1991_effects of unsteady phenomena on flow

8/12/2019 1991_Effects of Unsteady Phenomena on Flow

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7 4 P. Grenier - - Effects of unsteady pheno men a on f low meter ing

ffec ts of un s teady phen om ena on f lo wmeteringP G R E N I E R

A f t e r c l a s s if i c a ti o n o f th e v a r io u s s t e a d y a n d u n s t e a d y p h e n o m e n a t h a t c a n d i s t u r bg a s fl o w, i n f o r m a t i o n g a t h e r e d b y G a z d e F r a n c e s R e s e a rc h D i v i s i o n o n t h eeffec ts o f uns tea dy d i s tu rbances , su ch as those gen era te d by p ressure reducers , i sr e v i e w e d . E x p e r i m e n t a l r e su l ts a r e g i v e n f o r o r i f ic e p l a t e s, t u r b in e , v o r t e x a n du l t r a s o n i c m e t e rs , s h o w i n g t h a t th e e r ro r s i n d u c e d c a n b e o f t h e s a m e o r d e r a s, o rg r e a t e r t h a n , t h o s e c r e a t e d b y s t e a d y d i s t u r b a n c e s . M e t h o d s f o r m i n i m i z i n g t h e s eeffec t s and research tha t s t i l l needs to be done a re d i scussed .

Key words : i n s t a l l a t ion e ff ec ts , o r i f i c e p l a t e f l owm ete r s , t u rb ine f l owm ete r s , vo r t exf lowm ete r s , u l t r a son i c f l owm ete r s , p r e s su re r educe r s , uns t ead y f l ow

B a c k g r o u n d

T h e n e e d f o r a c c u r a t e m e a s u r e m e n t o f ga s f l o w isi n c re a s i n g r a p i d l y w i t h t h e r e q u i r e m e n t f o r c o s t a n de n e rg y s a v in g s a n d e n v i r o n m e n t a l c o n s i d e r a t io n s .

T h r o u g h o u t t h e g a s i n d u s t r y, m a n y m e t e r s a r eused i n r e l a t i ve ly d i s tu rbed cond i t i ons , s i nce a p r e s -su re reduc e r i s f r equen t ly p r e sen t in t he nea r ups t r eamreg ion . Ove r r ecen t yea r s , many e ffo r t s have beenm a d e t o e l i m i n a t e m e t e r i n g e r r o r s r e l a t e d t o t h e m e a ncha rac t e r i s t i c s o f t he f l ow. Ho we ve r, i t i s c l ea r t ha ta l t h o u g h m a n y p o i n t s h a v e b e e n i m p r o v e d , t h e c a u s e so f s eve ra l l a rge e r ro r s s t il l r em a in unc l ea r and a r ed i f fi c u l t t o r e d u c e . K n o w l e d g e o f t h e m e a n c h a r a c t e r -i s ti c s o f t he f l ow can n o l onge r be cons ide red a ss u f fi c ie n t t o g u a r a n t e e t h e a c c u r a c y o f a f lo w m e a s u r e -me nt . l,2 , 3

Ty p e s o f d i s t o r t i o n s a f f e c t i n g t h e f u l l y d e v e l o p e dp r o f i l e

F o r g a s f l o w m e a s u r e m e n t t h e r e f e re n c e f l o w c o n -d i t i on i s t he fu l l y d eve lop ed p ro f i l e , w h ic h i s ob -t a ined a t t he ou t l e t o f a su ff i c i en t l eng th o f s t r a igh tp ipe wh a tev e r t he ups t r eam c ond i t i on ( see F igu re 1 ). Itshou ld be no t ed t ha t , t o be s t ab l e , bo th t he meanv e l o c i t y a n d t h e t u r b u l e n c e p r o f il e s m u s t c o m p l y w i t hthe fu l l y dev e lope d f ea tu re s . In p r ac t i ce , ga s f l ow -me te r s r a r e ly meas u re a fu l l y de ve lope d f l o w s ince fo reco no m ic r ea sons ups t r eam s t r a igh t l eng ths a re qu i t el im i t e d . T h e r e f o re m e a s u r e m e n t s m a d e w i t h a f lo w -me te r u sua l l y app ly t o a r e l a t i ve ly d i s to r t ed f l ow.Seve ra l t ypes o f d i s to r t i on can oc cu r : t hey a r e c l a s s i-f ie d i n to t w o m a i n f a m i l ie s ( s te a d y a n d u n s t e a d yd i s tu rbances ) .

