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CONTACT METHODS FOR DIAGNOSTICS OF THERMAL PLASMA
P. Stefanovij, P. Pavlovij, M. Jankovij, S. Oka
To cite this version:
P. Stefanovij, P. Pavlovij, M. Jankovij, S. Oka. CONTACT METHODS FOR DIAGNOSTICS OF THERMAL PLASMA. Journal de Physique Colloques, 1990, 51 (C5), pp.C5-281-C5-288.
�10.1051/jphyscol:1990534�. �jpa-00230841�
CONTACT METHODS FOR DIAGNOSTICS OF THERMAL PLASMA
P.Lj. STEFANOVIC, P.B. P A V L O V I ~ , M.M. JANKOVIC? and S.N. OKA Institut for Nuclear Sciences "Boris KidriC", vinCa Institut for Thermal Sciences and Energy Research, P.O. Box 522, 11001 Belgrade.
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On p r u t e dans ce papier l e principe de mesure, ainsi que des exemples d'applications possibles, pour l e s mathodes de mntact suivantes: l/ sorde enthalpique (calorim6riie), 2/ sonde de Pitot mobile, 3/ -le mobile. Les deux premikes n&hcdes sont directement insp- du tube de Pitot. Ia t r o i s i h ethode consiste en dew passages oil plus avec un 616rmt sensible de -1e l e long de l'i%mlemmt.lbplus de l a description d&ta.ill& de m e m&hode, on p r k t e quelques r6sultats exp6rheataux pour un j e t plasma air-azote 8 l a s o r t i e de l a tomhe.
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I n t h i s paper p r i n c i p l e of measurement, t o g e t h e r w i t h i l l u s t r a - t i v e examples of p o s s i b l e a p p l i c a t i o n s , a r e p r e s e n t e d f o r t h e following c o n t a c t methods: 1) e n t h a l p y ( c a l o r i m e t r i c ) probe, 2 ) f l y i n g P i t o t L p r o b e , 3 ) f l y i n g thermocouple. C a l o r i m e t r i c o r e n t h a l p y probe i s , i n f a c t , water cooled P i t o t - p r o b e f o r d i r e c t measurement of s t a g n a t i o n p r e s s u r e and s t a g n a t i o n e n t h a l p y . Dynamic method o f f l y i n g P i t o t - p r o b e e n a b l e s a b r i e f c o l l e c t i n g of experimental d a t a and i m p l i e s good dynamic c h a r a c t e r i s t i c s of pneumatic p a r t of measuring system. Measuring of plasma flow temperature by flying or dynamic thermooouple, c o n s i s t s of two o r more p a s s i n g s with s e n s i t i v e element of thermocouple along t h e diameter of t h e flow. Besides t h e d e t a i l e d d e s c r i p t i o n of each method, some experimental r e s u l t s a r e p r e s e n t e d f o r a i r - n i t r o g e n plasma j e t a t t h e e x i t of t h e experimental plasma t o r c h .1. INTRODUCTION
Term of thermal o r dense plasma i s r e l i e d with p a r t i a l l y d i s s o c i a t e d o r i o n i - zed gas, b u t n o t s o r a r e f i e d t h a t r a d i a t i o n p r o c e s s e s of energy t r a n s f e r beco- mes dominant compared t o p a r t i c l e s c o l i s i o n p r o c e s s e s . Term of thermal plasma is c l o s e l y connected with t h e c o n d i t i o n of l o c a l thermodynamic e q u i l i b r i u m
(LTE) which i m p l i e s unique value of temperature f o r every p a r t i c l e a t one s i n - g l e p o i n t . G r e a t e r d e v i a t i o n s from e q u i l i b r i u m plasma should be expected a t lower . p r e s s u r e s (<0.1 b a r )
.
Experimental i n v e s t i g a t i o n of flow parameters f o r dense o r thermal plasma (high temperature 5000-15000 K , multiphase flow, chemical r e a c t i o n s ) i s very complex problem. For d i a g n o s t i c s of t y p i c a l plasma flows, p l e n t y of c o n t a c t and o p t i c a l methods a r e p r e s e n t l y i n use.
