INVESTIGATIONS OF HEAT TRANSFER AND PRESSURE LOSS IN AN ENGINE-SIMILAR TWO-PASS INTERNAL BLADE COOLING CONFIGURATION

Transcription

1 INVESTIGATIONS OF HEAT TRANSFER AND PRESSURE LOSS IN AN ENGINE-SIMILAR TWO-PASS INTERNAL BLADE COOLING CONFIGURATION C. Waidmann* - R. Poer* - J. von Wolferdorf* M. Foi** - K. Semmler** * Intitut of Aeropace Thermodynamic (ITLR), Univerity of Stuttgart, Stuttgart, Germany ** MTU Aero Engine GmbH, Heat Tranfer and Combution (TESW), Munich, Germany chritian.waidmann@itlr.uni-tuttgart.de ABSTRACT In thi tudy, the preure lo and heat tranfer characteritic of a two-pa internal cooling channel with engine-imilar cro-ection were invetigated experimentally. The channel conit of a rib-turbulated trapezoidal leading edge pa, a harp 80 bend, and a ribbed rectangular outlet pa a typical for a low-preure turbine blade forward cooling cheme. Heat tranfer meaurement have been performed to obtain local cooling information on preure ide and uction ide urface. The tranient TLC (Thermochromic Liquid Crytal) technique ha been applied, CFD imulation are ued to addre the effect of tet-pecific inlet geometrie on the flow and temperature field in the tet channel. A technique to calculate fluid bulk temperature from the thermocouple meaurement uing the temperature field information of the CFD imulation ha been applied. NOMENCLATURE η Dynamic vicoity Nu Nuelt number Θ Normalized fluid temperature p Rib pitch ρ Denity p* Normalized preure lo A Cro-ection area Pr Prandtl number CFD Computational Fluid Dynamic PS Preure Side c p Specific heat capacity q w Wall heat flux d h Hydraulic diameter Re Reynold number e Rib height SS Suction Side EXP Experiment Streamwie ditance h Heat tranfer coefficient TC Thermocouple k Thermal conductivity TLC Thermochromic Liquid Crytal LPT Low Preure Turbine T Fluid temperature ṁ Maflow rate u Fluid velocity INTRODUCTION In the effort to enhance the efficiency of ga turbine, the turbine inlet temperature ha been increaed progreively. Thu, the thermal load of modern turbine component, epecially of the turbine blade i coniderably increaed. Therefore, turbine blade cooling ha become a crucial part of the efficient and afe operation of ga turbine. An overview over recent experimental and numerical tudie i given in Han et al. (2000). The mot important cooling technique i internal cooling, where extracted compreor air i led through erpentine cooling channel inide the blade. In general the