The author is with Gaz de France/DETN, Service M~ trologie etMateriels de r~seaux, 3, Che minde Villeneuve, 94 140 Alfortville,France

Steady d i s tu rbances

Steady d i s tu rbances app ly t o t he mean cha rac t e r i s t i c so f t he fl ow, such a s t he mean v e loc i t y p ro f i l e . Theya r e n o t t im e d e p e n d e n t a n d m o s t o f t h e s tu d i e s m a d eo n t h e b e h a v i o u r o f f lo w m e t e r s i n d i s t u rb e d c o n d i t i o n sa re r e l a t ed t o t h i s t ype o f d i s tu rbance . The ma in t ypesare 2:

[ ] A x i s y m m e t r ic d i s t u rb a n c e : t h e m e a n v e lo c i t y p r o -f i le i s f l a t te r o r sha rpe r t han t he fu l l y dev e lope d

pro f i le , e . g . due t o change s i n p ipe d i am e te r[ ] A s y m m e t r ic d i s t u rb a n c e : t h e m e a n v e l o c i ty p r o f il e

Mean velocity profile

Pipe wall Centre Pipe wall

Figure I Example of a ful ly develope d veloci ty prof i leand its associated turbulence profile

0955-5986/91/010074-07 1991 Butterworth-Heinemann Ltd


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Flow Meas Instrum Vol 2 January 1991 75

i s no t sym m et r i ca l , e . g . a t t he ou t l e t o f a bend[ ] S w i r l : i n th i s c a s e, a n o r t h o r a d i a l c o m p o n e n t o f t h e

ve loc i t y c r ea t e s a he l i co ida l f l ow, e . g . a f t e r twoc o n s e c u t i v e b e n d s i n d i f f e r e n t p l a n e s

The e ff ec t s o f t he se d i s tu rbances have been s tud i ede x t e n s i v e ly f o r m o s t t y p e s o f m e t e r. A l t h o u g h m a n ypo in t s a r e s t il l unc l ea r, t he p hys i c s o f t he se d i s tu rb -a n c e s a n d t h e i r e ff e ct s o n g a s fl o w m e t e r s is n o w w e l ld o c u m e n t e d . A l l s t e a d y d i s t u rb a n c e s e x c e p t s w i r lw h i c h c a n b e r e m o v e d b y u s i n g q u i t e s i m p l e f lo w

c o n d i t i o n e r s ) d e c r e a s e i n i n t e n s i t y o v e r r e a s o n a b l el eng ths . Fo r t h i s rea son , s t eady d i s tu rbances w i l l no tbe d i s cus sed fu r the r he re .

nsteady disturbancesU n s t e a d y d i s t u r b a n c e s m o d i f y t h e f l o w v e l o c i ty a t ag i v e n p o i n t , th e i n d u c e d c h a n g e v a r y i n g w i t h t i m e .U n s t e a d y d i s t u r b a n c e s a r e m u c h m o r e d i f f ic u l t t oc h a r a c t e r i z e a n d s t u d y, a n d m o s t o f t h e m c a n p r o p a -ga t e ove r cons ide rab l e l eng ths t yp i ca l l y s eve ra l

d o z e n s o r h u n d r e d s o f m e t re s ) 1T h e m a i n t y p e s o f u n s t e a d y d i s t u r b a n c e c a n b ede f ined a s fo l l ows .

Flow steps

F l o w s t e p s a r e t h e s i m p l e s t t y p e b e c a u s e t h e y a r e apas sage from a s t eady s t a te t o an o the r s t eady s t at e. Acyc l i c e xam ple i s sho wn in F igu re 2 . Such st eps a r egene ra t ed b y gas app l i ances l i ke hea t e rs . F low s t epsc a n v a r y t h e f l o w b e t w e e n m a x . a n d m i n . v a l u e s o rb e t w e e n n o m i n a l a n d z e r o f l o w.

Turbulence

Tu r b u l e n c e is a r a n d o m f l u c tu a t i o n o f t h e v e l o c i t y t h a tis s u p e r i m p o s e d o n t h e m e a n v a l u e . T h e tu r b u l e n c e isu s u a l l y d e s c r ib e d b y t w o n u m b e r s :

[ ] t h e tu r b u l e n c e i n te n s i ty, w h i c h i s t h e r e la t iv e a m -p l i t u d e o f t h e f l u c t u a t i o n s t o t h e a m p l i t u d e o f t h em e a n v e l o c i t y

[ ] t h e c o r re l a t i o n l e n g th , w h i c h is a n i n d i c a t i o n o f th es i ze o f t he s t ruc tu re s t ha t a r e p ropaga t ed .

Tu r b u l e n c e is a l w a y s p r e s e n t i n f l o w a n d p l a y s a nimp or t an t r o l e i n t he s t ab i l i t y o f a ve loc i t y p ro f i l e : t heh ighe r the l eve l o f t u rbu l en ce t he f a s te r t he changes i na f l ow p ro f i l e . Tu rb u len t s t ruc tu re s tr ave l a t a speed o f

Flow axial velocity ~ Over meteringat stop

Turbinerot tion speed ~ Under meteringat start

Velocity

TimeFigure 2 Flow m etering error due to flo w steps

t he s ame o rde r a s t he f l ow i ts e lf . Tu rbu l en ce is c r ea t edby the i n t e r ac t i on be tween va r ious f l ow l aye r s , e . g .w i t h p i p e w a l l o r je t s c o m i n g f r o m s i d e - b ra n c h e s .

