Journal of Engineering for Gas Turbines and Power最新文献

{"title":"The Influence of Inlet Asymmetry on Steam Turbine Exhaust Hood Flows.","authors":"Zoe Burton,&nbsp;Simon Hogg,&nbsp;Grant L Ingram","doi":"10.1115/1.4026003","DOIUrl":"https://doi.org/10.1115/1.4026003","url":null,"abstract":"<p><p>It has been widely recognized for some decades that it is essential to accurately represent the strong coupling between the last stage blades (LSB) and the diffuser inlet, in order to correctly capture the flow through the exhaust hoods of steam turbine low pressure cylinders. This applies to any form of simulation of the flow, i.e., numerical or experimental. The exhaust hood flow structure is highly three-dimensional and appropriate coupling will enable the important influence of this asymmetry to be transferred to the rotor. This, however, presents challenges as the calculation size grows rapidly when the full annulus is calculated. The size of the simulation means researchers are constantly searching for methods to reduce the computational effort without compromising solution accuracy. However, this can result in excessive computational demands in numerical simulations. Unsteady full-annulus CFD calculation will remain infeasible for routine design calculations for the foreseeable future. More computationally efficient methods for coupling the unsteady rotor flow to the hood flow are required that bring computational expense within realizable limits while still maintaining sufficient accuracy for meaningful design calculations. Research activity in this area is focused on developing new methods and techniques to improve accuracy and reduce computational expense. A novel approach for coupling the turbine last stage to the exhaust hood employing the nonlinear harmonic (NLH) method is presented in this paper. The generic, IP free, exhaust hood and last stage blade geometries from Burton et al. (2012. \"A Generic Low Pressure Exhaust Diffuser for Steam Turbine Research,\"Proceedings of the ASME Turbo Expo, Copenhagen, Denmark, Paper No. GT2012-68485) that are representative of modern designs, are used to demonstrate the effectiveness of the method. This is achieved by comparing results obtained with the NLH to those obtained with a more conventional mixing-plane approach. The results show that the circumferential asymmetry can be successfully transferred in both directions between the exhaust hood flow and that through the LSB, by using the NLH. This paper also suggests that for exhaust hoods of generous axial length, little change in C_p is observed when the circumferential asymmetry is captured. However, the predicted flow structure is significantly different, which will influence the design and placement of the exhaust hood internal \"furniture.\"</p>","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":"136 4","pages":"0426021-426029"},"PeriodicalIF":1.5,"publicationDate":"2014-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1115/1.4026003","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"33158456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design and Experimental Study of an Over-Under TBCC Exhaust System.","authors":"Jianwei Mo,&nbsp;Jinglei Xu,&nbsp;Liuhuan Zhang","doi":"10.1115/1.4025314","DOIUrl":"https://doi.org/10.1115/1.4025314","url":null,"abstract":"<p><p>Turbine-based combined-cycle (TBCC) propulsion systems have been a topic of research as a means for more efficient flight at supersonic and hypersonic speeds. The present study focuses on the fundamental physics of the complex flow in the TBCC exhaust system during the transition mode as the turbine exhaust is shut off and the ramjet exhaust is increased. A TBCC exhaust system was designed using methods of characteristics (MOC) and subjected to experimental and computational study. The main objectives of the study were: (1) to identify the interactions between the two exhaust jet streams during the transition mode phase and their effects on the whole flow-field structure; (2) to determine and verify the aerodynamic performance of the over-under TBCC exhaust nozzle; and (3) to validate the simulation ability of the computational fluid dynamics (CFD) software according to the experimental conditions. Static pressure taps and Schlieren apparatus were employed to obtain the wall pressure distributions and flow-field structures. Steady-state tests were performed with the ramjet nozzle cowl at six different positions at which the turbine flow path were half closed and fully opened, respectively. Methods of CFD were used to simulate the exhaust flow and they complemented the experimental study by providing greater insight into the details of the flow field and a means of verifying the experimental results. Results indicated that the flow structure was complicated because the two exhaust jet streams interacted with each other during the exhaust system mode transition. The exhaust system thrust coefficient varied from 0.9288 to 0.9657 during the process. The CFD simulation results agree well with the experimental data, which demonstrated that the CFD methods were effective in evaluating the aerodynamic performance of the TBCC exhaust system during the mode transition.</p>","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":"136 1","pages":"0145011-145018"},"PeriodicalIF":1.5,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1115/1.4025314","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"33158453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of Cavity on the Performance of Dual Throat Nozzle During the Thrust-Vectoring Starting Transient Process.","authors":"Rui Gu,&nbsp;Jinglei Xu","doi":"10.1115/1.4025243","DOIUrl":"https://doi.org/10.1115/1.4025243","url":null,"abstract":"<p><p>The dual throat nozzle (DTN) technique is capable to achieve higher thrust-vectoring efficiencies than other fluidic techniques, without compromising thrust efficiency significantly during vectoring operation. The excellent performance of the DTN is mainly due to the concaved cavity. In this paper, two DTNs of different scales have been investigated by unsteady numerical simulations to compare the parameter variations and study the effects of cavity during the vector starting process. The results remind us that during the vector starting process, dynamic loads may be generated, which is a potentially challenging problem for the aircraft trim and control.