NASA. Comparison of Predicted and Experimental External Heat Transfer Around a Film Cooled Cylinder in Crossflow. NASA Technical Memorandum 83017

Transcription

1 NASA Technical Memrandum Cmparisn f Predicted and Experimental External Heat Transfer Arund a Film Cled Cylinder in Crssflw Francis S. Stepka and Raymnd E. Gaugler Lewis Research Center Cleveland, hi Prepared fr the Twenty-eighth Annual Internatinal Gas Turbine Cnference spnsred by the American Scietyuf "Mechanical Engineers Phenix, Arizna, March 27-31, 1983 NASA

2 CMPARISN F PREDICTED AND EXPERIMENTAL EXTERNAL HEAT TRANSFER ARUND A FILM CLED CYLINDER IN CRSSFLW ABSTRACT Francis S. Stepka* and Raymnd E. Gaugler* Natinal Aernautics and Space Administratin Lewis Research Center Cleveland, hi Calculatins were made f the film cling prvided by rws f hles arund the circumference f a cylinder in crssflw and the results were cmpared t experimental data btained frm a NASA grant t Purdue University. The calculatins and experimental data were fr cnditins that simulate mst f thse that are typical f air cled turbine vane leading edges. Injectin was frm single and multiple rws f hles lcated at different angular lcatins frm the stagnatin line. The hles in the rws were angled nrmal t the flw directin and at a 25 degree angle t the cylinder wall. The calculatins and experimental data were fr several cnstant values f blwing ratis fr all rws and fr different blwing ratis fr each rw, representing a simulatin f a cmmn clant plenum supply t multiple rws f hles. The calculatins were made using a finite difference bundary layer cde, STAN5, develped under NASA cntract with Stanfrd University and mdified at the NASA Lewis Research Center. Cntrary t initial expectatins that injectin wuld trip the bundary layer flw int the turbulent regime, the results indicated that the high free stream acceleratin apparently kept the flw laminar fr hles in the first 45 degrees past stagnatin. The trend in Stantn number reductin due t clant injectin was predicted with generally gd agreement at the lwer blwing rates, but fr multiple rws f hles, agreement was pr beynd the first rw. INTRDUCTIN The durability f gas turbine vanes and blades is t a large extent dependent n the ability t effectively cl the leading and trailing edges. In essentially all advanced large aircraft engines, the leading edges are cled by a film f air ejected frm rws f hles. This cling air first picks up heat inside the airfil and in its passage thrugh the film injectin hles. Externally it prvides a cl layer f gas clse t the metal surface. It is this external cling effect that is addressed in this wrk. *Member, ASME. The current film cling hle gemetries and arrays at the leading edges are based n iteratins f empirically btained heat transfer and cling air flw data. Much f this infrmatin is prprietary t the engine manufacturers and is airfil gemetry and engine specific. Much published experimental data, hwever, is available n film cled flat surfaces and t a lesser extent n film cled curved surfaces r cylinders in crssflw. A gd bibligraphy f infrmatin in this area is presented by Luckey and L'Ecuyer (1). Reference 1 als presents recent heat transfer data fr a variety f single and multiple rw arrays f film cling hles in a cylinder in crssflw. N analytical methd is knwn t be currently used t predict the external heat transfer n filmcled leading edges. It was, therefre, the purpse f the study reprted herein t evaluate the use f a cmputatinal bundary layer cde t predict the external heat transfer prvided by the film ejected frm rws f hles in a cylinder in crssflw simulating a turbine vane leading edge. Use was made f a versin f the tw dimensinal, finite-difference bundary layer cde STAN5 (ref. 2) which was mdified t include the effect f clant injectin and surface curvature (refs. 3 t 5). Predictins were cmpared t experimental data btained frm reference 1. The predicted and experimental data were fr parameters that simulate mst f thse that are typical f air-cled turbine vane leading edges. The leading edge Reynlds number (based n cylinder diameter) was 9.0x10, the gast-wall temperature rati was 1.7, and the clant exit temperature was equal t the wall temperature. Injectin f the clant was frm single and multiple rws (2 t 5) f hles lcated at different angular lcatins (5 t 76.6 degrees) frm the stagnatin line. The axes f the hles were in a plane nrmal t the flw directin and angled 25 degrees with respect t the cylinder axis. The calculatins and experimental data were fr tw different blwing schemes. In ne, the blwing rate was the same fr each rw, and in the ther, the clant supply pressure was held fixed, simulating a cmmn clant plenum supply t multiple rws f hles. The predicted and experimental data are presented in terms f a reductin in Stantn number with cled film injectin cmpared t Stantn number withut clant injectin. CNDITINS AND METHD F ANALYSIS Cnditins The cnditins f the analysis cnducted herein were thse f the experiment cnducted n a film cled cylinder in crssflw at Purdue University under cntract t NASA (ref. 1). The parameters f the analysis and experiments were such as t simulate mst f thse that are typical f air-cled turbine vane leading edges. The leading edge Reynlds number (based n cylinder diameter) was 9.0xl0 4, the gast-wall temperature rati was 1.7, and the clant exit temperature frm the cylinder was equal t the wall temperature. The Mach number f the gas stream was.03 which is lw cmpared t abut.1 t.2 fr typical turbine vanes. Hwever, studies (refs. 6 and 7) have shwn n significant effect f Mach number n heat transfer at lw Mach numbers. The turbulence intensity f the gas stream fr the analysis and experiment was abut 4 percent. This is, hwever, lw cmpared t abut 7 t 20 percent expected in engines. The analysis was applied t the 15 cm diameter cylinder in the experiment which had clant

