Volume 5B: Heat Transfer — General Interest; Internal Air Systems; Internal Cooling最新文献

{"title":"Unsteady Turbine Rim Sealing and Vane Trailing Edge Flow Effects","authors":"Iván Monge-Concepción, Shawn Siroka, Reid A. Berdanier, M. Barringer, K. Thole, Christopher W. Robak","doi":"10.1115/gt2021-59273","DOIUrl":"https://doi.org/10.1115/gt2021-59273","url":null,"abstract":"\u0000 Hot gas ingestion into the turbine rim seal cavity is an important concern for engine designers. To prevent ingestion, rim seals use high pressure purge flow but excessive use of the purge flow decreases engine thermal efficiency. A single stage test turbine operating at engine-relevant conditions with real engine hardware was used to study time-resolved pressures in the rim seal cavity across a range of sealing purge flow rates. Vane trailing edge (VTE) flow, shown previously to be ingested into the rim seal cavity, was also included to understand its effect on the unsteady flow field. Measurements from high-frequency response pressure sensors in the rim seal and vane platform were used to determine rotational speed and quantity of large-scale structures (cells). In a parallel effort, a computational model using Unsteady Reynolds-averaged Navier-Stokes (URANS) was applied to determine swirl ratio in the rim seal cavity and time-resolved rim sealing effectiveness. The experimental results confirm that at low purge flow rates, the VTE flow influences the unsteady flow field by decreasing pressure unsteadiness in the rim seal cavity. Results show an increase in purge flow increases the number of unsteady large-scale structures in the rim seal and decreases their rotational speed. However, VTE flow was shown to not significantly change the cell speed and count in the rim seal. Simulations point to the importance of the large-scale cell structures in influencing rim sealing unsteadiness, which is not captured in current rim sealing predictive models.","PeriodicalId":385341,"journal":{"name":"Volume 5B: Heat Transfer — General Interest; Internal Air Systems; Internal Cooling","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130318265","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":"A New Experimental Approach for Heat Transfer Coefficient and Adiabatic Wall Temperature Measurements on a Nozzle Guide Vane With Inlet Temperature Distortions","authors":"T. Bacci, A. Picchi, B. Facchini, S. Cubeda","doi":"10.1115/gt2021-59304","DOIUrl":"https://doi.org/10.1115/gt2021-59304","url":null,"abstract":"\u0000 Modern gas turbines lean combustors allow to limit NOx pollutant emissions by controlling the flame temperature, while maintaining high turbine inlet temperatures. On the other hand, their adoption presents other challenges, especially concerning the combustor-turbine interaction. Turbine inlet conditions are generally characterized by severe temperature distortions and swirl degree, which, in turn, is responsible for very high turbulence intensities. Several past studies have focused on the description of the effects of these phenomena on the behavior of the high pressure stages of the turbine, both considering them as separated aspects, and, in very recent years, accounting for their combined impact. Nevertheless, very limited experimental results are available when it comes to evaluate the heat transfer coefficient (HTC) on the nozzle guide vane external surface, since relevant temperature distortions present a severe challenge for the commonly adopted measurement techniques. The work presented in this paper was carried out on a non-reactive, annular, three-sector test rig, made by a combustor simulator and a NGV cascade. Making use of three real hardware burners of a Baker Hughes heavy-duty gas turbine, operated in similitude conditions, it can reproduce a representative swirling flow, with temperature distortions at the combustor-turbine interface plane. This test apparatus was exploited to develop an experimental approach to retrieve reliable heat transfer coefficient and adiabatic wall temperature distributions simultaneously, in order to overcome the known limitations imposed by temperature gradients on state-of-the-art methods for HTC calculation from transient tests. A non-cooled mockup of a NGV doublet, manufactured using low thermal diffusivity plastic material, was used for the tests, carried out using IR thermography with a transient approach. In the authors’ knowledge, this presents the first experimental attempt of measuring a nozzle guide vane heat transfer coefficient in the presence of relevant temperature distortions and swirl.","PeriodicalId":385341,"journal":{"name":"Volume 5B: Heat Transfer — General Interest; Internal Air Systems; Internal Cooling","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131072667","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 Measurements for Array Jet Impingement With Castellated Wall","authors":"Taehyun Kim, E. Jung, Minho Bang, Changyong Lee, H. Moon, H. Cho","doi":"10.1115/gt2021-58895","DOIUrl":"https://doi.org/10.1115/gt2021-58895","url":null,"abstract":"\u0000 Impingement cooling is one of the powerful cooling methods in high-temperature devices. For the gas turbine applications, impingement