The Design and Testing of an Axial Compressor having a Mean Stage Temperature Rise of 3 deg C

Transcription

1 LBAY!~OYAL "... -,v,+'~ ET ESTABL!S'+'~,,'=-N. & M. No (16,775) A..C. Techncal eport MNSTY OF SUPPLY AEONAUTCAL ESEACH COUNCL : EPOTS AND MEMOANDA The Desgn and Testng of an Axal Compressor havng a Mean Stage Temperature se of 3 deg C " " By. A. D. S. CATE, S. J. AN1)EWS,and E. A. FELDE Cro~m Copyrght eserved.,... LONDON HE MAJESTY'S STATONEY 1957 FVE SHLLNGS NET OFFCE

2 The Desgn and Testng of an Axal Compressor havng a Mean Stage Temperature se of 3 o des C By A. D. S. CA~TE, S. J. ANDEWS and E. A. FELDE COMMUNCATED BY THE PNCPAL DECTO Or SCEHTHC ESEACH (A), VNSTY OF SUPPLY eports and Memoranda Wo. 2985* 2Vovember, 1953 Summary.--Ths report descrbes a compressor whch was desgned to gve a mean stage temperature rse of 30 des C. t has sx stages so that the overall pressure rato at the desgn pont s 4.5 : 1. Full detals of the factors whch led to the form adopted and of the desgn tself are gven n the report. The test results fully substantated the desgn assumptons. n partcular, usng standard desgn data, t s possble to acheve temperature rses of about 30 deg C wthout sacrfcng unduly any desrable performance features. Such temperature rses were consderably above those beng used at the tme ths work was carred out, and are n fact substantally above the mean value used n present-clay desgns. Detals of the stage characterstcs and the matchng of the compressor have been gven n the report, together wth some other ponts of specal nterest. 1. ntroducton.--n 1944 the Natonal Gas Turbne Establshment--or Power Jets (esearch & Development) Ltd., as t then was--started desgn work on an advanced form of axal compressor, later known by the seral reference 109. The compressor was subsequently bult and tested, the results substantatng n a large measure the desgn objectves. Although the complete desgn detals and the test results have receved lmted crculaton and certan nformaton generally publshed (ef. 1), no formal report of the desgn detals and test results has been made. Ths report has therefore been prepared to provde comprehensve desgn and test data and to serve as a reference for further comparatve work now proceedng on the compressor. 2. Descrpton of Compressor Desgn Features.--The salent feature of the desgn was an attempt to ncrease the mean stage temperature rse from an average contemporary value of somewhat less than 20 des C, to the hghest possble value compatble wth the cascade data then avalable. The desgn study showed that a rse of 30 des C per stage was about the lmt. Assumng an overall adabatc effcency of 85 per cent, t seemed that a pressure rato of about 4.5 : 1 could be obtaned from a sx-stage compressor. A mass flow of 70 lb/sec was adopted to gve a compressor of sutable sze for the exstng test facltes. A constant outsde or rotor tp dameter was desrable to mantan the hghest possble blade speeds n the later stages. Assumng an nsde/outsde dameter rato at nlet to the frst stage of 0.6, ths beng the lower lmt of contemporary practce, t was found that the performance outlned above could be obtaned from a compressor n. n outsde dameter runnng at 9,500 r.p.m. Ths gves a rotor tp blade velocty of 1,010 ft/sec. The mass flow corresponds to 21.7 lb/sec/sq ft frontal area, neglectng casng thckness. *N.G.T.E. eport.148, receved 15th May, A. 1

