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Novel multi-effect diffusion solar distiller (MED) was developed to improve the performance and reliability of conventional MED. Conventional MED consists of several flat metal plates (effect plates), each one equipped with a wick that serves as both an evaporation surface and a seawater feeding medium. However, the wick-plate structure has several problems such as higher manufacturing cost, lower performance, and durability deterioration. The new wick-free plates (WFPs) have many horizontally patterned grooves on an evaporation surface of a flat plate and can evenly spread and retain the feed saline water on the surface like as fabric wick. Experimental results showed that the performance of the proposed novel MED equipped with WFP (WFP-MED) is similar to that of conventional MED with wick-plate and even better productivity up to 7 % due to lower thermal resistance of WFP. Production stability with respect to the fluctuation of feed flow rate of WFP-MED is better than that of conventional MED. Moreover, WFP-MED is more effective in increasing productivity by increasing the number of effects. The 3-effect diffusion distiller with WFP has 0.84 of distillation efficiency under 10.8 MJ/m2 of solar insolation.

배열 충돌제트는 국소 열전달 성능이 우수하여 가스터빈의 연소기, 베인, 블레이드 등과 같이 높은 냉각성능이 필요한 분야에 적용되고 있다. 하지만 제트가 충돌 후 발생하는 횡방향유동의 영향으로 하류방향으로 갈수록 제트가 편향되어 열전달 성능이 감소하게 된다. 이에 본 연구에서는 제트 홀 사이의 공간을 증가시킨 파형 구조를 이용하여 냉각 성능을 향상시키는 연구를 진행하였다. 제트 홀의 평균유량은 레이놀드수 10,000이며 ANSYS-CFX 17.2를 사용하여 수치해석을 진행하였다. 변형된 파형구조는 날개 모양의 구조물을 추가로 설치하여 충돌 후 냉각공기가 유입되어 흐를 수 있는 이차유로를 형성함으로써 충돌면에서의 평균 Nusselt 수가 기존 파형구조보다 높게 나타났다. 또한 제트판과 충돌면 사이 간격(h/d)이 클수록 제트의 발달로 인해 정체점에서의 최대 Nusselt 수가 증가하였다. 따라서 제트판과 충돌면 사이의 간격(h/d)이 작을수록 변형된 파형구조의 열전달 성능이 기존 파형구조보다 냉각성능이 높게 나타나는 것을 확인하였다.

The appropriate coolant mass flow of turbine blade rim seal has become an important issue as turbine blades are exposed to increasingly higher thermal load owing to increased turbine inlet temperature. If the coolant is deficient, hot gas ingresses to the rim seal, or if sufficient, the efficiency of turbine decreases. Therefore, we analyzed sealing effectiveness of rim seal derive appropriate coolant mass flow rate at various conditions. The experimental facility was modified from one designed for an aero-engine gas turbine. Rotational Reynolds number varied from 3 &times, 105 to 5 &times, 105 based on rotational speed. Pressure was measured at various locations in the shroud, endwall, and rim seal. CO2 concentration was measured at various rim seal locations to analyze sealing effectiveness. Measured results showed that 1.35% coolant mass flow rate of rim seal exhibited a little ingress effect, whereas lower coolant mass flow rates exhibited higher ingress effect. A predicted correlation for sealing effectiveness of rim seal was derived at various rotational Reynolds number and coolant mass flow rate. The correlation will be useful for turbine cooling design, helping to predict sealing effectiveness of rim seals during preliminary design processes for new gas turbines.

