Shear Stress Transport Scale-adaptive Simulation Research Articles

Three-Dimensional Numerical Simulation of a Two-Phase Supercritical Open Channel Junction Flow

This study investigates the computational fluid dynamics (CFD) modeling of supercritical open channel junction flow using two different turbulence models: k-ω shear stress transport (SST) and k-ω SST scale-adaptive simulation (SAS), in conjunction with Volume of Fluid (VOF) and mixture multiphase models. The efficacy of these models in predicting the intricate free surface fluctuation and free surface elevation in a supercritical junction is evaluated through a comprehensive analysis of time-averaged free surface data obtained from CFD simulations and Light Detection and Ranging (LIDAR) measurements. The dimensionless Reynolds (Re) and Froude (Fr) numbers of the investigated scenario were Fr = 9 and Re = 5.1 × 104 for the main channel, and Fr = 6 and Re = 3.3 × 104 for the side channel. The results of the analysis demonstrated a satisfactory level of agreement with the experimental data. However, certain limitations associated with both CFD and LIDAR were identified. Specifically, the CFD performance was limited by the model’s incapacity to consider small-scale turbulent effects and to model air bubbles smaller than the cell size while the LIDAR measurements were limited by instrument range, inability to provide insight into what is happening below the water surface, and blind spots. Nonetheless, the k-ω SST turbulent model with the VOF multiphase model most closely matched the LIDAR results.

Effects of free tip shape and aspect ratio on flow around a finite cylinder with two free tips at subcritical Reynolds numbers

The influence of free tip shape and aspect ratio (AR) on the flow past a finite circular cylinder with two free tips is experimentally and numerically investigated over a range of Reynolds numbers (Re) from 0.69×104 to 6.16×104. Cylinders with two flat, radiused, hemispherical, and conical tips are considered, with AR ranging from 10 to 30. Laboratory experiments are performed in a closed-return wind tunnel. Numerical simulations are conducted using the Shear-Stress Transport Scale-Adaptive Simulation (SST-SAS) model. It is found that the drag coefficient of the flat tip, and the lift coefficient of the hemispherical tip, are the largest. Both lift and drag coefficients increase with AR, while the influence of free tip shape gradually decreases with AR. Results suggest that vortex structure and flow pattern change very significantly with AR, and are related to the free tip shape, especially near the free tips. The influence of free tip shape on the pressure coefficient is concentrated within a range of 3D from the tips, where D is the cylinder diameter. As the distance from the free tip increases, the difference in the pressure coefficients of the cylinder with different ARs first decreases and then increases, experiencing a minimum when the distance from the tip is 3D.

Influence of Door Gap on Aeroacoustics and Structural Response of a Cavity

Numerical aeroacoustic analysis using the Shear Stress Transport–Scale Adaptive Simulation turbulence model was conducted on a weapon bay model based on the M219 geometry with doors incorporating radar cross-section reduction features. The effect of the introduction of a gap between the doors and the cavity edge on the aeroacoustic and structural response of the cavity was analyzed at Mach 0.85. The effect of introducing 3 deg of sideslip was also investigated. Both mean and unsteady flow analyses were conducted. The results showed a strong palliative effect of the door gap with and without sideslips. The overall analysis of the spectral signature on the forces and moments acting on the doors indicated the possibility of fluid–acoustic coupling, as all acoustic spectra showed a predominant tone located at the same frequency of the first structural mode.

프란시스 수차 모델 내 흡출관의 내부 유동 특성에 미치는 공기 주입구의 영향

Swirling flow inside draft tube at part load condition during cavitation inception induces large pressure fluctuations. For suppression of the draft tube surge, fins with air injection holes are employed on the draft tube wall. The protrusion of air injection holes obstructs the incoming flow and creates flow complexities near the holes. The present study transiently investigates the effect of protrusion of these holes on the performance and flow phenomena of the Francis turbine numerically. Reynolds averaged Navier-Stokes (RANS) equations are solved along with a two-phase mixture model using Scale Adaptive Simulation Shear Stress Transport (SAS-SST) model to solve the turbulent flows. The numerical methodology is then verified by an experiment based on the International Standard (IEC 60193) norms. The hole protrusion reduces the efficiency of the turbine and exhibits higher strength of the vortex rope which is minimized using fins without holes. The swirl number is reduced by about 34% for the draft tube without holes. The random pressure fluctuations caused by the hole’s intrusiveness are also suppressed when the holes are removed.