2 channel are equipped with rib turbulator to enhance the heat tranfer. Invetigation on engine relevant cooling geometrie have been undertaken e.g. by Jackon et al. (2009) uing the tranient TLC technique in combination with detailed CFD invetigation. In thi tudy a two-pa internal cooling configuration wa invetigated. The firt paage ha a trapezoidal cro-ection and repreent the leading edge paage of a turbine blade. A 80 bend connect thi inlet paage to an outlet paage with a rectangular cro-ection. Further the experimental reult of heat tranfer and preure lo meaurement are compared to numerical reult of a CFD imulation. The tranient TLC technique ha been applied to meaure the local heat tranfer ditribution for Reynold number between Re = 5000 and Re = An introduction to thi technique i given by Ekkad and Han (2000) and Ireland and Jone (2000). Advanced evaluation method are decribed by Poer et al. (2007), Poer et al. (2009) and Poer and von Wolferdorf (200). In thi tudy a mall-cale model i ued (model length L = 400mm). For thi kind of model the local fluid bulk temperature hitory ha to be meaured accurately by everal thermocouple to obtain reliable heat tranfer evaluation. For well mixed, turbulent channel flow the thermocouple meaurement along the centerline are a ufficient approximation of the fluid bulk temperature, the repreentative parameter for thee ort of heat tranfer application. However, thermocouple pair that are ditributed in cro-ection parallel to the rib at everal poition in the trapezoidal inlet paage and in the bend region are ued to account for poible kewed temperature profile. Their data are averaged in potproceing to obtain the repective bulk temperature. Numerical CFD imulation have been conducted to gain a better undertanding of the fluid temperature field. Steady tate RANS imulation have been applied a often done in tudie on internal blade cooling e.g. by Iacovide and Launder (995) and Walker and Zauner (2007). In addition to the LPT geometry, the inlet and outlet geometry of the air upply ytem, a ued in the experiment, have been included in the CFD analyi to imulate the boundary condition of the experiment. The CFD analyi revealed a deflection of the flow toward the leading edge in the inlet region of the channel. Thi reult in a deviation of the meaured (centerline) temperature from the wanted fluid bulk temperature. A method to compenate thee deviation in the heat tranfer evaluation ha been applied. For thi method the teady-tate CFD imulation are ued to determine correction factor for the tranient temperature data of the experiment. EXPERIMENTAL AND NUMERICAL SETUP Experimental etup Channel Geometry Fig. how the internal cooling channel and the invetigated urface. The inlet paage (pa ) repreent a leading edge cooling channel with a radial outward flow and ha a trapezoidal croection with a hydraulic diameter of d h = 975m. Pa i followed by a 80 bend and an outlet paage (pa 2) with a radial inward flow and a rectangular cro-ection with a hydraulic diameter of d h2 = 269m. The total length of each paage i 400 mm. The preure idewall and the uction idewall are equipped with 45 kewed rib. The rib with a quare cro-ection have a pitch to hydraulic diameter ratio of p d h =.0 and a rib-height to hydraulic diameter ratio of d e h = 0.. In paage there are 8 rib on the uction idewall and 7 rib on the preure idewall. Paage 2 ha 5 rib on the uction idewall and 4 rib on the preure idewall. The rib arrangement i taggered with an offet of p between the rib of the uction ide and preure ide. The perpex model for the experimental invetigation i hown in Fig. 2. It conit of four main part: the ribbed uction and preure idewall, the divider web and the tip wall whoe ditance equal the height of the econd cooling paage. The perpex allow for an optical acce for the heat tranfer meaurement. The minimum thickne of the perpex i 20 mm. The connection to the inlet and exit channel are adapted to the tet facility a will be decribed in the ection on the numerical modeling. 2

3 bend SS pa 2 pa 2 S a Sp PS pa 2 a PS p channel cro-ection pa direction of flow Figure : CAD-model and cro-ection Figure 2: Perpex model Figure 3: Tet facility, Poer et al. (2009) Figure 4: Model on tet facility Tet Facility Fig. 3 how the chematic drawing of the tet facility. Thi facility provide a teady air upply with adjutable ma throughput and air temperature. The preure level inide the model and the ma flow rate i et by Laval nozzle uptream and downtream of the model. Depending on the invetigated Reynold number, a uitable combination of nozzle diameter i choen. To aure that the Laval nozzle operate above the critical preure ratio, a vacuum pump i ued to uck the air from the model. The tet condition are et and adjuted before the tart of an experiment while the airflow bypae the model. Fig. 4 how the intrumented Perpex model mounted on the tet facility. The urface are captured at a frame rate of 5 fp via a ingle Sony DFW-X70 color video camera. Thu video ynchronization iue are avoided. The camera provide a progreive can reolution of 024 x 768 pixel and ha a direct view on the tet model through gimbal-mounted mirror. For lighting of the model, OSRAM 930 fluorecent lamp with a warm white color temperature of 3000 K are ued. Temperature and Preure Meaurement The model wa equipped with 20 thermocouple (Type K) and 3 preure tap. Fig. 5 how the poition of the thermocouple. The ingle TC are poitioned along the centerline. The TC-pair T02/T03, T05/T06, T08/T09, T0/T, T2/T3, and T4/T5 are evenly ditributed in cro-ectional plane parallel to the rib. Three Agilent HP34907A data acquiition unit with HP channel multiplexer card were ued for TC fluid temperature meaurement. The poition of the preure tap are depicted in Fig. 6. Preure lo meaurement were conducted eparately in teady tate experiment for different Reynold number. A digital enor array (type DSA 306 by Scanivalve Corp.) wa ued to meaure local tatic preure difference 3

