|
 |
| UFDC Home | Search all Groups | World Studies | Federal Depository Libraries of Florida & the Caribbean | | Help |
|
|
|
| UFDC Home | Search all Groups | World Studies | Federal Depository Libraries of Florida & the Caribbean | | Help |
 Material Information
Subjects
Notes
Record Information
|
| Full Text |
|
AtA L-77 RB No. L5C30 NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS WAllTIME'li REPORT ORIGINALLY ISSUED April 1945 as Restricted Bulletin L5C30 EFFECTS OF COMPRESSIBILITY AND LARGE AIBLES YAW ON PRESSURE INDICATED BY A TOTAL-PRESSURE TUBE By Milton D. Humphreys Langley Memorial Aeronautical Laboratory Langley Field, Va. WASHINGTON NACA WARTIME REPORTS are reprints of papers originally issued to provide rapid distribution of advance research results to an authorized group requiring them for the war effort. They were pre- viously held under a security status but are now unclassified. Some of these reports were not tech- nically edited. All have been reproduced without change in order to expedite general distribution. DOCUMENTS DEPARTMENr L -77 7 Digitized by the Internet Archive in 2011 with funding from University of Florida, George A. Smathers Libraries with support from LYRASIS and the Sloan Foundation http://www.archive.org/details/effectsofcompres001a I T T. L 5 '.A T" -' ? .. "T.. -'T T r IneA Lon..e ed L5L50 le rc r t L'c-e O n12 of ^."'w : from.. g t r1 G tL e h AL' : -,:, v1rt:j1. At 1-C C .-a . L Ye s r tl r I; n r0 ?. o ie n t"t ..,:e 'o t.. c,'- i-t 31.f .r., .-1 i 1.'. t r,. 'ei t 1-an onI we re c.i a e ..ine r t.r T,. e rof c -ar:- ir .. .n'- t :-,n:el c { "..ch nr.., t .-, !rg,, i3 G ,:. r..' _" r Lan 1 c.o .-:,w f of w at les ran to Ts e result Z n ri L t3. s' at1 in r" w s d "s i c L.*'e inof t..or l- l n reassa.r re. i ,t frr' .- t h sn-e of r 3 rw this c r' e o eor Sof r 0 tC 1 n :. .- '.e At ilat l. cr -,.nt "' ,n h nhre 'rr n'., t.- ic'i -e -rhe utota-I a l .near t .,res v ie with o '" t n t t -.-! Fe ..r str ean An .;'t inc-.l of :,w as thereforane .'cor., ic e'' t: -:' et r m'-te. Thh e f' t-r.s -. t.oured L ad a Iotal rescue n : e r i on oac to1br.v- r-.,ss fr e r0.r : ,v. t h nl ovr f w r: tne-of-.w range T 1 T T.'- -' IC,:! from toaila 1le Two r -iton nof totle nres.s. e .tuberes- h tot-.-l-,,n..es ;re t',h"es '.a\ed wit?": "r, ..... .: t.:, i:l-A ..ilr str'ean s bt Led in thiso llrert huld tte nl of : [,c n An -L-.' t .;.. IoL1-n ','s3 r,-e.? fore h1: -n c,:.nc-. L ,,i to aet, r- rr. e rhe r.i -,,.i re 7. u.' red bv a Lota]- -res: 3ur e t':.e f', r 11acb n n p.Z;-.s f r:'," 0.5 tj C..q ov r tr.-z ni le-of--,kw r :ange from 1 to 1iCc 'Two b-,.'ri.. cf ',ta. ali- ,-esslle tu'.e ,e:' t s F d s r l-nd rl os : ,.,' flat -.ose The- In for:.i;.;ti,?i, .b~t'a:ier In t.his reTort should f-cilltate ,nal:/3-s cf flc.w- i rectc.n 2measur'2-:,L.nts 3 .nri otJL-r ac rod,'.iamic p ronrer ties. FACA RB 7o. L5C30 APPARATUS :. 