Pulsation

P u l s a ti o n i s a h o m o g e n e o u s v a r i a t io n i n t h e f l o wve loc i t y o f a la rge po r t i on o f space s ee F igu re 3 ). I t i s

t h e r e f o r e d i f f e r e n t f r o m t u r b u l e n c e : o n o n e h a n d b e -c a u s e th e c h a n g e a t a g iv e n m o m e n t is t h e s a m e i n aw h o l e r e g i o n ; o n t h e o t h e r h a n d b e c a u s e t h e a m -p l i t ude ca n o f t en be much h ighe r. Pu l sa t i on i s u sua l l yinduced by compres so r s o r i n s t ab i l i t i e s o f p r e s su rer educe r s .

Acoustic disturbance

A c o u s t i c d i s t u r b a n c e s r e s u l t f ro m t h e p r o p a g a t i o n o facou s t i c wave s . I n a qu i t e l a rge r ange o f f r equenc i e s ,o n l y p l a n e w a v e s c a n b e a c t i v e . I n t h o s e c o n d i t i o n s ,t h e p r e s s u r e a n d v e l o c i t y c h a n g e s a r e d u e t o t h es u p e r im p o s i t io n o f t w o p l a n e w a v es , o n e g o i n g d o w n -

s t r eam, the o the r go in g ups t r eam , bo th a t t he l oca ls p e e d o f s o u n d . A t a g i v e n f r e q u e n c y, s t a n d i n g w a v esys t ems can f r eque n t ly be obse rved s ee F igu re 4 ) .

E v e n w i t h p l a n e w a v e s , a c o u s t i c d i s t u r b a n c e s c a nb e q u i t e c o m p l e x p h e n o m e n a t o c h a r a c t e ri z e s in c e ,even fo r a f i xed f r equen cy, t he ve loc i t y f l uc tua t i ong e n e r a t e d c a n b e v e r y d i ff e r e n t f ro m o n e p o i n t t oa n o t h e r. In a d d i t i o n , w h e r e a s t h e c o m p o n e n t w a v e st r ave l a t t he speed o f sound , t ha t i s no t t he ca se fo rt h e r e s u lt in g v e l o c i ty a n d p r e s s u re f l u c t u a t io n s w h i c ha re t he quan t i t i e s t ha t c an be measu red ) .

A c o u s t i c d i s t u r b a n c e s a r e u s u a l l y g e n e r a t e d b yv ib ra t i ons o r p r e s su re d rops . Mos t p r e s su re r educe r scan gene ra t e l a rge acous t i c d i s tu rbances .

Figure 3 Pattern of the velocity disturbances generatedby pulsation

Area of high amplitude

[ ] Area of low amplitude

l l i i l[ f iFigure 4 Pattern o f the velocity disturbances generatedby a system o f acoustic standing waves


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7 6 P. Grenier - - Effects of unsteady phenom ena on f low meter ing

Propagation of large distorted flow patterns

In some cond i t i ons , l a rge d i s to r t ed f l ow pa t t e rn s canbe gene ra t ed and t r ave l a t a ve loc i t y o f t he s ame o rde ras the f low i tse lf . These s t ruc tures d i ffer f rom regu lart u r b u l e n c e b y t h e i r s iz e , i n o t h e r w o r d s b y t h e i rco r r e l a t i on l eng th .

F igu re 5 g ives an example o f such s t ruc tu re s

be ing gen e ra t ed by a c la s s i ca l o r i f ic e p l a t e w i th a fu l l ydev e lope d u ps t r eam p ro f i l e . P r e s sure r educe r s can a l sobe a sou rce o f such d i s tu rbances .

E v i d e n c e o f u n s t e a d y d i s t u r b a n c e e f f e c t s inv a r i o u s f l o w m e t e r s

O r i f i c e p l a t e

Or i f i ce p l a t e s can be s ens i t i ve t o pu l sa t i ons . A numbero f p a p e r s h a v e b e e n p u b l i s h e d o n t h e s u b j e c t . F i g u r e6 g ives an example o f t he e f f ec t o f a pu l sa t i on on aco rne r- t apped o r i f i c e p l a t e o f d i ame te r r a t i o 0 .7 . 4 -9