4 T [ C] T09 T08 preure ide T2 T3 uction ide T T0 preure ide P07 uction ide P06 T06 T05 T4 T5 T6 T07 P05 P08 P09 P0 P04 T03 T02 T7 T8 T9 T04 P03 P P2 P02 T20 T0 P0 P3 Figure 5: Thermocouple poition Figure 6: Preure tap poition time [] T0 T02 T04 T05 T06 T07 T08 T09 T0 T T2 T3 T4 T5 T6 T7 T8 T9 T20 = 0 mm /dh = 0 = 800 mm /dh = 40 = 375 mm /dh = 8.99 = 425 mm /dh = 2 = 400 mm /dh = = 400 mm /dh = Figure 7: Fluid temperature v. time Figure 8: Definition of /dh p i p 3 (i =..2) with repect to the outlet preure at preure tap P3. Fig. 7 how the thermocouple data for a tranient experiment at Re = Due to heat loe in the air upply path between bypa valve and model, an ideal fluid temperature tep change cannot be achieved. It can be een that the fluid temperature development further downtream i delayed compared to the inlet of the channel. Uing the dimenionle channel coordinate dh a given in Fig. 8 the treamwie fluid temperature profile i hown in Fig. 9 for different point in time. The field of view for the optical meaurement tart at dh = 6.00 and end at dh = For a comparion between the tranient experiment and the teady tate CFD imulation the dimenionle temperature Θ(t) = T local(t) T out (t) T in (t) T out (t) with T in (t) = T T 0 (t) and T out (t) = T T 20 (t) i introduced. The dimenionle temperature for the CFD imulation i defined imilarly with T in = T ( dh =.07) at the coordinate of T0 and T out = T ( dh =39.5) at the coordinate of T20. Fig. 0 how the imilarity of the fluid temperature profile from the tranient tet evaluated uing Θ along the channel and the teady-tate CFD imulation. Heat Tranfer Meaurement Heat tranfer meaurement were conducted for Reynold number between Re=5000 and Re=40000 uing the tranient TLC technique. Sprayable narrowband TLC (SPN/R38CW by Hallcret Ltd.) with an indication temperature of T T LC 38 C have been ued to indicate the channel wall temperature. The TLC were calibrated on a dedicated calibration facility. Before the tart of the experiment the model i iothermal at ambient temperature. The fluid temperature change i induced by witching the bypa valve to lead the heated air through the model. The video camera capture 4

5 T [C ] Θ t = T local(t) T out (t) T in (t) T out (t) bend bend dh Figure 9: Fluid temperature v. coordinate EXP (0) EXP (90) EXP (60) EXP (50) EXP (40) EXP (30) EXP (25) EXP (20) EXP (5) EXP (0) EXP (5) EXP (3) EXP (2) EXP () dh Figure 0: Theta v. coordinate CFD the TLC colorplay from outide through the Perpex, while the channel wall heat up. Synchronization of the video and the temperature and preure meaurement wa realized with the help of LED light, that are indicating the operation of the bypa valve. In potproceing the video i analyzed with the help of the in-houe code ProTeIn [Poer et al. (2007)] to determine the TLC indication time (maximum green intenity) for each pixel of the video. Together with the local fluid bulk temperature hitory T f (,t), which wa interpolated from the thermocouple data, thee indication time are ued to determine the heat tranfer coefficient h for each pixel. Thi i performed with the olution of Fourier one-dimenional heat conduction equation for a emi-infinite wall and a convective boundary condition, taking into account the real fluid temperature hitory T f (,t) by a erie of mall dicrete temperature tep T f ( j, j ) uing the Duhamel uperpoition principle, T w T 0 = N j= [ ( h 2 (t τ j ) exp ρ w c p,w k w ) ( erfc h t τ j ρw c p,w k w )] T f ( j, j ) () where T w = T T LC i the wall temperature at the time of indication, T 0 i the initial model temperature and ρ w, c p,w, and k w are the material propertie of Perpex. The reult are preented in the form of normalized Nuelt number Nu/Nu 0, where the hydraulic diameter d h of paage wa ued a reference length for all Nuelt number. Nu = h d h k (2) Heat tranfer enhancement i viualized by normalization with a reference Nuelt number Nu 0 (Nuelt number of mooth channel), which wa determined with the Dittu-Boelter correlation: Nu 0 = 23 Re 0.8 Pr 0.4 (3) A form of data reduction i preented by egment-averaged Nu/Nu 0 -diagram. The uction and preure ide wall were divided in rib-egment (i.e. ector between the rib), a hown in Fig. 7. For thee egment the Nu/Nu 0 -value were area-averaged. Segment are numerated in flow direction, where negative egment number correpond to paage and poitive number to paage 2. Another form of data reduction i preented by line-averaged Nu/Nu 0 -value that are plotted over /dh. For preure and uction ide, averaging-line parallel to the rib are choen. In practice thi i realized by defining parallelogram in the Nu/Nu 0 -ditribution plot which are then warped to rectangle. The parallelogram are adjuted to the rib-angle, a illutrated exemplary for the preure ide in Fig.. Image-warping algorithm that are implemented in LabVIEW are ued. In the reulting diagram the rib appear vertically. Line averaging wa then carried out by averaging vertical pixel line. The bend region could not be captured entirely by thi proce, a can be een in Fig.. 5

