C P I to /^3 C.P. No. 163

(16.555) A.R.C. Technical Report

MINISTRY OF SUPPLY

AERONAUTICAL RESEARCH COUNCIL

CURRENT PAPERS

a

Calibration of the R.A.E. No. 18 (9 In. x 9 In.) Supersonic Wind Tunnel

Part II. Tests at Atmospheric Stagnation Pressure

By

W. T. Lord, M.Sc, G. K. Hunt, B.Sc.(Eng.),

R. J. Pallant and J. Turner , NATIONAL &Ai TURWNE

E»TABL18HM

21JULW54

rn*Na \

LONDON: HER MAJESTY'S STATIONERY OFFICE

1954

Price 2s. 6d. net

C.P. No. 163

Technica l Note No, Aero.2236

September, 1933

ROYAL AIRCRAFT ESTABLISHviENT

C a l i b r a t i o n of the R.A.E. No. 18 (9" x 9") Supersonic Wind Tunnel

P a r t I I : - Tes t s at Atmospheric S tagna t ion P res su re

by

W.T. Lord, M.Sc. , G.K. Hunt, B .Sc . (Eng . )

R . J . P a l l a n t , and

J . Turner

SUMMARY

This report presents d is t r ibut ions of Mach number in the empty-working section of the R.A.E. No. 18 (9" x 9") Supersonic Wind Tunnel at nominal Mach numbers of 1.4, 1.5, 1.6, 1.8 and 1.9, for condensation-free flow at atmospheric stagnation pressure and at a stagnation temperature cf 35°C« The r e su l t s confirm that the accuracy of the t e s t s i s of the order predicted in Part I . The mean measured Mach numbers are 1.41, 1.51? 1.61, 1.81 and 1.91 when calculated from values of p i t o t and stagnation pressures . The major contributions to the non-uniformity of the flow are from the disturbances which ar ise from the junctions of the windows with the side walls of the tunnel; these disturbances are of the order of +0.015 in Mach number, whilst the maximum gradual var ia t ions in the flow caused by other sources are of the order of +0.010. An indicat ion cf the boundaries of the working section for each Mach number i s given.

Note (August, 1953)

Since the accounts of the calibration contained in Parts I and II were written (Part I: December, 1951i Part II: March, 1952), the tunnel equipment has been greatly improved and its limitations are no longer as severe as those described here; the improvements do not invalidate the present results, but no further detailed calibration measurements have been made.

LIST OF CONTENTS Page

1 Introduction 3

2 Description of modified pitot shower 3

3 Discussion of test procedure 3

4 Presentation and interpretation of Mach number distributions 4

5 Conclusions 5

6 Remarks on recent modifications 7

List of symbols 8

Reference A

LIST OF TABLES

Guide to traverses

Estimated total experimental errors

Typical values of discontinuities at window junctions

Table

1

2

3

LIST OF ILLUSTRATIONS

Modified p i t o t shower

Method of s t i f f e n i n g t r a v e r s i n g gear for p i t o t shower

P o s i t i o n s of t r a v e r s e s

D i s t r i b u t i o n s of Mach number d i f f e r e n c e s mn

" abso lu te Mach numbers M n

m n IvI n

m n

M n II

II

It

II

t»

»

n

I I

»

I I

n

I I

I I

I I

t»

i t

m n M n

m n M

n

I n d i c a t i o n of work ing-sec t ion boundar ies f o r

M = 1.4

M = 1.4

i s 1,5 M a 1.5

M = 1.6

M = 1 .6

M = 1 .8

5 a 1.8

M = 1.9

B a 1.9

B « 1.4* 1.5, 1.6, 1.8, 1.9-

F igure

1

2

3

4(a)

4(b)

5(a)

5(b)

6(a)

6(b)

7(a)

7(b)

8(a)

8(b)

