Volume 6A: Heat Transfer — Combustors; Film Cooling最新文献

{"title":"Effect of Location and Rotational Reynolds Number on Film Cooling of Rotating Blade Pressure Side","authors":"Meng Long, Li Haiwang, Xie Gang, Zhou Zhiyu","doi":"10.1115/gt2022-82189","DOIUrl":"https://doi.org/10.1115/gt2022-82189","url":null,"abstract":"\u0000 The film cooling performance on the pressure side of turbine blades with single-row film holes is experimentally investigated. Three blades with single-row film holes at three locations (x/S = 10%, 29%, and 48%) of the pressure-side are studied at three rotating Reynolds numbers of 3.6 × 105, 5.4 × 105, and 7.2 × 105 (i.e., the rotational speeds of 400 rpm, 600 rpm, and 800 rpm). The pressure-sensitive paint (PSP) technology is used to measure the film cooling distribution at three blowing ratios (BR = 0.50, 1.00, and 1.50). The results indicate that the film cooling performance varies with the location of pressure side. Upstream of the pressure side, the film cooling performance is poor, with the film trajectories deflecting mainly upward. Downstream of the pressure side, the cooling effectiveness is higher, with the film trajectories deflecting upward and downward. The film trajectories closer to the downstream location are longer than those upstream, and are more prone to detach from the wall at higher blowing ratios. Moreover, the cooling performance slightly improves as the rotating Reynolds number increases.","PeriodicalId":267158,"journal":{"name":"Volume 6A: Heat Transfer — Combustors; Film Cooling","volume":"123 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115686778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimized Film Cooling Flow on a Contoured Endwall Within a Transonic Annular Cascade","authors":"Timothy A. Burdett, Izhar Ullah, L. Wright, Je-Chin Han, John W. McClintic, Daniel C. Crites, A. Riahi","doi":"10.1115/gt2022-78519","DOIUrl":"https://doi.org/10.1115/gt2022-78519","url":null,"abstract":"\u0000 Film cooling was measured on the endwall of a five-vane annular cascade in a blowdown wind tunnel at an exit Mach number of 0.9. The adiabatic film cooling effectiveness was calculated from the partial pressure of oxygen measured with binary pressure sensitive paint (BPSP). Cylindrical film cooling holes were located in the upstream and passage regions with the coolant-to-mainstream mass flow ratio (MFR) independently varied for each region. One row was located upstream of the vanes and supplied by an upstream plenum. Two rows were located in the passage between two vanes and supplied by a downstream plenum. Three total MFRs were investigated: 1%, 1.5%, and 2%. For a given total MFR, four combinations of upstream and downstream MFRs were compared to an even split of coolant. Coolant-to-mainstream density ratios (DRs) of 1.0 and 2.0 were investigated. The most efficient use of coolant hinged on balancing the downstream MFR for the second row due to the endwall pressure gradient preventing coolant from exiting the holes or a high jet velocity causing liftoff. For this row, selecting the optimum MFR increased the area-averaged film cooling effectiveness by up to 200% with a reduction in row 1 of less than 25%. At high downstream MFRs, increasing the density ratio delayed liftoff and increased film cooling effectiveness in row 2 by 65%. However, at low MFRs, increasing the density ratio reduced film cooling effectiveness in row 2 by 60%.","PeriodicalId":267158,"journal":{"name":"Volume 6A: Heat Transfer — Combustors; Film Cooling","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127073840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Crossflow Effect on Heat Transfer and Flow Characteristics of Simplified Double Wall Cooling Structure","authors":"Juan He, Qinghua Deng, K. Xiao, Z. Feng","doi":"10.1115/gt2022-82769","DOIUrl":"https://doi.org/10.1115/gt2022-82769","url":null,"abstract":"\u0000 Double wall cooling is regarded as one of the advanced cooling technologies of modern gas turbines, but its internal cooling is always confronted with crossflow effect. To reveal the conjugate heat transfer characteristics under different crossflow configurations, this paper utilized ANSYS CFX to numerically simulate a double wall cooling model with staggered impingement holes and film holes. CFX numerically solves steady three-dimensional Reynolds-Averaged Navier-Stokes (RANS) equations. Both the overall cooling and internal heat transfer performance of four different crossflow mass flow ratios (CMFR = 0, 0.25, 0.5, 0.75) under four impingement jet Reynolds numbers (Rej = 15,000, 25,000, 35,000, 45,000) are compared in detail. The calculated results show that the CMFR has significant influence on double wall cooling performance. The averaged blowing ratio increases with the increase of jet Reynolds number under the same crossflow configuration, and it decreases with the increase of CMFR under the same impingement jet Reynolds number. The area-averaged Nusselt number decreases with the increase of CMFR at the CMFR ranging from 0.25 to 0.75, but the area-averaged overall cooling effectiveness increases with the increase of CMFR since better film coverage plays a dominated role in the enhancement effect of double wall cooling. In addition, the influence of solid thermal conductivity is also taken into