3 ejectin frm single and multiple rws f hles lcated at different angular lcatins frm the stagnatin line. The axes f the hles were nrmal t the gas stream and at a 25 degree angle with the cylinder wall. Figure 1 (adapted frm ref. 1) and the inset schematically illustrates the film cling hles in the cylinder and ther features such as cylinder cnstructin and the lcatins f heat flux gages. The temperature f the cpper uter wall f the test cylinder was kept cnstant at 294 K by water-cled inner passages shwn in the figure and described in detail in reference 1. The mainstream temperature fr the analysis and experiment was cnstant at 500 K and the mainstream velcity was 14.3 m/sec. The rws f film cling hles in the cylinder were lcated at angles f 5, 22.9, 40.8, 58.7, and 76.6 degrees frm the stagnatin line. The specific cnfiguratins f the film-cled cylinder analyzed are summarized in Table I and include the fllwing: single rws at either 5, 22.9 r 40.8 degrees at cnstant blwing ratis thrugh the hles, and 2-, 3-, and 5-rw cnfiguratins at either a cnditin f cnstant blwing rati thrugh all hles r fr a cnditin f a cnstant clant plenum supply t all the rws. The 2-rw cnfiguratins had rws lcated at angles f 22.9 and 58.7 degrees frm the stagnatin line, the 3-rw cnfiguratin had rws at 5, 40.8, and 76.6 degrees, and the 5-rw cnfiguratin had rws at 5, 22.9, 40.8, 58.7, and 76.6 degrees. The spanwise hle spacing t hle diameter ratis, S/d, were either 5 r 10 fr the single rws. The 2- and 3- rw cnfiguratins had an S/d rati.f 10 and a circumferential spacing t hle diameter, P/d, f 10. The 5-rw cnfiguratin had S/d = P/d = 5. Figure 2, taken frm reference 1, shws schematically an unwrapped view f the cylinder and shws lcatins f the hle rws and sme f the instrumentatin that were used t btain the lcal and spanwise averaged Stantn numbers dwnstream f a rw f hles. Methd f Analysis A mdified versin f the STAN5 bundary layer cde was used t calculate Stantn number distributins fr the experimental cnditins. The mdificatins t STAN5 included the full-cverage film cling mdel described by Crawfrd, et. al. (3) with sme minr changes, and the mdificatins described by Gaugler (4). Luckey and L'Ecuyer (1) reprted their data as the nrmalized Stantn number reductin as a functin f lcatin, SNR, defined as the difference between nn-film cled and film cled Stantn numbers divided by the nn-film cled Stantn number. Thus, in rder t directly cmpare the calculatins with the data, STAN5 was run first fr the case f n film cling, then re-run with film cling cnsidered, and the nrmalized Stantn number reductin calculated. The mdificatin t the STAN5 film cling mdel allwed the prgram t cntinue running in the event that sme f the injected clant penetrated thrugh the bundary layer. The riginal mdel described in reference 3 terminated prgram executin in that case. Fr the cases studied here, the bundary layer was quite thin at the injectin lcatins and significant prtins f the clant penetrated thrugh t the free stream. In reference 4 it was recmmended that the bundary layer be frced t transitin t turbulent flw at the first film cling lcatin. Hwever, fr the data in this study, with a highly accelerated free stream, transitin might be suppressed. T check this, STAN5 was run bth with and withut the frced