Volume 7B: Heat Transfer最新文献_第4页

Penetration and Mixing Characteristics of Inclined Jets in Crossflow at Low Momentum Flux Ratios 低动量通量比下斜射流在横流中的侵彻与混合特性

Volume 7B: Heat Transfer Pub Date : 2020-09-21 DOI: 10.1115/GT2020-14949

Rahul B. Vishwanath, Timothy M. Wabel, A. Steinberg

{"title":"Penetration and Mixing Characteristics of Inclined Jets in Crossflow at Low Momentum Flux Ratios","authors":"Rahul B. Vishwanath, Timothy M. Wabel, A. Steinberg","doi":"10.1115/GT2020-14949","DOIUrl":"https://doi.org/10.1115/GT2020-14949","url":null,"abstract":"\u0000 This study investigates the factors affecting low momentum jets that are injected at an angle relative to a crossflow stream, which is relevant to film-cooling technologies. Quantitative measurements of the jet fluid concentration were obtained based on planar laser induced fluorescence (PLIF) from acetone vapor that was seeded into the jet. The jets were injected at four different axial locations downstream of the leading edge of a flat plate, resulting in different boundary layer thicknesses at the injection location. At each location, the jet-to-crossflow momentum flux ratio was varied from 0.5–5. The jet centerline trajectories were affected not only by the momentum flux ratios, but also by the approaching crossflow boundary layer thickness, with the jets penetrating the least for the thickest boundary layers. Measurements of the jet fluid concentration along the jet centerline showed an exponential decay rate of −1.3 across all cases. However, the behavior in the immediate vicinity of the jet depended on the boundary layer thickness, with thicker boundary layers resulting in a slower decay. Hence, the concentration profiles were shifted relative to the injection point depending on the injector position on the plate. The concentration profiles perpendicular to the jet axis were self-similar when scaled with the profile half-width.","PeriodicalId":147616,"journal":{"name":"Volume 7B: Heat Transfer","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126320213","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}

引用次数: 1

Numerical Study on Film Effectiveness and Heat Transfer Characteristics of Aero-Engine Nose Cone With Hot Air Film 含热空气膜的航空发动机前锥膜效能及传热特性数值研究

Volume 7B: Heat Transfer Pub Date : 2020-09-21 DOI: 10.1115/GT2020-14649

T. Yang, Li Zhang, Hui-ren Zhu, Xing Wang

{"title":"Numerical Study on Film Effectiveness and Heat Transfer Characteristics of Aero-Engine Nose Cone With Hot Air Film","authors":"T. Yang, Li Zhang, Hui-ren Zhu, Xing Wang","doi":"10.1115/GT2020-14649","DOIUrl":"https://doi.org/10.1115/GT2020-14649","url":null,"abstract":"\u0000 When the aircraft works in an environment containing supercooled water droplets, it is easy to cause the engine inlet nose cone on the windward side to freeze, which not only affects the performance of the engine, but also leads to flight accidents. Therefore, it is necessary to research the anti-icing technology of aero-engine nose cone components. At present, the air intake cone of the aircraft mainly forms a thermal anti-icing system by means of hot film anti-icing and heating impingement anti-icing.\u0000 In this paper, the effects of blowing ratio, film hole pitch, hole shape and film hole arrangement method on film heating effectiveness and heat transfer characteristics are studied by numerical simulation methods for the hot film anti-icing system of the nose cone. The results show that with the increase of the blowing ratio, the film heating effectiveness in the downstream area quickly decreases first and then increases, and the range of change aggrandizes. Under the given condition, as the pitch between the film holes decreases, the area covered by the film extends, and the heating effectiveness improves significantly. In the case of high blowing ratio, the advantage of film heating effectiveness of waist-shaped film hole is more apparent. The laterally-averaged film heating effectiveness of the staggered film holes is much higher than that of the aligned film holes. For the characteristics of film heat transfer, the hole pitch and hole shape has little effect on the heat transfer characteristics at low blowing ratio. In the case of high blowing ratio, the heat transfer effect will be greatly weakened when the hole pitch is increased, moreover the heat transfer efficiency of the waist-shaped hole is better. In the region near the exit of the secondary row film hole, the heat transfer characteristics of the staggered structure is stronger than that in the aligned structure. In addition, it is found that the high heat transfer region for staggered arrangement shows W–shaped.","PeriodicalId":147616,"journal":{"name":"Volume 7B: Heat Transfer","volume":"122 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122432404","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}