9

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1 Introduction

The aims and programme of the ca l ibra t ion of the R.A.E. No. 18 (9"x9») Supersonic Wind Tunnel were set out in Part I 1 , in the discussion of the preliminary invest igat ions which were necessary before resu l t s of sufficient accuracy could be obtained. Part I I describes the t e s t s which have been made (during November and December 1951) in the most s t r a i g h t ­forward case when the stagnation pressure i s atmospheric. The t e s t s were performed with a i r free from condensation shocks, at nominal Mach numbers M of 1.4, 1.5, 1.6, 1.8, 1.9 which represent the fu l l working range of the tunnel, and at a stagnation temperature of 35°C

We present the d i s t r ibu t ions of measured Mach number along representat ive l ines throughout the empty working section, together with d i s t r ibu t ions of the. measured differences between the Mach numbers at corresponding points away from and on the tunnel cen t r e - l ine . The Mach number at each point i s calculated from the p i to t pressure there and the stagnation pressure in the reservoi r .

The pressure t raversing instrument, the p i t o t shower, has been modified from the design described in Part I , but the modifications do not make the t e s t s less comprehensive. By means of the shower, the p i to t pressure was measured simultaneously at nine points arranged i n a pa t t e rn 5" square in planes perpendicular to the tunnel cen t re - l ine at in terva ls of J" over a t o t a l length of 18".

The modified shower and the scheme of the t raverses are i l l u s t r a t e d in F i g s . 1 , 2, 3.

2 Description of modified p i to t shower

The t e s t s described in th i s report were carried out using a new p i t o t shower which was constructed from a modified design of the or ig ina l shower (see F i g s . 1 , 2) . The modifications were made to f a c i l i t a t e the rigging of the shower in the tunnel , to reduce the poss ib i l i t y of leaks and to s t ab i l i s e the shower against vibrat ions pa r t i cu la r ly at M = 1.8 and 1.9. The size of the shower was reduced to 5" square, and the tube supports were sweptback to allow the centre- l ine p i to t tube to be in the same plane as the others without i t s reading being affected by the conical shield.

The arrangements for measuring the pressure were prec ise ly the same as described in Part I for the or ig inal shower.

3 Discussion of t e s t procedure

The procedure followed in performing the ca l ibra t ion was outlined in Part I , but i t may be well to r e i t e r a t e b r i e f l y the chief points .

For a t e s t at a given M and at atmospheric stagnation pressure (p0

= -50), the M l i ne r was fixed in the tunnel so that the pos i t ions of i t s throat and end were coincident, as nearly as could be seen with the naked eye, with the appropriate l ines scribed_on the tunnel wal ls . The tunnel was evacuated of wet a i r and flow at M established at low pressure to reduce buffet t ing of the shower by the tunnel shock. Fresh a i r was then introduced through the dr ie rs and the stagnation pressure maintained at_.atmospheric throughout the t e s t . The nominal stagnation temperature TQ was adjusted to be 35°C, and the humidity Q checked to be below the corresponding c r i t i c a l value for condensation-free flow. The automatic speed control was used to keep the compressor speed to within.+50 r.p.m. of i t s nominal value. The pressure traverse was s tar ted at i t s upstream point , to reduce the posi t ion error due to slackness in

- 3 -

the f lexible drive, and pressure measurements made, every J" , when the readings of the water manometers were steady. To prevent the pressures being disturbed by unexpe'cte/3 f luctuat ions in the compressor speed, they were clamped before reading and then checked when l a t e r undamped. Occasional measurements of humidity were made during each run.

Each f u l l t raverse was checked by a repeat run under the same basic conditions, in some cases with, and in others without, the l ine r being moved. In the check t raverses the pressures were not always read' every J". The various quant i t ies which were changed between similar t raverses are l i s t ed in Table I for comparison with the d is t r ibu t ions of Mach number given in Figs. 4 , - 8 .