consideration. It is revealed that solid thermal conductivity has great influence on double wall cooling. Under all crossflow configurations, the overall cooling effectiveness increases with the increase of solid thermal conductivity, but the increase rate slows down with the increase of thermal conductivity.","PeriodicalId":267158,"journal":{"name":"Volume 6A: Heat Transfer — Combustors; Film Cooling","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129944590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of Freestream Turbulence on Air-Mist Film Cooling: Two-Phase Flow Simulations","authors":"A. Dwivedi, S. Sarkar","doi":"10.1115/gt2022-81923","DOIUrl":"https://doi.org/10.1115/gt2022-81923","url":null,"abstract":"\u0000 Air-mist film cooling is a potential technique to protect the surface of turbine vanes operating at high temperatures for improved thermal efficiency. The variation in the performance of air-mist film coolant is evaluated here for a wide range of freestream turbulence (0.2 to 10%) like the operating condition of the gas turbine. The investigated domain consists of a flat plate with a series of discrete holes of 35° streamwise orientation and connected to a common delivery plenum chamber via a pipe of diameter D = 12.7mm. A two-phase mist consisting of finely dispersed water droplets of 10.0μm in an airstream at a mist concentration of 3.0% is introduced as a secondary flow. The blowing ratio and density ratio are 0.5 and 1.2, respectively, where the Reynolds number based on the diameter of the hole is 1.0 × 104. The Reynolds Averaged Navier Stokes equation in the Eulerian-Lagrangian frame is used to simulate the two-phase flow by ANSYS Fluent 15.0 with the k-ε realizable model. The simulation resolves the mean thermal-flow field and dynamics of droplets. The injected droplets in the crossflow behave like a small heat sink as they evaporate while advecting downstream and are expected to provide improved protection of the heated surface. High turbulence intensity enhances the mixing of droplets with the crossflow, thereby improving the spanwise diffusion of droplets. Reduction of the strength of the counter-rotating vortex pair is also evident. The area-averaged film cooling effectiveness increases by 21.5%, with an increase of turbulence intensity from 0.2 to 10%. However, the increase in aerodynamic losses is almost as high as 39%.","PeriodicalId":267158,"journal":{"name":"Volume 6A: Heat Transfer — Combustors; Film Cooling","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116222260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Aero-Thermal Analysis of Non-Axisymmetric and Flat Endwalls Under the Operational and Geometrical Uncertainties","authors":"Zhiqin. Tao, Jie Wang, Liming Song, Jun Li","doi":"10.1115/gt2022-83159","DOIUrl":"https://doi.org/10.1115/gt2022-83159","url":null,"abstract":"\u0000 Given the rapidly increasing turbine inlet temperature and aerodynamic loads, turbine endwalls are bearing exceptionally harsh flow and thermal conditions. Therefore, the turbine endwalls must be meticulously and efficiently designed, with special attention to the influences of geometric and operational uncertainties. This is of vital importance to the efficient and reliable operation of gas turbines. In this paper, a generic uncertainty analysis framework was established for different endwall schemes. Operational fluctuations of the mainstream and geometrical tolerances of the purge slot were taken as input uncertainties. The aero-thermal performance of a benchmark flat endwall and a non-axisymmetric endwall contouring (NEC) was statistically analyzed and compared under the propagation of the input uncertainties. Results showed that, despite the impact of the input uncertainties, the NEC endwall remained effective in enhancing the statistical performance of all three criteria. It was noteworthy that the NEC endwall also greatly reduced the sensitivity of the areas dominated by secondary vortices to the input uncertainties. However, its profiled regions were found to be highly sensitive to the input uncertainties. Furthermore, the influential uncertain parameters were also identified and compared for the flat and NEC endwalls. The inlet flow angle was the most significant parameter for the three performance criteria of the flat endwall. However, for the NEC endwall, the importance of the inlet flow angle was significantly reduced. Instead, the mainstream turbulence intensity became the most influential parameter for the aerodynamic and heat transfer performance, and the slot width became the most influential parameter for the film cooling performance. The underlying flow physics was well explained by CFD results.","PeriodicalId":267158,"journal":{"name":"Volume 6A: Heat Transfer — Combustors; Film Cooling","volume":"183 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124635361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Effect of Diffuser Shape for Film Cooling Holes With Constant Expansion Angles and Area Ratio","authors":"Evan Lundburg, S. Lynch, Kevin Liu, Hongzhou Xu, M. Fox","doi":"10.1115/gt2022-81520","DOIUrl":"https://doi.org/10.1115/gt2022-81520","url":null,"abstract":"\u0000 Shaped film cooling holes are used in gas turbine components to deliver coolant to the high temperature surfaces of turbine blades