G. Vivarelli, João A. Isler, F. Montomoli, S. Sherwin, P. Adami
{"title":"High-Order Spectral/hp Compressible and Incompressible Comparison of Transitional Boundary-Layers Subject to a Realistic Pressure Gradient and High Reynolds Number","authors":"G. Vivarelli, João A. Isler, F. Montomoli, S. Sherwin, P. Adami","doi":"10.1115/gt2022-82100","DOIUrl":"https://doi.org/10.1115/gt2022-82100","url":null,"abstract":"\u0000 Within the literature, there are limited high-order results concerning large Reynolds number flows under the influence of strong adverse pressure gradients, mainly due to the computational expense involved. The main advantage in employing high-order methodologies over standard second-order finite-volume solvers, relates to their ability to increase accuracy with a significantly lower number of degrees of freedom. In theory, this would permit Direct Numerical Simulation sort of analysis. Yet, there is still a significant computational cost involved. For this reason, an efficient approach to analyse such flows by means of a Nektar++ high-order Implicit Large Eddy Simulation is proposed.\u0000 The flow conditions considered in this case cause a separation bubble to form with consequent turbulent transition. In particular, Tollmien-Schlichting instabilities trigger Kelvin-Helmholtz behaviour, which in turn cause the turbulent transition.\u0000 The bulk of the study will be carried out with the incompressible flow solver, as it is assumed that compressibility effects are negligible within the boundary layer. An initial 2D analysis will be conducted to determine the necessary spatial resolution and whether it is possible to consider a subset of the overall simulation domain to reduce the computational expense. Once this will have been established, the 3D results will be achieved by Fourier expansion in the cross-flow direction. These results will prove the cost-effectiveness of the methodology, that could be used within an industrial setting with a limited turn-around time. Additionally, a comparison between the results achieved by means of the Nektar++ compressible flow solver in 2D and 3D will be provided, to assess any differences that may be present.","PeriodicalId":191970,"journal":{"name":"Volume 10C: Turbomachinery — Design Methods and CFD Modeling for Turbomachinery; Ducts, Noise, and Component Interactions","volume":"21 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":"130582710","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":"Calculating Windage Losses: A Review","authors":"Fernando Karg Bulnes, T. Kerr, Aaron M. Rimpel","doi":"10.1115/gt2022-82570","DOIUrl":"https://doi.org/10.1115/gt2022-82570","url":null,"abstract":"\u0000 Windage is the effect of aerodynamic drag on the surfaces of a rotating system due to fluid shear effects. The fluid-friction losses that occur on the rotor of rotating machines often constitute a non-negligible drag on the system that must be estimated for proper sizing of the driving or driven element. This is especially true in high-pressure environments, such as hermetic compressors and turbines. Fluid-friction loss modeling is based on the size and rotation speed of the shaft, the density of the fluid, and an empirically-determined drag coefficient. The drag coefficient is generally a function of the Reynolds number but may also be dependent on the Taylor number. Several papers have provided empirical predictions for drag coefficients based on the Reynolds and Taylor numbers of the fluid, but other factors such as rotor shapes, assemblies, and surrounding fluid conditions can also affect the drag coefficient. There are two main geometries for a rotor: a face parallel to the axis of rotation, and a face that is perpendicular. The gap between the rotating component and the stationary housing also plays an important role in the drag coefficient. This review summarizes and compares these findings in a way that makes it easy for the reader to predict the total windage losses on a system for any rotor shape, speed, or operating condition. A quick reference table is presented in the conclusions section.","PeriodicalId":191970,"journal":{"name":"Volume 10C: Turbomachinery — Design Methods and CFD Modeling for Turbomachinery; Ducts, Noise, and Component Interactions","volume":"14 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":"127933882","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":"On the Impact of the Turbulence Model on the Secondary Flow Structure of a Highly-Loaded Compressor Stage","authors":"Riccardo Toracchio, F. Fontaneto, K. Hillewaert","doi":"10.1115/gt2022-83163","DOIUrl":"https://doi.org/10.1115/gt2022-83163","url":null,"abstract":"\u0000 RANS turbulence models still represent a weak point of industrial simulations of turbomachinery flows. In presence of a large blade loading the turbulence model can impact severely on the prediction of the