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

{"title":"Shape Optimization of the Laidback Fan-Shaped Film Cooling Hole on Pressure Surface of Turbine Guide Vane","authors":"Yan-huan Jiang, Zhi Tao, Haiwang Li, Zhiyu Zhou","doi":"10.1115/gt2022-82358","DOIUrl":"https://doi.org/10.1115/gt2022-82358","url":null,"abstract":"\u0000 The present study employed computational fluid dynamics (CFD) to explore the effect of the shape parameters of fan-shaped holes on film cooling effectiveness, and the optimum values and variation laws of each shape parameter to maximize the averaged film cooling effectiveness were presented. Meanwhile, experimental verification was used in the optimum holes and reference cylindrical holes.\u0000 Among the shape parameters of a laidback fan-shaped film hole, the injection angle, the hole diameter and the hole length were fixed as 30 degrees, 0.5 millimeter and 2 millimeters, respectively, and the three shape parameters, the forward expansion angle, the lateral expansion angle, and the shaped-length ratio, were selected as design variables by the Box-Behnken Design (BBD) method. And RSM (Response Surface Methodology) was used to obtain the optimized values of each parameter. Results show that the film cooling effectiveness of the optimized hole (15-20-0.25) was higher than that of the reference cylindrical holes by 336%. The factors influence analysis showed the film cooling effectiveness increased as the forward expansion angle increased, and increased and then decreased with the lateral expansion angle and the shaped-length ratio. The points of the change in trends were when the lateral expansion angle was almost equal to 15 degrees and the shaped-length ratio was nearly 0.475, respectively. Moreover, there was the oscillation of the film cooling effectiveness distribution, possibly due to the asymmetric and irregular distribution of velocity w of the injected coolant along the downstream direction, when the holes outlet area was excessive. In general, the variation laws were not monotonous; therefore, all shape parameters should be considered simultaneously to achieve shape optimization of the laidback fan-shaped film cooling hole on pressure surface of turbine guide vane.","PeriodicalId":267158,"journal":{"name":"Volume 6A: Heat Transfer — Combustors; Film Cooling","volume":"32 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":"126758637","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":"Interaction Mechanism of Transonic Squealer Tip Cooling With the Effect of High-Speed Relative Casing Motion","authors":"W. Xie, Hongmei Jiang, Shaopeng Lu, Xue Peng, Qiang Zhang","doi":"10.1115/gt2022-83169","DOIUrl":"https://doi.org/10.1115/gt2022-83169","url":null,"abstract":"\u0000 The relative casing motion can significantly influence the turbine blade tip aerothermal performance. In this study, experimental investigation was conducted in a newly developed high-speed disk rotor rig which can mimic engine realistic highspeed casing relative motion while enabling full optical access to a transonic turbine blade tip surface. Spatially-resolved tip heat transfer data, including heat transfer coefficient and film cooling effectiveness, were obtained for a cooled transonic squealer tip by infrared transient thermal measurement. Combined with closely coupled RANS CFD analysis, this paper reveals an interesting interaction mechanism between the cooling injections from the pressure side and the cavity floor with and without the effect of relative casing motion. Both experimental data and CFD results show a consistent trend in both heat transfer and cooling performance. With the cavity cooling only, the cooling performance reduces with the effect of relative casing motion. However, with additional cooling injection from the pressure side, a significant improvement in the combined cooling performance with the relative casing motion can be observed. Such opposite trend highlights the importance of relative casing motion when ranking different tip cooling designs. With the consideration of relative casing motion, extra tip cooling benefit can be obtained by combining cooling injections from two different locations.","PeriodicalId":267158,"journal":{"name":"Volume 6A: Heat Transfer — Combustors; Film Cooling","volume":"96 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":"133625276","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":"Development and Evaluation of Shaped Film Cooling Holes Designed for Additive Manufacturing","authors":"Michael T. Furgeson, Emma M. Veley, Christopher Yoon, D. Gutiérrez, D. Bogard, K. Thole","doi":"10.1115/gt2022-83201","DOIUrl":"https://doi.org/10.1115/gt2022-83201","url":null,"abstract":"\u0000 Film cooling remains a critical technology for cooling gas turbine components. In recent years, additive manufacturing (AM) has been used to develop novel film cooling hole designs which significantly increase the film cooling effectiveness. However, engine scale AM builds have imperfections and roughness that can have a noticeable effect on performance. In this study, 9-9-3 shaped film cooling holes were constructed at engine scale using metal AM, specifically direct laser metal sintering (DMLS). These “as built” geometries were characterized through computerized tomography (CT) scans to quantify deviations from holes with design intent, or “as-designed” holes. To evaluate the performance of the “as-built” holes compared to “as-designed” holes, both