transitin t turbulent flw. The use f the full cverage film cling mdel f reference 3 fr the case f film cling arund the leading edge f a cylinder represents a significant departure frm the cnditins fr which the mdel was riginally develped; i.e., flat plate, zer pressure gradient, many rws f hles. Hwever, it is the nly mdel available, and this data prvides a test f the assumed physics f the injectin and entrainment prcess. It is expected that the largest errr in, the results will ccur in the vicinity f the injectin hles, since the mdel is strictly tw-dimensinal. Hwever, dwnstream f the injectin lcatin, the tw dimensinal mdel might be sufficient t mdel the spanwise averaged results. RESULTS AND DISCUSSIN Single Rws f Hles The initial calculatins fr injectin frm single rws f hles at 5 and 22.9 degrees frm the stagnatin line shwed that in the experiment the injected flw apparently did nt trigger the bundary layer int the turbulent regime dwnstream f the rws. This is cncluded because the assumptin f laminar flw in the calculatins gave the best agreement with the experimental heat transfer data. The calculated spanwise averaged nrmalized Stantn number reductins, SNR, arund the cylinder fr injectin at 5 and 22.9 degrees cmpared with that experimentally btained (in reference 1) are shwn in figures 3 and 4 respectively. Figure 3 shws that generally gd agreement is btained ver the range f blwing ratis, M, frm 01 t 1.02 fr the hle spacing t diameter rati, S/d, f 5 and similarly gd agreement fr a rw f hles with S/d = 10 and M = 1.0. The agreement at M=1 was better than fr the higher values f M where the predicted values f SNR were generally lwer than the experimental data. Cmparisn between predictin and experimental data fr injectin frm a rw at 22.9 degrees, in figure 4, als shws generally gd agreement using the assumptin f laminar flw in the calculatin. Figure 4(c) shws the large discrepancy that wuld ccur if the calculatin assumed turbulent flw after injectin. It shuld be nted that at the higher blwing ratis, M, f 0.77 and 1.00 fr bth the hle spacing t diameter ratis f 5 and 10 respectively, the predicted SNR is initially lwer than measured fr nly the first data pint, then becmes higher further dwnstream. Cmparisn f predicted and experimental data fr injectin at 40.8 degrees in figure 5 shws that except fr the data nearest the hles the measured SNR is significantly lwer than predicted using the assumptin f laminar flw. The slpe f the majrity f the data hwever is better represented by the laminar rather than the turbulent curves. The figure shws that as the blwing rati M increases frm.25 t.77 the experimental SNR becmes prgressively lwer than that predicted. It might als be nted that fr injectin frm a single rw f hles at this angular lcatin, experimental SNR, except near injectin, is negative and becmes mre negative with increase in blwing rati, indicating a detrimental effect f clant injectin n external heat transfer. It might be interesting at this pint t examine the effects f the injectin entrainment-diffusin mdels used and their cntributin t the data trends, lking fr insights int ptential changes that might be made t imprve agreement with experimental data. Because f the thin bundary layer at the 5 degrees injectin lcatin, the calculated ut-