I t was predicted in Part I t ha t , with the exist ing tunnel equipment and by following the established procedure i t should be possible to measure

( i ) the difference between the Mach number at any point i n the empty working section and the Mach number at the corresponding point on the tunnel cent re- l ine correct to within +0.002 at a l l M,

( i i ) the absolute Mach number at any point correct to within l imits varying from +0.006 at S = 1.4 to +0.004 at A a 1.9,

except in the immediate v ic in i ty of large disturbances of the order cf +0.01O, say, where the posi t ion error may be large . These predict ions are here confirmed.

4 Presentat ion and in te rpre ta t ion of Mach number d i s t r ibu t ions

The d i s t r ibu t ions of Mach number along the l ines of t raverse for each value of R are presented in two f igures:

(a) shewing the d i s t r ibu t ions of the measured difference mn between the Mach number Mn at a point on the n^b l ine and the simultaneous Mach number M5 at the corresponding point on the centre - (No. 5) l ine

(b) showing the d is t r ibu t ions of the measured absolute Mach number Mn at a point on the n t n l ine

Each figure gives the resu l t s cf two traverses in each of the Posi t ions I and I I ; the r e su l t s of a fu l l t raverse are presented as a "jointed curve", obtained by joining consecutive points by s t ra ight l i n e s , whilst the check resu l t s are plot ted as crosses in the v ic in i ty of that curve.

The agreement between two corresponding t raverses i s best i l l u s t r a t e d by;the d i s t r ibu t ions of mn, which should not disagree by more than 0.004 in the cases when the l ine r was moved or by more than 0.002 with the l iner unchanged, except near large disturbances.

r^he d is t r ibu t ions of Mn, which are subject t o larger errors than those of mn, give an idea of the trends of the local Mach number and indicate the posi t ions of the large disturbances. Als,o, in conjunction with the values of the estimated expevjmental error AM (see Table 2) they may^be used to give an idea of the d i s t r ibu t ions of the mean Mach number Mn from the r e l a t ion |Mn-Mn|< A M. No attempt has been made to draw these Mn d i s t r ibu t ions from jus t two examples of Mn dis t r ibu t ions , since th i s would be largely guesswork. However, the maximum discrepancy which may^be allowed between any two corresponding values of Mn i s c lea r ly 2AM, and i t may. be seen from Table 2 and Figs. 4(b) ,-8(b) that the r e su l t s of a l l check runs l i e well within t h i s error of the resu l t s of the corresponding f u l l t raverses .

- 4 -

Simply joining experimental points by s t ra igh t l ines to produce Mn dis t r ibu t ions may defeat the object of the ca l ib ra t ion to discover the posi t ions and magnitudes of "comparatively large" disturbances, since large changes in Mn may occur in distances much smaller than the JM

in te rva l s of the t raverses . However, in many such cases the posi t ions of the disturbances 'are well established by the disagreement of the check r e su l t s there . I t i s found that the disturbances which are eas i ly ident i f ied l i e close to the theore t ica l envelopes of the disturbances from the two window junct ions. Consequently the in tersec t ions of these envelopes with the l ines of t raverse are indicated in Figs .4(b) , -8(b) to f a c i l i t a t e the tracing of disturbances which are not apparent from the ra ther coarse t r averses . We may point out, however, tha t there is not necessar i ly a measurable disturbance at every point on the envelopes since the disturbance fronts caused by the window junctions are by no means uniform: Table 3 gives typ ica l measurements of the differences i n l eve l between the tunnel side walls and the windows at several points on the circumference of the windows. The window A (see Fig.3) was unchanged for a l l the runs, but a window B-j was used for runs at M= 1 «4,

1.5 and 1.6 and a new windov/- B2 for runs at M = 1.8 and 1.9. Discrepancies between the theore t ica l and experimental posi t ions of the disturbance envelopes are due to an unavoidable constant small r o l l i n the p i t o t shower during a l l t r averses .