In a turbine passage, the wake, which affects the heat transfer of a turbine blade, occurs periodically due to rotation of the blade. We analyzed the effect of wake on the endwall of the turbine blade according to the relative position of the turbine blade and the vane in a stationary condition. The naphthalene sublimation method was used to measure the heat transfer and detached eddy simulation (DES) was used to analyze flow characteristics. The wake from the vane was simulated by using a cylindrical rod upstream of the blade. The cylindrical rod was placed in four which positions that were aligned leading edge-to‑leading edge. The pressure and Q criterion distributions varied according to the position of the upstream wake. As the position of the upstream wake changed, the point at which the passage vortex and wake met varied. Wake and passage vortex met at x/Cx = 0.2 in position 1 and at x/Cx = 0.55 in position 2. After the wake and passage vortex had met, the secondary flow scattered. Therefore, the local and averaged heat transfer varied due to flow characteristics. Thus designers of film cooling holes on endwalls should consider these effects to ensure appropriate cooling performance.

The installation of floating photovoltaic systems has been gradually increasing to meet the demand for clean and eco-friendly power generation. However, hurricanes subject the solar panels to harsh conditions with large drag and lift forces. Balancing the wind loads and buoyancy force is important to prevent floating structures from sinking or overturning. In this study, numerical simulations were performed to predict the wind loads on solar panels at various turbulence intensities (0.1–0.3) and wind speeds (35–75 m/s). The first row of solar panels showed the highest drag and lift coefficients at different turbulence intensities. The drag and lift coefficients of the solar panel array gradually decreased along the wind direction because of the sheltering effect of the first row of solar panels. Furthermore, the drag and lift forces on the solar panels increased with the turbulent kinetic energy, especially for the first row of solar panels. The effect of the wind angle of attack was also analyzed, and the in-line wind direction cases (0° and 180°) showed higher drag and lift coefficients than the other cases. The drag and lift coefficients showed similar values regardless of the wind speed because of the turbulent flow condition. Correlations were derived to predict the drag and lift forces on solar panels at various wind speeds, which can be used as guidelines for designing the structure of a floating photovoltaic system and its solar panels.

Improving the cooling performance of internal channels is important to extend the lifespan of hot components exposed to heat in many types of machinery. This study was performed to examine the effects of placing a delta-winglet-pair (DWP) upstream of a single dimple in an internal cooling channel. The local heat/mass transfer coefficients (H/MTCs) were measured in the vicinity of the dimple by the naphthalene sublimation method (NSM). The cooling performances under laminar, transitional, and turbulent flow conditions were compared at different values of the DWP incidence angle ( β ). The DWP enhanced local H/MTCs within the dimple cavity due to intensified secondary vortices. With increasing the DWP incidence angle, the distance between the symmetrical vortices increased resulting in a different level of H/MTC enhancement. The optimum DWP incidence angle ranged between 30 ∘ β 45 ∘ depending on the flow condition. The resulting area-averaged H/MTCs clearly indicated enhancement from the DWP. Under the laminar flow conditions, the H/MTCs were enhanced by 87%–125% from installing the DWP. The absolute H/MTCs were highest under the transitional flow conditions. Based on the present investigation, the installation of the DWP in the dimpled channel is highly recommended for both laminar and transitional flow conditions.

Rim-seals are exposed to one of the most complex flows in modern high-efficiency gas turbines. The flow physics in the vicinity of rim-seals should be understood before predicting the hot gas ingestion that may cause a rise in disc temperature and a catastrophic failure. To investigate the seal performance of rim-seals, experiments were performed using a high-speed rotating test-rig and followed up that the unsteady flow analysis approach was proposed. The rotating rig consisted of 1.5-stage axial turbines with a double rim-seal. Local pressures and CO2 concentrations were measured to evaluate flow characteristics and sealing performance. At a rotational Reynolds number of 1.0 × 106, the circumferential pressure distribution on the vane endwall platform and corresponding distribution of the circumferential sealing effectiveness of the rim-seal were measured. The results of the unsteady Reynolds-averaged Navier–Stokes (URANS) model were in a good agreement with the experimental results. Time-averaged, time-resolved flow observations under various conditions revealed unsteadiness of rim-seal flow; ingress and egress occurred repeatedly over time at all circumferential locations. The results validated unsteady ingestion from a reduction in sealing effectiveness of up to 30% at any instant compared to the time-averaged sealing effectiveness. As the rotational speed increased, the asymmetric pressure distribution of the main flow increased, and the average sealing effectiveness decreased up to 50%. The novelty of this study is that instantaneous hot gas-ingestions reached to a location significantly deeper into the disc cavity than that obtained from time-averaged predictions. It is concluded that understanding the nature of unsteady flow and its effects to hot gas-ingestion is vital to the reliable design of turbine rim-seals.