Experimental and Numerical Investigation of Stall Mechanism in Centrifugal Pump Impeller

Stall is a complex flow phenomenon in centrifugal pumps at part load conditions. However, there is no clear description of the stall evolution process and mechanism, which is critical for stall control. Based on a high-frequency Particle Image Velocimetry (PIV) system (10k Hz) and a non-refraction experimental bench, emphasis is laid on the flow structures near the initial stall conditions. The results show that as the flow rate decreased, the flow separation occurred at the middle of the blade suction side and then evolved into a stall vortex which moved to the impeller’s inlet direction and kept growing. Subsequently, it broken into two vortexes when reaching the location where the impeller cross-sectional area is the smallest. One stall vortex continued its motion toward the passage inlet direction, while the other vortex separates to the impeller outlet. As the stall vortex’s size at the impeller inlet enlarged, the flow incident direction at the impeller inlet was directed to the blade suction side, which caused the stall vortex on the suction side to disappear. The stall mechanism is explained in detail using both experiments and numerical simulations. Meanwhile, the Scale Adaptive Simulation-Shear Stress Transport (SAS-SST) hybrid model is used to simulate several flow rate conditions near the stall initial stage. The findings indicate that the increasing adverse pressure gradient and the high-pressure zone move along the suction blade towards the impeller inlet as the flow rate is reduced; however, the relative velocity is constantly decreasing. When the fluid can’t provide enough kinetic energy to maintain its continuous flow along the suction surface, flow separation occurs. The stall vortex, which results from flow separation, blocks the passage impeller. The increasing adverse pressure from the impeller outlet to the inlet is the main cause of flow separation; and the adverse pressure gradient is a major manifestation of the stall vortex.

Internal flow characteristics in the draft tube of a Francis turbine model by air injection under low flow rate condition

Abstract Undesirable internal flow features under low flow rates in the draft tube of a Francis turbine are caused by the vortex ropes with precession. These vortex ropes cause performance degradation and increase the instability of turbine systems. The effects of anti-swirl fins on the wall of the draft tube were observed in the previous study to suppress the generation of the vortex rope. However, vortex ropes still remained near the cone of the draft tube. Thus, extra methods to suppress the vortex rope are needed. In this study, the influences of air injection were investigated from the cone of the runner to suppress the vortex rope characteristics in the draft tube of a Francis turbine model. For investigating the unsteady flow and pressure phenomena by injecting the air in the draft tube, unsteady-state Reynolds-averaged Navier–Stokes calculations were carried out with a turbulence model of a scale-adaptive simulation shear stress transport. By injecting the air into the draft tube, the hydraulic efficiency was reduced, however, the visible vortex ropes in the draft tube were suppressed. Additionally, the unsteady pressure phenomena also were reduced by injecting the air.

Effect of Air Injection on the Internal Flow Characteristics in the Draft Tube of a Francis Turbine Model

Under low flow-rate conditions, a Francis turbine exhibits precession of a vortex rope with pressure fluctuations in the draft tube. These undesirable flow phenomena can lead to deterioration of the turbine performance as manifested by torque and power output fluctuations. In order to suppress the rope with precession and a swirl component in the tube, the use of anti-swirl fins was investigated in a previous study. However, vortex rope generation still occurred near the cone of the tube. In this study, unsteady-state Reynolds-averaged Navier–Stokes analyses were conducted with a scale-adaptive simulation shear stress transport turbulence model. This model was used to observe the effects of the injection in the draft tube on the unsteady internal flow and pressure phenomena considering both active and passive suppression methods. The air injection affected the generation and suppression of the vortex rope and swirl component depending on the flow rate of the air. In addition, an injection level of 0.5%Q led to a reduction in the maximum unsteady pressure characteristics.

Optimization of axial water injection to mitigate the Rotating Vortex Rope in a Francis turbine

Rotating Vortex Rope (RVR) resulting from flow instabilities inside draft tube affects the hydraulic turbine's efficiency and wear. Among the passive and active RVR mitigation methods, the water injection method has been widely investigated lately. The present research focuses on the dynamics of RVR mitigation using the water injection method and the optimization of exergy loss during the water injection. The numerical simulations are performed using a reduced turbine geometry consisting of one stay vane, two guide vanes, one runner passage by applying periodic boundary conditions at side boundaries, and a complete draft tube. The pressure fluctuations, velocity field, and the RVR structure are well captured using the Shear Stress Transport - Scale Adaptive Simulation (SST-SAS) turbulence model. The results of the local swirl number during the load variation show that the onset of flow instabilities and RVR formation are created due to a decrease of the axial momentum below the runner cone. The required axial momentum flux of water injection is calculated for a stable swirl number and the local minimum ratio of dimensionless loss to the pressure recovery factor. The numerical results show that the rotating and plunging components of the pressure fluctuations inside the draft tube reduce during the water injection. The pressure recovery of the draft tube improves. The dynamics of RVR mitigation are visualized using λ2 criterion and the spectrogram of pressure probes on the draft tube wall. An optimum water flow rate and jet velocity for a fixed axial momentum are proposed. The results show that a water jet with a large radius and low velocity is more effective to mitigate the RVR and minimizing the draft tube losses.