0 TODS The tests were made in the Langley rectangular bhih-sneed tunnel, which is an induction-tyne tuimel having sc 4- by 1J-inch. test section. Atmosrheric air Is inruced to flow through the tunnel by an induction nozzle located downstream from the test section. yceot for a small loss of pressure result'in from the nrssage of air through the screens at the tunnel entrance, the total pressure at tle test section is approximately -qual to atmospheric pressure '.I's wind tunnel is basically similar to the '..A.C.A. hi -h-speed wind tunnel described in reference 1. The round-nose and the flat-nose total-pressure tubes used in this investigation were ie of brass tb-in- hav'.ig an outside dia*r.eter of 0.125 inch and walls 0.0254 inch thicli. 'he tubes were constructed in the form of an L with a h3ad 1 inch l:: at an angle of 900 to the suprort1-- handle (f:T. 1). The total-pressure tube was mounted in the center of the test section with the surporting spindle normal to the tunnel wall and passing out through a hole of 1 a rroxinately -inch diameter drilled in the wall. The head o! the tube could be rotat- about the spindle axis through the : "le-of-- "w r..- and could be locked In -.-n" desired position. T total pressure measured above absolute zero with air at rest H' pressure indicated b' total-oreseure 'oub free-stream Dach n,..:, r I.Ix 'uch number at nose of tube computed on asesm p- tionsathat flow is adiabatic and that :i' equals static pressure at nose of tube n fre :-stream static rrecsure NACA RB No. L5C30 q free-stream dynamic pressure [2-pV 2 p density, slugs oer cubic foot " velocity of mean free stream, feet ncr second angle of yaw of instrument head PREC ISIO 0 It is believed that practically all the errors to wiich the quantities measured in this investigation are subject are of an accidental nature. The variation in 'ach number in the test section narallel and normal to the tunnel axis is insignificant for these tests. Tunnel constriction effects should be negllgitile because of che small size of the total-nressure tube relative to the tunnel size. Air-flow misalinement and the error 10 in alinement of the total-oress;re tube are within it * The tree-stream static ,resaure and the error in total pressure as indicated by the total-pressure tubes wv re m.easu'.red by: visual observation of liquid-filled manome ters. Liquids of different densities were used in the manometers for various range of pressure dif- ferances to insure large rises of the liquid and thereby rmunimize the errors in readings. An indication of the magnitude of the accidental error involved in these data is given in figures 2(a) and 2(b), each of which shows the scatter for two tests with the total-nre3sure tube at an angle of yaw of 650. Check points are indi- cated by flagged symbols. The data presented have been correct-ed for t-he total-pressure loss resulting from the nass-el of the air through the screens at the tunnel entrance. The amount of this loss was determined by measurements -made in the test section and in the low-speed region ahead of the entrance cone and was checked by computa- tions of the pressure loss thro-ugh screens. RESULTS AND DISCUSSION The variation of total-pressure error, in terms of total pressure, with Mach number for the round-nose and MACA RB Pc-. L5C50 for the flat-nose tubes is shown in figures 2(a) and 2(b), respectively. At constant angles of yaw of 200 or -~-. ater, the total-oressure error incre-as.ed