T u r b i n e m e t e rG D F h a s d o n e a lo t o f re s e a rc h o n t h e b e h a v i o u r o ftu rb ine me te r s und e rgo ing uns t eady d i s tu rbances . 14-18Th i s s t a r t ed w i th f l ow s t eps ( s ee F igu re 7 ) : s i nce t he sedis turbances are crea ted a t the user ' s s i te , i t i s notu s u a l l y p o s s i b l e f o r t h e g a s c o m p a n y t o t a k e a n yac t ion a t t he sou rce o f t he p rob l em . I t wa s the re fo ren e c e s s a ry t o s t u d y m e t e r b e h a v i o u r i n o r d e r t o d r a wu p s o m e r e c o m m e n d a t i o n s . I t a p p e a r e d i n p a r t i c u l a rt h a t o v e r - s i z in g c o u l d c o n s i d e r a b l y i n c re a s e th e p r o b -lem . 11

Instantaneous so pressureines

Instantaneous lowines

Figure 5 Instantaneous flow downstream o f an orificepla te

LU

1 0

5

ho = AP._._sAp

+

++

I+ I +1 I I t I I I

0 0 . 5 1 . 0

h

Figure 6 Error generated by a pulsat ion induc ing afluctuation ho in the differential pressure for a cornertapping or i f ice pla te of d iameter ra t io 0 .7

5o

4 O

3 0

L ~ 2 0

lO

. . . . . T i e . ~

Q S t o p p e d f l o w. S o ~ . .~ d f l o w .Q m ~ M a x .f l o w o f t h e m e t e r

= I i I I I I I I20 4 0 6 0 8 0 1 O 0

O/Q,.=

Figure 7 E xample o f the error generated in a turbinemete r by s teps o f f low

Du r ing t h i s re sea rch p rog ram me , an d l a te r on ,some e ff ec t s o f by -pas se s ( s ee F igu re 8 ) we rer e c o r d e d : t h e w a y a m e t e r s t o p s a n d a l s o t h e w a y i tw o r k s i n 's t e a d y ' c o n d i t i o n s c a n b e a f f ec t e d b y t h ea m o u n t o f f l o w t h r o u g h t h e b y - p a ss . T h e g a s j e t a t t h et e e j u n c t i o n b e t w e e n t h e b y - pa s s a n d t h e m a i n b r a n c hi s r e spons ib l e fo r gene ra t i ng no i se and pu l sa t i on : f o rt h e s i t u a t i o n s h o w n i n F i g u r e 9 , t h e i n d u c e d m e t e r i n ge r r o r is a b o u t + 3 a t 2 0 o f t h e m a x i m u m f l o wcap ac i ty o f t he me te r. 16 I t sho u ld be n o t ed t ha t t h i sc o n f i g u r a t i o n s h o w s t h a t u n s t e a d y d is t u r b a n c e s c a np ropaga t e ups t r eam and r each t he me te r t h rough f i t -t i ngs such a s con t ro l va lves (no t i n son i c cond i t i ons ) .

In subsequen t r e sea rch p rog rammes , t he e f f ec t o fpu l sa t i ons on t u rb ine me te r s was s tud i ed sys t ema t i c -a l l y. F igu re 10 show s typ i ca l m e te r ing e r ro r s re l a t ed tothe pu l sa t i on i n t ens i t y and f r equency , a t a f l owra t e o f0. 25 (~max 10,12

A n o t h e r i n t e re s t in g p o i n t w a s d is c o v e r e d w h e nm e a s u r i n g t h e m e a n v e l o c i t y p r o f i l e s d o w n s t r e a m f r o ma p r e s s u r e r e d u c e r a n d f r o m a b e n d , a n d c o r r e l a t i n gthe me te r e r ro r t o s t eady d i s to r t i ons o f t he ve loc i t y

B y p a s s D N 5 0

D N 1 O E x h a u s t

c o n v o

Figure 8 Example o f a meter d is turbed b y the do wn -st ream f luctuat ions gen erated by a by-pass

E< I

0 1 O 0 2 0 0F r e q u e n c y H z )

< I3 0 0 0 1 O 0 2 0 0

F r e q u e n c y ( H z )3

Figure 9 Comparison of f requency spectra of the f luc-tuat ing veloci ty a t the meter wi th b) and w ithout a)flow via the by-pass


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Flow Meas. Instrum. Vol 2 January 1991 7 7

O

Figure 10 Me tering error created in a turbine meter asa function of pulsation frequency and amplitude

pro f i l e . F igu re 11 show s the ve loc i t y p ro f i l e ob t a ined5 D d o w n s t r e a m o f th e b e n d . 13 5 D D o w n s t r e a m o f th ep re s su re r educe r, the m ean ve lo c i t y p ro f i l e i s qu i t es imi l a r, bu t t he e r ro r o f t he me te r i s r a the r d i f f e r en t : a t0 .25Qmax , i t i s ab ou t +2 fo r t he p r e s su re r educe r,le s s t h a n 0 . 2 f o r t h e b e n d . T h i s s h o w s th a t k n o w -l edge o f t he me an ve loc i t y p ro f i l e i s no t neces sa r i lysu ff i c i en t t o p r ed i c t t he me te r ing e r ro r.