3 Prevous work had shown that the maxmum stage temperature rse would be obtaned usng a flud outlet angle of about 35 deg (see ef. 2). However, ths would have entaled a weght/ power rato and outsde dameter n excess of ther mnmum values. Snce the work was beng carred out prmarly for arcraft engne applcaton, ths was consdered undesrable. An outlet angle of 25 deg was fnally adopted. Ths value entaled lttle loss n stage temperature rse, and gave the mnmum weght/power rato, together wth an outsde dameter approachng the mnmum value (see Fg. 97 of ef. 2). These fgures have snce been checked usng the latest cascade data. The new calculaton would suggest that the maxmum stage temperature rse s hardly affected by outlet angle, at least over the range 20 to 35 deg. Wth the type of hgh-speed desgn envsaged, a blade twst approachng constant reacton was obvously desrable. A compromse between constant reacton and half vortex was adopted n whch the Much number at nlet to the stator was constant along the blade length. Wth the assumpton of a radally constant axal velocty ths gave the now well known 'constant c~3' blade twst. The secton of 50 per cent reacton was kept at the mean dameter for all stages. The Much numbers at the mean dameter are 0.72 at the frst stage and 0.70 at the last. The hghest Much number s 0.8 at the frst-stage rotor tp. The blades themselves were desgned for zero ncdence at all sectons. A parabolc camber-lne was used for the frst tme n a compressor. t was beleved that the hgher throat areas assocated wth these blades would be benefcal. The devaton rule was substantally the same as that gven n ef. 3. Both rotor and stator blades were tapered n thckness from root to tp, but the chords were kept constant. For manufacturng purposes the blade sectons were defned at two statons, one near the root and the other near the tp of the blade. ntermedate sectons were obtaned by a lnear nterpolaton between these datum sectons. n estmatng the stage temperature rse a constant work done factor of 0.86 was used throughout. The annulus heghts were determned from the mean mass flow on the bass of a constant axal velocty. No allowance was made for the growth of the boundary layer on the annulus walls. t wll be apprecated from the above comments that the smplest possble desgn assumptons were made throughout. t was hoped to acheve the hgh performance only by pushng exstng desgn methods and data to the lmt, the ephemeral attractons of over-elaboraton beng frmly ressted. The mechancal desgn and constructon of the compressor s not representatve of ether arcraft or ndustral technque. t was dctated largely by the possble expermental work that was envsaged, and by the manufacturng facltes avalable. For example, t was antcpated that the aerodynamc desgn nnovatons could result n a serous msmatchng of the stages and a consequent loss of effcency--though ths fear subsequently proved unfounded. Hence the mechancal desgn was such that all the stages could be tested separately f necessary, or alternatvely any group of stages could be tested. Provson was als0 made for addng two more stages to the compressor though an eght-stage verson has not yet been tested. A further feature of the desgn was a provson permttng shroudng to be used on the stators n place of the smple radal clearance adopted n the orgnal desgn. Ths feature also has not been ncorporated n any desgn so far. All these features resulted'n a compressor that was somewhat heaver than normal arcraft practce. The blade chord lengths were reduced n successve stages to gve the same gas bendng stress for each row. Ths was about 4½ tons/sq n. at the desg n pont wth standard nlet condtons. The drect centrfugal stress vared from 12½ tons/sq n. n the frst-stage rotor blade to 5 tons/sq n. n the sxth. The axal length of the compressor over all the blade rows (ncludng the.g.v's) s 18.1 nches. The blades were manufactured by the lost wax process, tle rotors beng cast n Vtallum and the stators n H.. Crown Max. They are thus not representatve of compressor practce. A drawng showng the general arrangement of the compressor s reproduced n Fg. 1. Detals of the bladng are gven n Appendx. 2