adiabatic and overall cooling effectiveness were measured experimentally for 5x scale models. The larger scale enabled the use of finite deposition modeling (FDM) to construct hole geometry that closely matched the “as-designed” holes and the CT scans of the “as-built” holes. Two versions of the 9-9-3 hole were studied, the 9-9-3 rounded inlet (RI) hole with rounding at the inlet, and the 9-9-3 rounded inlet and exit (RIE) hole with additional rounding at the hole inlet, and rounding at the hole exit. Results showed that the adiabatic effectiveness and overall cooling effectiveness for the “as-built” holes were similar to the performance of the “as-designed” film cooling holes for both hole geometries tested.","PeriodicalId":267158,"journal":{"name":"Volume 6A: Heat Transfer — Combustors; Film Cooling","volume":"1982 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":"121195746","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 Evaluation of a Wavy Trailing Edge Cooling Design as an Alternative to Pressure Side Cutback Cooling","authors":"Izhar Ullah, Timothy A. Burdett, L. Wright, Je-Chin Han, C. Lee","doi":"10.1115/gt2022-78286","DOIUrl":"https://doi.org/10.1115/gt2022-78286","url":null,"abstract":"\u0000 This study measures the film cooling effectiveness along the trailing edge of a turbine blade in a linear cascade. The film cooling effectiveness is measured and analyzed using the pressure sensitive paint (PSP) technique. Two different trailing edge designs are investigated including the standard pressure side cutback and the new alternating discharge design (referred to as a wavy trailing edge design). The alternating discharge design is a new design with a wavy structure between the pressure and suction surfaces at the trailing edge. The new wavy structure allows the coolant to discharge from the trailing edge so that it alternates between the pressure and suction surfaces. Testing is carried out in a five-blade, linear, steady state cascade with inlet and exit Mach numbers of 0.20 and 0.30, respectively. The freestream turbulence intensity is measured to be 10.5% upstream of the blade leading edge. Coolant-to-mainstream mass flow ratios (MFR) vary from 0.30% to 1.25% and coolant to mainstream density ratios (DR) of 1.0, 1.5 and 2.0 are examined. The total pressure loss coefficients are also acquired to compare the aerodynamic loss between the two trailing edge designs. The pressure loss coefficient is acquired by traversing a group of pitot static probes across the blade span in a plane downstream of the trailing edge, resulting in a pressure map at the exit plane. A positive MFR and DR effect is witnessed with almost no change in aerodynamic loss. The results provide the potential of the alternating discharge as a promising trailing edge design and provide gas turbine designers with an improved trailing edge cooling scheme having acceptable aerodynamic loss.","PeriodicalId":267158,"journal":{"name":"Volume 6A: Heat Transfer — Combustors; Film Cooling","volume":"655 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":"116482597","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":"Printability and Overall Cooling Performance of Additively Manufactured Holes With Inlet and Exit Rounding","authors":"Emma M. Veley, K. Thole, Michael T. Furgeson, D. Bogard","doi":"10.1115/gt2022-83313","DOIUrl":"https://doi.org/10.1115/gt2022-83313","url":null,"abstract":"\u0000 To improve cooling effectiveness of gas turbine hardware, various film cooling hole shapes have previously been researched. Unique design modifications have recently been made possible through the design freedom allotted by additive manufacturing. As one example, creating a rounded inlet for a film-cooling hole can mitigate separation at the inlet. This study explores various geometric features by exploiting the uses of additive manufacturing for shaped film cooling holes at engine scale. Both printability and cooling performance were evaluated.\u0000 Resulting from this study, additively manufactured holes with hole inlet and exit rounding were printed with some variations from the design intent. The largest deviations from the design intent occurred from dross roughness features located on the leeward side of the hole inlet. The measured overall effectiveness indicated that an as-built inlet fillet decreased in-hole convection as well as decreased jet mixing compared to the as-built sharp inlet. Including an exit fillet, which prevented an overbuilt diffuser exit, was also found to decrease jet mixing. A particular insight gained from this study is the importance of the convective cooling within the hole to the overall cooling performance. In-hole roughness, which is a result of additive manufacturing, increased convective cooling within the holes but also increased jet mixing as the coolant exited the hole. The increased jet mixing caused low overall effectiveness downstream of injection.","PeriodicalId":267158,"journal":{"name":"Volume 6A: Heat Transfer — Combustors; Film Cooling","volume":"37 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":"121559360","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 of Energy Transport in Highly Compressible Transverse Jets","authors":"Hao Guo, P. Jiang, Yinhai Zhu","doi":"10.1115/gt2022-81307","DOIUrl":"https://doi.org/10.1115/gt2022-81307","url":null,"abstract":"\u0000 Large eddy simulation is performed to study the thermal energy transport and mixing process