引用次数: 0

Nozzle Passage Endwall Effectiveness Values With Various Combustor Coolant Flow Rates: Part 2 — Endwall and Vicinity Surface Effectiveness Measurements 不同燃烧室冷却剂流量的喷嘴通道端壁有效性值:第2部分-端壁和附近表面有效性测量

Volume 7B: Heat Transfer Pub Date : 2020-09-21 DOI: 10.1115/GT2020-15581

Kedar P. Nawathe, R. Zhu, Enci Lin, Y. Kim, T. Simon

{"title":"Nozzle Passage Endwall Effectiveness Values With Various Combustor Coolant Flow Rates: Part 2 — Endwall and Vicinity Surface Effectiveness Measurements","authors":"Kedar P. Nawathe, R. Zhu, Enci Lin, Y. Kim, T. Simon","doi":"10.1115/GT2020-15581","DOIUrl":"https://doi.org/10.1115/GT2020-15581","url":null,"abstract":"\u0000 Effective coolant schemes are required for providing cooling to the first stage stator vanes of gas turbines. To correctly predict coolant performance on the endwall and vane surfaces, these coolant schemes should also consider the effects of coolant streams introduced upstream in the combustor section of a gas turbine engine. This two-part paper presents measurements taken on a first-stage nozzle guide vane cascade that includes combustor coolant injection. The first part of this paper explains how coolant transport and coolant-mainstream interaction in the vane passage is affected by changing the combustor coolant and endwall film coolant flow rates. This paper explains how those flows affect the coolant effectiveness on the endwall. Part one showed that a significant amount of coolant injected upstream of the endwall is present along the pressure surface of the vanes as well as over the endwall. Part two shows effectiveness measurement results taken in this study on the endwall and pressure and suction surfaces of the vanes. Sustained endwall coolant effectiveness is observed along the whole passage for all cases. It is uniform in the pitch-wise direction. Combustor coolant flow significantly affects cooling performance even near the trailing edge. The modified flow field results in the pressure surface being cooled more effectively than the suction surface. While the effectiveness distribution on the pressure surface varies with combustor and film coolant flow rates, the suction surface remains largely unchanged.","PeriodicalId":147616,"journal":{"name":"Volume 7B: Heat Transfer","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132154065","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}

引用次数: 0

Large Eddy Simulation of the 7-7-7 Shaped Film Cooling Hole at Axial and Compound Angle Orientations 轴向和复合角取向下7-7-7型气膜冷却孔的大涡模拟

Volume 7B: Heat Transfer Pub Date : 2020-09-21 DOI: 10.1115/GT2020-14439

K. Tracy, S. Lynch

{"title":"Large Eddy Simulation of the 7-7-7 Shaped Film Cooling Hole at Axial and Compound Angle Orientations","authors":"K. Tracy, S. Lynch","doi":"10.1115/GT2020-14439","DOIUrl":"https://doi.org/10.1115/GT2020-14439","url":null,"abstract":"\u0000 Shaped film cooling holes are used extensively for film cooling in gas turbines due to their superior performance in keeping coolant attached to the surface, relative to cylindrical holes. However, fewer studies have examined the impact of the orientation of the shaped hole axis relative to the main flow direction, known as a compound angle. A compound angle can occur intentionally due to manufacturing, or unintentionally due to changes in the main flow direction at off-design conditions. In either case, the compound angle causes the film cooling jet to roll up into a strong streamwise vortex that changes the lateral distribution of coolant, relative to the pair of vortices that develop from an axially oriented film cooling hole. In this study, Large Eddy Simulation (LES) using the Wall-Adapting Local Eddy Viscosity (WALE) model was performed on the publicly available 7-7-7 shaped film cooling hole, at two orientations (0°, 30°) and two blowing ratios (M = 1, 3). Laterally-averaged film effectiveness was largely unchanged by a compound angle at a blowing ratio of 1, but improved at a blowing ratio of 3. For both blowing ratios, the lateral distribution of film was more uniform with the addition of a 30° compound angle. Both wall normal and lateral turbulent convective heat transfer was increased by the addition of a compound angle at both blowing ratios.","PeriodicalId":147616,"journal":{"name":"Volume 7B: Heat Transfer","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121253129","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}

引用次数: 4

Transfer Function Based Optimization of Film Hole Sizes With Conjugate Heat Transfer Analysis 基于传递函数的膜孔尺寸优化与共轭传热分析