4 2.2. Manufacturng Errors a~d Blade Detals of Test Compressor.--t s well known that small changes n blade angles can have a marked effect on compressor performance. The 109 compressor was bult to be wthn the standard N.G.T.E. manufactur'_ng tolerances, but a number of errors were present. The compressor was accepted wth these errors to expedte the tests. For checkng purposes most of the blades n stage 1 rotor were examned n detal. A plot of the derb/ed blade nlet and outlet angles s shown n Fg. 2. t wll be observed that the blade outlet angles, whch determne the performance, are generally wthn a 0.5 deg band, though a few are as far out as deg. The scatter appears qute random. Sample blades were also examned from the other rows. The error n the blade outlet angles for each row has been tabulated n Appendx a. n general the measured blade angles are less than the desgn, though n vew of the lmted number of blades nspected t s doubtful f any quanttatve data can be deduced. Snce these measurements were taken the compressor has been completely strpped, and rebult wth new dscs sutable for 9verspeed testng. No detal measurements of blade angle were taken at the tme of the rebuld, though the only dfference would be due to the dsc fr tree broachngs and such dfferences should be very small. Qute recently the bladng of ths buld of the compressor was re-nspected usng the very latest technques. The detals of ths examnaton are gven n Appendx (b). Ths nspecton confrms that the blade outlet angles are generally lower than desgn, especally n the earler stages. The arthmetc mean of the error n all rows s 0.4 deg. An estmaton of the performance of the compressor based on ths nspecton reports shows that the desgn pressure rato of 4.5 : 1 should be obtaned at a flow of about 72 lb/sec nstead of at the desgn value of 70.0 lb/sec. 3. Test Technque.--The locaton of the 109 compressor n the test cell s shown n Fg. 3. The ar path to the compressor nlet s also ndcated on ths fgure. The compressor was mounted n a swung frame so that the power nput could be measured by the torque reacton on the stator casng. Unfortunately, the precmeter used for ths purpose was only consdered relable for one set of tests. n addton to the torque measurements, however, the temperature rse over the bladng was measured drectly. esstance elements were used at nlet, and four thermocouples equally spaced around the annulus at outlet. To allow for velocty profles, total pressures were measured by four combs of fve ptots equally spaced around the annulus. Each tube was placed at the centre of equal annulus areas, and an arthmetc mean was taken as the total pressure at the comb. Wall statcs were used to measure statc pressures. The locaton of all the nstrumentaton s shown n Fg. 3. Themass flow was measured by a calbrated ventur at entry to the test cell as shown n Fg. 3. A correcton for leakage nto the cell when operatng at sub-atmospherc nlet pressures had to bemade. The maxmum correcton was about 5 per cent of the total mass flow. n addton to the overall measurements, the statc pressure at the casng was measured between each stage to obtan some ndcaton of the stage operatng condtons. Two ponts located dametrcally opposte each other were employed for ths purpose. The arthmetc mean of these was taken as the statc pressure between the rows. t s consdered that the absolute accuracy of the major performance parameters are: mass: flow 4-2 per cent, effcency 4-2 per cent, and pressure 4-1 per cent. n order to keep wthn the power lmtatons of the exstng test facltes, t was necessary to. resort to nlet throttlng at the hgher speeds. One effect of ths was to reduce the gas bendng stress below the desgn values, whch were based on standard entry condtons. n addton the test eynolds number was reduced below the desgn value. As the nlet throttlng was only apprecable at the hgher flows t s not consdered to have had any sgnfcant effect on the performance, though the effcency may perhaps be some one per cent below the value that would be obtaned wth standard entry condtons. The table overleaf gves the mean cell condtons for each speed ~n the seres tests, and ndcates the degree of throttlng employed. 3