4 put frm the STAN5 cde shwed that even at a blwing rati, M, f 1 the majrity f the clant penetrates thrugh the bundary layer. nly 16.2 percent f the clant remained in the bundary layer. As the blwing rati increased t 1.02 the percent f clant in the bundary layer decreased t 5.2 percent. Reviewing the discrepancy between predicted and experimental data in figure 3(b) indicates that a mdel which retained mre clant in the bundary layer wuld imprve the agreement. At the 22.9 degrees injectin lcatin a larger percentage f clant is retained in the bundary layer. At M= the percentage f clant retained was 23.3 percent fr hle spacing t diameter rati S/d=5 (figure 4(a)) and 45 percent fr an S/d=10 (figure 4(c)). As M increased t.77 and 1.0 fr the respective S/d values the percentage f clant left in the bundary layer decreased t 18.1 percent and 13.2 percent respectively (figures 4(b) and 4(d)). At this lcatin, a mdel which retained less clant in the bundary layer with increasing M wuld make experimental and predicted SNR shw greater agreement. This is ppsite frm the cnclusin drawn frm figure 3. This wuld indicate that a mre cmplex mdel is required t imprve the agreement. Multiple Rws f Hles, Cnstant Blwing Rate Figures 6, 7, and 8 shw the cmparisn between data and calculatin fr the 2-, 3-, and 5-rw cases, with each rw having the same blwing rate. Agreement is generally gd fr the first rw in each case, as wuld be expected based n the single rw results already presented. Hwever, the agreement deterirates rapidly when additinal rws f hles are cnsidered. Still, the basic trends in the data are preserved in the calculatins, i.e. a sharp rise just dwnstream f a hle rw, fllwed by a rapid drp ff which shws a tendency t level ff. Multiple Rws f Hles, Plenum Supply Figure 9 shws the cmparisn f data and calculatins fr three cases where the clant supply t each rw had the same pressure, such as wuld ccur if the hles were fed frm a cmmn plenum. This results in the blwing rati, M, increasing with distance frm the stagnatin line due t the drp in freestream static pressure arund the cylinder. The same pattern f behavir is bserved in the cmparisn, with the first rw cmparing fairly well and subsequent rws shwing pr agreement. Discussin f Analysis There were a number f cncerns in applying the mdified STAN5 bundary layer prgram (which included effects f clant injectin and surface curvature) t the film cled cylinder data. Perhaps the greatest cncern was applicability f the mdels in the subrutine CL f the STAN5 prgram which accunted fr the injectin and clant entrainment prcess and fr the effects f injectin n the turbulent transprt terms. The reasn fr this was that the respective empirically derived parameters that accunted fr these effects, DELMR, t cntrl the jet entrainment, and ALAM, t cntrl the turbulent mixing length augmentatin, were btained fr different ejectin gemetry than n the cylinder and they were btained frm experiments n a flat plate. The hle gemetries fr which the parameters were btained were rws f hles with their axes nrmal t the mainstream and the wall, rws f hles with their axes slanted 30 degrees t the wall, in a plane nrmal t the wall and parallel t the mainstream, and rws f hles with their axes angled 45 degrees with the mainstream and 30 degrees with the wall. This latter injectin is generally referred t as cmpund angled injectin. The empirically btained trend f the parameters DELMR and ALAM with blwing rati fr the 3 injectin gemetries shwed different slpes and levels fr the DELMR parameter and same slpe but different levels fr the ALAM parameter. Fr the purpse f this analysis the cmpund angled injectin cnfiguratin was assumed t be the clsest t the injectin cnfiguratin n the cylinder analyzed herein and all the calculatins were made based n DELMR and ALAM parameters derived fr the cmpund angled injectin. Anther cncern was n the applicability f transitin mdels. Initially it was thught that the injectin might trip the bundary layer int turbulent flw. S tw mdels were used, ne in which flw was assumed t transitin int turbulent flw after a rw f hles and the ther mdel which triggers the flw turbulent after the mmentum thickness Reynlds number exceeds 200. Clearly mre wrk is required in rder t better understand the effect f film cling n the transitin f a bundary layer in a highly curved and accelerating regin. SUMMARY AND CNCLUSINS Cntrary t initial expectatins that clant injectin frm the rws f hles wuld trip the average bundary layer flw int the turbulent range, cmparisns f calculated versus experimental results indicated that the high flw acceleratin aft f rws f hles at 22.9 degrees frm stagnatin and in sme cases t 40.8 degrees frm stagnatin apparently kept the flw laminar. Fr injectin frm single rws f hles, predicted and experimental spanwise averaged nrmalized Stantn number reductins (difference between nnfilm cled and film cled Stantn numbers divided by the nn-film cled Stantn number) generally shwed gd agreement dwnstream f injectin frm single rws f hles at 5 and 22.9 degrees frm stagnatin. Cmparisns, except fr trends, were pr fr injectin at 40.8 and 58.7 degrees frm stagnatin. Fr injectin frm multiple rws f hles, generally gd agreement was btained between predictin and experiment fr the first rw f hles. Pr agreement was btained at succeeding dwnstream rws. The predictins generally fllwed the trend f the experimental data, particularly agreeing with ften large negative values f Stantn number reductins (indicating increased rather than decreased heat transfer by clant injectin). Fr cases where the agreement is pr, the predicted curves f Stantn number reductin generally shwed lwer reductins than the experimental data. Bth the predicted and experimental data shwed that fr simulated cnditins f a plenum supply t a 'shwerhead 1 film cled turbine vane leading edge, the Stantn number reductins were small r negative dwnstream f the film injectin. This indicated little benefit r a detrimental effect due t film injectin. f curse, there wuld still be the cling prvided by the flw f clant internal t the vane, but this study nly addressed the uter surface heat transfer due t the clant film. REFERENCES 1. Luckey, D. W., and L'Ecuyer, M. R., "Stagnatin Regin Gas Film ClingSpanwise Angled Injectin frm Multiple Rws f Hles," NASA CR , Apr