6 /dh=3 /dh=4 /dh=6.69 /dh=9.45 Figure : Image-warping method for line-averaging, preure ide Symbol Value Variance Unit Meaning ρ w 90 0 [ kg /m 3 ] Denity of Perpex at 20 C c p,w [ J /kgk] Specific heat capacity of Perpex k w 0.9 [ W /mk] Heat conduction of Perpex at 20 C T varie 0.2 [K] Fluid temperature T T LC [K] Calibrated TLC indication temperature t varie 0.2 [] Detection time Table : Parameter of uncertainty analyi Uncertainty Analyi The uncertaintie in the analyi of heat tranfer meaurement were determined conidering the uncertaintie of temperature meaurement, time meaurement and material propertie of Perpex. Tab. contain the parameter of the uncertainty analyi. The relative tandard deviation of the heat tranfer coefficient i illutrated (exemplary for Re = 20000) in Fig. 2. It depend on the heat tranfer coefficient itelf. Higher heat tranfer coefficient and fater TLC indication reult in higher local uncertaintie. It can be een that the relative tandard deviation of few area can be 5% and higher. However, for mot area the relative tandard deviation i in a range between 5% and 0%. Uncertaintie due to lateral conduction are not conidered. The variation in the material propertie of the fluid during an experiment i the caue for additional uncertaintie. The TLC technique implie local time-invariant heat tranfer coefficient. However, due to an increaing fluid temperature and therefore increaing thermal conductivity and dynamic vicoity, the Reynold number drop and we expect a variation in the heat tranfer coefficient. Conidering the Dittu-Boelter-correlation for a turbulent internal flow with forced convection, we can tate following dependency for the heat tranfer PS SS Figure 2: Relative tandard deviation of h for Re=20000 (cale: 0-5%) 6

7 Figure 3: CFD-model (with inlet geometry) Location Boundary Condition impoed Value FLUID DOMAIN Air aumed to be incompreible with c p = kg J K contant propertie k = 26 m W K η = N m 2 WALL Contant temperature T wall = 30.73K INLET Ma flow deduced from the For Re = OUTLET deired Reynold number and inlet temperature impoed Static preure Table 2: CFD-parameter T inlet 380K ṁ 089 kg coefficient: h(t ) d h k(t ) ( ) ṁ 0.8 ( ) Re 0.8 Pr 0.4 dh η(t ) cp (T ) 0.4 = (4) η(t ) A k(t ) The ma flow rate ṁ i metered and can be kept contant during the experiment by auring critical flow through the two Laval nozzle, ee Fig. 3. The fluid temperature typically range between 20 C and 70 C during the experiment. In thi range the temperature dependency of pecific heat capacity c p can be neglected. Therefore Eq. 4 can than be implified to h(t ) k(t )0.6 η(t ) 0.4 (5) A variation in fluid temperature between 20 C and 70 C reult in a variation of the Reynold number of about 5% and a variation in the heat tranfer coefficient of about 3%. Numerical Setup In Fig. 3 and Tab. 2 the CFD model and the boundary condition impoed for the numerical calculation are ummed up. To enable to do a good comparion between the CFD reult and the meaurement, imilar boundary condition a thoe ued for the experimental reearche are impoed. A pretudy ha hown that the variation of the inlet temperature and the variation of c p, k and η ha a mall influence on the reult. To avoid ome computation error occurring when the fluid temperature i cloe to the wall temperature, the inlet temperature ha been impoed higher than in the experiment. Grid Generation ICEM CFD 30 from ANSYS ha been ued for generating the tructured meh in the following invetigation. The mehing proce i a multi-block tructured meh with about 8 million node. The global blocking tructure i done with an L-grid and O-grid method becaue of the rib near to the bend and to control the boundary layer around every wall of the model. The max y+ remain below 5, which i mall enough to have a near wall meh independency and to apply the low-re approach at the wall. 7