5 Speed (r.p.m.) ,770 5,049 7,075 7,550 8,050 9,000 9,560 Cell pressure (lb/sq n. (absolute)) Cell temperature (deg C (absolute)) The test eynolds number at entry to the frst-stage rotor s ~. Ths s based on blade chord and flud approach velocty at 72 lb/sec corrected mass flow, whch corresponds to maxmum effcency at the desgn speed. t s well above the crtcal value of about ~. At some future date t s hoped to retest ths compressor wth standard entry condtons. 4. Test esults for Sx-stage Compressor Overall Performance.--The overall test results for the sx-stage compressor have been plotted as pressure rato and effcency aganst mass flow, n Fgs. 4 and 5 respectvely. All the quanttes have been reduced to standard nlet condtons of 14.7 lb/sq n. and 288 deg C (absolute). The performance has been deduced from the followng seres of tests : Seres Prelmnary set of tests ntended chefly for the mechancal provng of the compressor. The aerodynamc results have not been ncluded n Fgs. 4 and 5 though the agreement wth later tests s consdered good. Seres Orgnal buld for whch the blade nspecton detals are gven n Appendx. The torque measurements were consdered relable for ths seres of tests. The effcency based on the torque was consstently 2 per cent less than that based on the temperature rse measurements. Seres The compressor was rebult wth new dscs permttng an overspeed up to 10,500 r.p.m. The torque measurement was consdered unrelable for ths seres of tests. The thermocouples measurng the compressor outlet temperature were repostoned. t was beleved that part of the 2 per cent dfference between the torque and temperature effcences was due to temperature stratfcaton. The thermocouples were therefore moved to a poston where the temperature varaton should have been less. Seres V These were a lmted seres of tests wth the compressor lagged. (esults not ncluded.) t wll be seen from Fgs. 4 and 5 that reasonably good agreement has been obtaned between the varous test seres. Snce between the seres and seres tests, not only was the nstrumentaton changed, but the compressor tself was completely strpped and rebult, the agreement can be taken as ndcatve of test accuracy. t s consdered that the curves gven n the fgures represent the true performance of the actual bladng. A comparson of the test performance wth the desgn pont performance (modfed for the blade manufacturng errors) s made n the table below : Desgn Test Pressure rato : : 1 Mass flow (lb/sec) Adabatc effcency (per cent) Temperature rse (deg C) (mean of seres and ) The assumptons upon whch the desgn was based have therefore been fully justfed, and t would seem that stage temperature rse of the order of 30 deg C are qute feasble. A more detaled examnaton of the results shows that the compressor s matched just below the desgn pont. The maxmmn polytropc effcency occurs at a flow of 69 1b/see at 9,000 r.p.m. At ths pont the overall pressure rato s 4.1 : 1 and the mean stage temperature rse 27-4 deg C. The polytropc effcency s 89 per cent. The surge lne, referred to ths pont, s better than average, though the knk s perhaps a lttle larger than would be obtaned from a compressor of the same pressure rato havng more conventonal stage temperature rses.

6 The overspeed performance s not as good as mght be desred. The peak polytropc effcency falls from 88-4 per cent to 85.5 per cent n overspeedng from the desgn value of 9,500 r.p.m. to 10,000 r.p.m. An addtonal ncrease of speed to 15,000 r.p.m, causes a further drop to 82.0 per cent. Ths drop s, of course, due to the hgh Math numbers at the frst stage, and mght be less serous f blades wth a better hgh-speed performance were used Stage Characterstcs.--The stage characterstcs, derved from the nterstage statc pressures, have been plotted out n detal n Fg. 6. A consderable scatter of the test ponts s, of course, present, but t s consdered no worse than average for ths type of work. Mean curves have been drawn through the ponts, and these have been redrawn together for comparson on Fg. 7. t wll be observed that the stage characterstcs are all very smlar, wth the excepton of stage one. Ths gves a much hgher peak pressure rato, due no doubt to the more favourable flow condtons at entry to the stage. t can also be seen from the detal characterstcs n Fg. 6, that at the matchng speed of 9,000 r.p.m, all the stages are operatng at practcally ther peak -pressure rato near the surge pont (.e., each of the ponts marked 1 are near the peak of ther respectve stage characterstc). t follows that ths compressor s well matched. The early fears of a msmatchng due to the hgh stage temperature rses were completely unfounded, and the smple desgn technque adopted appears qute satsfactory for such desgns. t wll also be observed from the stage characterstcs that the earler stages are operatng well over the stall pont at the lower speeds--the compressor beng unsurged of course. A close examnaton of the frst stage characterstcs shows that above the knk speed,.e., above 8,000 r.p.m, the stage s operatng on the normal unstalled part of the characterstc. Below the knk speed t s always operatng on the stalled part of the characterstc. t can be concluded that the knk n the surge lne s due to the complete stallng of stage 1 at speeds below 8,000 r.p.m. The matchng of the compressor under dfferent operatng Condtons s also llustrated n Fg. 8. For each stage, the ncdence at the mean dameter s presented n relaton to the overall characterstcs. Tt~ese have been calculated from the mean stage characterstcs gven n Fg. 7. Strctly speakng, they apply to the overall characterstcs calculated from them, though the dfference between these and the measured characterstc s, of course, qute small. The good matchng of the stages n ths compressor s well llustrated by the curves. For example, t wll be noted that the zero ncdence lne (desgn ncdence) of each stage cuts the matchng speed characterstc (roughly 9,000 r.p.m.) at almost dentcal flows. Some further analyss of the performance of the 109 compressor, ths tme based on the mean stage characterstcs deduced from the overall results, s also gven n ef. 1. The data presented s part of a general survey of compressor performance n whch the mean stage characterstcs are used as the bass of a performance predcton method. 5. Test esults for Four-stage Compressor.--As part of a general nvestgaton of stage characterstcs, stage matchng, and surgng, the last four stages of the compressor were tested separately. t has already been shown how the knk n the surge lne of the sx-stage compressor was assocated Wth the stallng of the frst stage. By testng a reduced pressure rato compressor, t was hoped to delay the onset of ths stall to lower speeds, thereby obtanng a correspondng move ll the knk n the surge lne. For these tests the frst- and second-stage bladng was removed and replaced by blank roots. The nlet gude vanes were retaned n ther normal poston as shown n Fg. 1. Ths arrangement was not altogether desrable. The mean ar outlet angle from the gude vanes s only 22.8 deg, whereas that from the second-stage stator s 26.9 deg. The actual dfference wll be greater than 4-1 deg due to the axal acceleraton n the part of the annulus normally occuped by stages one and two. The alternatve of testng the frst four stages was not possble wthout usng replacement dscs n the ffth and sxth stages to avod choldng at outlet. 5