The e s sen t i a l points of an in t e rp re t a t ion of the Mach number d i s t r ibu t ions for a given M therefore seem to be:

(1) to note the agreement between corresponding t raverses by comparing t h e i r mn d i s t r i bu t ions ,

(2) to compare the trends of correspondyig Mn d i s t r ibu t ions and, i f poss ib le , deduce the form of the M^ d i s t r ibu t ion ,

(3) to note the posi t ions and, if poss ible , the magnitude of the disturbance3 from the window junctions,

(4) to estimate the measured overal l mean Mach number M* throughout the working section ~ M* i s thus an_experimental value of the theore t i ca l nominal Mach number M - and the l ike ly maximum var ia t ions from i t ,

(5) to estimate the approximate upstream l imi t of the working section a t t h i s given ft, and to note any regions of f a i r l y uniform or v io lent ly non-uniform flow downstream of i t ,

(6) to l i s t any p e c u l i a r i t i e s of the d i s t r i bu t i ons .

5 Conclusions

This report presents the d i s t r ibu t ions of Mach number along specified representat ive l ines throughout the empty.working section for the f u l l working range of nominal Mach number M = 1.4, 1.5, 1.6, 1.8, 1.9, for condensation-free flow at atmospheric stagnation pressure and at a stagnation temperature of 35°C.

The r e su l t s confirm that the accuracy of the t e s t s i s of the order predicted i n Part I . Thus, comparable d i s t r ibu t ions of mn, the measured difference between the Maoh number Mn at a point on the n^b l i n e of t raverse and the simultaneous Mach number Mr at the corresponding point on the centre (No.5) l i ne , agree to within +0.002 at a l l M, except near large disturbances of order greater than +0.01. The agreement i s even closer when the l ine r i s not moved between performing the t raverses . Further, the d i s t r ibu t ions of Mn for comparable t raverses agree to within + AM, where AM var ies with M and i s given in Table 2, except near

- 5 -

large disturbances. The steadiness of the readings in a l l t e s t s , and the very sa t i s fac tory agreement between r e su l t s of comparable t e s t s , ccnfirm the bel ief that a l l t e s t s were performed with a i r suff ic ient ly dry to prevent the occurrence of condensation shocks.

Comparable t raverses show the same trends of Mach number gradient , except near steep disturbances where the in te rva l s of the traverses are too coarse to.permit a proper comparison.

The la rges t disturbances in the working section ar ise from the window junctions with the side walls and from the jo in t between the recess block and the top l ine r (see F ig .3 ) . In fac t , the l a t t e r disturbance i s so large , about +0.050, t ha t , with the expansion from the ends of a shaped l ine r , i t forms the downstream boundary of the effective working section. The disturbances a r i s ing from the window junctions are of the order of +0.015 and are serious, since they affect the flow in more than half of the working section. In view of the r e l a t i ve ly smooth flow upstream of the region influenced by the window junctions, which tends to eliminate the l ine r s themselves as sources of any large non-uniformities of flow, i t i s clear that pa r t i cu la r a t ten t ion should be paid to ensure smooth jo in t s between the side walls and windows or mounting p l a t e s .

The values of the overal l mean Mach number M* are +0.01 higher than the corresponding values of nominal Mach number M. The maximum var ia t ions due to the window junction disturbances are about +0.015. Neglecting these " a r t i f i c i a l " disturbances, the gradual var ia t ions due to other causes are of the order of +0.010, which should represent the l imit of var ia t ion with per fec t ly smooth window j o i n t s .

By measuring the posi t ions in the three horizontal planes of t raverse where the Mach number begins to decrease s tead i ly in an upstream di rec t ion , and drawing a mean plane through them at the appropriate Mach angle to the flow di rec t ion , i t i s possible to estimate roughly the beginning of the working section for each M. Fig.9 indicates the estimated boundaries of the effective working sect ions , and shows that the t e s t s described here adequately cover the effective working sections.

The close agreement which i s obtained even when the l ine r has been removed and replaced between comparable traverses i s a j u s t i f i c a t i o n of the simple method of l i ne r i n s t a l l a t i o n which i s used i n the ca l ib ra t ion .