Dimples are widely known to increase heat transfer coefficients in internal passages with a minimal pressure drop. The naphthalene sublimation method was used to measure local heat transfer coefficient variations of single dimple imprint channel with the analogy between heat and mass transfers. The effect of a boundary layer trip-wire with different diameters was compared under different flow conditions (1000 S h / S h 0 ). However, under the laminar flow (Re ~ 1000), the flow was re-laminarized, resulting in a negligible effect of the trip-wire. Without a trip-wire, the heat and mass transfer increase was limited to the downstream of dimple cavity. With installation of a trip-wire, even the upstream of dimple cavity exhibited increased heat and mass transfer variations with enhanced turbulent intensity. As the diameter of a trip-wire increased, the area-averaged Sherwood number ratio ( S h ¯ ¯ / S h 0 ) under the transitional and turbulent flow conditions (3000

The wakes that occur periodically owing to blade rotation, affect the HTCDs (heat transfer coefficient distributions) on the turbine blade tip and shroud. We investigated the wake effects on the HTCDs from the turbine blade tip with different configurations and the corresponding shroud. The NSM (naphthalene sublimation method) was used for measuring the local heat/mass transfer distributions (LHMTDs). Five different tip shapes were compared. The flow characteristics near turbine blade tip and shroud varied with respect to different tip shape. Especially, swirling flow and tip leakage flow patterns varied, which affected the HTD on the tip & shroud. In addition, the local heat transfer distributions (HTCDs) on the tip and the shroud varied with different tip configurations. However, when the wake effects were induced, the HTCDs on the tip & shroud became relatively uniform. Furthermore, the magnitudes of HTCDs on the tip & shroud were relatively similar in region of 0.3

A wake is induced in turbine passages due to the interaction of turbine stators and rotors. Each stage of the turbine blade has different geometric parameters, namely, the turning angle, leading edge radius, and solidity, which all vary. Comparison of flow and thermal characteristics between the first and second-stage blades was carried out. The flow and thermal characteristics of the first-stage blade endwall were investigated for various Strouhal numbers to determine the wake effect. Numerical simulations and experiments were performed to compare the flow and thermal characteristics of the different stage blades. Experiments were performed using a five-bladed linear cascade with moving cylindrical rods simulating the wake effect. The effective area and strength of secondary vortices differed in each stage of blade, which resulted in different local heat transfer distributions. In addition, the local heat transfer characteristics changed depending on the Strouhal number. The ‘without wake’ case ( St = 0) showed non-uniform heat transfer distribution on the endwall with the occurrence of horseshoe, passage and corner vortices. The ‘with wake’ effect cases ( St ≠ 0) showed a more uniform heat transfer distribution on the endwall. The wake effect disturbs the occurrence of secondary vortices. With an increase in the Strouhal number, the endwall is exposed to higher thermal load.

A rotor blade is affected by the unsteady wake from the stator in the previous stage. An unsteady wake causes differences in the flow and heat transfer distribution on the external surface of the rotor blade. Therefore, the effect of unsteady wake should be studied for optimal design of blade cooling. To investigate the effect of an unsteady wake, this study measured the local heat transfer distribution over the entire external blade surface using the naphthalene sublimation method. Several rods moved across the inlet of the cascade to make the unsteady wake and the Strouhal number was varied from 0.0 to 0.3. The heat transfer on the entire pressure-side surface in an unsteady wake increases due to the high turbulence. The unsteady wake flow disturbs the developing passage vortex and tip leakage flow. As a result, the heat transfer near the endwall and tip surfaces in the unsteady wake case is lower than that in the steady case.