S o , p r e s s u re r e d u c e r s w o u l d s e e m t o b e t h e w o r s tf i t ti ng fo r a me te r. The exp l ana t ion i s p ro ba b ly l i nke dw i t h t h e la rg e a m o u n t o f e n e rg y in v o l v e d i n t h ee x p a n s i o n o f ga s t h r o u g h s u c h a d e v ic e . F o r a nex t e rna l no i se l eve l o f 80 dBA, t he d i s tu rbance l eve l

i n si d e t h e p ip e w i l l b e u s u a ll y b e a b o u t 1 4 0 - 1 5 0 d B Af o r l o w p r e s s u r e f lo w s , w h i c h m e a n s v e l o c i t y f l u c t u -a t i ons o f the o rde r o f + 0 .5 -1 .5 m s -1 ( r e f. 1 ) .

Th i s ene rgy l eve l i nc r ea se s w i th t he p r e s su red r o p . F i g u re 1 2 s h o w s t h i s e ff e c t o n a m o d e r n t u r b i n em e t e r : f o r t h e l o w e s t p r e s s u r e r a t i o ( u p s t r e a m : d o w n -s t r eam o f the p r e s su re r educe r ) , no s ign i f i can t i n f lu -e n c e is o b t a i n e d a n d t h e e r r o r c u r v e o f th e m e t e r is n od i f fe r e n t f r o m t h o s e o b t a i n e d w i t h a n u p s t r e a m s t r a ig h tl eng th o r be nds . Fo r t he h igh e r p r e s su re r a t io , as i g n i f ic a n t e r r o r i s o b t a i n e d , w h i c h is a l m o s t a c o n -s t a n t o v e r t h e w h o l e r a n g e , e x c e p t a t l o w f l o w s , w h e r ei t i s h igher.

V o r t e x m e t e r

The e ff ec t o f pu l sa t i ons on vo r t ex me te r s was s tud i ed sys -t em a t i ca l l y by u s ing w a te r and a i r t e s t benc hes 19-26.F i g u re 1 3 s h o w s s o m e e x p e r i m e n t a l r e s ul ts . T h e v o r t e xp h e n o m e n o n c a n b e a f fe c t e d b y a s u p e r i m p o s e d p u l -s a t io n a t e s s e n t i a ll y t w o f r e q u e n c i e s : t h e f r e q u e n c y o ft h e n a t u r a l v o r t e x s h e d d i n g ( w i t h o u t p u l s a t i o n ) a n d i t sd o u b l e . Vo r t e x e m i s s i o n i s t h e n f o r c e d a n d n o l o n g e rc o r r e s p o n d s t o t h e a c t u a l f l o w r a t e . I n s o m e c o n d i t i o n s ,p u l s a t io n s c a n a l s o t e m p o r a r i l y d e s t r o y th e a l t e r n a t ev o r te x l a u n c h i n g , e . g. b y s t im u l a t i n g a s i m u l t a n e o u sl a u n c h i n g o n b o t h e d g e s .

Vor t ex me te r s can a l so be s ens i t i ve t o t he no i seg e n e r a t e d b y l a rg e u p s t r e a m p r e s s u re d r o p s , as s h o w ni n F i g u re 1 4 . 28 S o m e p r o b l e m s w e r e a l s o o b s e r v e dwi th dow ns t r e am l a rge p re s su re d rop s 19-26.

Figure 11 Mean velocity profile measured 5D dow n-stream o f a single bend

-~ ~ Upstream condition:y + 72 D straight length

+ ~ o 2 bends in different p lanesx pressure reduction 2.1:1

2 pressure reduction 3.2:1

0 100 200 300 400Flowrate (m3 h 1)

Figure 12 Behaviour of a m odern turbine meter invarious conditions

T h e l e ve l o f t u r b u l e n c e is a l s o o f im p o r t a n c e t ovo r t ex me te r s : an i nc rea se in the t u rbu l en ce l eve lr e su l t s i n f a s t e r i n t e r ac t i ons be tween f l u id pa r t i c l e s ,w h i c h l e ad s to a h i g h e r fr e q u e n c y f o r a g i v e n f l o w -

ra te 27 (see Figure 15) . F or tha t reas on, vo r tex me tersu s u a l l y i n c l u d e a n u p s t r e a m g r i d t o g e n e r a t e a m i n i -m u m l e ve l o f t u r b u l e n c e .

U l t r a s o n i c m e t e r

A l t h o u g h o n l y a f e w t e s t s w e r e m a d e o n t h i s t y p e o fme te r, t hey a l so s eem to be s ens i t i ve t o some uns t eadyd i s tu rbances .