5 Crawfrd, M. E., and Kays, W. M., "STAN5A Prgram fr Numerical Cmputatin f Tw-Dimensinal Internal and External Bundary Layer Flws," NASA CR-2742, Dec Crawfrd, M. E., Kays, W. M., and Mffat, R. J., "Full-Cverage Film Cling n Flat Isthermal Surfaces: A Summary Reprt n Data and Predictins," NASA CR-3219, Jan Gaugler, R. E., "Sme Mdificatins t, and peratinal Experiences with, the Tw-Dimensinal, Finite-Difference Bundary Layer Cde, STAN5," ASME Paper 81-6T-89, Mar Adams, E. W., and Jhnstn, J. P., "A Mixing Length Mdel fr the Predictin f Cnvex Curvature Effects n Turbulent Bundary Layers." ASME Paper prpsed fr presentatin at the 28th Internatinal Gas Turbine Cnference, Phenix, Arizna, Mar , Liess, C., "Experimental Investigatin f Film Cling with Ejectin frm a Rw f Hles fr the Applicatin t Gas Turbine Blades," ASME Paper 74-GT-5, Apr., Papell, S. S., and Trut, A. M., "Experimental Investigatin f Air Film Cling Applied t an Adiabatic Wall by Means f an Axially Discharging Slt." NASA TN D-9, Aug., TABLE I--CNDITINS ANALYZED Single Rw Injectin, Unifrm Blwing Rw lcatin, angle frm stagnatin, degrees Hle spacing-t-diameter rati, S/d , Blwing Rati, M [ Multiple Rw Injectin, Unifrm Blwing Hle spacing-t-diameter rati, S/d = 10 2 rws 3 rws 5 rws Rw lcatins, angle frm stagnatin, degrees 22.9 & , 40.8, & , 22.9, 40.8,58,7&76.6 Blwing Rati, M Multiple Rw Injectin, Blwing Distributin Simulating Plenum-t-Mainstream Pressure Rati f 1.01; S/d = 5 2 rws 1 Rw lcatins, 22.9 & 58.7 I! 3 rws 5 rws angle frm stagnatin, degrees 5, 40.8 & 76.6 II 5, 22.9, 40.8, 58.7 & 76.6 Blwing Ratis, M, Thrugh Respective Rws 1.08, ,.95, , 1.08,.95,.92,.92