cooling is commonly applied in the transition piece of a combustor and in the leading edge, suction and pressure sides of a turbine blade/vane. In the suction side and pressure side, impingement cooling is applied as a form of an array jet. However, due to the small gap between the jet hole and target surface, the wall jet faces a crossflow inside of the gap. This crossflow has an adverse effect on the jets and deteriorates the heat/mass transfer performance. Therefore, several studies have been conducted to minimized the crossflow effect. The present study also investigated the effect of crossflow reduction in the gap by having a castellated hole plate. The heat/mass transfer was measured using the naphthalene sublimation method. Heat/mass transfer data are compared among three different cases. One is the baseline case which is simple array impinging jets. Others are the castellated cases with and without rib structures on the target wall. Jet-to-jet spacing (s/d) and jet-to-target spacing (z/d) are selected as geometrical variables. Also, the experiments were conducted for the Reynolds numbers (based on jet hole diameter) of 5,000, 15,000 and 30,000. The baseline case was named as B case, the castellated case without rib structure as C case and with rib structure as CR case. Both C and CR cases showed the crossflow reduction effect and resulted high and similar Nusselt number values.","PeriodicalId":385341,"journal":{"name":"Volume 5B: Heat Transfer — General Interest; Internal Air Systems; Internal Cooling","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132808948","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":"Studying the Effect of Porosity of Porous Layer Coating on the Performance of the Horizontal Tubular Falling Film Evaporator","authors":"A. Ibrahim, H. Elgamal, A. Elmekawy","doi":"10.1115/gt2021-58921","DOIUrl":"https://doi.org/10.1115/gt2021-58921","url":null,"abstract":"\u0000 Through the recent decades, many studies have focused on finding efficient methods to enhance the heat transfer performance in heat exchangers. Therefore, using porous media attracted many researchers, as it is such a simple, efficient, and low-cost technique in enlarging the surface contact area of heat transfer through the fluid pass. Nevertheless, there is little work associated with using porous media to enhance the thermal performance of falling film evaporators. The present study seeks to discuss numerically the liquid flow behaviour over falling film evaporator tubes in the case of bare tubes and tubes with porous layer coating. The two-dimensional multi-phase numerical simulations are also carried out in order to investigate the effect of the porosity ratio of the porous medium added to the tubes in the heat transfer performance. Furthermore, deducing the way to select a decent porosity ratio to be used to get the best thermal performance is demonstrated through the study. Time-averaged results gained from the numerical simulations have been compared to those of bare-tube falling film evaporator to observe much higher heat transfer performance represented in the average surface Nusselt number (Nu) which increased by 3 times.","PeriodicalId":385341,"journal":{"name":"Volume 5B: Heat Transfer — General Interest; Internal Air Systems; Internal Cooling","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128412363","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 in Rotating, Trailing Edge, Converging Channels With Full and Partial Height Strip-Fins","authors":"I. Sahin, I-Lun Chen, L. Wright, Je-Chin Han, Hongzhou Xu, M. Fox","doi":"10.1115/gt2021-58877","DOIUrl":"https://doi.org/10.1115/gt2021-58877","url":null,"abstract":"\u0000 A wide variety of pin-fins have been used to enhance heat transfer in internal cooling channels. However, due to their large blockage in the flow direction, they result in an undesirable high pressure drop. This experimental study aims to reduce pressure drop while increasing the heat transfer surface area by utilizing strip-fins in converging internal cooling channels. The channel is designed with a trapezoidal cross-section, converges in both transverse and longitudinal directions, and is also skewed β = 120° with respect to the direction of rotation in order to model a trailing edge cooling channel. Only the leading and trailing surfaces of the channel are instrumented, and each surface is divided into eighteen isolated copper plates to measure the regionally averaged heat transfer coefficient. Utilizing pressure taps at the inlet and outlet of the channel, the pressure drop is obtained. Three staggered arrays of strip-fins are investigated: one full height configuration and two partial fin height arrangements (Sz = 2mm and 1mm). In all cases, the strip fins are 2mm wide (W) and 10mm long (Lf) in the flow direction. The fins are spaced such that Sy/Lf = 1 in the streamwise direction. However, due to the convergence the spanwise spacing Sx/W, was varied from 8 to 6.2 along the channel. The rotation number of the channel varied up to 0.21 by ranging the inlet Reynolds number from 10,000 to 40,000 and rotation speed from 0 to 300rpm. It is found that the full height strip-fin channel results in a