In this study, we investigated whether vortex control of forward and backward injection jets with different vortex strengths contributed to enhanced film cooling effectiveness. Various hole arrangements, composed of primary and sister holes, were used to control vortex strengths and vortex interactions between film cooling jets. Numerical simulations were conducted to obtain and analyze the flow characteristics and film cooling effectiveness of six sister hole arrangements, composed of forward and backward injection holes, for blowing ratios of 1 and 2. Hole arrangements with backward injection holes showed improved film cooling effectiveness and laterally wide coverage of film cooling jets. Hole arrangements with forward injection primary holes and backward injection sister holes showed coverage of the entire surface by the film cooling jets, due to the backward injection jets from sister holes and the formation of outward vortexes. Additionally, the other hole arrangement, consisting of forward injection sister holes in the first row and backward injection primary holes in the second row, produced an anti-kidney vortex and improved film cooling effectiveness at high blowing ratios.

Total cooling effectiveness was determined on a film cooled surface with staggered array jet impingement cooling at various Biot numbers. Heat transfer experiments were conducted using infra-red thermography for materials of three thermal conductivities: stainless steel ( k = 13.4 W/m K), Corian ( k = 1 W/m K), and polycarbonate ( k = 0.2 W/m K). Conjugated heat transfer was analyzed with the combined effects of conduction through the test plates and convective heat transfer due to the arrayed jet impingement. The inclination angle of the film cooling holes was 35° and that of the jet impingement holes was 90°. The film and jet impingement holes on each plate were arranged in staggered patterns, and the film cooling holes and jet impingement holes were also positioned in a staggered pattern. The jet Reynolds number, based on hole diameter, was 3000 and the equivalent blowing ratio was 0.3. The diameter of the film cooling holes and the jet impingement holes was 5 mm. The distance between jet and film hole plates was varied in the range 1 ⩽ H / d ⩽ 5. Total cooling effectiveness was measured with and without jet impingement. When jet impingement was added to the internal cooling, the averaged total cooling effectiveness was enhanced about 8.4%. At low Biot numbers, meaning that cooling performance dominated over the conduction effect, the temperature distribution became more uniform due to higher conductive heat transfer. The total cooling effectiveness was strongly related to the Biot number of the plate, and the correlation between total cooling effectiveness at various Biot numbers was determined to predict the total cooling effectiveness in an actual gas turbine engine. The effect of H / d ratio was limited, to within 2.7%.

The cooling of the tip surface of a turbine blade is a critical issue with respect to the increase in turbine inlet temperatures. Guide vanes, ribs, pins, dimples, and protrusions have been used by previous researchers in the tip turning region in internal two-pass channels to increase the cooling effect on the tip surface. However, external heat transfer at the tip surface is not uniform. Thus, different local heat transfer measurements are needed for cooling the tip surface. Discrete guide vanes have been suggested to control the cooling effect on tip surfaces. Numerical simulations were performed in six different guide vane cases in a two-pass channel to compare the effects of discrete guide vanes. In a two-pass channel, ribs were installed at 45°. The Reynolds number, which is based on hydraulic diameter and velocity, was fixed at 10,000 in each case. The results indicated that the base case and U-vane case showed high heat transfer at the tip surface of the first channel but low heat transfer at the tip surface of the second channel. Also, the heat transfer on the tip surface was asymmetrical. In comparison, the heat transfer on the tip surface was asymmetrical in discrete guide vane cases. The 1S2S case showed high heat transfer on the tip surface of the second passage pressure side and the 1P2P case showed high heat transfer on the tip surface of the second passage suction side. The arrangement of discrete guide vanes caused different flow characteristics in comparison with the U-vane case. Thus, the design of discrete guide vanes can control heat transfer on the tip surface effectively.