6 MAINSTREAM FLW CLING AIR FLW CLANT FLW 25 HEAT FLUX GAGE MAINSTREAM FLW STAGNATIN LINE RW N. 1 SIDE VIEW HLE RIENTATIN DRP-IN SEGMENT WATER CLANT CHANNEL ENTRANCE WALL CLANT CHANNEL DRP-IN SEGMENT BERYLLIUM CPPER CYLINDER STAINLESS STEEL CYLINDER SLID-LINED HLES SHW A TYPICAL TEST CNFIGURATIN DASHED-HLES SHW THER TEST CNFIGURATINS 0 \-FILM CLANT HLE (4.76mm DIA.) p = 25 TEST CYLINDER (0.15 M DIA., 01 M LENGTH) Figure 1. - Schematic f the test cylinder. HEAT FLUX GAUGE THERMCUPLE PRESSURE TAP 1 a D--- I G I LI- C UJ UJ ; UJ --ttl^lt^...^ PI (H - D-Q D Q&-----Q-a Q Figure 2. - Schematic f the instrumentatin in the film cling regin.

7 DATA, REF. 1 PREDICTED C L. LLJ Di i -.1 \ -.2 C - "A ~V^. 1 ~~ ^ INJECTIN LCATIN f Ma) 1 1 ^00 J 0 t l(b) 1.6 ; " ' 2 0 LU.. UJ K -\ VP -.2 C. - t 1(0 1 ( ANGLE FRM STAGNATIN LINE (a) Blwing rati, M,=. 51, hle spacing/diameter, S/d = 5. (b) Blwing rati, M = 1.02, S/d = 5. (c) Blwing rati, M = 1.00, S/d = 10. Figure 3. - Stantn number reductin fr injectin frm a single rw f hles at 5 degrees frm stagnatin.

8 .6.3 DATA, REF. 1 PREDICTED «cn REDUCTIN, LU C s z < 1/1? Kn - ^.,, <">.6 1 INJECTIN LCATIN <a> 1 t ^X^^ - ^^^- 0 0 ~,, /-LAMINAR FLW \ ^x> -- \ \ ~~ \ -TURBULENT FLW V \ Q (d) 1 It (c) It \ () ANGLE FRM STAGNATIN LINE, deg (a)m = 1, S/d-5. (c)m-, S/d-10L (b)m-.77, S/d-5. (d)m- 1.0, S/d-ltt Figure 4. - Stantn number reductin fr injectin frm a single rw f hles at 22.9 degrees frm stagnatin, fr different blwing rates, M, and hle spacing-t-diameter ratis, S/d.

9 DATA, REF. 1.6 rkcuiicu, LMIVHIMMK 1 ~ PREDICTED, TURBULENT i - 4 t z" CD LLJ «-1 LLJ C ^ 1 " i - ~~ V^^^ - ^-^ 1 1 I \ \ \ \\ u ~~ \ INJECTIN \ LCATIN \ (a) tl 1 \l 1 6 _ S>^^^ \ \ \ \ \ <b> 1 1 f 1 1 \ 1 1 Q; z' -3-2 a» - 1 LLJ DQ s n = U> 1 '.I SE? -2 n ' -4. ^> I \ \ 0 (D v^ \ ~~ \ (c) If l\ ANGLE FRM STAGNATIN LINE (a) Blwing rati, M, =. 25, hle spacing/diameter, S/d = 5. (b) Blwing rati, M = 1, S/d = 5. (c) Blwing rati, M =. 77, S/d = 5. Figure 5. - Stantn number reductin fr injectin frm a single rw f hles at 40.8 degrees frm stagnatin.

10 .6 a: C z'.3 i C-> :. t LtJ Qi. Qi I LJU! C s n i c -2 ' -4 0 DATA, RE. 1 PREDICTED _ 0 ^P ^^. _- ^--^_ ^~-J \ INJECTIN \ ~~ LCATINS \ (a) N ~~~ f^-^ _ ^?T~~ ~»-^ ^ 1 ^~~~~~~~~ j 0 IW 1 1 tl 1.6 QX 4 1 C z'.3 t!. C a LLJ Di I C 5 n ^ "Z. i _ -.1 K. ^ g_ n 1 9 C -. t (c) tl ANGLE FRM STAGNATIN LINE (a) Blwing rati, M, =. 50, hle spacing/diameter, S/d= 10. (b) Blwing rati, M =.75, S/d = 10. (c) Blwing rati, M = 1.00, S/d = 10. Figure 6. - Stantn number reductin fr injectin frm 2 rws f hles, at 22.9 and Unifrm blwing rati, M, thru bth rws.