Temperatures of 5000 K and more exceed m e l t i n g p o i n t of a l l t e c h n i c a l materi- a l s , s o some s p e c i a l c o n s t r u c t i o n s had t o be developed t o enable a p p l i c a t i o n of c o n t a c t methods. Contact methods a r e based on small dimension probes: a ) c o - o l e d f o r s t a t i c ( p o i n t by p o i n t ) measurements and b ) uncooled f o r dynamic mea- surements. Although c o n t a c t methods induce some flow d i s t u r b a n c e and u s u a l l y g i v e s lower accuracy ( t y p i c a l range (5-10%) compared with o p t i c a l methods,- a r e widely used i n thermal plasma d i a g n o s t i c s because:
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they a r e based on cheap commercial s e n s o r s and i n s t r u m e n t s ,-
they can be q u i c k l y i n s t a l l e d , and e a s i l y and inexpensively used,-
they can measure a whole p r o f i l e o r even a flow f i e l d i n a s h o r t p e r i o d of time ( f o r dynamic methods t y p i c a l scanning p e r i o d i s of t h e o r d e r 1 s e c ) . Paper p r e s e n t s development and a p p l i c a t i o n p o s s i b i l i t i e s f o r : 1) m i n i a t u r e ca- l o r i m e t r i c o r e n t h a l p y probe, 2 ) dynamic method of f l y i n g P i t o t - p r o b e andArticle published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1990534
C5-282 COLLOQUE DE PHYSIQUE
3 ) dynamic method o f f l y i n g thermocouple.
2. ENTHALPY (CALORIMETRIC) PROBE
For measuring t h e d i s t r i b u t i o n o f p r e s s u r e and e n t h a l p y i n t h e r m a l plasma flows (T<15000 K ) , e n t h a l p y probe i s w i d e l y s p r e a d e d e x p e r i m e n t a l . m e t h o d / 1 , 2 , 3 , 4 / . T h i s method e n a b l e s measuring t h e l o c a l v a l u e s of s t a g n a t i o n p r e s s u r e and en- t h a l p y i n f l o w f i e l d w i t h h i g h g r a d i e n t s o f thermodynamic and f l o w p a r a m e t e r s . S p e c i a l advantage of t h i s method i s h i g h quenching v e l o c i t y o f "gas-sample"
which e n a b l e s a s i m u l a t i o n o f f r e e z i n g d e v i c e i . e . e x a m i n a t i o n o f p o s s i b l e p r o d u c t s of chemical r e a c t i o n . F o r t h i s r e a s o n e n t h a l p y probe i s w i d e l y u s e d I n plasma c h e m i s t r y and m a t e r i a l p r o c e s s i n g .
Method i s b a s e d on two measurements i n e a c h measuring p o i n t : w i t h and w i t h o u t a s p i r a t i o n o f "gas-sample" through t h e c e n t r a l c h a n n e l o f d i a m e t e r d i ( f i g u r e 1 ) . I n regime w i t h o u t a s p i r a t i o n , s t a g n a t i o n p r e s s u r e and " t a r a " h e a t f l u x ( % ) from plasma t h r o u g h o u t e r probe s u r f a c e t o c o o l a n t w a t e r a r e measured
( Q ~ = ~ c @ T ~ ; m-mass f l o w r a t e , d p - s p e c i f i c h e a t c a p a c i t y and Tb-temperature ri- se o f c o o l a n t w a t e r ) . I n regime w i t h a s p i r a t i o n , h e a t f l u x t o c o o l a n t w a t e r i s e q u a l t o t h e sum of h e a t f l u x t h r o u g h t h e o u t e r probe s u r f a c e (Qa) and h e a t f l u x from "gas-sample" (mcp~Ta=Qa+G(hi-h,); h i and h, a r e s t a g n a t i o n e n t h a l p y of t h e " g a s sample" a t t h e i n l e t and o u t l e t o f t h e probe. I f a s p i r a t i o n i s i s o - k i n e t i c s i . e . i f mass flow r a t e o f g a s sample G , i s e q u a l ( o r l e s s ) t o t h e f r e e s t r e a m mass flow r a t e ( G S ~ W ~ ? T / ~ ; W and p a r e f r e e s t r e a m v e l o c i t y and d e n c i t y o f t h e q a s a t t h e i n l e t o f t h e p r o b e ) . h e a t f l u x e s t o t h e o u t e r probe s u r f a c e i n two regimes
e n t h a l p y : a r e e q u a l (Qa=Qb)- and o b t a i n formula f o r measured S t a g n a t i o n
There a r e few b a s i c r e q u i r e m e n t s which e n t h a l p y probe h a s t o meet i n o r d e r t o q u a l i f y it self as a d i a g n o s t i c s t o o l :
1) The p r o b e h a s t o b e r i g i d and t h e r m a l l y p r o p e r l y p r o t e c t e d t o s u r v i v e e x t r e - mely h o s t i l e environment o f plasma f l o w s .