Fixed inducing points online Bayesian calibration for computer models with an application to a scale-resolving CFD simulation

This paper proposes a novel fixed inducing points online Bayesian calibration (FIPO-BC) algorithm to efficiently learn the model parameters using a benchmark database. The standard Bayesian calibration (STD-BC) algorithm provides a statistical method to calibrate the parameters of computationally expensive models. However, the STD-BC algorithm does not scale well with regard to the number of data points and also it lacks an online learning capability. The proposed FIPO-BC algorithm greatly improves the computational efficiency of the algorithm and, in addition, enables online calibration to be performed by executing the calibration on a set of predefined inducing points.To demonstrate the procedure of the FIPO-BC algorithm, two tests are performed, finding the optimal value and exploring the posterior distribution of 1) the parameter in a simple function, and 2) the high-wave number damping factor in a scale-resolving turbulence model (scale adaptive simulation shear-stress transport model/SAS-SST). The results (such as the calibrated model parameter and its posterior distribution) of FIPO-BC with different inducing points are compared to those of STD-BC. It is found that FIPO-BC and STD-BC can provide very similar results, once the predefined set of inducing points in FIPO-BC is sufficiently fine. Given that fewer datapoints are needed in the proposed FIPO-BC algorithm, compared to the STD-BC algorithm, it will be a more computational efficient algorithm. In our demonstration test cases, the proposed FIPO-BC algorithm is at least ten times faster than the STD-BC algorithm. Meanwhile, the online feature of the FIPO-BC allows continuous updating of the calibration outputs and potentially reduces the workload on generating the database.

Effect of Fins on the Internal Flow Characteristics in the Draft Tube of a Francis Turbine Model

Undesirable flow phenomena in Francis turbines are caused by pressure fluctuations induced under conditions of low flow rate; the resulting vortex ropes with precession in the draft tube (DT) can degrade performance and increase the instability of turbine operations. To suppress these DT flow instabilities, flow deflectors, grooves, or other structures are often added to the DT into which air or water is injected. This preliminary study investigates the effects of anti-cavity fins on the suppression of vortex ropes in DTs without air injection. Unsteady-state Reynolds-averaged Navier–Stokes analyses were conducted using a scale-adaptive simulation shear stress transport turbulence model to observe the unsteady internal flow and pressure characteristics by applying anti-cavity fins in the DT of a Francis turbine model. A vortex rope with precession was observed in the DT under conditions of low flow rate, and the anti-cavity fins were confirmed to affect the mitigation of the vortex rope. Moreover, at the low flow rate conditions under which the vortex rope developed, the application of anti-cavity fins was confirmed to reduce the maximum unsteady pressure.

Numerical Study of a Francis Turbine over Wide Operating Range: Some Practical Aspects of Verification

Hydropower plays an essential role in maintaining energy flexibility. Modern designs focus on sustainability and robustness using different numerical tools. Automatic optimization of the turbines is widely used, including low, mini and micro head turbines. The numerical techniques are not always foolproof in the absence of experimental data, and hence accurate verification is a key component of automatic optimization processes. This work aims to investigate the newly designed Francis runner for flexible operation. Unsteady simulations at 80 operating points of the turbine were conducted. The numerical model consisted of 16 million nodes of hexahedral mesh. A SAS-SST (scale adaptive simulation-shear stress transport) model was enabled for resolving/modeling the turbulent flow. The selected time-step size was equivalent to one-degree angular rotation of the runner. Global parameters, such as efficiency, torque, head and flow rate were considered for proper verification and validation. (1) A complete hill diagram of the turbine was prepared and verified with the reference case. (2) The relative error in hydraulic efficiency was computed and the over trend was studied. This allowed us to investigate the consistency of the numerical model under extreme operating conditions, far away from the best efficiency point. (3) Unsteady fluctuations of runner output torque were studied to identify unstable regions and magnitude of torque oscillations.