more non-uniform spanwise heat transfer distribution than the partial height strip-fin channel. Both trailing and leading surface heat transfer coefficients are enhanced under rotation conditions. The 2mm height partial strip-fin channel provided the best thermal performance, and it is comparable to the performance of the converging channels with partial length circular pins. The strip-fin channel can be a design option when the pressure drop penalty is a major concern.","PeriodicalId":385341,"journal":{"name":"Volume 5B: Heat Transfer — General Interest; Internal Air Systems; Internal Cooling","volume":"145 8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125854588","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":"Rotating Brush Seal Design and Performance Testing","authors":"N. Sarawate, Deepak Trivedi","doi":"10.1115/gt2021-02334","DOIUrl":"https://doi.org/10.1115/gt2021-02334","url":null,"abstract":"\u0000 Brush seals are widely used in various turbomachinery applications because they provide reduced leakage than labyrinth seals in a compact space. Brush seals are generally mounted on static components and their flexible bristle tips engage the rotor to form a dynamic seal. In this paper, development of a brush seal mounted on a rotor is discussed. Benefits of this enhancement to brush seal include avoiding localized rubs on the rotor, which reduces heating of a local spot and resulting rotor bow and instabilities. The bristles are angled circumferentially instead of axially and are supported by a conical backplate. Under rotation, the bristles are pushed towards the backplate by the centrifugal force. Seal configurations are designed to fit into interstage and inter-shaft locations. A modeling approach for predicting stiffness and operating stresses in these seals also is outlined. A test setup is developed to characterize the performance of rotating brush seals under engine-representative centrifugal force and pressure differentials. Presented results demonstrate that brush seal can achieve tight effective gaps and desired performance after undergoing initial wear.","PeriodicalId":385341,"journal":{"name":"Volume 5B: Heat Transfer — General Interest; Internal Air Systems; Internal Cooling","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126220494","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 and Flow Characteristics of the Jet Array Impingement","authors":"Mingqian Ren, Xueying Li, Jing Ren","doi":"10.1115/gt2021-59573","DOIUrl":"https://doi.org/10.1115/gt2021-59573","url":null,"abstract":"\u0000 An experimental and numerical study is performed to investigate heat transfer and pressure loss characteristics for impingement. Experimental heat transfer is measured by the thermochromic liquid crystal. The CFD model uses a steady state RANS approach and the shear stress transport (SST). The effect of Reynolds number (5000–25000), the distance between the holes and the distance from the hole to target on the impingement is investigated in the present study. Local Nusselt number as well as area and line average values are gotten experimentally and numerically. Besides, numerical simulations provide the detailed flow characteristics of the problem and complement experimental measurements. The result shows that the heat transfer increases with Reynolds number increasing. But the qualitative distribution of local heat transfer does not change with the increase of Reynolds number, when it is sensitive to P/D and Z/D. The performance of heat transfer is best when Z/D = 2. And the high heat transfer region of Z/D = 1 is closer to the exit than that of Z/D = 2 and Z/D = 3. The main reason is the effect of cross flow and the momentum of the jet reaching the wall. The performance of heat transfer is best when P/D = 5. And the high heat transfer region of P/D = 4 is closer to the exit than that of P/D = 5 and P/D = 6. The main reason is the effect of cross flow and interactions between jets.","PeriodicalId":385341,"journal":{"name":"Volume 5B: Heat Transfer — General Interest; Internal Air Systems; Internal Cooling","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122524005","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":"Simulation of Air/Mist Cooling Among Shock Waves and Passing Wakes Interactions in a Transonic Gas Turbine Stage","authors":"Ting Wang, R. Abdelmaksoud","doi":"10.1115/gt2021-59874","DOIUrl":"https://doi.org/10.1115/gt2021-59874","url":null,"abstract":"\u0000 This paper presents a 2-D numerical investigation of the effect of interactions of moving wakes and shock waves on mist cooling performance over airfoils in the first stator-rotor stage of a transonic gas turbine. The discrete phase model (DPM) is used to simulate and track the evaporation and movement of the tiny water droplets. Breakup and coalescence sub-models are used to simulate the interaction between the droplets themselves. A linear sliding mesh technique is used to study the transient stator-rotor interaction. The results show that the passing unsteady wakes caused by the blade rotation press the mist on the blade suction side flowing near the blade surface, providing more enhanced film cooling effectiveness. The weak oblique shock