2 ) The p r o b e must b e s m a l l enough t o e n s u r e s u f f i c i e n t s p a r t i a l r e s o l u t i o n and s m a l l d i s t u r b a n c e o f t h e flow.
3 ) The p r o b e h a s t o b e s e n s i t i v e t o d e t e c t e n t h a l p y v a r i a t i o n s i n f l o w f i e l d w i t h h i g h g r a d i e n t s o f f l o w p a r a m e t e r s .
Dimensions o f i . d . ( 1 . 6 mm) and 0 . d . (3.2 mm) a r e choosen t o s a t i s f y a l l p r e - v i o u s l y mentioned c r i t e r i o n s . Dimensions g1.6/83.2 and c o n s t r u c t i o n w i t h s t a - i n l e s s s t e e l t u b e s argon welded a t t h e p r o b e s t i p , e n a b l e r e l i a b l e work o f t h e p r o b e i n t h e r m a l plasma w i t h e n t h a l p y up t o 10 MJ/kg, s t a g n a t i o n h e a t f l u x up t o 8 MW/m and mass f l o w r a t e o f c o o l a n t w a t e r o f minimum 10 g / s , and h i g h sen- s i t i v i t y o f t h e probe S= (ATa- &Tb) /bTa<27%. Accuracy o f t h e measurement depends
&a a c c u r a c y of measurements o f t e m p e r a t u r e and mass flow r a t e o f c o o l a n t w a t e r , and o f measurement o f mass flow r a t e o f gas through t h e c e n t r a l c h a n n e l o f t h e p r o b e , and h a s been d e t e r m i n e d a p p r o x i m a t e l l y a t 5% /5/. Under t h e assumption o f LTE One can c a l c u l a t e t e m p e r a t u r e from measured v a l u e o f s t a g n a t i o n enthalpy, and v e l o c i t y from measured v a l u e o f s t a g n a t i o n p r e s s u r e . T h i s means t h a t u s e o f e n t h a l p y probe a t r e a l e x p e r i m e n t a l s i t u a t i o n ( f r e e j e t , model o f plasma r e a c - t o r ) e n a b l e s one t o g e t d i s t r i b u t i o n o f f o u r b a s i c flow p a r a m e t e r s . From t h e expences p o i n t o f view, t h i s i s g r e a t advantage i n comparison w i t h o t h e r expe- r i m e n t a l methods f o r plasma f l o w s d i a g n o s t i c s . F i g u r e s 5-8 p r e s e n t a x i a l pro- f i l e s o f j e t flow f i e l d w i t h c o n s t a n t v a l u e l i n e s o f s t a g n a t i o n e n t h a l p y , s t a g - n a t i o n p r e s s u r e , t e m p e r a t u r e and v e l o c i t y o b t a i n e d from measurement by e n t h a l p y probe f o r one working regime o f t h e e x p e r i m e n t a l plasma t o r c h .
3. D I N A M I C MEASUREMENT OF STAGNATION PRESSURE
Dynamic measurement i s based on f a s t p a s s i n g s w i t h P i t o t - p r o b e a l o n g t h e diame- t e r o f plasma flow /6,7/. E x p e r i m e n t a l i n s t a l l a t i o n i s s c h e m a t i c a l l y p r e s e n t e d a t f i g u r e 3. An uncooled P i t o t - p r o b e 2 , w i t h p r e s s u r e t r a n s d u c e r 3, i s f i x e d d i r e c t l y on pendulum 1. Pendulum o s c i l a t e s w i t h i n t h e p l a n e p e r p e n d i c u l a r t o j e t a x i s . During t h e r a p i d probe f l i g h t a c r o s s t h e j e t , p r e s s u r e s i g n a l i s r e - c o r d e d i n memory o f computer. O p t i c a l p o s i t i o n d e t e c t o r 4 i s u s e d t o c o s r e l a t e t h e t i m e dependence o f p r e s s u r e - s i g n a l - w i t h r a d i a l c o o r d i n a t e . T h i s method i s v e r y u s e f u l b e c a u s e o f s e v e r a l adventages:
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a whole p r e s s u r e p r o f i l e can b e measured i n v e r y s h o r t p e r i o d o f time.-