and vanes to improve their durability. In general, shaped holes are created by expanding the outlet of the hole, resulting in a large area at the outlet of the hole that diffuses the flow. It has been shown in past studies that increasing the diffuser outlet to meter inlet area ratio causes a lower average momentum of the coolant jet at the hole exit, thereby producing better cooling performance. Instead of increasing the size of the diffuser section by increasing the area ratio, the present study focuses on changing the cross-section shape of the diffuser. This is done to mimic changes observed in the diffuser shape of conventionally manufactured film cooling holes. The present study utilizes 10-10-10 diffuser expansion angles and maintains a constant diffuser to meter area ratio. However, the diffuser shape is varied by changing the diffuser edge angle, κ, located between the diffuser sidewall and the diffuser downstream wall. Three film cooling hole shapes were tested using three different diffuser edge angles, resulting in a narrow outlet, a wide outlet, and a standard outlet film cooling hole. Each hole shape was tested in a large wind tunnel with coolant supplied to the film cooling holes at three different blowing ratios by a co-flow and counterflow delivery channel, similar to the delivery method in a turbine vane with an internal baffle. In addition, the film cooling holes were tested with simulated diffuser roughness. Adiabatic effectiveness measurements indicate that film cooling hole performance is most impacted by diffuser roughness. The film cooling hole shape arising from the diffuser edge angle directly impacts the sensitivity to blowing ratio and coolant feed direction. Therefore, it is recommended that manufacturing of film cooling holes focus on reducing roughness in the diffuser for the highest performance. It is also recommended that the tolerance of the film cooling hole shape be biased towards wider film cooling holes to minimize sensitivity to the blowing ratio and coolant feed direction.","PeriodicalId":267158,"journal":{"name":"Volume 6A: Heat Transfer — Combustors; Film Cooling","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129321493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Conjugate Heat Transfer of Cylindrical and Trenched Film Cooling Designs With Array Jet Impingement","authors":"Lukas Fischer, A. Sanchez, Fabian Schleich, Fabian Feller, Richard Raffelt, M. Pfitzner","doi":"10.1115/gt2022-80810","DOIUrl":"https://doi.org/10.1115/gt2022-80810","url":null,"abstract":"\u0000 A numerical film cooling study involving different external cooling designs, thermal barrier coating (TBC) and internal cooling methods is performed. The steady Reynolds Averaged Navier Stokes (RANS) equations are solved including conjugate heat transfer (CHT). The heat transfer coefficient and material properties of the TBC and vane material lead to a proper scaling of the Biot number with respect to real engines. The cooling efficiency of the external surface and of the wall interface between TBC and vane are evaluated. Three film cooling designs, namely standard effusion hole film cooling as well as transverse and optimized trenches are investigated. Moreover, the effect of array jet impingement and convective channel cooling is investigated onto the external and interface cooling efficiency. The jet Reynolds number of the impingement and effusion cooling is varied between 3100–12300 at blowing ratios between 0.3 and 1.2. The main-stream Reynolds number varied between 4500 and 11000 depending on the tested density ratio. The external cooling efficiency of both trench designs showed to be superior to the standard effusion case. With respect to the interface cooling efficiency, there was an improvement in efficiency of 0.1 visible for the trenched designs compared to the standard effusion hole design. Moreover, flow ingestion into the trenches and the external heat flux and heat transfer coefficient are investigated.","PeriodicalId":267158,"journal":{"name":"Volume 6A: Heat Transfer — Combustors; Film Cooling","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127344345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Turbine Vane Passage Cooling Experiments With a Close-Coupled Combustor-Turbine Interface Geometry Part 1: Describing the Flow","authors":"Kedar P. Nawathe, Aaditya R. Nath, Yong W. Kim, T. Simon","doi":"10.1115/gt2022-80225","DOIUrl":"https://doi.org/10.1115/gt2022-80225","url":null,"abstract":"\u0000 Due to the proximity of the first stage gas turbine vanes to the combustor, coolant introduced to the combustor walls interacts with the endwall film coolant and changes the vane passage flow physics. Recent results show that combustor coolant contributes significantly to cooling the endwall and vane surfaces. In this paper, the traditional combustor-turbine interface was modified to improve overall cooling performance. The performance of this new injection cooling scheme on passage fluid dynamics and surface cooling is assessed. The first of this two-part paper reports detailed experimental tests that document secondary flows and coolant transport throughout the vane passage for four combustor coolant flowrates. The experimental facility imitates combustor coolant injection and engine-level turbulence and has a modified transition duct design, called the ‘close-coupled combustor-turbine interface.’ The ‘impingement vortex’ seen in previous studies with combustor cooling appears as the dominant secondary flow. It is observed in the present study over a wide range of flowrates, confirming its tie to the combustor coolant flowrate and not the combustor-turbine interface geometry. It was found, however, that the location and size of the impingement vortex are affected by coolant flowrate. The second of this two-part paper discusses the impact of the observed secondary flows on cooling vane passage surfaces.","PeriodicalId":267158,"journal":{"name":"Volume 6A: Heat Transfer — Combustors; Film Cooling","volume":"142 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116565265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Large Eddy Simulation Based Optimization of a Fan-Shaped Cooling Hole Geometry to Enhance Cooling Performance","authors":"Shubham Agarwal, L. Gicquel, F. Duchaine, N. Odier, J. Dombard, D. Bonneau, Michel Slusarz","doi":"10.1115/gt2022-79923","DOIUrl":"https://doi.org/10.1115/gt2022-79923","url":null,"abstract":"\u0000 In this study, a shaped hole optimization approach based on Large Eddy Simulations and Efficient Global Optimization (EGO) is presented. The shape of a fan-shaped hole used for turbine film cooling is then optimized to maximize the film cooling performance and the numerical problem is modeled using flow configurations close to those in real gas turbine conditions. Four of the most important geometrical parameters defining a cooling hole shape, namely the depth of the expanded section, the hole inclination angle and the forward and the lateral expansion angles are selected as the design variables to obtain the optimal hole shape. Forty design cases at start are selected via an Optimal Latin Hypercube Sampling method (OLHS) and further more are added during the successive iteration steps of the optimization algorithm. The handling of these design cases including the CAD creation of the geometries, computational domains, meshes and finally the numerical setup is handled by the LES based autonomous tool which has been previously validated [1]. Finally, the Bayesian based EGO [2] method along with the Expected Improvement (EI) as the acquisition function is used to maximize the surface averaged film cooling effectiveness as the objective function. After several database enrichment steps to reduce the overall modal error of the response surface an optimal shape of the cooling hole with the highest cooling performance is obtained. The optimal geometry thus obtained has a significantly higher cooling performance than the reference hole shape which is also confirmed via the study of the fluid flow distribution in both the cases. Overall, this study shows that, Large Eddy Simulations can be successfully coupled along with an EGO based optimization approach to obtain the optimal shaped cooling hole in a computer-aided optimization setting.","PeriodicalId":267158,"journal":{"name":"Volume 6A: Heat Transfer — Combustors; Film Cooling","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123123019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Investigation of the Effects of Thermal Barrier Coating on Twisted Blade Full Film Cooling","authors":"Haojun Yan, Cun-liang Liu, Li Zhang, Yu-hang Guo","doi":"10.1115/gt2022-82118","DOIUrl":"https://doi.org/10.1115/gt2022-82118","url":null,"abstract":"\u0000 Film cooling and thermal barrier coating technologies are often used in thermal protection of aero-engine turbine blades. But the film-hole structure can be often affected by thermal barrier coatings (TBC) spraying, resulting in the variations of aerodynamic and thermal performances of film cooling. In this paper, adiabatic film cooling effectiveness distribution contours of twisted vanes with multi-row film cooling holes in fan-shaped cascade tunnel were obtained by PSP technology. The effects of TBC on twisted vanes film cooling effectiveness were studied, which was sprayed by electron beam physical vapor deposition (EB-PVD). Three typical density ratio (DR) of 1.0, 1.5 and 2.0 and three mass flow ratio (MFR) of 8.92%, 10.45% and 12.21% were test. The air was selected as the mainstream, nitrogen, carbon dioxide and 15% sulfur hexafluoride mixd with 85% argon were independently selected as secondary flow to produce three density ratios of 1.0, 1.5 and 2.0.\u0000 The results indicate that TBC improves film cooling effectiveness on suction surface by 6.2%–16.67%, and significantly reduces the film cooling effectiveness on the leading edge (37.7%–52.7%) and gill areas of the pressure surface (28.8%–32%). In these three regions, the difference between vanes with and without TBC is slightly affected by the change of MFR, and gradually decreased with the increase of density ratio. The film cooling effectiveness of the pressure surface near the trailing edge is less weakened by the TBC, where the maximum reduction is 8.92%. Compared with the cylindrical hole rows, TBC has less impacts on film cooling effectiveness at fan-shaped hole rows.","PeriodicalId":267158,"journal":{"name":"Volume 6A: Heat Transfer — Combustors; Film Cooling","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125214387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}