waves do not exert a significant effect on the air/mist cooling effectiveness. Injecting a 10% mist ratio noticeably improved the cooling enhancement by reducing the wall temperature values up to 200 K in some locations. Injecting the tiny water droplets does not cause a noticeable pressure loss compared to the air-only cooling case. Injecting mist doesn’t alter the effect of shocks.","PeriodicalId":385341,"journal":{"name":"Volume 5B: Heat Transfer — General Interest; Internal Air Systems; Internal Cooling","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123197022","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":"Jet Impingement Heat Transfer Enhancement With Different Crossflow Diverter Shapes","authors":"Juan He, Qinghua Deng, Z. Feng","doi":"10.1115/gt2021-59080","DOIUrl":"https://doi.org/10.1115/gt2021-59080","url":null,"abstract":"\u0000 Impingement cooling is an effective cooling structure in gas turbine blades, but the downstream heat transfer will be reduced seriously by crossflow. It has been proven that equipping a crossflow diverter in impingement channel can make jet free from crossflow and enhance the downstream heat transfer. In this paper, in order to obtain a kind of crossflow diverter with advantageous heat transfer performance, the flow and heat transfer characteristics of four crossflow diverters (Semi-Circular (SC), Semi-Rectangular (SR), Semi-Diamond (SD) and Semi-Four-pointed Star (SFS)) are compared in detail. To this end, a Baseline impingement cooling configuration is considered, in which the pitches on the streamwise and spanwise directions of impingement jets are all 6D and the distance from jet to target surface is 2D. Through detailed numerical verification, SST k-ω turbulence model is finally selected, and all simulations are performed under Reynolds number ranging from 3,500 to 14,000. It is found that the crossflow diverter can change the local jet Reynolds number distribution and effectively reduce the local mass velocity ratio of crossflow to jet. Results reveal that the crossflow diverter increases the heat transfer and inevitably increases the friction loss, but all of them can improve the comprehensive heat transfer performance over the simulated flow range. When the Reynolds number is 14,000, the best heat transfer performance can be achieved, and the comprehensive heat transfer performance parameters of SC, SR, SD and SFS cases can increase by up to 11.0%, 14.3%, 12.2% and 14.7% respectively. After determining SFS-shaped crossflow diverter with the best comprehensive heat transfer performance, the influence of its streamwise position on heat transfer and friction loss is also studied. The SFS-shaped diverter is placed at 2D, 2.5D, 3D, 3.5D and 4D from the center of adjacent upstream jet, respectively. Results show that the heat transfer and friction loss change a little when the distance increases from 2D to 3D, but the heat transfer decreases sharply and friction loss increases seriously when the distance increases from 3D to 4D.","PeriodicalId":385341,"journal":{"name":"Volume 5B: Heat Transfer — General Interest; Internal Air Systems; Internal Cooling","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115396727","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":"Jet Impingement Heat Transfer in a Rectangular Channel With Smooth and Pinned Target Walls","authors":"Yasser S. Alzahrani, L. Wright, Andrew F. Chen, Je-Chin Han","doi":"10.1115/gt2021-59343","DOIUrl":"https://doi.org/10.1115/gt2021-59343","url":null,"abstract":"\u0000 An experimental study was completed to quantify heat transfer enhancement, pressure loss, and crossflow effect within a channel of inline impinging jets. The jet diameter is 5.08 mm and the jet-to-jet spacing in the streamwise and spanwise directions is fixed at x/d = 11.1 and y/d = 5.9, respectively. The effect of jet-to-target surface spacing was considered with z/d = 3 and 6. For both of the jet-to-target surface spacings, a smooth surface, the reference case, and a surface roughened with partial height pins were investigated. The roughened surface has a staggered array of 120 partial height copper pin fins. The pin to jet diameter and the pin height to diameter ratios are D/d = 0.94 and H/D = 1.6, respectively. Regionally averaged heat transfer coefficient distributions were measured on the target surface, and these distributions were coupled with pressure measurements through the array. The heat transfer augmentation and pressure penalty were investigated over a range of jet Reynolds numbers (10K–70K). The results show high discharge coefficients for all the cases. The channels with the tight jet-to-target surface spacing experience double the cross-flow effect of its increased spacing counterpart. The addition of surface roughness showed a negligible effect on the crossflow. The best heat transfer performance was observed in the impingement channel with the pinned target surface at z/d = 3.","PeriodicalId":385341,"journal":{"name":"Volume 5B: Heat Transfer — General Interest; Internal Air Systems; Internal Cooling","volume":"02 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130996809","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}