uncooled probe w i t h s m a l l dimensions can be u s e d w i t h minimal flow d i s t u r - b a n c e s .Main problem o f t h e method i s phase and a m p l i t u d e d i s t o r t i o n o f i n l e t s i g n a l i n a c o u s t i c p a r t o f measuring system, f i g u r e 3, which c o n s i s t s o f t h e P i t o t probe t u b e , volume V 1 , and t h e chamber above t h e t r a n s d u c e r membrane, volume v 2 -
B a s i c d i f f e r e n t i a l e q u a t i o n s g o v e r i n g t r a n s i e n t one d i m e n s i o n a l a d i a b a t i c flow o f c o m p r e s s i b l e f l u i d w i t h f r i c t i o n i n d u c e d by u n i t s t e p p r e s s u r e f u n c t l o n a t t h e i n l e t o f t h e P i t o t p r o b e ( x s O , p=pOI u=O; T > O , p=pO+pm) a r e :
where i s : X - d i s t a n c e from i n l e t , a l o n g P i t o t p r o b e , T - t i m e , U - v e l o c i t y , p-pres- s u r e , R - f r i c t i o n r e s i s t a n c e , p - d e n s i t y , C-speed o f sound. L a p l a c e t r a n s f o r m o f t h e above e q u a t i o n s g i v e s d i f f e r e n t i a l e q u a t i o n wich governs dynamic b e h a v i o r of t h e pneumatic s y s t e m i n complex ( f r e q u e n c y ) domain. T r a s f e r f u n c t i o n @ ( S ) of t h e pneumatic system i s a r a t i o o f t h e s o l u t i o n s o f t h i s d i f f e r e n t i a l equa- t i o n a t t h e b o u n d a r i e s o f t h e s y s t e m i . e . p r e s e n t s t h e r a t i o between i n l e t s i g n a l , P (x=O , S ) , and i t s r e s p o n s e i n volume V 2 , P ( x = l l , S ) , i n complex a r e a :
P ( x = l l , S )
@ ( S ) =
P(x=O,S) = {cosh ( L J ( ~ + s p ) s / p J
+
VL J ( R + S P ) S / P s i n hI L
J ( ~ + s p ) s / p l } t 4 )e
where i s : S - l a p l a c e t r a n s f o r m v a r i a b l e , ~ = 3 2 p / d f ( d e r i v e d f o r l a m i n a r flow from Hagen-Pois'euille l a w ) , L = l l / c , V=V2/V1 ( F i g . 4 ) . T r a n s f e r f u n c t i o n c a n B@fve a s a b a s e f o r s e l e c t i o n o f t h e p r e s s u r e t r a n s d u c e r and d e s i g n of P i t o t t u b e w i t h good dynamic c h a r a c t e r i s t i c s . M a i n demands f o r t h i s p u r p o s e a r e f o l l o w i n g :
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volume V2 above t h e t r a n s d u c e r membrane h a s t o be minimized,-
l e n g t h o f P i t o t - p r o b e t u b e h a s t o b e a s s h o r t a s p o s s i b l e , h a v i n g i n mind t h a t such an o p t i m a l l e n g t h can s t i l l p r o t e c t t r a n s d u c e r a g a i n s t h i g h t h e r m a l S t r e s s e s ,-
an o p t i m a l i n t e r n a l d i a m e t e r o f t h e P i t o t - p r o b e t u b e h a s t o be choosen i n a way t o meet a l o c a l measurement r e q u i r e m e n t s and t o g i v e a good dynamic c h a r a c t e r i s t i c o f t h e measuring system a t t h e same t i m e .B e s i d e e r r o r s c h a r a c t e r i s t i c f o r s t a t i c P i t o t - p r o b e measurements, a c c u r a c y o f t h i s method depends on dynamic c h a r a c t e r i s t i c s o f t h e measuring system. With c a r e f u l s i z i n g o f t h e probe and by c o r r e c t c h o i c e o f p r e s s u r e t r a n s d u c e r , r e - l a t i v e e r r o r can be d e c r e a s e d t o 5 % f o r d i a g n o s t i c s o f plasma f l o w s which h a s been e x p e r i m e n t a l l y proved by c a l i b r a t i o n measurements / 7 / . Example o f t h i s method performances i s shown a t f i g u r e 9 which p r e s e n t s i s o b a r s i n a x i a l c r o s s s e c t i o n of t h e j e t .