7 The test results are presented for the last four stages n Fgs. 9 and 10. They have been plotted as pressure rato and effcency aganst mass flow. All the quanttes have been referred to the standard nlet condtons of 14.7 lb/sq n. and 288 deg C absolute, even though t nvaldates drect comparson wth these stages n the sx-stage buld. Applyng the 'approprate correctons one would expect ths compressor to be matched at about 8,100 r,p.m. Wth standard nlet condtons (ths corresponds to 9,000 r.p.m, when operatng after the frst two stages of the sx-stage compressor). Also ncluded on these fgures are some calculated characterstcs. These were obtaned usng the stage characterstcs deduced from the tests on the sx-stage compressor. Supe~fcally the agreement between the calculated and test performance s good, as mght be expected from the method of calculaton. t wll be noted, however, that the knk n the surge lne occurs at much hgher speeds than predcted. Further nsght nto the detal performance can be obtaned from an examnaton of the test stage characterstcs, whch have been plotted n Fg. 11. From these t s seen ~hat the frst stage of ths compressor (that s stage 3 of the normal buld) s always operatng n the stalled condton, even at flow coeffcents whch gve unstalled flow m the sx-stage compressor. The hgh nlet angle from the standard.g.v's and the contractng annulus are beleved to be responsble for ths. Chokng of the H.P. stages prevents the flow beng ncreased suffcently to unstall the stage, except n the aerodynamcally overspeed condton. n ths condton, however, the characterstcs for ths stage have every appearance of shock stall,.e., the frst stage s always stalled. Ths s reflected n the overall results whch show much lower effcences than would be expected from the sx-stage results. t s also to be noted from these stage characterstcs that the peak pressure obtaned from stage 3 s hgher than that obtaned n the sx-stage buld. Ths s presumably due to the hgher work-done factor n the absence of the front two stages. Any further comparson of the two compressors s nvaldated by the stalled stage. t may be of nterest to note, however, that roughly the same characterstcs have been obtaned from stage 4 n both compressors. Ths could suggest that the presence of a stalled row has lttle effect on the performance of subsequent stages, a feature whch cannot be substantated from the characterstcs of the ffth and sxth stages on account of chokng. At least the maxmum flows n the sxth stage are approxmately nversely proportonal to the square root of absolute temperatures at ext from the four- and sx-stage compressors, whch would suggest chokng. 6. Comhtsons.--The test results on the 109 compressor have fully substantated the desgn assumptons. n partcular, usng standard desgn data t s possble to acheve mean stage temperature rses of about 30 deg C wthout sacrfcng unduly any desrable performance features. Such temperature rses were consderably above those beng used at the tme ths work was beng carred out, and are n fact substantally above the mean value used n present day desgns. k Full detals of the desgn and ponts of specal nterest have been gven n the man body of the report. EFEENCES No. Author 1 A.. Howell and. P. Bonham 2 A.. Howell 3 A.D.S. Carter Ttle, etc. Overall and stage characterstcs of axal-flow compressors. Proc..Mech.E. Vol. 163, p Desgn of axal compressors. Proc..Mech.E. Vol. 153, p The low-speed performance of related aerofols n cascade. C.P. 29. September,