I t i s possible that a more detai led analysis of pa r t i cu l a r d i s t r i bu ­t ions may reveal cha rac t e r i s t i c s peculiar to individual l iners . One such pecu l ia r i ty i s noticed in the Mn d i s t r ibu t ions for the M =1 .6 l ine r (see F ig .6(b) ) . There i s a r e l a t i ve ly steep negative Mach number gradient in the cen t ra l horizontal plane (see M. , Mtj, M5) between points 10 and &§- where the Mach number f a l l s about 0.3l ; t h i s gradient, which seems to be perpetuated in the other planes (see M ,̂ M2, M? near point 13, and My, M3, MQ near point 8) , i s well upstream of any a r t i f i c i a l disturbances and i s presumably due to the shape of the l i n e r .

Although i t i s not easy to assess the r e l a t ive merits of the Mn dis t r ibu t ions of the different l i n e r s , we note_that the la rges t "non-a r t i f i c i a l " var ia t ions are observed with the M=1.9 l i ne r , whilst the one which gives closest r epea tab i l i ty of r e su l t s and for which the a r t i f i c i a l disturbances may be most eas i ly isolated i s the M = 1.6 l i ne r I ronica l ly , the design of t h i s l i ne r included an eroneous boundary-layer correct ion.

- 6 -

6 Remarks on recent modifications

The t e s t s described here were performed during November and December, 1951. Now, in March, 1952, we must mention two modifications which have become permanent features of the tunnel.

The window B2 which was used during Runs 13, 20 has superseded the window B-i used for Runs 1, 12, and i s now in constant use in the tunnel . Typical measurements of the d iscont inui t ies between the side wall and these windows are given in Table 3 . There i s no improvement i n Bp, though in th i s case the cement junction between glass and s t ee l i s in tac t whilst i n B^ i t had crumbled in several p laces . I t i s possible that inaccuracies in the side walls make a substant ia l contribu­t ion to the t o t a l d i scon t inu i t i e s .

The shims which were placed between the bottom wall of the tunnel and the shaped l iners to f ix them in the i r correct posi t ions (see Part I) have been incorporated into the l i n e r s . I t was found that during the few months of the preliminary inves t iga t ion and accurate t e s t s the l i ne r s for M = 1.4, 1.5, 1.8, 1.9, which are made of teak, had shrunk somewhat, whilst the 1 = 1.6 l i ne r , which i s made of permali, was apparently unchanged. Thus, future d i s t r ibu t ions may be expected to d i f fer from those given here by a l i ne r basic er ror , which, however, should be small, say of order +0.002, and may in fact be allowed for by the generous errors estimated for the present r e s u l t s . We suggest that the l i ne r s should be inspected per iodica l ly , say once a month, to t e s t for shrinkage, and when the shrinkage i s appreciable, about 0.010", extra shims should be incorporated into the l ine r s to bring them backeto the i r design posi t ions as scribed on the tunnel wal l . The l i ne r s for M = 1.4, 1.5, 1•6, 1.8, 1.9 were checked as conforming to the i r design posi t ions on March 5th, 1952.

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m n

L i s t of Symbols

Mach number d i f f e r ence ( see below)

pQ s t a g n a t i o n p r e s s u r e

M. Mach number

•££. Reynolds number per inch

T s t a g n a t i o n temperature

A denotes "abso lu te e r r o r i n

0 abso lu te humidity

S u p e r s c r i p t s :

denotes nominal value

denotes mean value at a po in t over any number of t e s t s

denotes o v e r a l l mean value throughout working s e c t i o n over any number of t e s t s

appl ied to Mach number

only

Subscr ipt / . :

n number of tube i n p i t o t shower

(1 < n < 9)

For example:

t h Mn measured Mach number at a g iven p o s i t i o n of the n tube

JJ_ » M " " " » " c e n t r a l (No.5) tube

mn = Mn - ME Mach number d i f f e rence between p o s i t i o n s of n t h and c e n t r a l tubes w i th shower in a given p o s i t i o n

No. Author

1 Lord, 17. T. and

Beastall, D.