with increasing Mach number. The rate of change of the error wi'th '.ch number increased as the angle of :ow was increased from 200 to approximately 900, where the rate of c A,-- of the error was at a maximum. At angles of yaw from 900 to 1800, the slopes decreased with incr-asilng angle of yaw. The variation in ,he total-oressure error with .'ach number became increasingly irregular in the free-stream Sch number range from 0.7 to 0.8 for angles of s ,-- between 1100 and 1500 (figs. 2(a) and 2(b)). If the flow is assumed to be adiabatic and the pressure measured b{ the tube H' is assumed to correspond to t?he static pressure of the flow in the vicinity of the opening in the nose of the tube for these conditions, the local lMach number T can be computed. The value of H for a T.ch number of 1.0 would be 0472. H It can be seen that the irregularities in the curves P7 HI occur near a value of H of 0.472 and are possibly H due to the formation or movement of shock. The variation of total-nressure error, in terms of free-stream dynamic pressure, with .:h number is shown in figure 3. For angles of yaw greater th.vi 200, the total-pressure error had a small, nonlinear variation with Mach number. This variation became irregular at the higher angles of yaw and the most pronounced direc- tional changes occurred near 90. No error was incurred in the measurement of total pressure by either the round- nose or the flat-nose tube over the Mach number range extending from 0.5 to 0.9 for an angle-of-yaw range from 00 to 100 (figs. 2 and 3). The variation of the total-oressure error, in terms of total pressure, with angle of -'ai.v is presented in figure 4 for several :`."ch numbers. The curves were obtained by cross-plotting the data presented in fig- ure 2. The results show that the total-pressure error increased with increasing the angle of :-w from 20 to approximately 670 and then decree,--d as the angle of yaw was increased to 1300. At an an,-le of yaw of 180, the nrssure measured at the nose of each total-or.ssure tube was arppro:-irrately 'TACA RB ro. L5C30 5 th-. sa,e for equal FI.'ach num,':ra and .'s be low free- str. n.i static pressure PC, a..t all sCe ',.i3. T'-,e relation \ .'r r p, , '"or tither tube at s-n Incli n'-t icon of 1-00 to the aiir stream is correct within 12 r.-rc.-nt of H-H ov-r H th": 2n nu,-'lD':r rc!e svsti -at d. Th'.s -gr e nment '-.3s cnt 3 a possible r-et..: of dr .et 'r':in.in 3t-.ttic pres- s'.'re e ns cf a s Zfl in. L .. "L.-At t.,t ..i bL.e nuz.fs l in :.::3 "inst 1 lat.s L s. T., :ar. tc ion ',n t t.,l---r,.: s r--- .r.' m", ii terms 0o ti s. .-.c '1 ;; :, 2 "- --'.. .* L.- 9 1 T'i .o i'f -c. l of "ar "'or c,'oist.az. F.'. -. nu'.]b-: 3 'j s- .n in '"i ureC 5, a cro' 'lot of tY. ta.. in '-1 ure ..'. e eas the flat- no's-. t uoe had a nv-.l -1. .1, r- v -i--I tlinn of c ctal-r.res.- 're e c.'r r d ::. :..le a ;:a v '.- r' :i. ,l' r r-j ,e frci 50'' o L f. 7 cr ,3 ,t tA' n.j :- r.'.e .':', -.u .-rol:, tu-I'.e bar' t sc c .n -... '. Lat c', t\ tha; r A- nc' i tuc .0"I D. uj si 1-- fos'r i;se ". -" Lesi'. of ti.'? Y- .. e''-*t 'ne ; ead a Cin "c n.'.J-n so ti.tLes 1 L an inel,.1..-d =n.le o.f 12. c l .. 