Simulation of stochastic pressure loads on a medium head Francis runner

In recent years, major advances have been made in simulating dynamic and transient flows in hydraulic turbines. Overall, computational fluid dynamics (CFD) and finite element analysis (FEA) simulations have been quite successful and have helped to advance knowledge beyond the best efficiency point. The simulation of transient operations like startup and runaway has nearly become part of the standard toolbox. However, numerically predicting stochastic flows, such as those occurring during speed-no-load (SNL) regime, remains a challenge. Since these flows can have a significant impact on turbines’ life expectancy, CFD methods need to be improved. In this paper, we examine the SNL regime in a Francis turbine in which extensive dynamic fluctuations were measured. The approach used was to first focus on the CFD methodology required to better predict stochastic pressure loads with hybrid turbulence models such as the Scale-Adaptive Simulation–Shear-Stress Transport (SAS-SST) model and the relatively new Stress-Blended Eddy Simulation (SBES) model. This will then allow us to determine the amount of LES content required to accurately predict large-scale turbulent structures and the corresponding pressure fluctuations that they generate on blades.

Investigation of Rotating Vortex Rope formation during load variation in a Francis turbine draft tube

Rotating Vortex Rope (RVR) has been a matter of focus for years due to the major effects on hydraulic turbine’s efficiency. The exact procedure of RVR formation is still vague. The present research focuses on the dynamics of the RVR formation during the load variation employing transient numerical simulations. Two different geometries including the full geometry and the reduced one, which consists of one stay vane, two guide vanes, one runner blade, one splitter blade and full draft tube, are considered. In order to capture the transient swirling flow features inside the draft tube, the Shear Stress Transport-Scale Adaptive Simulation (SST-SAS) model is utilized to approximate the turbulent stresses. The pressure results inside the draft tube agree well with the experimental measurements. Moreover, the velocity results show the central low-axial-velocity and high-tangential-velocity region in the draft tube properly. The flow structure is visualized using λ2 criterion. The dynamic of RVR and the physics behind the RVR formation are investigated during the load variation. The results indicate four flow regimes with different characteristics during RVR formation. The first flow regime is a stable swirling structure occurring at Best Efficiency Point (BEP). The second flow regime occurs at the beginning of the load variation where signs of flow instabilities appear. These instabilities are temporary and washed down by the upstream flow. Expanding the instabilities and creating the vortical structures in the draft tube are the important flow features in the third flow regime. The fourth flow regime is the presence of a developed rotating rope occurring at the Part Load (PL) condition. The flow regimes differ according to the size and shape of the stalled region during load rejection inside the draft tube cone. They also reveal that despite some shortcomings, the reduced model is reliable to simulate the RVR transient formation. The full geometry simulations could be also applicable for practical problems provided that the modified time step is slightly greater than the main blade rotational angle is used.

Study on the Accuracy of RANS Modelling of the Turbulent Flow Developed in a Kaplan Turbine Operated at BEP. Part 2 - Pressure Fluctuations

The aim of the paper is to investigate the limitations of unsteady Reynolds-averaged Navier-Stokes (RANS) simulations of the flow in an axial turbine. The study is focused on modelling the pressure pulsations monitored on the runner blades. The scanned blade geometry renders the meshing process more difficult. As the pressure monitor points are defined on the blade surface the simulation relies on the wall functions to capture the flow and the pressure oscillations. In addition to the classical turbulence models, a curvature correction model is evaluated aiming to better capture the rotating flow near curved, concave wall boundaries. Given the limitations of Reynolds-averaged Navier-Stokes models to predict pressure fluctuations, the Scale Adaptive Simulation-Shear Stress Transport (SAS-SST) turbulence model is employed as well. The considered test case is the Porjus U9, a Kaplan turbine model, for which pressure measurements are available in the rotating and stationary frames of reference. The simulations are validated against time-dependent experimental data. Despite the frequencies of the pressure fluctuations recorded on the runner blades being accurately captured, the amplitudes are considerably underestimated. All turbulence models estimate the correct mean wall pressure recovery coefficient in the upper part of the draft tube.

