio of the amplitude to the frequency of the alternating lift forces of the planar member is used as a measure of the density of fluid moving through the flow passage.

11. The combination as set forth in Claim 8 wherein the force receiving member is connected to the other extremity of the planar member by a free-flexing joint.

12. The combination as set forth in Claim 8 wherein the force receiving member is connected to the other extremity of the planar member by an elastically flexible joint.

13. The combination as set forth in Claim 8 wherein the transducer means includes at least one Piezo electric element under a pressurized contact with a thin flange from which the force receiving member extends.

14. The combination as set forth in Claim 9 wherein said combination include an electromagnet intermittently exerting a lateral force of known magnitude of the planar member, from which the ratio of the ampli-tude of the signals from the transducer moans to the magnitude of the forces on planar member is determined for calibration purpose.

15. The combination as set forth in Claim 8 wherein the force receiving members connected to the planar member by an extension member disposed generally parallel to the central axis of the flow passage wherein one extremity of the extension member is connected to the other extremity or the planar member opposite to said to extremity and the other extremity of the extension member is connected to the force receiving member.

16. The combination as sot forth in Claim 15 wherein said transducer means provides signals related to the amplitudes of alternating lift forces on the planar member as a measure of mass flow rate of fluid moving through the flow passage.

17. The combination as set forth in Claim 16 wherein the ratio of the amplitude to the frequency the alternating lift forces on the planar member is used as a measure of the density of fluid moving through the flow passage.

18. The combination as set forth in Claim 15 wherein the force receiving member is connected to the extension member by a free-flexing joint.

19. The combination as sot forth in Claim 15 wherein the force receiving member is connected to the extension member by an elastically flexible joint.

20. The combination as sot forth in Claim 15 wherein the transducer means includes at least one Piezo electric element under a pressurized contact with a thin flange from which the force receiving member extends.

21. The combination as set forth in Claim 16 wherein said combination includes an electromagnet inter-mittently exerting a lateral force of known magnitude on the combination of the planar member and the extension member, from which the ratio of the amplitude of the signals from the transducer means to the magnitude of the forces on the planar member is determined for calibration purpose.

22. An apparatus for measuring fluid flow comprising in combination :
a) a body including a flow passage extending from one extremity to the other extremity of the body;
b) a vortex generator of an elongated cylindrical shape disposed across a first cross section of the flow passage; and c) a vortex detector comprising a planar member disposed across a second cross section of the flow passage generally parallel to the vortex generator on a plane generally parallel to the central axis of the flow passage wherein one extremity of the planar member is secured to the wall of the flow passage, a lever member including a fulcrum means disposed genernally parallel to the central axis of the flow passage with one extremity connected to the other extremity of the planar member opposit-to said one extremity, and a motion detector means for detecting movements of the other extremity of the lever member;
wherein said motion detector means provides signals related to the frequencies of vortex shedding from the vortex generator as a measure of fluid flow through the flow passage.

23. The combination as set forth in Claim 22 wherein said motion detector means provides signals related said motion detector means provides signals the planar member as a measure of mass flow rate of fluid moving through the flow passage.

24. The combination as set forth in Claim 23 wherein the ratio of the amplitude to the frequency of the alternating lift forces on the planar member generated by vortices shed from the vortex generator is used as a measure of the density of fluid moving through the flow passage.

25. The combination as set forth in Claim 23 wherein said combination includes an electromagnet for intermittently exerting a lateral force of known magnitude on the combination of the planar member and the lever member, from which the ratio of the amplitude of signals from the motion detector means to the magnitude of the forces on the planar member is determined for calibration purpose.