8 Figure 4: Dimenionle temperature field (CFD) Figure 5: Dimenionle temperature profile in cro-ection, /dh=5 (CFD) Numerical Method The Any CFX 30 code ha been ued for olving the Reynold-average Navier-Stoke equation and the tranport equation for the turbulent quantitie. To enure convergence, the reidual have to be maller than 0 4 for the tranport equation and maller than 0 4 for the energy equation. Control urface were alo ued to monitor the convergence. Turbulence Model The computation ha been made with the SST turbulence model and an automatic near wall treatment. It mean that the formulation depend on the local grid pacing at the wall. A the current meh provide a well near-wall reolution, the low Reynold formulation wa applied. The patial dicretization i quai 2 nd order. Pot-proceing The ANSYS CFX 3 pot-proceor wa ued to evaluate the heat tranfer and the preure lo. According to the experimental data the Nuelt number wa evaluated at the urface between two rib. The Nuelt number i calculated uing the bulk temperature T b, which i a local ma-flow-averaged temperature. A T b = T ρ u da A ρ u da (6) Nu = h d h k = q w (T w T b ) dh k To obtain the bulk temperature at one point of the channel, the local total fluid temperature i computed on the plane correponding to the required poition in the flow direction. Thi provide the fluid temperature evolution in the complete channel for an inlet temperature. Correction of Thermocouple Data Fig. 4 and Fig. 5 how ome reult of the CFD imulation. Illutrated are the temperature field in the form of the dimenionle temperature Θ 2 = T total T wall T bulk T wall for Re= Θ 2 repreent the deviation between local total temperature and bulk temperature. It can be een that the inlet geometry with it widening cro-ection caue a deflection of the flow toward the leading edge. Due to thi divergence from a fully developed tube flow, the thermocouple meaurement along the channel centerline no longer repreent the fluid bulk temperature in the inlet region of the channel. However, the CFD data can be ued to upport the evaluation of the experiment a hown e.g. in Jenkin et al. (202) and Jackon et al. (2009). Since the cro-ection temperature profile at each (7) 8