8 APPENDX Blade Detals of 109 Compressor nner annulus dameter (nlet) (n.) Outer annulus dameter (nlet) (n.) Annulus area (nlet) (n?).. Mean blade secton dameter (n.) Camber-lne Poston of maxmum camber (per cent). Camber angle (deg)... Stagger (deg).. Blade nlet angle (deg) Blade outlet angle (deg) ~ Chord (n.)... Number of blades Ptch/chord rato.. Base profle.. Thckness/chord rato (per cent) Throat/ptch rato.. Devaton angle (deg).. Ar outlet angle (deg).. Blade twst Frst Stage Last Stage.G.V. otor Stator otor Stator "~ s Parabolc Parabolc Parabolc Parabolc Parabolc O O. 80 O O. 82 O- 78 O. 65 O. 64 C4 C4 C4 C5 C O. 87 O- 70 O. 68 O. 73 O "1 4"8 4"6 4" Constant oq Constant o% 7

9 APPENDX 109 Compressor--Blade nspecton Detals (~) Org~ al Buld used for Test Seres and 7 (nspecton, October, 1946).G.V. Stage 1 S Stage 2 Stage 3 S Stage 4 Stage 5 S Stage 6 nspecton dameter " $ Error n/~2 (deg) " O " oo No. blades nspected (b) ebuld used for Test Seres [[ and V (nspecton, November, 1952).G.V. Stage 1 S Stage 2 S Stage 3 S Stage 4 S Stage 5 [ S Stage 6 S nspecton dameter t Error n/~2 (deg) " No. blades nspected

10 \ NOTE :* /, \, \ \ \ \ \\ '040' ",,060" DJ~[T~. CLF.AAN~.[ )T~ TH~b~T DL0~K L t, ~LAMPJ~ 00.T STAtNF~D "OS' "~0 WOKNG C0~)]TO~. ~',X'~Y,, \ Ds 4,95"o4///:s/o6o63 ~ ~, /0/:6 CL

11 o lh u- o o (3 (::3 c3 o (.L-JaQ) ~~' 37~NV o 1371N 3(::]V78 y2,w wlj o 90 -, o (:3 cd Q c2~ c> o 07 0o J.-} - - C~:~d,) ~' 37~NV ±371n0 ~rv7g J ) J '< t~ 3 W 121 CD ~b O O,2 A TUBNE OOM / ve-t OUTLET TOTAL- HEAD 5TA~E COMB 3TATC~ j OUTLET\ TNEMO-, / / NL.ET ES ] LSTAN,~ (~SSPA~" - r f L J 5TEAM r ~7 ~ 5W~NC~NG ~ 5UPPO~TS Fo. 3. nstallaton of compressor n test cell. B 9

12 6'P 5EE5 :E E) N f'.p,m. 5EE.5 Tn X N?.p.m. 54 BO o F- W m W } -p z ttl J 80 O~ w L >- U z ba 11 b_ 111 t3 70 3?' ~ &O CO,~ECTED A~ MASS PLOW {LB/SEC )? ,o ~o ~o,~o _so ~o 70 8o CO~ECTED A4~ MA55 FLOW~B/SEC) FG. 5. EFFCENCE5 'mlotred 4BOYE DEVED =OM TEMPE~AT~J~E MEA5ut~EMENT CALUE5 ~DM /;OQ, UE MEASU,~EMENT,~% LESS.='Ol~ TE5T SEF-.5 n" BUT NO ~EL,ABL "O~GUE MEASUL~EMEN ~ ~ALABLE ~0~ TE5T 5ELSE5 m Overall effcency characterstcs for sx-stage compressor. FG. 4. Overall pressure characterstcs for sx-stage compressor.