</p>","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":"136 1","pages":"0145021-145026"},"PeriodicalIF":1.5,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1115/1.4025243","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"33158454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Conceptual Mean-Line Design of Single and Twin-Shaft Oxy-Fuel Gas Turbine in a Semiclosed Oxy-Fuel Combustion Combined Cycle.","authors":"Majed Sammak,&nbsp;Egill Thorbergsson,&nbsp;Tomas Grönstedt,&nbsp;Magnus Genrup","doi":"10.1115/1.4023886","DOIUrl":"https://doi.org/10.1115/1.4023886","url":null,"abstract":"<p><p>The aim of this study was to compare single- and twin-shaft oxy-fuel gas turbines in a semiclosed oxy-fuel combustion combined cycle (SCOC-CC). This paper discussed the turbomachinery preliminary mean-line design of oxy-fuel compressor and turbine. The conceptual turbine design was performed using the axial through-flow code luax-t, developed at Lund University. A tool for conceptual design of axial compressors developed at Chalmers University was used for the design of the compressor. The modeled SCOC-CC gave a net electrical efficiency of 46% and a net power of 106 MW. The production of 95% pure oxygen and the compression of CO₂ reduced the gross efficiency of the SCOC-CC by 10 and 2 percentage points, respectively. The designed oxy-fuel gas turbine had a power of 86 MW. The rotational speed of the single-shaft gas turbine was set to 5200 rpm. The designed turbine had four stages, while the compressor had 18 stages. The turbine exit Mach number was calculated to be 0.6 and the calculated value of AN² was 40 · 10⁶ rpm²m². The total calculated cooling mass flow was 25% of the compressor mass flow, or 47 kg/s. The relative tip Mach number of the compressor at the first rotor stage was 1.15. The rotational speed of the twin-shaft gas generator was set to 7200 rpm, while that of the power turbine was set to 4800 rpm. A twin-shaft turbine was designed with five turbine stages to maintain the exit Mach number around 0.5. The twin-shaft turbine required a lower exit Mach number to maintain reasonable diffuser performance. The compressor turbine was designed with two stages while the power turbine had three stages. The study showed that a four-stage twin-shaft turbine produced a high exit Mach number. The calculated value of AN² was 38 · 10⁶ rpm²m². The total calculated cooling mass flow was 23% of the compressor mass flow, or 44 kg/s. The compressor was designed with 14 stages. The preliminary design parameters of the turbine and compressor were within established industrial ranges. From the results of this study, it was concluded that both single- and twin-shaft oxy-fuel gas turbines have advantages. The choice of a twin-shaft gas turbine can be motivated by the smaller compressor size and the advantage of greater flexibility in operation, mainly in the off-design mode. However, the advantages of a twin-shaft design must be weighed against the inherent simplicity and low cost of the simple single-shaft design.</p>","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":"135 8","pages":"0815021-815028"},"PeriodicalIF":1.5,"publicationDate":"2013-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1115/1.4023886","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"33158559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of Computational Fluid Dynamics and Coupled Fluid-Solid Modeling for a Direct Transfer Preswirl System.","authors":"Umesh Javiya,&nbsp;John Chew,&nbsp;Nick Hills,&nbsp;Klaus Dullenkopf,&nbsp;Timothy Scanlon","doi":"10.1115/1.4007752","DOIUrl":"https://doi.org/10.1115/1.4007752","url":null,"abstract":"<p><p>The prediction of the preswirl cooling air delivery and disk metal temperature are important for the cooling system performance and the rotor disk thermal stresses and life assessment. In this paper, standalone 3D steady and unsteady computation fluid dynamics (CFD), and coupled FE-CFD calculations are presented for prediction of these temperatures. CFD results are compared with previous measurements from a direct transfer preswirl test rig. The predicted cooling air temperatures agree well with the measurement, but the nozzle discharge coefficients are under predicted. Results from the coupled FE-CFD analyses are compared directly with thermocouple temperature measurements and with heat transfer coefficients on the rotor disk previously obtained from a rotor disk heat conduction solution. Considering the modeling limitations, the coupled approach predicted the solid metal temperatures well. Heat transfer coefficients on the rotor disk from CFD show some effect of the temperature variations on the heat transfer coefficients. Reasonable agreement is obtained with values deduced from the previous heat conduction solution.</p>","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":"135 5","pages":"0515011-515019"},"PeriodicalIF":1.5,"publicationDate":"2013-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1115/1.4007752","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"33158558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Emission Reduction of Fuel-Staged Aircraft Engine Combustor Using an Additional Premixed Fuel Nozzle.","authors":"Takeshi Yamamoto,&nbsp;Kazuo Shimodaira,&nbsp;Seiji Yoshida,&nbsp;Yoji Kurosawa","doi":"10.1115/1.4007868","DOIUrl":"https://doi.org/10.1115/1.4007868","url":null,"abstract":"<p><p>The Japan Aerospace Exploration Agency (JAXA) is conducting research and development on aircraft engine technologies to reduce environmental impact for the Technology Development Project for Clean Engines (TechCLEAN). As a part of the project, combustion technologies have been developed with an aggressive target that is an 80% reduction over the NO_x threshold of the International Civil Aviation Organization (ICAO) Committee on Aviation Environmental Protection (CAEP)/4 standard. A staged fuel nozzle with a pilot mixer and a main mixer was developed and tested using a single-sector combustor under the target engine's landing and takeoff (LTO) cycle conditions with a rated output of 40 kN and an overall pressure ratio of 25.8. The test results showed a 77% reduction over the CAEP/4 NO_x standard. However, the reduction in smoke at thrust conditions higher than the 30% MTO condition and of CO emission at thrust conditions lower than the 85% MTO condition are necessary. In the present study, an additional fuel burner was designed and tested with the staged fuel nozzle in a single-sector combustor to control emissions. The test results show that the combustor enables an 82% reduction in NO_x emissions relative to the ICAO CAEP/4 standard and a drastic reduction in smoke and CO emissions.</p>","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":"135 3","pages":"0315021-315028"},"PeriodicalIF":1.5,"publicationDate":"2013-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1115/1.4007868","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"33158557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}