9 PS PS SS SS (a) EXP, Re=20000 (b) CFD, Re=23000 Figure 6: Local Nu/Nu0 thermocouple poition i known from the CFD imulation, a correction factor K can be calculated for each thermocouple. K i = T TC,i,CFD T re f,cfd T bulk,i,cfd T re f,cfd with i = T 0, T T 20 (8) where T TC,i,CFD i the local temperature at the poition of thermocouple i, T re f,cfd i a contant reference temperature and T bulk,i,cfd i the bulk temperature at the channel coordinate of thermocouple i. K i then ued to calculate the bulk temperature hitory T bulk,i,exp (t) from the thermocouple meaurement T TC,i,EXP (t). T TC,i,EXP (t) T re f,exp (t) T bulk,i,exp (t) T re f,exp (t) = K i with T re f,exp (t) = T T 05(t) + T T 06 (t) 2 (9) Due to the kewed temperature profile at the inlet, not the inlet temperature T T 0 but the average of thermocouple T05 and T06 further downtream wa choen a reference point T re f,exp (T re f,cfd wa determined repectively). The calculated bulk temperature T bulk,i,exp (t) can then be ued to replace the thermocouple data T TC,i,EXP (t) in the heat tranfer evaluation. Thi method i teted exemplarily for the uction ide for an experiment at Re = 20000, a hown in Fig. 9. RESULTS The reult of the heat tranfer meaurement and the CFD imulation are preented in three different way: Local Nu/Nu 0 -ditribution, egment averaged Nu/Nu 0 and line averaged Nu/Nu 0 - data. Local Nu/Nu0-ditribution Fig. 6a how the contour plot for the heat tranfer enhancement for an experiment at Re= The repective reult of the CFD imulation at Re=23000 i given in Fig. 6b. Data Reduction to Segment Averaged Nu/Nu0 Fig. 7 how the numbering of the rib egment. The reult of the data reduction i given in Fig. 8. On the uction ide, experiment and CFD how a good match. However, on the preure ide the Nu/Nu 0 -value of the CFD imulation are ditinctly higher than the experimental Nu/Nu 0 -value, epecially in paage. Thi high heat tranfer i due to the high velocity and temperature concentrated cloe to the preure and leading edge in the CFD computation, a hown in Fig. 4 and 5. The effect of the tube and the conical entrance ection guiding the flow on the leading and preure ide eem to be amplified in the CFD computation. In Fig. 9 the reult of experiment, CFD and thermocouple-corrected experiment are compared exemplary for the uction ide. A deviation between experiment and TC-corrected experiment i hown 9

10 Bend Bend Nu/Nu Bend Bend Nu/Nu0 CFD - PS Re23k 9 8 PS bend CFD - SS Re23k EXP - PS Re20k EXP - SS Re20k SS bend.5.0 Segment Figure 7: Numbering of rib egment Figure 8: Segment avg. Nu/Nu0, Re=20000(EXP), Re=23000(CFD) CFD - SS Re23k EXP - SS Re20k EXP - SS Re20k - TC corr.5.0 Segment Figure 9: Segment avg. Nu/Nu0, SS, TC-corrected, Re=20000(EXP), Re=23000(CFD) in the inlet region, where the difference between the meaured thermocouple data T TC,i,EXP and the calculated bulk temperature T bulk,i,exp are the highet. Here the TC-corrected Nu/Nu 0 -value exceed the original Nu/Nu 0 -value. In paage 2 the TC-corrected value are lightly lower than the original value. Data Reduction to Line Averaged Nu/Nu0 Fig. 20 how the reult of data reduction to line averaged Nu/Nu 0 -value. A with the egment averaged reult, we find generally a good agreement between CFD and experiment on the uction CFD - SS Re23k EXP - SS Re20k CFD - PS Re23k EXP - PS Re20k Nu Nu 0 Nu Nu dh (a) uction ide dh (b) preure ide Figure 20: Nu/Nu0, Re=20000(EXP), Re=23000(CFD) 0

11 CFD - SS Re5k EXP - SS Re5k CFD - PS Re5k EXP - PS Re5k Nu Nu 0 Nu Nu dh (a) uction ide dh (b) preure ide Figure 2: Nu/Nu0, Re= CFD - SS Re40k EXP - SS Re40k CFD - PS Re40k EXP - PS Re40k Nu Nu 0 Nu Nu dh (a) uction ide dh (b) preure ide Figure 22: Nu/Nu0, Re=40000 ide. On the preure ide, the CFD-value exceed the experimental value. Thereby the trend with firt increaing and then decreaing heat tranfer i imilar between EXP and CFD for the inlet pa, wherea directly after the bend the trend i different for a hort ditance in the outlet pa. Fig. 2 and 22 how the reult for Re = 5000 and Re = The reult how the ame trend for all Reynold number. Preure Lo For a comparion of the preure lo meaurement and the CFD-preure-data the preure at tap P2 near the outlet of paage 2 wa et a reference preure. The preure difference between each tap and P2 were then normalized with the dynamic preure at the inlet of pa. p i = p i p P2 ρ 2 u2 with i = P0, P02... P3 (0) The inlet velocity u wa determined uing the meaured channel ma flow rate and the fluid denity ρ wa determined uing the fluid inlet temperature (at thermocouple T0) and preure (at preure tap P0). The tatic accuracy of the ued preure meaurement module with a range of pid ( 7.24kPa) i pecified with ±20.69Pa (±0.2% of full cale range). The CFD-data repreent area averaged tatic preure computed on plane perpendicular to the flow direction. The reult how a good agreement between experiment and CFD imulation.