Tracking the vortex core from a surface-piercing flat plate by particle image velocimetry and numerical simulation

The wake flow around the tip of a surface piercing flat plate at an angle of incidence was studied using two-dimensional particle image velocimetry as part of benchmarking the particle image velocimetry technique on the moving carriage in the Australian Maritime College towing tank. Particle image velocimetry results were found to be in close agreement with those of the benchmarking work presented by the Hydro Testing Alliance, and a method of tracking the tip-vortex core near a free surface throughout numerical simulation has been demonstrated. Issues affecting signal to noise ratio, such as specula reflections from the free surface and model geometry were overcome through the use of fluorescing particles and a high-pass optical filter. Numerical simulations using the ANSYS CFX Solver with the volume of fluid method were validated against the experimental results, and a methodology was developed for tracking the location of the wandering vortex core experimentally and through simulation. The ability of the scale-adaptive simulation shear stress transport turbulence model and the shear stress transport model to simulate three-dimensional flow with high streamline curvature was compared. The scale-adaptive simulation shear stress transport turbulence model was found to provide a computationally less resource-intensive method of simulating a complex flow topology with large eddies, providing an insight into a possible cause of tip-vortex aperiodic wandering motion. At high angles of attack, vortex shedding from the leading edge separation of the test geometry is identified as a possible cause of the wandering phenomena. In this study, the vortex centre and point of extreme core velocity were found not to be co-located. The point of extreme stream wise velocity within the vortex core was found to be located within half the vortex radius of the vortex centre.

Correlation Between Pressure Recovery of Highly Loaded Annular Diffusers and Integral Stage Design Parameters1

Exhaust diffusers significantly enhance the available power output and efficiency of gas and steam turbines by allowing lower turbine exit pressures. The residual dynamic pressure of the turbine outflow is converted into static pressure, which is referred to as pressure recovery. Since total pressure losses and construction costs increase drastically with diffuser length, it is strongly preferred to design shorter diffusers with steeper opening angles. However, these designs are more susceptible to boundary layer separation. In this paper, the stabilizing properties of tip leakage vortices generated in the last rotor row and their effect on the boundary layer characteristics are examined. Based on analytical considerations, for the first time, a correlation between the pressure recovery of the diffuser and the integral rotor parameters of the last stage, namely, the loading coefficient, flow coefficient, and reduced frequency, is established. Experimental data and scale-resolving simulations, carried out with the shear stress transport scale-adaptive simulation (SST-SAS) method, both show excellent agreement with the correlation. Blade tip vortex strength predominantly depends on the amount of work exchanged between fluid and rotor, which in turn is described by the nondimensional loading coefficient. The flow coefficient influences mainly the orientation of the vortex, which affects the interaction between vortex and boundary layer. The induced velocity field accelerates the boundary layer, essentially reducing the thickness of the separated layer or even preventing separation locally.

Pressure fluctuation characteristics in the sidewall gaps of a centrifugal dredging pump

PurposeThe purpose of this paper is to study the pressure fluctuation characteristics in the sidewall gaps of a centrifugal dredging pump in detail and discover the excitation sources.Design/methodology/approachAn unsteady numerical simulation with shear–stress transport–scale-adaptive simulation (SAS-SST) model was conducted for a centrifugal pump considering the sidewall gaps. The numerical codes were validated by a model test carried out in China Water Resources Beifang Investigation, Design and Research Co., Ltd. Fast Fourier transform was used to obtain the frequency components of the pressure fluctuation.FindingsPressure fluctuation characteristics inside the pump were analyzed for a condition near the design point. In the sidewall gaps, the circumferential, radial and axial distribution of the pressure fluctuation amplitude follow different laws. The non-axisymmetrical distribution of pressure fluctuation in the sidewall gaps shows that the unsteady flow in the volute casing which has a non-axisymmetrical geometry imposes an evident effect on the flow field in the sidewall gaps and the interaction between the main flow and the clearance flow cannot be neglected. There are several frequency components appearing as the dominant frequencies at different locations in the sidewall gaps, but the relatively stronger pressure fluctuations are all dominated by the rotating frequency. It indicates that the rotating impeller, which originally makes the shrouds rotate, is the primarily excitation source of the pressure fluctuations in the sidewall gaps.Originality/valueThe pressure fluctuation characteristics in the sidewall gaps of centrifugal pumps were first comprehensively analyzed. Unsteady flows in the sidewall gaps should be considered during the design and operation of centrifugal pumps.