end-wall flow and secondary structures in the blade passage, with an important effect on the computed global performance and flow stability. This paper presents a turbulence model comparison for the characterization of a highly-loaded low-pressure compressor at multiple operating points using 3D RANS simulations. The turbulence models mostly employed for the design and analysis of axial compressors are considered, with the aim of providing a clear physical description of their impact on the critical flow features of the machine. It will be shown that no single turbulence model is generally better than others and the prediction depends on the operating point, with increasing discrepancies as the mass-flow is reduced.","PeriodicalId":191970,"journal":{"name":"Volume 10C: Turbomachinery — Design Methods and CFD Modeling for Turbomachinery; Ducts, Noise, and Component Interactions","volume":"3 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":"128788072","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":"Validation of Broadband Noise Prediction Methodology Based on Linearised Navier-Stokes Analyses","authors":"Ricardo Blázquez-Navarro, R. Corral","doi":"10.1115/gt2022-84013","DOIUrl":"https://doi.org/10.1115/gt2022-84013","url":null,"abstract":"\u0000 This paper presents an integral validation of a synthetic turbulence broadband noise prediction methodology for Fan/Outlet-Guide-Vane (OGV) interaction. The test vehicle is the ACAT1 fan, a modern scaled-down fan, experimentally analysed in 2018 within the TurboNoiseBB project. Three operating points, namely Approach, Cutback, and Sideline, and two different rig configurations in terms of the axial gap between the fan and OGV are examined within this work. The methodology consists of using a RANS solver to model the fan wake and the use of two-dimensional frequency-domain linearised Navier-Stokes simulations to resolve the acoustics, including quasi-3D corrections to obtain representative results. The RANS results with no ad-hoc tuning are compared in detail against hotwire data to determine the degree of uncertainty incurred by this kind of approach. The predicted broadband noise spectra and noise azimuthal decompositions are compared against the experimental data. The spectral levels are well predicted, despite an average under-prediction of around 3dB. The noise azimuthal decompositions feature a remarkable agreement with the experiment, denoting accurate modelling of the main physics governing the problem. The impact of increasing the fan/OGV axial gap is quantified numerically for the first time. It is concluded that increasing the gap is detrimental for the broadband noise footprint, unlike intuitively could be expected. Overall, the presented broadband noise methodology yields robust broadband noise predictions at an industrially-feasible cost and enables a deeper understanding of the problem.","PeriodicalId":191970,"journal":{"name":"Volume 10C: Turbomachinery — Design Methods and CFD Modeling for Turbomachinery; Ducts, Noise, and Component Interactions","volume":"429 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":"122869672","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":"Comparison of Stall Point Predictions in a Transonic Axial Compressor Rotor Using Single Passage and Three Passage CFD Geometries","authors":"Benjamin Meinster, W. Smith, G. Hobson, A. Gannon","doi":"10.1115/gt2022-83478","DOIUrl":"https://doi.org/10.1115/gt2022-83478","url":null,"abstract":"\u0000 An investigation is presented which compares the predicted stall points and underlying flow fields for single-passage and three-passage CFD geometries of a transonic axial compressor rotor. The two cases are run using the commercial CFD code ANSYS CFX and compared to experimental data. The two predicted stall points are found to differ from each other, and both under-predict the rotor’s performance compared to the experimental data. However, the steady-state flow fields are found to be identical for all operating points short of the stall point. A mechanism is then proposed to reconcile the difference in predicted stall points with the identical steady-state flow fields. By the mechanism proposed, the addition of multiple passages makes flow through the three-blade geometry less stable, which causes the rotor to stall earlier.","PeriodicalId":191970,"journal":{"name":"Volume 10C: Turbomachinery — Design Methods and CFD Modeling for Turbomachinery; Ducts, Noise, and Component Interactions","volume":"11 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":"121521898","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":"Numerical Investigation of the Effects of Tip Clearance and Rotor Cavities on the Performance of a 1.5-Stage High-Work Turbine","authors":"T. Hansen, E. Munktell, G. Scheuerer, Kim Zwiener","doi":"10.1115/gt2022-81059","DOIUrl":"https://doi.org/10.1115/gt2022-81059","url":null,"abstract":"\u0000 