'ine r. r v' ari ai on in cal ibration f2t::or a0. .il:. r u' a' r -t '. Ln order to -ive n. in i-. .t in of nos. -'i e af' l of maTinressi'il ity on ci-.. cal briatc.n f'c tor of a ;a he-ad, the slo -es of th:- curves of .f;l ure 5(1) L-.re shIown in r"igure 6 ",r angles of :'-i' b.etveen C0 and 0 T i-'L curve in,.'icates a ';iial effect of ccor:pre- sibility on the c a L ration of a vn'J head havin rom-n-:cose tubes if bhe :-aw h.? a supr rt is as 'urr-.d to iave nr el hl i infl'u nee. Tests made to deter-ina the ef'feLts of cor,,pre.3cibiLity an-' ai-.Tle of :'a& on th, --ressure m-T surged b" A rou id- nose anr.- a flat-nose total-ure..sure tub'.e ; ndiated that: 1. Total-opr-ssur: t.es. of the t.-n tested' in this invest iLation would give tru9 total prc.ssurc for anrlgs of yaw of 0 to 100 for .M.ach numbers from 0.5 to 0.0. "T.CA RB No. L5C50 2. At constant 1Jach numbers, the round-nose tube had a linear variation of total-pressure error aith -r-le of '-aw at ,i.rles ran nog ",-:;. 500 to 700. 'T' flat-nose tube had a nonlinear variation of the total- ni-ess-l.re error with angle of yay, in ths range. The roiund-nose tl'bes set at an included angle of 1200 should therefore be desirable for use as co -.,--=!ts of a Y-tyro yaw he*. .- s yaw head should give a linear variation in calibration factor over an angular range of 100. .. .n-- i.enorial Aeronautical Laboratory Ilational Advisorv Comnittee for Aeronautics '1: i d, Va. 1. Stack, John: The ?:.A.C.A. High-3S--':i--ind Tr'L2el and Tests of Six Proneller '-.ctions. NACA Ren. "D. 463, 19Q33. NACA RB No. L5C30 Spindle - Brass tubin O/ZS'o "OOZS, Enlarged view (a) Round nose. Spindle Enlaryed view of (6) Flat nose. NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS. Figure / .- 7Tofe/--pressure tubes. Sose of /7ose nose Fig. 1 Fig. 2a NACA RB No. L5C30 f ooo "I , ,; .-- 1 -- A/. i i q) Z31 ,-__ -- NACA RB No. L5C30 Fig. 2b O OS r Ln G o 0 ---,,- '- 1'' S0 __.- _- zz - ,-- oa ns d-i040- '77~f NACA RB No. L5C30 -I -i---- I-.o , ^^ftH-11t ,14-14 cqn-ssiud-ilo-_L 140 kk 0'c 0 .0 too Vg " Fig. 3a '14: lz NACA RB No. L5C30 Fig. 3b ~ a oo J n i o o LO N q___ ko___ ___ Qr ) > 10 Ii W-- H9 71 . n- f NACA RB No. L5C30 a9 ZZi ,_ _.,__, ,_ .. ! S -I 0 .7- M I I- _b 4Z :,- q" - i-_ .___ -7/ --- -- ,9 -- 0 l /i .' / / /2 % -<0 & = V A A h-f -?,--l-,8" J * -~~jai .^- l- .9.jns,?,j -1v_ q i_ _^_ T^ __ ___ 0 __'^A^ ^ I __ 1 ____ __ _I ____ ^_^_._ _' -- ---- V 0 Io Io I4 I\ I o ,H- Fig. 4a NACA RB No. L5C30C Fig. 4b Kl I N L A I N K '. v O -- 2 '____ __i__ __ __ z- u.* z- I-0I' I-'. I I4_jZ - -- Ii_-- __- /1 / / / O .--H-H /' / --- ,- ,- ^ ^- ! - --- ..... ,.... .... \ - ,,"\'1 ? 0. t. ',o IT. ^ c --. Q H-- ". ojlJ ajnS~e.,/f-Io/_ ,H-H NACA RB No. L5C30 I 1-I / zz: I i0 '\ ,// 0 Q < oo oo oo o Q) so o 6i ^ ^S 0oS ^ ) Q^ (0 o ^U -o^ einssud- /IlopJ_ Fig. 5a ,77^ '/-O/A NACA RB No. L5C30 0 N 'JoJ~I~9 ~Jn&&aJd-it24oJ M z ^2 -- -o oO Z Of-'- ^ 0 LI 0 00 -11- o "^ v --o s ' Fig. 5b NACA RB No. L5C30 0 0 2- v . S>- .V o. -------------------- ___ __ __F Fig. 6 UNIVERSITY OF FLORIDA 3 1262 08105 0097 ; .A ;'-'SITY OF FLORIDA "'N. -,NTS DEPARTMENT' ..i. N SCIENCE LIBRARY SV-i. FL. 0. 11"011 ,ci[ -,ViLLE, FL "211 -70' LSA ,1 |