F i g u r e 1 6 s h o w s a c o m p a r i s o n o f r e s u l t s o b t a i n e din two d i f f fe r en t u ps t r eam co n f igu ra t i ons . I n one ca se ,a l e n g t h o f p i p e o f r e d u c e d d i a m e t e rD N 1 0 0 ) w a sp l a c e d u p s t re a m o f th e u p s t r e a m l e n g th o fD N 200 . Int h e o th e r , t h e w h o l e u p s t re a m l e n g th w a s m a d e f r o mD N 2 0 0 .

In t he f i r s t con f igu ra t i on , t he r educ t ion i n d i a -m e t e r w a s r e s p o n s i b l e f o r i n c r e a s i n g t h e n o i s e a n d


5/7

78 P. G r e n i e r E ffe cts o f u n s t e a d y p h e n o m e n a o n f lo w m e t e r i n g

8uJ

0

o . . . . .

J ~ F vs n a t u r a l f r e q u e n c y o ft h e

/ / _ . vortexaunchingPulsation rate=0.2

i I 1 I1 2

Fp/Fvs

F i g u r e 1 3 E r ro r g e n e r a t e d b y a p u l s a t i o n o n a v o r t e xm e t e r

8uJ

1

o

-1

-2

- 3

-4

o

+

I I I I

2 3 4

Pressure a t i o

F i g u r e 1 4 M e t e r i n g e r r o r o b s e r v e d a t a g i v e n f l o w r a t ea s a f u n c t i o n o f t h e p r e s s u r e r a t i o a t a n u p s t r e a mp r e s s u r e d r o p l o c a t i o n

8P_LLI

. ~ T u r b u le n c e in te n s ity

1o

- - - - - 6 , - . . . . . . .

3

I I I5 10 15

Veloc ity (m s1 )

F i g u r e 1 5 I n f l u e n c e o f g r i d t u r b u l e n c e o n a v o r t e xf l o w m e t e r

vibra t ion level , especia l ly a t h igh ve loc i t ies , resul t ingin a me ter ma lfunctio n. 29,~

G D F R e s e a r c h P r o j e c t : F l o w m e t e r i n g d i a g n o s i s

For a number of years now, i t has been acceptedwo r ldw ide t ha t a f lowm ete r 's pe r fo rmance mus t becons idered in re la t ion to f low charac ter i s t ics such asthe mean v e loc i ty prof i le . So far only the s teady

C o n d i t i o n AC o n d i t io n i ~ DN 200 C DN 200 ~DN 30

A 1 9 m M e t e r 1 5 m

Condi t ion FIo ,=w N 2 0 0 M ~ N 3 0 0B v 3 1 m

64

28LU -2

-4

- + Con di t ion A + '~ +o C o n d i t i o n B

> 1 0 0 0

+ + o -I- o ~)~ o+

-6


6/7

Flow Meas . Ins t rum. Vol 2 January 1991 79

o f v e l o c i t y p r o f i le m e a s u r e m e n t s o r s t u d y o f t h eb e h a v i o u r o f v o r t e x m e t e rs i n p u ls a t e d f lo w s

[ ] e x p e r i m e n t a l a n d t h e o r e t i c a l w o r k is s ta r t in g i nc o l l a b o r a t i o n w i t h P a ris 6 t h U n i v e r s i t y i n o r d e r t oi d e n t i f y, s e p a r a t e a n d c h a r a c t e r i z e t h e v a r i o u s u n -s t e a d y d i s t u r b a n c e c o m p o n e n t s a n d t h e i r e f f e c t s o ns e v e r a l t y p e s o f m e t e r

[ ] a r e s e a rc h c o n t r a c t h a s b e e n s e t u p i n e a r l y 1 9 9 0w i t h C E RT i n To u l o u s e a n d S N G S O t o s t u d y t h ee f fe c t s o f p u l s a t i o n s a n d p r e s s u r e d r o p s t h r o u g hp r e s su r e re d u c e r s o n t u r b i n e a n d v o r t e x m e t e rs

[ ] a p ro p o s a l f o r an i n t e r c o m p a r i s o n o f e x p e r i m e n t a la n d n u m e r i c a l t e st s o n u n s t e a d y d i s t u r b a n c e s e f -f e c ts o n t u r b i n e m e t e r s h a s b e e n m a d e t o E E C -B C R ,i n c l u d i n g G D F, C E RT a n d I ST p a r t i c i p a t i o n ( S u r r e yU n i v e r s i t y a n d C E RT a r e i n a d d i t i o n p r o p o s i n g as i m i l a r p r o g r a m m e w i t h v o r t e x m e t e r s )

T h e t o t a l c o s t f o r G D F is e s t i m a t e d t o b e 11 M F o v e rf ive years .