of a round laminar jet in a fully-turbulent high-Mach-number crossflow. In this study, the energy equation of highly compressible fluid is systematically analyzed and the contributions of each term in the equation are compared quantitatively. Turbulent enthalpy transport is found to be in the same order of magnitude as the advection term associated with mean motion and thus is not negligible when considering the convective heat transfer problem of film cooling, which differs from the conclusion drawn from the incompressible-jets-in-crossflow studies. The inaccuracy of RANS turbulent modeling caused by counter-gradient transport of enthalpy is explained in detail and a more reasonable three-dimensional analysis method is proposed for in-depth mechanism analysis and turbulent model improvement. The numerical results also show that the contribution of mean motion to the overall kinetic energy dissipation in thermal energy transport is dominant in the near-field region where jets and crossflow interact and mix intensively while the turbulent kinetic energy dissipation term predominates in most other regions. Moreover, the irreversible increase in entropy caused by dissipation and heat transfer in the flow field is compared. The results show that the entropy production due to the latter one cannot be ignored when dealing with large temperature difference film cooling which is common in high-pressure turbines.","PeriodicalId":267158,"journal":{"name":"Volume 6A: Heat Transfer — Combustors; Film Cooling","volume":"104 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":"123109561","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":"Heat Transfer Coefficient and Adiabatic Effectiveness on a Film-Cooled Pressure Side: Results and Assessment of the IR-Based Measurement Technique Reliability","authors":"T. Bacci, A. Picchi, S. Galeotti, B. Facchini, S. Cubeda","doi":"10.1115/gt2022-81161","DOIUrl":"https://doi.org/10.1115/gt2022-81161","url":null,"abstract":"\u0000 The precise knowledge of the external heat transfer coefficient and of the film cooling coverage characteristics is crucial to an efficient design of a turbine nozzle guide vane. From an experimental point of view, thermal methods allow to retrieve both the heat transfer coefficient and the adiabatic wall temperature, but their reliability is generally questionable, as they suffer from problems as thermal conduction. In the present work, a well-known literature nozzle guide vane (VKI LS89 profile) was provided with a simplified cooling system made by a single row of cylindrical holes on the pressure side. A transient thermal technique was employed to characterize both the adiabatic effectiveness and the heat transfer coefficient. The uncertainty and the reliability of thermal technique, which are generally a weak point, were evaluated. The former aspect was addressed by means of virtual experiments, considering both the effect of the measured temperature noise and of the inaccuracies introduced by the physical model adopted for the post-processing. For the latter aspect, adiabatic effectiveness findings were compared to the ones achieved on the same test article from Pressure Sensitive Paint measurements, which have a limited and known degree of uncertainty. The overall results showed that, once a proper approach is taken, the thermal technique is able to accurately retrieve reliable results with an acceptable resolution, even on a test case with dimensions close to real engines. Different fluid-dynamic conditions were investigated to assess the effect of blowing ratio and free-stream turbulence on film cooling performances. The results indicate that the introduction of film cooling on the vane surface significantly enhances the heat transfer coefficient with respect to the uncooled case. Net Heat Flux Reduction was also computed, showing that film effectiveness can not always compensate for the HTC augmentation, highlighting the necessity of properly considering the heat transfer coefficient enhancement.","PeriodicalId":267158,"journal":{"name":"Volume 6A: Heat Transfer — Combustors; Film Cooling","volume":"1 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":"114728356","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":"Wall Curvature Effect on Overall Thermal Performances of Film Cooling Covered by Thermal Barrier Coatings With Various Geometries","authors":"Wenxiao Zhou, J. Pu, Tiao Zhang, Jian-hua Wang, Wei-long Wu, Hang Su","doi":"10.1115/gt2022-82796","DOIUrl":"https://doi.org/10.1115/gt2022-82796","url":null,"abstract":"\u0000 Film cooling coupling with surface thermal barrier coating (TBC) has been widely adopted, bringing to an intensive need of comprehensive overall thermal characteristics. In present work, combined effects of hole-geometry, wall curvature, and cooling air flowrate on the metal overall effectiveness and wall heat flux were discussed. Typical local regions of turbine vanes were simplified as convex, concave, and flat walls. Spraying TBC generated four hole-configurations, including Standard Cylindrical-hole (SC), transverse Trenched-hole (TT-hole), and two modified trenched-holes with Semicircle-shaped Trench (ST) and Sine Wave-shaped Trench (SWT). The ST reduces the exposed area and the SWT improves the fluid-diversion effect of TT. Based on the engine-matched hot-side Biot-numbers, overall cooling effectiveness measurements were carried out under typical blowing ratios (BRs) from 0.5 to 2.0, through