Thermal cracks occur on heat recovery steam generator (HRSG) casing, leading to heat loss. The possibility of reducing the number of thermal cracks appearing in HRSG casing with the use of thermal spreaders was investigated. Before designing thermal spreader, measuring temperature and numerical analysis were performed to find the reason of thermal cracks in HRSG. Temperatures were measured at different heights on the HRSG casing, enabling to determine the temperature gradient in the casing. The largest temperature gradient occurred toward the lower region of the HRSG casing. Then, the highest thermal stress and thermal cracks were showed in this lower region due to the large temperature gradient. To reduce thermal stress in this region, thermal spreader which has large thermal conductivity was designed. Designed thermal spreaders were installed on the HRSG casing to reduce the temperature gradient of the HRSG casing. Where thermal spreaders were used, the average temperature gradient of the HRSG casing decreased from 52 °C to 16 °C. The maximum thermal stress was reduced by 16% and the average thermal stress was reduced by 26%.

The characteristics of fluid flow and heat transfer, which are affected by the guide wall in a jet impinged leading edge channel, have been investigated numerically using three-dimensional Reynolds-averaged Navier–Stokes analysis via the shear stress transport turbulence model and gamma theta transitional turbulence model. A constant wall heat flux condition has been applied to the leading edge surface. The jet-to-surface distance is constant, which is three times that of the jet diameter. The arrangement of the guide wall near the jet hole is set as a variable. Results presented in this study include the Nusselt number contour, velocity vector, streamline with velocity, and local Nusselt number distribution along the central line on the leading edge surface. The average Nusselt number and average pressure loss between jet nozzle and channel exit are calculated to assess the thermal performance. The application of the guide wall is aimed at improving heat transfer uniformity on the leading edge surface. Results indicated that the streamwise guide wall ensures the vertical jet impingement flow intensity and prevents the flow after impingement to reflux into jet flow. Thus, a combined rectangular guide wall benefits the average heat transfer, thermal performance and heat transfer distribution uniformity.

This study focused on finding the maximum productivity by optimizing vertical multi-effect diffusion solar distiller (VMED) and lowering the water cost of that. The numerical model of the VMED was experimentally validated, and then used to find the optimal conditions for the essential variables. The VMED consists of a glass cover, plates, wicks, and a seawater feeding unit. Each effect has a cotton-cloth wick attached to one side of the plate. This VMED repeatedly using condensation latent heat can get more production than that of conventional solar still. The numerical result showed that the optimum values of the gap distance of double glass cover and the number of effects were 25–30 mm and 10–15, and the feed flow rates of spring, summer, fall, and winter were optimal in 9, 16, 10, and 3 g/min, respectively in supplying same flow rate into all the effects. The maximum productions for all seasons (spring, summer, fall, and winter) were 16.6, 36.0, 19.0, 2.5 kg/(m2·d), respectively in South Korea. Economic analysis showed that the potential water price of the VMED was 6.1 $/m3, which was more competitive in the market than other solar desalination systems with a small capacity of

Film cooling effectiveness and heat transfer were measured in squealer tip configurations on the blade tip surface. Three different shelf squealer tip geometries were studied: conventional, vertical, and inclined. The experiment was carried out in a wind tunnel with an inlet mainstream Reynolds number, based on the axial chord length of the blade, of 140,000. The experiments were conducted in five blades in linear cascade with an averaged turbulence intensity of 8.5%. The film cooling effectiveness and heat transfer coefficient on the tip surface were obtained using the transient IR thermography technique. For the pressure side film cooling holes, averaging blowing ratios (M) of 1.0 and 2.0 were set. The results showed the film cooling effectiveness distributions on the tip surface. Owing to the mainstream, the cooling effect appeared after x/Cx = 0.15 and the film cooling effectiveness tended to increase toward downstream of the trailing edge. Additionally, the heat transfer distributions were investigated regarding the film cooling holes. In the presence of film cooling holes, the heat transfer distribution had more uniformity than without them on the pressure side. As the blowing ratio increased from 1 to 2, the heat transfer was decreased on the tip surface. The heat transfer ratio represented the change of heat transfer distribution with and without film cooling holes. Those of results were compared in three squealer tip geometries. The overall area-averaged net heat flux reduction (NHFR) levels on the tip surface were enhanced as the blowing ratio increased. The NHFR of the shelf squealer tip configurations was better than that with the conventional squealer tip.Copyright © 2018 by ASME