Long-term object ivesT h e a v a i l a b i l it y o f a m e t h o d t o c h a r a c t e r iz e e n t i r e l yt h e f l o w a t a m e t e r l o c a t i o n i s a k e y p o i n t f o r f u t u r ed e v e l o p m e n t s , w h a t e v e r t h e y a r e, c o n t r i b u t i n g t o i n -c r e a s i n g t h e q u a l i t y o f i n d u s t r i a l ga s f l o w m e a s u r e -m e n t . S e v e r a l d i r e c t i o n s a r e o p e n , d e p e n d i n g o n d i f -f e r e n t s t r a t e g ic c h o i c e s :

[ ] D e t e r m i n a t i o n o f t h e c h a r a c t e r is t ic s o f f lo w o nm a n y i n d u s t r ia l f l o w m e t e r i n g s i te s. T h i s w o u l d l e adt o t h e b u i l d i n g o f a d a t a b a s e d e s c r i b i n g th e a c t u a ls i tu a t i o n , w h i c h c a n b e u s e d t o d e c i d e th e m a i np o i n t s o n w h i c h e f fo r ts s h o u l d b e m a d e .

[ ] D e f i n i t i o n o f r e f e re n c e u n s t e a d y d i s t u r b a n c e s ,

a g a i n s t w h i c h m e t e r s c a n b e t e s t e d (a s is d o n e f o rs t e a d y d i s t u r b a n c e s , f o r i n s t a n c e w i t h I S O D P 9 9 5 1o n t u r b i n e m e t e r s )

[ ] D e s i g n o f n e w m e t e r s a b l e t o s t a n d a g i v e n l e v e l o fd i s t u r b a n c e , o r

[ ] D e s i g n o f p re s s u r e r e d u c e r s g e n e r a t i n g lo w i n t e n -s i t y d i s t u r b a n c e s .

C o n c l u s i o n s

P a r t i c u l a r l y b e c a u s e o f p r e s s u r e r e d u c e r s , g a s f l o wm e t e rs o f te n m e a s u r e a q u i t e d is t u r b e d f l o w. U n s t e a d yd i s t u r b a n c e s c a n c r e a t e s i g n i f i c a n t m e t e r i n g e r r o r s , b u tu n l i k e s t e a d y d i s t u r b a n c e s t h e y a r e g e n e r a l l y n o t c a n -

c e l l e d b y f l o w c o n d i t i o n e r s o r s t r a i g h t l e n g t h s .B e f o r e i m p r o v e m e n t s c a n b e m a d e t o m e t e r s o r

p r e s s u r e r e d u c e r s , i t is v e r y i m p o r t a n t t h a t a m e t h o df o r a c c u r a t e l y c h a r a c t e r i z in g a c o m p l e x u n s t e a d y d is -t u r b a n c e is a v a i l a b l e a n d l a rg e ly a c c e p t e d . G D F sF l o w M e t e r i n g D i a g n o s i s P r o j e c t is t r y i n g t o t a k e t h a tf irs t s tep.

R e f e r e n c e sG e n e r a l

1 Grenier Ph. L es ~ c o u l e m e n t s i n s t a t io n n a i r e s d a n s I i n d u -s t r i e gaz i~ re . P re sen ted a t ATG Conf . , Cannes , F rance(1983)

2 H e b r a r d , P. e t a l C a r a c t ~ r i s a t i o n d e l a v e i n e g a z e u s eI a v a l d u n d ~ t e n d e u r e n v u e d a m ~ l i o r e r l a p r e c i s i o n d u

comptage sur les pos tes de d ~te n te .R e p . C E RT2113/3/DERMES(1983)

3 Grenier, Ph . ,and Bosch M. Synth~se des connaissancesacquises sur les cond it ions d ut i l isat ion des m oyens decomptage aux laboratories du SM M (GD F) et du CERT(ONERA).Rep. GDF/DETN M.CER MAP 90/ 1/065(1990)

O r i f i c e

4 Badjura, R. A. et al. Pulsatile flow through an orifice.Final Rep. NSF Grant EN G74-103 99ADI (1979)

5 Mottram, R. C. Measuring pulsat ing f low with a differen-tial p ressure m eter. Presen ted at 2nd Int. Syrup. Flow, ISA(1981 )

6 Keyse r, D. R. Unsteady orif ice f lo w me asurem ent, i tstheory and observations. Presented at 2nd Int . Symp.Flow, ISA (1981 )

7 M art in, C. N . B. Effects of upstream bends and valves onorif ice plates pressure distr ibution and discharge c oeffici-ents. Int. J. Heat Fluid F low3 (1982) 135-141

8 Gajan, P. et al. D~bitm~trie par diaphragme en ~coule-ment perturbS: une approche sur les sources d erreur etles rem~ des possibles. Presented at ATG Conf. , Paris ,France (1986)