capturing wall temperatures by an infrared thermal sensor and thermocouples. Conjugate heat transfer simulations were also conducted, showing good agreement with the experimental data and hence providing additional insights into the heat transfer features and film cooling jet behaviors. The results indicated that the wall curvature effects on overall thermal parameters are relatively weaker, in comparison with the hole-geometry and BR. The trenches can further weaken the wall curvature effect. Comparisons of trench-designs reveals that achievement of strong fluid-diversion in trench is an important principle of trench-modification, which can acquire not only superior overall cooling characteristics, but also a relatively large ability to prevent the hot gas ingestion and the hole-blockages by harmful contaminant-depositions.","PeriodicalId":267158,"journal":{"name":"Volume 6A: Heat Transfer — Combustors; Film Cooling","volume":"82 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":"114071086","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":"Identification of Fluctuation Modes for a Cylindrical Film Cooling Hole Using the Spectral Proper Orthogonal Decomposition Method","authors":"Nicola Rosafio, Giove De Cosmo, S. Salvadori, M. Carnevale, D. Misul","doi":"10.1115/gt2022-79528","DOIUrl":"https://doi.org/10.1115/gt2022-79528","url":null,"abstract":"\u0000 Film cooling is the main technology adopted to guarantee safe working conditions of vanes and blades in high-pressure turbine stages. Recent experimental investigations highlighted that unsteady interaction between the coolant jet and the hot gas contributes to the lateral dispersion of cold flow over the cooled surface. Hence, considering the harsh working environment of these devices, a fair prediction of their thermal performance requires accurate modelling of the interaction between cold and hot gases. In this paper, an experimental setup originally studied at the University of Karlsruhe during the EU-funded TATEF project is numerically investigated to determine the influence of high-frequency unsteady fluctuations on the thermal performance of the cooling device. The case study consists of a film cooling hole positioned on a flat plate, working at engine-like conditions. Unsteady Reynolds-Averaged Navier-Stokes equations are solved for a compressible flow in transonic regime on a hybrid mesh. Turbulence is modelled using the Scale-Adaptive Simulation method to correctly predict the interaction between the coolant and the main flow. Three different sets of conditions are analyzed by varying the blowing ratio from 0.5 to 1.5, aiming at highlighting the unsteady mechanisms occurring for different penetrations of the coolant into the hot gas. Time-averaged unsteady results are compared with the available experimental data to determine to what extent hybrid modelling allows for correctly predicting film cooling performance at different blowing ratios. Instantaneous solutions are then analyzed to investigate the time-dependent flow field in the vicinity of the jet exit section and on the cooled surface. Spectral Proper Orthogonal Decomposition is enforced to identify the principal fluctuation modes associated with the time-dependent coolant penetration into the main flow.","PeriodicalId":267158,"journal":{"name":"Volume 6A: Heat Transfer — Combustors; Film Cooling","volume":"1 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":"126400727","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 Effusion Film Cooling on a Cylindrical Leading Edge Model","authors":"I. Huang, Kuan-Hsueh Lin, Chih-Yung Huang, Yao-Hsien Liu","doi":"10.1115/gt2022-82178","DOIUrl":"https://doi.org/10.1115/gt2022-82178","url":null,"abstract":"\u0000 Effusion film cooling is effective for cooling high temperature turbine blades because it requires less coolant and produces a more uniform temperature distribution than conventional film cooling. Effusion cooling for a cylindrical model representing the leading edge of a gas turbine blade was investigated. The experiment was performed in a low-speed wind tunnel at a Reynolds number of 100,000. Pressure sensitive paint was used to measure the adiabatic film cooling effectiveness. Additive manufacturing was used to fabricate a porous structure on the test cylinder for effusion cooling. Both simple and compound angles were used for cooling injection. The effects of streamwise and spanwise hole spacings, turbulence intensities (1%, 8.7%), and blowing ratios (0.075, 0.15, 0.3, and 0.6) were studied. The effusion hole diameter was 0.1 cm, and the spanwise hole pitch-to-diameter ratios were either 2 or 4. Compared with conventional film cooing, effusion cooling achieved higher cooling effectiveness and produced better coolant coverage. Increasing the streamwise spacing noticeably reduced the cooling effectiveness for the simple-angle design due to film liftoff; the compound-angle designs thus achieved higher effectiveness. The simple-angle holes were more sensitive to changes in the mainstream turbulence intensity; increases in the turbulence intensity promoted the mixing of the coolant with the mainstream. Moreover, effusion cooling was more resistant to coolant lift-off at high blowing ratios.","PeriodicalId":267158,"journal":{"name":"Volume 6A: Heat Transfer — Combustors; Film Cooling","volume":"70 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":"134035501","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}