The paper presents CFD simulations about the effects of tip clearance and rotor cavities on the performance of a 1.5-stage high-work turbine. The experimental test case to which the simulation results are compared is the 1.5-stage unshrouded high-work turbine investigated by Behr et al. [1]. The authors performed the simulations on three homogeneously refined meshes. The results on the three meshes were used to quantify discretisation errors applying Richardson extrapolation. The mesh-related discretisation errors for the mass flow rate, total pressure ratio, and mechanical efficiency were below 0.2 % on the finest mesh. The simulation results agreed well with the experimental data. In particular, the loss topologies induced by the hub and shroud passage vortices and the tip-leakage vortex compared well to the measured contours. The simulations showed a consistent and realistic response to the addition of the rotor cavities, with increased mass flow rates and reduced efficiency, shifting the hub passage vortices upwards. Increasing the tip gap decreased the efficiency and strengthened the tip-leakage vortex; decreasing the tip gap had the opposite effect.","PeriodicalId":191970,"journal":{"name":"Volume 10C: Turbomachinery — Design Methods and CFD Modeling for Turbomachinery; Ducts, Noise, and Component Interactions","volume":"46 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":"121534346","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}
Tedja Verhulst, E. Ng, Yongmann M. Chung, D. Judt, C. Lawson
{"title":"Predicting Cavitation Erosion on Two-Stage Pumps Using CFD","authors":"Tedja Verhulst, E. Ng, Yongmann M. Chung, D. Judt, C. Lawson","doi":"10.1115/gt2022-84165","DOIUrl":"https://doi.org/10.1115/gt2022-84165","url":null,"abstract":"\u0000 Cavitation is a common problem that occurs in pumps which reduces its useful life and bring increased operating costs to the user. A study of cavitation erosion on a two-stage centrifugal pump has been carried out using Computational Fluid Dynamics (CFD). Most cavitation studies on pumps have been focused on modelling the severity of cavitation; specifically, on understanding its visual effects and performance penalties. Few works have been carried out to predict the most erosion-sensitive areas inside a pump. The focus of this study is on modelling the permanent damage that would be caused by cavitation and to identify specific areas within the pump which are most susceptible to erosion. The model is first validated against experimental data from another work. Once the simulation has been successfully calibrated, the cavitation simulation is carried out again with the subject pump. Not only does this work extend the findings previous works by predicting cavitation erosion on a two-stage pump, but the pump rotation speed is also varied to observe how the erosion-sensitive areas on the pump changes as a result. A specific focus on the Gray Level Method is carried out to predict the erosion damage on the pump. This technique is chosen as it has been experimentally proven with single-stage radial pumps, using specialized CFD code. It is found that the algorithm used to predict erosion when applied with commercial CFD packages, are useful in distinguishing areas inside the pump which are most vulnerable to erosion damage. The Scherr-Sauer cavitation model coupled with the κ-ω SST turbulence model have been used to run the cavitation simulations.","PeriodicalId":191970,"journal":{"name":"Volume 10C: Turbomachinery — Design Methods and CFD Modeling for Turbomachinery; Ducts, Noise, and Component Interactions","volume":"17 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":"133530602","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":"Harmonic Method for Simulating Unsteady Multispool Interactions","authors":"Feng Wang, L. di Mare","doi":"10.1115/gt2022-83460","DOIUrl":"https://doi.org/10.1115/gt2022-83460","url":null,"abstract":"\u0000 Modern civil jet engines arrange components on spools with different rotational speeds in order to improve compressor stall margin, overall engine performance, etc. The unsteady interactions among these components can be significant and should be considered at an early design stage if possible. URANS is a common approach to simulate these unsteady effects, but the disparity in time scales in a multispool simulation can lead to expensive URANS simulations. Harmonic methods are effective and efficient approaches to simulate unsteady interactions among turbomachinery components, but their applications to multispool simulations remains a challenge. The objective of this paper is to address this challenge. This paper extends the Favre-averaged non-linear harmonic method to simulate multispool turbomachinery components using a unified bladerow interface which transfer disturbances with arbitrary blade counts at any