This study was an experimental investigation of the effect of an intersecting rib on heat/mass transfer performance in rectangular channels with angled ribs and different aspect ratios. In a rib-roughened channel with angled ribs, heat/mass transfer performance deteriorates as the channel aspect ratio increases, since the vortices induced by angled ribs diminish with increasing aspect ratio. A longitudinal rib that bisects the angled ribs is suggested to overcome this disadvantage. The heat transfer performance of angled rib configurations with a 60° attack angle were tested with and without an intersecting rib using naphthalene sublimation method. The channel aspect ratio is varied from 1 to 4. When the intersecting rib was present, additional vortices were generated at every point of intersection with the angled ribs. Thus the heat/mass transfer performance was significantly enhanced for all channel aspect ratios when an intersecting rib was added to an ordinary angled rib configuration.

The matrix cooling channel was used for gas turbine blade cooling passage. The matrix cooling structure is useful for the structure stability however the cooling performance of internal cooling channel was not enough for cooling. Therefore, we designed the rib configurations in the matrix cooling channel to enhance the cooling performance. The numerical simulation was conducted to analyze cooling performance of rib configured matrix cooling channel. Three different rib configurations were used which are vertical rib, angled rib and c-type rib. Three configurations were adopted in two positions of matrix cooling channel which is one fourth and three fourth of channel. The result shows that downstream rib has much higher cooling performance than upstream rib. Furthermore, the angled rib in the channel has much higher cooling performance than vertical rib. This is because; the angled rib improves the swirl effect of matrix cooling channel more effectively. The friction factor was increased with the installation of rib. However, the thermal performance was increased with the installation of rib in the matrix cooling channel., {"references":["Bunker, R. S, \"Latticework (vortex) cooling effectiveness part 1: stationary channel experiments,\" ASME Paper, 2004, No. GT2004-54157.","Acharya, S., Zhou, F., Lagrone, J., Mahmood, G. and Bunker, R. S, \"Lattice (vortex) cooling effectiveness: rotating channel experiments,\" ASME Paper, 2004, GT2004-53983.","Su, S., Liu, J. J., Fu, J. L., Hu, J. and An, B. T. \"Numerical investigation of fluid flow and heat transfer in a turbine blade with serpentine passage and latticework cooling,\" ASME Turbo Expo, 2008, GT2008-50392","Saha, K., Guo, S., Acharya, S. and Nakamata, C, \"Heat transfer and pressure measurements in a lattice-cooled trailing edge of a turbine airfoil,\" ASME Turbo Expo, 2008, GT2008-51324","Oh, I. T., Kim, K. M., Lee, D. H., Park, J. S., and Cho, H. H, \"Local heat/mass transfer and friction loss measurement in a rotating matrix cooling channel,\" Journal of Heat Transfer, 2012, Vol.134, No.1, 011901.","Hagari, T., and Ishida, K, \"Numerical investigation on flow and heat transfer in a lattice (matrix) cooling channel,\" ASME Turbo Expo, 2013, GT2013-95412","Carcasci, C., Facchini, B., Pievaroli, M., Tarchi, L., Ceccherini, A., and Innocenti, L, \"Heat transfer and pressure loss measurements of matrix cooling geometries for gas turbine airfoils,\" Journal of Turbomachinery, 2014, Vol.136, No.12, 121005.","Luan, Y., Bu, S., Sun, H., and Sun, T, \"Numerical Investigation on Flow and Heat Transfer in Matrix Cooling Channels for Turbine Blades,\" ASME Turbo Expo, 2016, GT2016-56279","Luan, Y., Yang, L., Wan, B., and Sun, T. \"Large Eddy Simulation of Flow and Heat Transfer Mechanism in Matrix Cooling Channel,\" ASME Turbo Expo, 2017, GT2017-63515\n[10]\tBu, S., Yang, Z., Zhang, W., Liu, H., and Sun, H, \"Research on the thermal performance of matrix cooling channel with response surface methodology,\" Applied Thermal Engineering, 2016, Vol.109, pp.75-86.\n[11]\tGillespie, D. R., Ireland, P. T. and Dailey, G. M, \"Detailed flow and heat transfer coefficient measurements in a model of an internal cooling geometry employing orthogonal intersecting channels,\" ASME Paper, 2000, 2000-GT-653.\n[12]\tDeng, H., Wang, K., Zhu, J., and Pan, W., \"Experimental study on heat transfer and flow resistance in improved latticework cooling channels,\" Journal of Thermal Science, 2013, Vol.22, No.3, pp.250-256."]}