13 0.9 KEY TO SYMBOLS. x r.a~. / ' ^'P~ o 8980 st>.m, Z A 75 0 ~p,m, /~, ~\. 0"8 o 6000 *:.p.m. _ v 50o~ *:,p.m, ~.p.m. z _~LF= DENOTES POSTON OF TEST PONT F~(]M.SUGE. J~/ '0 0"7 0"9 "e ~t~ x 4 % % P l- Z W J h tl. LL E) { El W :3 n trl ttl (L 0% 0"5 0"4 0"3 0'E J " 4 ' "t ~.5"rA~E 3,, s~ " L,/AP~e.fU ~= "70 ~P//a NOTE TML50~,DNATE x / / =o.ao -- E~E'S TO STA(~E,/ ///,~ \ ONLY. _SU~SEO, LJENT // e 5TAraE5 D,BPLAOED A5 / NDGATED ~0~ / CLATY /, ",:~ ' / 5TA~ % g <3 F- 7Z B o E t, l.u Q [J 0"8 (]'7 0"6 tl/ tq 0'5 bl. oz !!,', 15TA~E (, (].~ 0'0 0"~ FG. 6. / 4x ~ ~,...STA~( *5 6,7?/~puL-o.~o 0"3 0'4 0'5 0% % 0'8 FLOW COEFFCENT Va/u Stage characterstcs deduced from test on sx-stage compressor (seres n). FG. 7.,> > "l~j,..~^ 0'3 0' 0.5 0'6 0"7 O'B FLOW COEFFCENT V~./U Comparson of stage characterstcs deduced from tests on sx-stage compressor.

14 .90 5"0 ~'0 O~ 't.o v tt o ~'0 n ~" ~NO 5TAQ //~, / "~0 5 L, f ' 0 ~/ O~ 'C H to ~0 30 ~'0 -~ ' 0 O Y eo ~o,o so 6o 7o 8o Ac~ ~.Ow (Ls/sEe) 13 O~ 3"0 nt "- tan tu,.o : 3 mo.staqe, ; 4,41,. 8900?n o ~ / 0 o /?0 5 " SO0~ FO 0 O ~ A~ ~co~ O-~/~c),804.0 ' " "q '6000 ', $00. o eo &O " o. o ~[Z 3'0 uj E u1 'n 5 ~ 5"rAQE +5o~X// /~ ~!=-o /S? :,o~s o Q & ::h 5TA~E 'O /' )':ao~o o 7o 5 89@0 to ~ ~ '16000 soo= 0 0 ~C ~0 &O "~0-80 ~, =Low. (LS/s~c) FG. 8. Varaton of ncdence through sx-stage compressor. 12

15 3' 80 tu ~J W n 11] n ' 1,1 13- h 7o bl h_ hl rn 6e o ~0 30 4o so &o ~0~ECTED ~Ass ~Lo~ (~B/sEc) 3G 0 Fro ~o 30 4O 50 C0~ECTED MASS FLOW (LB/,E0) Overall effcency characterstcs for last four stages. ~0 FG. 9. Overall'pressure characterstcs for last four stages.

16 0'8 8"7 3~56 KEY TO 5Y~80L5 4~_.9700 r.p.m, e/~"r %' o 91eP- r:p.'m, fz e,,,jo ~ - a531 r.o,m. ]4.~x 7973 np,m, o 69(=7 ~p.m. 5~63 r.p,m, 7 L 9UFFX DENOTE5 P0StTr}N // "----3TAE. O'& CAACTESTC5 FOM FQ, & FO 5tX 3TAC~E COMPE~ESSO 7 -~ / %, 7-- % 0- <3 l-- Z bj tl h JJ ttl ~z t/q t3 td 0.5 0' 0"3 O'P. 0" NOTE T1415 ODNATE EFES TO STAGE.3 ONLY -SUBSEQLENT 5TACaES D5PLACED A5 NDCATED FO CLATY / 93 ~o / o% ¼",~._ TAQE 4.STA~E f" ~ \ - 5TAE AP~?. ={ O.F' 03 0'4 ~LOW 0'5 0% 0"7 0"8 COEFFCENT va/a FG. 1. Stage characterstcs deduced from test on last four stages. 'J4372 Wt.20/9036 K7 10/56 D&Co. 34/ PNTED 1N GEAT BTAN