Volume 7B: Heat Transfer Pub Date : 2020-09-21 DOI: 10.1115/GT2020-14137

S. Dutta, Reid Smith

{"title":"Transfer Function Based Optimization of Film Hole Sizes With Conjugate Heat Transfer Analysis","authors":"S. Dutta, Reid Smith","doi":"10.1115/GT2020-14137","DOIUrl":"https://doi.org/10.1115/GT2020-14137","url":null,"abstract":"\u0000 With the improvements of 3D metal printing of turbine components, it is now feasible to produce ready to use production quality parts without casting and conventional machining. This new manufacturing technique has opened new frontiers in cooling optimizations that could not be practiced before. For example, it is now or in-the-near-future possible to have unconventional diameters of film holes. This paper seeks to optimize each film hole diameter at the leading edge of a turbine to achieve an optimum thermal objective. The design technique developed uses a transfer function-based learning model and can be used for both stationary and rotating airfoils. Proposed optimization procedure will also work on other parts of an airfoil; but our current analysis is limited to the leading-edge region. To apply this work on other critical regions, the corresponding heat transfer coefficients need to be implemented while building the transfer functions suitable for that specific component; however, the underlying optimization technique stays the same for any other component. Any optimization technique needs cost and benefit criteria. Cost is minimized in optimization to get maximum benefit with given constraints. In gas-turbine heat transfer, there is a ceiling constraint on maximum temperature that must be satisfied. This study minimizes the coolant flow with satisfying the constraints on average metal temperature and metal temperature variations that limit the life of turbine components. Proposed methodology provides a scientific basis for the sizing of film holes and is expected to decrease developmental cost of efficient thermal designs.","PeriodicalId":147616,"journal":{"name":"Volume 7B: Heat Transfer","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122935379","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}

引用次数: 4

Experimental Investigation of Film Cooling Performance on Blade Endwall With Diffusion Slot Holes and Stator-Rotor Purge Flow 带有扩散槽孔和定转子吹扫流的叶片端壁气膜冷却性能实验研究

Volume 7B: Heat Transfer Pub Date : 2020-09-21 DOI: 10.1115/gt2020-14417

Zhiqiang Yu, Jianjun Liu, Chen Li, B. An, Guangyao Xu

{"title":"Experimental Investigation of Film Cooling Performance on Blade Endwall With Diffusion Slot Holes and Stator-Rotor Purge Flow","authors":"Zhiqiang Yu, Jianjun Liu, Chen Li, B. An, Guangyao Xu","doi":"10.1115/gt2020-14417","DOIUrl":"https://doi.org/10.1115/gt2020-14417","url":null,"abstract":"\u0000 This paper focuses on the influences of the discrete hole shape and layout on the blade endwall film cooling effectiveness. The effect of upstream purge slot injection on the film cooling performance of the discrete hole was also investigated. The diffusion slot hole was first applied to the blade endwall. As a comparison, the cooling performance of the fan-shaped hole was also measured. Totally, six discrete-hole cooling configurations (2 hole shapes × 3 layouts) were investigated. Experiments were performed in a seven-blade linear cascade with the exit Reynolds number of 2.64 × 105. The average blowing ratios (BR) of the discrete holes changed from 0.5 to 2.5, and the coolant mass flow ratio of the purge slot (MFR) was fixed at MFR = 1.5%. The distributions of the cooling effectiveness on the blade endwall were measured by the pressure sensitive paint technique. Results indicate that the diffusion slot hole significantly increases the film cooling effectiveness on the blade endwall compared to the fan-shaped hole, especially at high blowing ratio. The maximum relative increment of the cooling effectiveness is over 40%. The layout with the discrete holes arranged lining up with the tangent direction of the blade profile offset curves exhibits a comparable film cooling effectiveness with the layout with the discrete holes arranged according to the cross-flow direction. The film cooling effectiveness on the pressure surface corner is remarkably enhanced by deflecting the hole orientation angle towards the pressure surface. The combination of purge slot and diffusion slot holes supplies a full coverage film cooling for the entire blade endwall at MFR = 1.5% and BR = 2.5. In addition, the slot injection leads to a non-negligible influence on the cooling performance of the discrete holes near the separation line.","PeriodicalId":147616,"journal":{"name":"Volume 7B: Heat Transfer","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117057721","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}

引用次数: 0

Numerical Evaluation of Surface Roughness Effects on Film-Cooling Performance in a Laidback Fan-Shaped Hole 扇形孔表面粗糙度对气膜冷却性能影响的数值评价