11 .3.2 DATA, REF. 1 PREDICTED LLJ C ae. ZD z f I (a) INJECTIN LCATINS I If I I.6 1/1.3 g.2 LU.1 LU C. I,1 I f Kc) ANGLE FRM STAGNATIN LINE (a) Blwing rati, M=0, hle spacing/diameter,s/d = 10. (b) Blwing rati, M =.75, S/d = 10. (c) Blwing rati, M = 1.25, S/d = 10. Figure 7. - Stantn number reductin fr injectin frm 3 rws f hles, unifrm blwing rati, M, thru hles.

12 01 LU C DATA, REF. 1 PREDICTED f H»» If Di LU Qi : LU C S z. < ANGLE FRM STAGNATIN LINE (a) Blwing rati, M,=0, hle spacing/diameter,s/d = 5. (b) Blwing rati, M-.75, S/d = 5. (c) Blwing rati, M = 1.26, S/d = 5. Figure 8. - Stantn number reductin fr injectin frm 5 rws f hles, unifrm blwing. Transitin t turbulent flw at third rw. 80

13 .6 DATA, REF. 1 PREDICTED.2 eg LLJ C.1 0.,1 <c h- ) c.<: - (a) INJECTIN LCATINS T I I I *l.6 eg C.3.2 eg UJ C.1 0. I ' f (0 I ANGLE FRM STAGNATIN LINE (a) Tw rws f hles, S/d -10. (b) Three rws f hles, S/d = 10. (c) Five rws f hles, S/d = 5. IN Clant plenum supply- Figure 9. - Stantn number reductin fr injectin frm multiple rws f hles. t-mainstream pressure rati = 1.01.

14 1 4 Reprt N NASA TM Title and Subtitle 2. Gvernment Accessin N CMPARISN F PREDICTED AND EXPERIMENTAL EXTERNAL HEAT TRANSFER ARUND A FILM CLED CYLINDER IN CRSSFLW 7. Authr(s) Francis S. Stepka and Raymnd E. Gaugler 9. Perfrming rganizatin Name and Address Natinal Aernautics and Space Administratin Lewis Research Center Cleveland, hi Spnsring Agency Name and Address Natinal Aernautics and Space Administratin Washingtn, D. C Recipient's Catalg N 5 Reprt Date 6 Perfrming rganizatin Cde Perfrming rganizatin Reprt N E Wrk Unit N 1 1 Cntract r Grant N 13. Type f Reprt and Perid Cvered Technical Memrandum 14 Spnsring Agency Cde 15 Supplementary Ntes Prepared fr the Twenty -eighth Annual Internatinal Gas Turbine Cnference spnsred by the American Sciety f Mechanical Engineers, Phenix, Arizna, March 27-31, Abstract Calculatins were made f the film cling prvided by rws f hles arund the circumference f a cylinder in crssflw and the results were cmpared t experimental data btained frm a NASA grant t Purdue University. The calculatins and experimental data were fr cnditins that simulate mst f thse that are typical f air cled turbine vane leading edges. Injectin was frm a single and multiple rws f hles lcated at different angular lcatins frm the stagnatin line. The hles in the rws were angled nrmal t the flw directin and at a 25 degree angle t the cylinder wall. The calculatins and experimental data were fr several cnstant values f blwing ratis fr all rws and fr different blwing ratis fr each rw, representing a simulatin f a cmmn clant plenum supply t multiple rws f hles. The calculatins were made using a finite difference bundary layer cde, STAN5, develped under NASA cntract with Stanfrd University and mdified at the NASA Lewis Research Center. Cntrary t initial expectatins that injectin wuld trip the bundary layer flw int the turbulent regime, the results indicated that the high free stream acceleratin apparently kept the flw laminar fr hles in the first 45 degrees past stagnatin. The trend in Stantn number reductin due t clant injectin was predicted with generally gd agreement at the lwer blwing rates, but fr multiple rws f hles, agreement was pr beynd the first rw. 17 Key Wrds (Suggested by Authr(sl) Film cling Cylinder crssflw Heat transfer 18 Distributin Statement Unclassified - unlimited STAR Categry Security Classif (f this reprt) Unclassified 20 Security Classif (f this page) Unclassified 21 N f Pages 22 Price" * Fr sale by the Natinal Technical Infrmatin Service, Springfield, Virginia 22161

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