12 p = p i p ref ρ 2 u Re40k EXP Re30k EXP Re20k EXP Re5k EXP Re40k CFD Re3k CFD Re23k CFD Re5k CFD dh Figure 23: Normalized Preure Lo CONCLUSIONS A two-pa internal cooling channel with engine-imilar cro-ection wa invetigated both experimentally and numerically. Heat tranfer meaurement have been performed uing the tranient TLC technique to obtain the local heat tranfer ditribution on the preure ide and uction ide urface. The local data were reduced to egment-averaged and line-averaged data and the reult have been compared to the CFD imulation. A good agreement i hown on the uction ide urface. However, for the preure ide the heat tranfer reult are ignificantly higher for the CFD imulation than for the experiment. A method to ue the fluid temperature field information of the teady-tate CFD imulation a a upport for the evaluation of the tranient experiment ha been applied. With the help of the CFD data, fluid bulk temperature are derived from the thermocouple meaurement. The calculated bulk temperature then replace the thermocouple data in the heat tranfer evaluation. The reult i preented exemplary for the uction ide and Re = A expected, the effect of thi correction method increae at location where the flow field clearly differ from a fully developed tube flow cauing a deviation of the bulk temperature from the meaured centerline temperature. For future tudie it i recommended that prior CFD imulation are ued to plan the poitioning of the thermocouple by evaluating the deviation between local fluid temperature and bulk temperature. Preure lo meaurement have been conducted and compared to the preure lo-data of the CFD imulation. The reult how a good agreement between experiment and CFD imulation. ACKNOWLEDGEMENTS The reearch leading to thee reult ha received funding from the European Union Seventh Framework Programme (FP7/ ) under grant agreement no (ERICKA). Reference S. V. Ekkad and J. C. Han. A tranient liquid crytal thermography technique for ga turbine heat tranfer meaurement. Meaurement Science and Technology, (7): , J. C. Han, S. Dutta, and S. V. Ekkad. Ga turbine heat tranfer and cooling technology. Taylor & Franci, New York and NY.a., ISBN X. H. Iacovide and B. E. Launder. Computational fluid dynamic applied to internal ga-turbine blade cooling: a review. International Journal of Heat and Fluid Flow, 6(6): ,

13 P. T. Ireland and T. V. Jone. Liquid crytal meaurement of heat tranfer and urface hear tre. Meaurement Science and Technology, (7): , D. Jackon, P. T. Ireland, and B. Cheong. Combined Experimental and CFD Study of a HP Blade Multi-Pa Cooling Sytem. ASME Conference Proceeding, 2009(48845):85 862, S. C. Jenkin, I. V. Shevchuk, J. von Wolferdorf, and B. Weigand. Tranient Thermal Field Meaurement in a High Apect Ratio Channel Related to Tranient Thermochromic Liquid Crytal Experiment. Journal of Turbomachinery, 34(3):03002, 202. R. Poer and J. von Wolferdorf. Tranient liquid crytal thermography in complex internal cooling ytem. VKI Lecture Serie - Internal Cooling in Turbomachinery, von Karman Intitute for Fluid Dynamic, (VKI LS ), 200. R. Poer, J. von Wolferdorf, and E. Lutum. Advanced evaluation of tranient heat tranfer experiment uing thermochromic liquid crytal. Proceeding of the Intitution of Mechanical Engineer, Part A: Journal of Power and Energy, 22(6):793 80, R. Poer, J. R. Ferguon, and J. von Wolferdorf. Temporal Signal Preproceing and Evaluation of Thermochromic Liquid Crytal Indication in Tranient Heat Tranfer Experiment. 8th European Conference on Turbomachinery Fluid Dynamic and Thermodynamic, page , D. Walker and J. Zauner. RANS Evaluation of Internal Cooling Paage Geometrie: Ribbed Paage and a 80 Degree Bend. ASME Conference Proceeding, 2007(47934): ,