J.-LU FERENCE

Title, etc.

"Calibration of the R.A.E. No. 18 (9" x 9") Supersonic Wind Tunnel: Part I: Preliminary Investigations". ARC 16,554. C.P. 162. September, 1953.

Wt~2078.0P163.K3 - Printed in Great Britain.

Table 1

Guide to t r a v e r s e s

M

1.4

1.5

1.6

1.8

1.9

2Sx io" 6

a

0 .38

0.37

0 .36

0.^4

F igu re

4

5

6

7

0.33

•

8

•

P o s i t i o n i

I

I I

I

I I

I

I I '

I i

I I

I

I I

Run

1

2

3

4

1 1

n |Windows! Type of Traverse 1

0.0002

0.0002

0.0003

0.0003

A, B1 F u l l

A, B-] I Check (Liner Moved)

A i F u l l 1

A i

5 ! 0.0003! A, B1 1 '

6

7

8

9

0.0004

0.0004

0.0003

0.0003

10 '0 .0003

11 |0 .0003

12 '.0.0002 i

13

14

15

16

0.0001

0.0001

0.0002

0.0001

17 jo.0001

18 |0.0001

A, B1

A

Check (Liner Unmoved)

F u l l

Check (Liner Moved)

F u l l

A '; Check (Liner Unmoved)

A, B1 j F u l l

A, B1 | Check (Liner Moved)

A j F u l l j •

A iCheck (Liner Unmoved)

A, B 2 ' F u l l

A, B 2

A

A

A, B 2

A, B 2

19 J0.0001 \ A 1 - - 1 - 1 ,1

:20 ;0.00011 A

Check (Liner Unmoved)

F u l l

Check (Line Moved)

F u l l

Check (Liner Moved)

F u l l

Check (Liner Moved)

- 9 -

Table 2

Est imated t o t a l exper imenta l e r r o r s

5

1.4

1.5

1.6

1.8

1.9

AM

0.006

0.005

0.004

0.004

0.004

Table 3

Tvp_ical values of discontinuities at window junctions

Positiuxj.

Upstream J u n c t i o n

Downstream J u n c t i o n

Dif ference i n Level Between Side Wall and S t e e l Rim

Window A

Top °

Centre

Bottom

Top

Centre

Bottom

-0 .002"

-0 .002"

0

-0 .002"

-0 .005"

Dif ference i n Level Between S t e e l Rim and Glass Pane

; Window i Windov/ j Window

B1 I B 2 . A

-0 .004" I -0 .004" I +0 .001"

- 0 . 0 0 1 "

-0 .002"

• 0

+0.003"

0

-0 .003"

-0 .002"

0

+0.005"

0

+0.002"

+ 0.002"

+0.002"

0

Window B1

0

-0 .002"

0

- 0 . 0 0 1 "

0

+0.003" ! 0

Window B 2

+0.001"

-0.002"

0

-0 .001"!

! +0. 001"

- 0 . 001" I i

These values indicate the orders and trends of the discontinuities. The measurements are accurate only to within +0.001", and removal and replacement of a window involves changes of similar order.

In window B-j, the cement joint between the steel rim and the glass panel contains cracks of depth > 0.010",

.. 10 -

< •

FIG.I MODIFIED PITOT SHOWER FULL SIZE

3 G)

FIG. 2

FIG.2 METHOD OF STIFFENING TRAVERSING GEAR FOR PITOT SHOWER.

FIG.3

VERTICAL SECTION THROUGH TUNNEL t

POSITION n POSITION I

W/////////A7^//////////^/M*

WIND E-5"

2-5"

Y////////////////////////////////M.

HORIZONTAL SECTION THROUGH TUNNEL £

(VIEWED FROM A B O V E )

FIG.3 POSITIONS OF TRAVERSES WITH PITOT

SHOWER.