4 . DYNAMIC THERMOCOUPLE METHOD
Essence o f t h i s method i s t o make a r a p i d p a s s i n g w i t h t h e j u n c t i o n o f t h e thermocouple through t h e c r o s s - s e c t i o n of plasma j e t and t o ,record i t s tempe- r a t u r e change. R a d i a l p r o f i l e o f j e t t e m p e r a t u r e can be c a l c u l a t e d by p r o c e s - s i n g o f c o n t i n u o u s t e m p e r a t u r e r e c o r d i n g s from two o r more p a s s i n g s ( f i g u r e 2 b ) . I n t h e f i r s t p a s s i n g s t a r t t e m p e r a t u r e o f thermocouple i s e q u a l t o room tempe- r a t u r e b u t i n t h e second thermocouple i s h e a t e d t o t e m p e r a t u r e 400-500°C.
I f we n e g l e c t r a d i a t i o n of t h e t i p , we can assume t h a t c o n v e c t i v e h e a t f l u x q ( r 1 ) a t any o b s e r v e d p b i n t ( p o i n t A, f i g u r e 2 a ) can be o b t a i n e d by d i f f e r e n - t i a t i n g of r e c o r d e d t e m p e r a t u r e s i g n a l T s ( r ) o f s p h e r i c thermocouple ( w i t h r a d i u s R ) .
where p i s d e n s i t y o f thermocouple m a t e r i a l and Cp i s i t s s p e c i f i c h e a t capa- c i t y . Under t h e assumption t h a t c o n v e c t i v e h e a t t r a n s f e r c o e f f i c i e n t s from plasma t o thermocouple t i p , a t t h e same o b s e r v e d p o i n t A , b u t i n d i f f e r e n t p a s s i n g s , a ' ( r l ) and a" ( r l ) , a r e e q u a l , we o b t a i n :
C5-284 COLLOQUE DE PHYSIQUE
from t h i s e q u a t i o n we f i n a l l y o b t a i n expresion f o r c a l c u l a t i n g t h e temperature of t h e plasma j e t a t observed p o i n t A.
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Basic parameter which d e f i n e s p o s s i b i l i t i e s of t h i s method, i s v e l o c i t y of thermocouple p a s s i n g through t h e plasma j e t . There a r e two o p o s i t e demands f o r t h i s v e l o c i t y :
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it has t o be high enough t o avoid t h e m e l t i n g of thermocouple,-
i t has t o be small enough t o l i m i t t h e i n i t i a l i r r e g u l a r regime of h e a t i n g t h e thermocouple, t o s m a l l r e g i o n of t h e j e t (1/20 of j e t d i a m e t e r ) / 8 / . Temperature probe i s s c h e m a t i c a l l y p r e s e n t e d a t f i g u r e 2b. K type thermocouple(chromel-alumel) has been used due t o i t s l i n e a r c h a r a c t e r i s t i c s . Thermocouple t i p was s p h g r i c , w i t h 0.95 mm i n diameter.
Demand f o r e q u a l i t y of convective h e a t t r a n s f e r c o e f f i c i e n t s a '(r) and a" ( r ) i s hard t o be f u l l f i l e d i n p r a c t i c e . C e r t a i n d i f f e r e n c e between temperature o f t h e f i l m , surrounding s p h e r i c thermocouple t i p , i n two p a s s i n g s can cause d i f - f e r e n c e i n h e a t t r a n s f e r c o e f f i c i e n t s of few p e r c e n t a g e s . Ratio between t h e s e b o e f f i c i e n t s K = a ' ( r ) / a l ' ( r ) can be experimentaly determined from t h r e e o r more p a s s i n g s a l o n g t h e same diameter o f t h e j e t . Value of K should be c o n t r o l l e d and c e r t a i n c o r e c t i o n s i n c a l c u l a t i o n procedure should be involved each time when K i s g r e a t e r t h a n 1.02. This value of K i n v o l v e s s y s t e m a t i c e r r o r i n ca-
l c u l a t i o n by e x p r e s s i o n ( 7 ) o f about 8% i n t h e d i r e c t i o n of i n c r e a s i n g t h e temperature. On t h ~ o t h e r hand c a l c u l a t i o n ( 7 ) i s c a r r i e d o u t under t h e a s s &
p t i o n of i d e a l i z e d h e a t t r a n s f e r regime from j e t t o thermocouple. Radiation of thermocouple j u n c t i o n i s n e g l e c t e d a s w e l l a s conduction l o s s e s i n i t s w i r e s . This causes s y s t e m a t i c e r r o r l e s s than 7.5% i n t h e d i r e c t i o n of d e c r e a s i n g t h e c a l c u l a t e d temperature. Systematic e r r o r s mentioned a r e o p o s i t e i n s i g n and they a r e balancing each o t h e r t o c e r t a i n amount.