Volume 7B: Heat Transfer Pub Date : 2020-09-21 DOI: 10.1115/GT2020-14525

A. Zamiri, S. You, J. Chung

{"title":"Numerical Evaluation of Surface Roughness Effects on Film-Cooling Performance in a Laidback Fan-Shaped Hole","authors":"A. Zamiri, S. You, J. Chung","doi":"10.1115/GT2020-14525","DOIUrl":"https://doi.org/10.1115/GT2020-14525","url":null,"abstract":"\u0000 This study numerically investigates the influences of cooling hole surface roughness in a laidback fan-shaped hole on the flow structure and film-cooling effectiveness. The three-dimensional compressible LES approach (large eddy simulation) is conducted in a baseline 7-7-7 laidback fan-shaped hole. The cooling hole is located on a flat plate surface with a 30-degree injection angle at a constant density ratio DR = 1.5 and two blowing ratios M = 1.5 and 3. The computational results were validated by the measurements in terms of velocity and thermal fields for both the smooth and rough holes. In order to numerically consider the influences of the surface roughness on cooling hole side, the equivalent sand grain roughness method was utilized. Different correlations between the equivalent sand grain roughness height and arithmetic average roughness height were numerically tested to find an accurate correlation in comparison to the measurements. The computational data revealed that the surface roughness of the hole interior walls increases the thickness of the boundary layers within the hole. This leads to a higher jet core flow at the hole exit and lower film-cooling performance at the surface of flat plate compared to those of the smooth cooling hole. The minimum area-averaged film-cooling performance was observed in the case of the highest blowing ratio and the largest surface roughness height. The present work reveals that the current LES approach by considering the proper equivalent sand grain roughness height is a powerful tool to obtain the accurate solution in the prediction of the heat transfer characteristics and the flow structures in the fan-shaped cooling holes.","PeriodicalId":147616,"journal":{"name":"Volume 7B: Heat Transfer","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129189255","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}

引用次数: 0

Nozzle Passage Endwall Effectiveness Values With Various Combustor Coolant Flow Rates: Part 1 — Flowfield Velocity and Coolant Concentration Measurements 不同燃烧室冷却剂流量的喷嘴通道端壁有效性值:第1部分-流场速度和冷却剂浓度测量

Volume 7B: Heat Transfer Pub Date : 2020-09-21 DOI: 10.1115/gt2020-15583

Kedar P. Nawathe, R. Zhu, Enci Lin, Y. Kim, T. Simon

{"title":"Nozzle Passage Endwall Effectiveness Values With Various Combustor Coolant Flow Rates: Part 1 — Flowfield Velocity and Coolant Concentration Measurements","authors":"Kedar P. Nawathe, R. Zhu, Enci Lin, Y. Kim, T. Simon","doi":"10.1115/gt2020-15583","DOIUrl":"https://doi.org/10.1115/gt2020-15583","url":null,"abstract":"\u0000 The stators of the first stage of a gas turbine are exposed to severe temperatures. The coolant streams introduced to prevent the stators from thermal damage further complicate the highly three-dimensional flow in the vane passage. Recent results have shown that, in addition to these coolant streams, the coolant streams injected for cooling the combustor also influence the flow physics and the cooling effectiveness in the first-stage stator vanes passage. However, the effects of changing the mass flow rate of these combustor coolant streams on the passage flowfield have not been studied. As understanding the coolant transport is necessary for analyzing changes in cooling effectiveness in the vane passage, detailed aerodynamic and thermal measurements along the whole vane passage are required. This two-part paper presents such measurements taken in a first-stage nozzle guide vane cascade for a variety of combustor coolant and endwall film coolant flow rates. The experiments were conducted in a low-Mach-number facility with engine-representative Reynolds numbers and large-scale high-level turbulence. The objective of the first part of the paper is to describe the flow that influences endwall and vane surface cooling effectiveness distributions, which are presented in the second part of this paper. The measurements show changes in the passage flowfield due to changes in both combustor coolant and endwall film coolant flow rates. Overall, the flow-physics remains largely unaffected by changes in coolant flow rates except in the endwall-vane surfaces region where the combustor coolant flow rate dominates changes in coolant transport. This is shown to have a high impact on endwall and vane surface cooling.","PeriodicalId":147616,"journal":{"name":"Volume 7B: Heat Transfer","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129322920","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}

引用次数: 0