Fluid–Structure Interaction Simulation of Vortex-Induced Vibration of a Flexible Hydrofoil

Fluid–structure interaction (FSI) is investigated in this study for vortex-induced vibration (VIV) of a flexible, backward skewed hydrofoil. An in-house finite element structural solver finite element analysis nonlinear (FEANL) is tightly coupled with the open-source computational fluid dynamics (CFD) library openfoam to simulate the interaction of a flexible hydrofoil with vortical flow structures shed from a large upstream rigid cylinder. To simulate the turbulent flow at a moderate computational cost, hybrid Reynolds-averaged Navier–Stokes–large eddy simulation (RANS–LES) is used. Simulations are first performed to investigate key modeling aspects that include the influence of CFD mesh resolution and topology (structured versus unstructured mesh), time-step size, and turbulence model (delayed-detached-eddy-simulation and k−ω shear stress transport-scale adaptive simulation). Final FSI simulations are then performed and compared against experimental data acquired from the Penn State-ARL 12 in water tunnel at two flow conditions, 2.5 m/s and 3.0 m/s, corresponding to Reynolds numbers of 153,000 and 184,000 (based on the cylinder diameter), respectively. Comparisons of the hydrofoil tip-deflections, reaction forces, and velocity fields (contours and profiles) show reasonable agreement between the tightly coupled FSI simulations and experiments. The primary motivation of this study is to assess the capability of a tightly coupled FSI approach to model such a problem and to provide modeling guidance for future FSI simulations of rotating propellers in crashback (reverse propeller operation).

СЕКЦИОНИРОВАНИЕ НАБЕГАЮЩЕГО ПОТОКА ПРИ СВЕРХЗВУКОВОМ ПОПЕРЕЧНОМ ОБТЕКАНИИ КРУГОВОГО ЦИЛИНДРА

The numerical simulation results of supersonic incident flow along a cross circular cylinder of different length in Mach number range from 2.5 up to 3.5 with Reynolds number Re= 2∙10 6 are presented in the article. Numerical simulation was carried out using unsteady three-dimensional Reynolds-averaged Navier–Stokes equations for compressible fluid. For the equation system closure four turbulence models such as SST (Shear Stress Transport), SAS SST (Scale-Adaptive Simulation Shear Stress Transport), DES (Detached Eddy Simulation) and LES (Large Eddy Simulation) were used. The numerical solution of the reference equations was obtained due to a control volume approach. In the calculations numerical methods that have the second order of approximation by space variables were used. The solution is presented to the task in three dimensional statement of flow around the infinite cylinder. Due to the results of the numerical modeling the availability of large-scale vortexes that bring to a sectioning of the incident flow was discovered. In process of streamlining the flow is divided into equal segments (sections) along the cylinder. Formed sections of the flow are structured along the cylinder and have the equal scale. The influence of the cylinder length on a sectioning scale and structure is considered. The numerical simulation results of the supersonic incident flow sectioning along a cross cylinder with the length 6d, 4d and 2d (where d is a diameter of current cylinder) are presented in the article. In this case the size of control volumes along the cylinder is constant. In addition Mach number influence on the sectioning scale and structure is considered. Mach number effect on origin and attenuation is done for the cylinder length 4d in Mach number range from 2.5 up to 3.5 with the constant Reynolds number. Also the causes of sectioning generating of the supersonic incident flow along the cross cylinder are discussed. The possible causes are space discontinuity of incident flow, flow instability in an area of the front critical point and interaction between the shock wave and vortex flow in a shock layer.

Impact of Swirl Flow on Combustor Liner Heat Transfer and Cooling: A Numerical Investigation With Hybrid Reynolds-Averaged Navier–Stokes Large Eddy Simulation Models

This paper reports the main findings of a numerical investigation aimed at characterizing the flow field and the wall heat transfer resulting from the interaction of a swirling flow provided by lean-burn injectors and a slot cooling system, which generates film cooling in the first part of the combustor liner. In order to overcome some well-known limitations of Reynolds-averaged Navier–Stokes (RANS) approach, e.g., the underestimation of mixing, the simulations were performed with hybrid RANS–large eddy simulation (LES) models, namely, scale-adaptive simulation (SAS)–shear stress transport (SST) and detached eddy simulation (DES)–SST, which are proving to be a viable approach to resolve the main structures of the flow field. The numerical results were compared to experimental data obtained on a nonreactive three-sector planar rig developed in the context of the EU project LEMCOTEC. The analysis of the flow field has highlighted a generally good agreement against particle image velocimetry (PIV) measurements, especially for the SAS–SST model, whereas DES–SST returns some discrepancies in the opening angle of the swirling flow, altering the location of the corner vortex. Also the assessment in terms of Nu/Nu0 distribution confirms the overall accuracy of SAS–SST, where a constant overprediction in the magnitude of the heat transfer is shown by DES–SST, even though potential improvements with mesh refinement are pointed out.