rotational speed. The regularization of non-reflective boundary condition is described for certain circumferential wave number of the zero-frequency mode. The capability of the proposed approach is demonstrated by simulating the transfer of hot streaks through full 3D high- and intermediate-pressure turbines in a three-shaft engine. The temperature distributions from the harmonic method show good agreement with direct unsteady simulation and the radial migration of the hot streaks towards the hub are captured very well by the proposed harmonic method. The Favre-averaged temperature field also shows good agreement with direct unsteady simulation. The required computational cost of the harmonic method can be roughly two orders of magnitude smaller than the direct unsteady simulations. This demonstrates the proposed method can be a promising design tool to trace hot streaks in multispool turbines at the early design stage.","PeriodicalId":191970,"journal":{"name":"Volume 10C: Turbomachinery — Design Methods and CFD Modeling for Turbomachinery; Ducts, Noise, and Component Interactions","volume":"89 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":"128190860","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}
Adrien Grenouilloux, G. Balarac, J. Leparoux, V. Moureau, G. Lartigue, P. Bénard, R. Mercier, P. Ferrey
{"title":"On the Use of Kinetic-Energy Balance for the Feature-Based Mesh Adaptation Applied to Large-Eddy Simulation in Complex Geometries","authors":"Adrien Grenouilloux, G. Balarac, J. Leparoux, V. Moureau, G. Lartigue, P. Bénard, R. Mercier, P. Ferrey","doi":"10.1115/gt2022-80315","DOIUrl":"https://doi.org/10.1115/gt2022-80315","url":null,"abstract":"\u0000 Static and dynamic feature-based mesh adaptation have gained momentum during the last decade as they allow to refine areas to capture specific flow features. These methods do not always guaranty that the budget of the kinetic energy of the mean field is mesh independent as it could be expected. In the present paper, a framework which uses the assessment of the kinetic energy budget to refine or coarsen the mesh resolution locally is presented in the framework of Large-Eddy Simulation (LES). The whole methodology is applied to two industrial configurations, namely the isothermal PRECCINSTA burner and a row of three jets impinging on a surface at Re = 23000 and a nozzle to plate distance of H/D = 5. Flow field quantities, including mean velocity and RMS or Nusselt number on the final grids are in good agreement with experimental data.","PeriodicalId":191970,"journal":{"name":"Volume 10C: Turbomachinery — Design Methods and CFD Modeling for Turbomachinery; Ducts, Noise, and Component Interactions","volume":"14 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":"126451458","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":"Evaluation of Surge Prediction Capabilities of Body-Force Model on a High-Speed Multi-Stage Axial-Radial Compressor","authors":"Hanxuan Zeng, Tengbo Fan, Zhenzhong Sun, Baotong Wang, Xinqian Zheng","doi":"10.1115/gt2022-82548","DOIUrl":"https://doi.org/10.1115/gt2022-82548","url":null,"abstract":"\u0000 Multi-stage axial-radial compressors are typical configurations of compression systems used in turboshaft engines. The aerodynamic instabilities encountered in this type of compressor are commonly identified as surge, which seriously threaten the operability and reliability of the compressor itself and even the entire engine. Therefore, correct prediction of surge characteristics and the aerodynamic loading are crucial during the design process. However, due to the complexity of compressor surge, high-fidelity numerical methods, like unsteady Reynolds-averaged Navier-Stokes (URANS) simulation, require enormous computational resources and time costs, which can barely be used in design iterations. Therefore, finding a more efficient way for surge prediction is essential.\u0000 This paper describes a general method of surge prediction based on an in-house code of body-force model. A high-speed multi-stage axial-radial compressor is used to evaluate the capabilities of this method to predict surge characteristics against URANS. The run-time is reduced by approximately 2 orders of magnitude. Key features of surge (i.e., flow reversal, flow resumption, and repressurization) and the aerodynamic loading during surge are compared. Overall, the results from the two method show a close matching. Additional analyses are also made on the fidelity limitations of this method in the prediction of finer surge features, and the corresponding modifications are proposed.","PeriodicalId":191970,"journal":{"name":"Volume 10C: Turbomachinery — Design Methods and CFD Modeling for Turbomachinery; Ducts, Noise, and Component Interactions","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":"131152862","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}