While d i f f e r e n t i a t i n g hemperature s i g n a l s and c a l c u l a t i n g h e a t f l u x by expres- s i o n (5), a d j a c e n t e r r o r occurs, which can be decreased by u s i n g equipment f o r automatic d a t a c o l l e c t i n g with high frequency. Sumar e r r o r of t h e method does n o t exceed 1 0 % , and having i n mind s i m p l i c i t y and e x p e d i t e v i t y of measuring procedure, we can conclude t h a t t h i s method can be r e a d i l y used when high ac-
curacy of measurement i s n o t an i m p e r a t i v e . Figure 1 0 p r e s e n t s t h r e e r a d i a l temperature p r o f i l e s f o r one working regime of experimental plasma t o r c h obta- i n e d by p r o c e s s i n g of c o n t i n i o u s temperature r e c o r d i n g s f o r s e v e r a l p a s s i n g s p e r c r o s s - s e c t i o n .
5. CONCLUSION
General adventage o f methods d e s c r i b e d i s t h e i r simple c o n s t r u c t i o n and, ac- c a r d i n g t o t h a t , t h e i r r e l a t i v e l y low c o s t , compared t o d i f f e r e n t c o n t a c t l e s s methods. P a r a l e l use of t h e s e methods e n a b l e s complete d i a g n o s t i c s of plasma
flow f i e l d , w i t h g e t t i n g a l l s i g n i f i c a n t flow parameters, f o r r e l a t i v e l y s h o r t time. Accuracy of t h e s e methods i s of t h e o r d e r 5 t o 10%, and from experimen- t a l i n v e s t i g a t i o n of plasma flows p o i n t of view, i s completely s a t i s f a c t o r y . During t h e developing process of c e r t a i n plasma technology, when g l o b a l diag- n o s t i c s of temperature and flow f i e l d s a r e o f p r i o r i n t e r e s t , t h e s e methods a r e of g r e a t importance. When main t a s k of measurement i s t o c o l l e c t e x p e r i - mental d a t a f o r mathematical modelling of plasma flow p r o c e s s e s , where high accuracy of measurements a r e of g r e a t importance, t h e i r a p p l i c a t i o n i s l i m i t e d . 6. LITERATURA
/ l / J.Grey, P.F.Jacobs, M.P.Sherman: Rev.Sci.Instrum. 33 (19621, No 7,
pp.738-741.
/2/ M.D.Petrov, V.A.Sepp: Tepl.Visok.Temperaturi, 8 (1970), No.4,pp.868-874, / 3 / A.A.Nekrasov, A.D.Pekin: I z m e r i t e l n a j a t e h n i k a , ( 1 9 7 2 ) , No.4, pp.47-48.
for Diagnostics Thermal Plasma at the Exit of Electric Arc Heater, ISPC-9, Pugnochiuso, Italy, September 4-8, (1989).
/6/ P.Barken, A.M.Whitman, AIAA Journal, 4, (1966), No 9, pp.1691-1693.
/7/ P.Stefanovi.6, S.Oka, P.Pavlovi6: Procesi perenosa v odnoi i dvuhfaznih sredah, zb.nauE.trud. pod redakcijom S.S.Kutateladze i S.Oke, No~osibirsk
(1986), SO AN SSSR, ITF pp.126-139.
/8/ S.P.Paljakov, P.F.Bulanij: UsoverKenstvovanie metoda dinamiEeskoi termopa- ri,
IF^,
30, (19761, No 3, pp.35-39.l-water inlet and outlet 2-micro orifice
3-electromagnetic valve 4-vacuum pump
5,6-differential pressu-re transducer
Fig.1. Enthalpy probe
COLLOQUE DE PHYSIQUE
brass t u b e
F i g . 2 a . T e m p e r a t u r e probe E i g . 2 b T e m p e r a u r e and f l u x s i g n a l s
F i g . 3 . SCHEMATIC DIAGRAM O F APPARATUS F i g . 4 . SCHEMATIC DIAGRAM O F 1 . PENDULLUM 2 . PITOT-PROBE MEASURING SYSTEM P I - 3 . PRESSURE TRANSDUCER 4 . O P T I - TOT-TUBE PRESSURE
C$& DETECTOR 5. TORCH TRANSDUCER
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COLLOQUE DE PHYSIQUE
Fig.9. Axial profiles of stagnation pressure o b t ~ i n e d by flying Pitot-probe
Fig.10. Radial profiles of temperature