FIG 4 (a)

POSITION n POSITION I

8 17 16 15 14 13 12 II 10 9 8 7 6 5 4 3 2

FIG 4(a) DISTRIBUTIONS OF MACH NUMBER DIFFERENCES m. M = I 4 PQ = 30 ~T̂ = 35 J\ - • 0003

FIG. 4(b)

POSITION n POSITION I

18 17 l£ 15 14 13 12 0 2 J 8 7 G 5 4 3 2

PATH OF DISTURBANCE FROM WINDOW A

PATH OF DISTURBANCE FROM WINDOW Bi

FIG.4(b) DISTRIBUTIONS OF ABSOLUTE MACH NUMBERS Mn

M- l -4 R - 3 0 * T 0 - 3 5 ° C 7 1 - 0 0 0 3

FIG.5(o)

POSITION H POSITION I

18 17 16 15 14 13 \Z II 10 3 8 7 6 5 4 3 2

K-* * »

FIG.5(aU>ISTRIBUT]ON OF MACH_ NUMBER ^DIFFERENCES m M= 15 |3 = 3 0 T . 35 JV= 0 0 0 4

o o

TV

POSITION n

FIG.5(b) POSITION I

18 17 16 15 14 13 12 II 10 9 8 7 6 5 4 3 2

M, 1-51 " >

PATH OF DISTURBANCE FROM WINDOW A

PATH OF DISTURBANCE FROM WINDOW B,

FIG. 5(b) DISTRIBUTION OF ABSOLUTE MACH NUMBERS Mn

M»l-5 TL-30" T0-35°C H * 0 0 0 4

FIG. 6 (a)

M,

•62r

•61 •

-60-

• l-oir

mi o

-oto i

+0-01

Tn8 ol"

-o-a -

+o-oir

m5 0

-0-01

+0-Olr

tn4 0 -

-0-01 -

+o-oi r

"m6 0 -

-o-oi L

+ 0'Olr

n 7 o-

-o-oi

+o-oir

•m* o

-o-oi

+ 0-01 r

-o-o i

8 r

|

« * i

f 16 IJ

/

POSITION

» 14 r

V

\

s c x_

^ y

^ » ^

<*

S i ^

W

H

r

n

j r

v>

s / » -

y / •

/ / .

2 1

<

^

^ T

^ 4

10 s

M l

- r \ A

1 Y\

>

8

m i

y -**

•t

-V-—

K U

^

X

h/

JTB ,

1 t X

1**A J- ,

1 '

7

_ „

\ \

V X -

y\ ><*

.

^H

vj

V

kv

£

•i ^

^

X

y>

- v ;

^

V*

,«*** r̂

u

POSITION I

5 4 3 2 1 0

*=S *V,

Pi V V j • « < 1

LIMIT OF FLOW UNDISTURED>

BY RECESS BLOCK

, ^

AJ V

^J

/nj

W r

w A

y 7*

1 / V Jr

, +j >

A V V

\ / V X

i/ V

1 ,/ 1/ i A V

1/ y

r*—I fU

If-v V

\ t v *

ky*

v*-

S^A.

\

V *

* \

- *

"V

. * • * - *

NA<. I « •«J1

• > i A

i

TJ

J

V

7)

*X:

\ \

A vs

• ^

X

A u -' ^

k'1

Ai

\ \

S X

/ \ / \ RUN II / » V RUN 12 / ^ V RUN 3 „ *»%" RUN 10

FIG.6(a) DISTRIBUTIONS OF MACH NUMBER DIFFERENCES TTIn

M = 1-6 T 0 = 3 0 T 0 -35 n = O O Q 3

FIG. 6(b) POSITION nr POSITION I

18 17 IS 15 14 13 12 0 9 8 7 G 5 4 3 2

M,

I-G2

M, I •«!•

1-60

1-62

M2 l-Glh

1-60-

l'62r

l-GI-

l-GO-

I-G2

M4 I'GI

I-GO

IG2r

Ms l>GI •

1-60

1-62

Mf i l-GI

I'GO

1-62

M7 I'61

l'60L

1-62

M8 1-61

I-601

1-62

M9 I'GI

l*GO

PATH OF DISTURBANCE FROM WINDOW A

PATH OF DISTURBANCE FROM WINDOW B,

FIG.6(b) DISTRIBUTIONS OF ABSOLUTE MACH NUMBER Mn

M = h 6 F - 3 0 " T 0 = 3 5 ° C A - 0 0 0 3

FIG. 7(a)

POSITION H POSITION I

1-82

Ms 1-81

1-80

TO,

TOi

TO3

TO4

TOft

m7

Tn8

+ 0'0lr

0

-0-01.