17 . & M. No Publcatons of the Aeronautcal esearch Councl ANNUAL TECHNCAL EPOTS OF THE AEONAUTCAL ESEACH COUNCL (BOUND VOLUMES) 1939 Vol.. Aerodynam~ Genera], Performance, Arscrews, Engnes. SOS. (5s. 9d.) Vol.. Stablty and Control, Flutter and Vbraton, nstruments, Structures, Seaplanes, etc. 63 s. (64 s. 9d.) 194oAero and Hydrodynamcs, Aerofols, Arscrews, Engnes, Flutter, cng, Stablty and Control, Structures, and a mscellaneous secton. Sos. (5S. 9d.) 941 Aero and Hydrodynamcs, Aerofols, Arscrews, Engnes, Flutter, Stablty and Control, Structures. 63 s. (64 s. 9d.) 1942 Vol.. Aero and Hydrodynamcs, Aerofols, Arscrews, Engnes. 75 s. (76s. 9d.) Vol.. Nose, Parachutes, Stablty and Control, Structures, V!braton, Wnd Tunnels. 47 s. 6d. (49s. 3~.) 1943 Vol.. Aerodynamcs, Aerofols, Arscrews. Sos. (81s. 9d.) Vol.. Engnes, Ftutter, Materals ~, Parachutes, Performance, Stablty and Control, Structures. 9os. (92s. 6d.) 1944 Vol.. Aero and Hydrodynamcs, Aerofols, Arcraft, Arscrews, Controls. 84s. ' (86s. 3d.) Vol.. l~lutter and Vbraton, Materals, Mscellaneous, Navgaton, Parachutes, Performance, Plates and Panels, Stablty, Structures, Test Equpment, Wnd Tunnels. 84 s. (86s. 3d.) 1945 Vo].. Aero and Hydrodynamcs, Aerofols. 3OS. (32S. 6d.) Vol.. Arcraft, Arscrews, Controls. 3OS. (32S. 6d.) Vol.. Flutter and Vbraton, nstruments, Mscellaneous, Parachutes, Plates and Panels, Propulson. 3OS (132s. 3d.) Vol. V. Stablty, Structures, Wnd tunnels, Wnd Tunnel Technque. 3OS. (32s. 3d.) ANNUAL EPOTS OF THE AEONAUTCAL ESEACH COUNCL~ s. (2s. 2d.) 1938 S. 6d. (s. 8d.) s. (3 s. 3d.) NDEX TO ALL EPOTS AND MEMOANDA PUBLSHED N THE ANNUAL TECHNCAL EPOTS, AND SEPAATELY ~ ~ ~ ~- Aprl, 195o & M. No. 26oo. 2s. 6d. (2s. 8d.) AUTHO NDEX TO ALL EPOTS AND MEMOANDA OF THE AEONAUTCAL ESEACH COUNCL-- 9O9-January, , & M. No s. (5s. 6d.) NDEXES TO THE TECHNCAL EPOTS OF THE AEONAUTCAL ESEACH COUNCL-- December, June 30, July, June 30, July, June 30, July, December 31, January, June 3o, & M. No. 185o.. & M. No & M. No & M. No. 215o.. & M. No. 225o. xs. 3d. (s. 5d.) S. (s. 2d.) 1s. (s. 2d.) xs. 3,/. (s. 5d.) s.,3d. (s. sd.) PUBLSHED EPOTS AND MEMOANDA OF THE AEONAUTCAL ESEACH COUNCL-- Between Nos & M. No S. 9 d. (S. xxd.) Between Nos & M. No. 245o. 2s. (2s. 2d.) t3etween Nos & M. No s. 6d. (2s. 8d.) Between Nos & M. No. 265o., 2s. 6d. (~s. 8d.) Prces n brackas ~wlude postage HE MAJESTY'S STATONEY OFFCE York House, Kngsway, London W.C.2; 423 Oxford Street, London W.! ; 13a Castl~ Street, Ednburgh 2; 39 Kng Street, Manchester 2; 2 Edmund Streot, Brmngham 3; 109 St. Mary Stroot, Cardff; Tower Lane,'Brstol 1 ; 80 Chchester Street. Belfast, or through ~ny bookaellev S.O. Code No & M. No. 2985