An experimental study has been conducted to investigate the heat-transfer characteristics of blade tips and shrouds with and without unsteady wakes. Depending on the presence of unsteady wakes, the local heat/mass-transfer coefficients of the tip and shroud were measured using the naphthalene sublimation method. Wakes from unsteady blades were modeled as wakes generated from moving cylindrical rod bundles. Test conditions were set to the Reynolds number of 100,000, based on an inlet velocity of 11.4 m/s and the axial chord length. The Strouhal number was varied from 0 to 0.22. For St = 0, high heat/mass-transfer coefficients appeared in regions where various flow patterns, such as flow reattachment, swirling flow, and vortexes, occurred. For St = 0.22, the heat/mass-transfer distributions of the tip and shroud were changed due to the unsteady wakes. Unsteady wakes made high turbulence intensity of leakage flow and flow patterns such as flow reattachment, swirling flow, and tip leakage vortex in the tip and shroud were changed and dispersed. There were also variations in the pitch-wise averaged Sherwood number of the blade tip and shroud on the presence of the unsteady wakes due to vortex shedding and dispersed flow patterns. Thus, considering the effects of unsteady wakes on the heat transfer of the blade tip and shroud, proper cooling designs for blade tips and shrouds should be investigated and adopted for effective cooling of gas turbine blades.

Key Words: Double-jet Film Cooling(이중분사 막냉각), Secondary Flow Channel(이차유로), Film CoolingEffectiveness(막냉각효율), Anti-Kidney Vortex(안티키드니와류), Numerical Analysis(수치해석)초록: 막냉각에관한많은연구들은주유동과이차유로가평행한형태로연구가이루어졌다. 하지만실제터빈블레이드에서이차유로의방향은일반적으로주유동의방향에수직한형태이다. 그래서본연구에서는이차유동의방향이이중분사막냉각의효율에미치는영향을수치해석을통해알아보고자한다. 분사율은1, 2이고횡방향분사각은22.5°이다. 분사율이1일때평행형상에서는안티키드니와류가잘형성되어막냉각효율이수직형상의경우보다더높다. 반면에분사율이2일때수직형상의막냉각효율은평행형상보다향상되었다. 많은유량의제트가서로반대방향으로분사되기때문에두형상모두막냉각효율이높게나타난다. 하지만안티키드니와류의영향은다른분사율보다상대적으로작다.Abstract: Several studies of film cooling were accomplished with a secondary flow channel parallel to themain flow. In real turbine blades, however, the direction of the secondary flow channel is generally normalto the main flow. Thus, this study performs a numerical analysis to investigate the effects of the direction ofsecondary flow on the effectiveness of double-jet film cooling. The blowing ratio is 1 and 2, and the lateralinjection angle is 22.5°. The parallel channel case creates a well-developed anti-kidney vortex with a blowingratio of 1, and the laterally averaged film cooling effectiveness of the parallel channel is enhanced comparedto the normal channel. The normal channel shows higher performance with a blowing ratio of 2. Both casesshow high film cooling effectiveness. These phenomena can be attributed to a high blowing ratio and flowrate rather than an anti-kidney vortex.