+ 0'0lr

0

-o-oi

+o-oir

0

-o -o i .

+0-01 (-

0-

-o-oi -

+O0lr

o-

-0-01

+o-oi r

0

-0-01

+0-01

0

-O-OI

TO9

+ 0-0l r

0

-O-OI •

B 1

( k 1

7 1

snr71

* N

G 1

i

***

5 1

x

.

V

\

^

f * ^ -

4 1

- _ X — -

* — 1

NflL V

">

3 1

X X

X

~ \ x

LH

- c * r ^

X

2 1

/ *

W '

/

y ,/

/

i i

xxjpJ

«n

[ * * X '

u

-»7>

< * \

/ •

,*r '

0 9 1

H n r ^ i * ^

" * * <

^J x:

IXJSJJJ

<**

* * \

X ,

/ ^ ^ RUN 15 * " « V RUN IG

• C W H

X

- r * ^

1-2

*

fc*

^

x*

i

X

*

U **J

V

L7\ * •«

»»

\ y

^

v *

is_yx X

f <

J

x * .

\ » f

x V

- » w

\

L WJ^

\T

X

V ) T

A •s

1

-s>* x-

/«

*"

5

^ 7 *

3 ^ 1.

r *V-

3 2

1 * ' ^

LIMIT OF FLOW UNDISTURBED. BY RECESS BLOCK x

xN«

^

^

X

^

X X

JL

7 *

SA

\ - y ^

/ * "

w

^

Sr'"

s y * Y

X

\ t~

\ '

\ * r

\p V

V V

u .. \

V

tv

r > -

/ • " v

/ A

. / * /

/ \ i

X V * * -

Ai^ w

X j ^ w,

1 0

*nJ

J Y

j f

i

J>*\

X fV\

1

Ayi

A * N / RUN 13 / « " « „ RUN 14

FIG.7(o) DISTRIBUTIONS OF MACH NUMBER DIFFERENCES TT1n

M - 1 8 P 0 - 30 To »35 f l - 0 0 0 2

FIG. 7(b)

POSITION n POSITION I

18 17 IG 15 14 13 12 II 10 9 8 7 G 5 4 3 2 0

PATH OF DISTURBANCE FROM WINDOW A

PATH OF DISTURBANCE FROM WINDOW B2

FIG7(b) DISTRIBUTIONS OF ABSOLUTE MACH NUMBERS Mn

M=l-8 " F - 3 0 " T0=35°C i i * - 0 0 0 2

FIG. 8 (a).

FIG. 8.(Q). DJSTRIBUTIONS OF MACH NUMBER DIFFERENCES m M= 19 T0~ 30 T; = 35 7C= OOOI

TV

FIG. 8(b)

POSITION U POSITION I

8 17 IG 15 14 13 12 II 10 9 8 7 G 5 4 3 2

PATH OF DISTURBANCE FROM WINDOW A

PATH OF DISTURBANCE FROM WINDOW B2

FIG.8(b) DISTRIBUTIONS OF ABSOLUTE MACH NUMBERS Mn

M-l -9 Po - 3 0 " To=35°C 7L -OOOI

FIG.9

///////VF//////,..'.,/////////TA////////////

FIG.9 INDICATION OF WORKING SECTION BOUNDARIES

C.P. No. 163 (16,555)

A.R.C. Technical Report

Crown Copyright Reserved

PUBLISHED BY HER MAJESTY'S STATIONERY OFFICE

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1954

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