9 Hebrard, P. et al. Com porteme nt des d~bitm?~tres en~coulement pu lsato ire, premiere part ie: diaphragme.Rep. CER T 1//2221(1985)

T u r b i n e s

10 Bonner, J . A. Pulsation effects on turbine me ters . Pre-sented at AGA Transmission Conf. (1976)

11 Grenier Ph. Etud e du comportement des compteursturbine fonctionnant en r~gime cyclique.Rep .GDF/DETN M .CERIG 70 305(1979)

12 Deneuve, F. et al. Influence des condit ions de montagesur la precision des compteurs ~ turbine, Erreurs decomptage e t pulsations de pression.Rep. GDF/DETNM.CERIG 82639 (1983)

13 Deneuve, F. eta / . Influence des cond it ions de montagesur la precision des compteurs ~ turbine, Erreurs decomptage et profils de vi tesse ~ I aval d un coude et d und~tendeur. Rep. GDF/DETN M.CERIG 83 459(1983)

14 Deneuve, F. Influence des condit ions de montage sur laprecision des compteurs h turbine, Mesure des f luctu-at ions de vi tesse.Rep . GDF/DETN M.CER IG 83 865(1983)

15 Deneuve, F. Essais de comptage sur deu x p ostes ded~tente de la DP T, Rapport f inal .Rep . GDF/DETNM.CER IG 83 893(1984)

16 Deneu ve, F. M esure de pulsations de vitesse et depression sur le banc de d ~bitm~trie de I usine ~ gazd Alfortvi l le .Rep. GDF/DE TN M.CER IG 84 037(1984)

17 Le Jan , B. E tude d une mod~lisation physique du com -

portement d un com pteur ~ turbine.Rep. GDF/DETNM.CER IG 84 806(1985)18 Deneuve, F. Etude des grandeurs d influenc e des comp -

teurs ~ turbine. Rep . GDF/DETN M.CERMA P 60 090(1986)

Vo r t e x

19 Bearman,P. W. et al. Vortex shedding from bluff bodiesin osci l latory f low: A report of Euro me ch 119.J. FluidMech. 99 (2) (1980) 225 -24 5

20 Barb i ,C. et al. Vortex shedding and lock-on of a circularcylinder in osci l latory f low.J. Fluid Mech. 170 (1986)5 2 7 - 5 4 4

21 Mot t ram,R. C. et al. Installation effects on vortex flowmeters. Presented at 2n d Int . Sym p. Fluid Control , M eas. ,Me ch. F low Visualisation, Flucome 88, Sheffield, UK(1988)


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8 0 P. G r e n i e r E ffe cts o f u n s t e a d y p h e n o m e n a o n f l o w m e t e r in g

22 Strzelecki , A.et al. Invest igat ion of f low phe nom ena in avortex f lowmeter by hot f i lm measurements , f low visual-izat ion and image processing. Presented at Flucome 88,Sheffield, UK (1988)

23 Blot , F. et al. Flow analysis over a vortex f lowmeter : anexpe rimental and compu tat ional approa ch. Presented at7th Symp. Turbulent Shear Flow, Stanford Universi ty,USA (1989)

24 Strzelecki , A. et al. Experimental analysis of flow p he-nomena in a vortex f lowmeter in s teady and pulsat i lef low condi t ions. Presented at Flomeko 89, Int . Conf .Flow Meas., DLisseldorf, RFA (1989)

25 Strzelecki , A. Etude du d~tachement tourbi l lonnaire en~coulement per turbS: appl icat ion ~ la d~bi tm~tr ie vortex.Th~se de doctorat Paul Sabat ier Universi ty, Toulouse,France (1989)

2 6 H e b r a r d , P. et al. Etude du com por teme nt d un d~b i t -

m~tre ~ vortex en ~coulement per turbS. Presented atIGRC Con f. , Tokyo, Jap an (1989)

27 Strzelecki , A. et al. Com por tement d un d~b i tm~t revor tex en ~cou lement pe r tu rbS: in f luence d une tu rbu l -ence de gr i l le . R e p . C E R T 2 / 2 38 1(1990)

28 Gren ie r, Ph . et al. Etude de la d~bi tm~tr ie vortex.Presented at ATG Conf., Paris, France (1990)

U l t r a s o n i c

29 Etcharren, M. E. Etude de la fa isabi li t~ d un d~bi tm~treul t rasonore adapt~ au t ransport industr ie l de gaz naturel .Th~se de Doctorat Bordeaux I Universi ty, France (1989)

30 Jean-Elie , Th. Etalonnage sou s pression en l igne d und~bitm~tre ~ ultrasons. R e p . G D F / D E T N S M M 4 8 0(1989)

1991_effects of unsteady phenomena on flow

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