Large eddy simulation applications in gas turbines

2009 ◽  
Vol 367 (1899) ◽  
pp. 2827-2838 ◽  
Author(s):  
Kevin Menzies
Keyword(s):  
Large Eddy Simulation ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Complex Geometry ◽  
Navier Stokes ◽  
Eddy Simulation ◽  
Wide Range ◽  
Large Eddy ◽  
Design Cycle ◽  
Flow Phenomena

The gas turbine presents significant challenges to any computational fluid dynamics techniques. The combination of a wide range of flow phenomena with complex geometry is difficult to model in the context of Reynolds-averaged Navier–Stokes (RANS) solvers. We review the potential for large eddy simulation (LES) in modelling the flow in the different components of the gas turbine during a practical engineering design cycle. We show that while LES has demonstrated considerable promise for reliable prediction of many flows in the engine that are difficult for RANS it is not a panacea and considerable application challenges remain. However, for many flows, especially those dominated by shear layer mixing such as in combustion chambers and exhausts, LES has demonstrated a clear superiority over RANS for moderately complex geometries although at significantly higher cost which will remain an issue in making the calculations relevant within the design cycle.

On the Combination of Large Eddy Simulation and Phenomenological Soot Modelling to Calculate the Smoke Index From Aero-Engines Over a Large Range of Operating Conditions

2017 ◽  
Author(s):  
Jean Lamouroux ◽  
Stéphane Richard ◽  
Quentin Malé ◽  
Gabriel Staffelbach ◽  
Antoine Dauptain ◽  
...  
Keyword(s):  
Large Eddy Simulation ◽  
Gas Turbines ◽  
Soot Formation ◽  
Operating Conditions ◽  
Extended Model ◽  
Eddy Simulation ◽  
Design Office ◽  
Wide Range ◽  
Large Eddy ◽  
Aero Engines

Nowadays, models predicting soot emissions are, neither able to describe correctly fine effects of technological changes on sooting trends nor sufficiently validated at relevant operating conditions to match design office quantification needs. Yet, phenomenological descriptions of soot formation, containing key ingredients for soot modeling exist in the literature, such as the well-known Leung et al. model (Combust Flame 1991). This approach indeed includes contributions of nucleation, surface growth, coagulation, oxidation and thermophoretic transport of soot. When blindly applied to aeronautical combustors for different operating conditions, this model fails to hierarchize operating points compared to experimental measurements. The objective of this work is to propose an extension of the Leung model, including an identification of its constants over a wide range of condition relevant of gas turbines operation. Today, the identification process can hardly be based on laboratory flames since few detailed experimental data are available for heavy-fuels at high pressure. Thus, it is decided to directly target smoke number values measured at the engine exhaust for a variety of combustors and operating conditions from idling to take-off. A Large Eddy Simulation approach is retained for its intrinsic ability to reproduce finely unsteady behavior, mixing and intermittency. In this framework, The Leung model for soot is coupled to the TFLES model for combustion. It is shown that pressure-sensitive laws for the modelling constant of the soot surface chemistry are sufficient to reproduce engine emissions. Grid convergence is carried out to verify the robustness of the proposed approach. Several cases are then computed blindly to assess the prediction capabilities of the extended model. This study paves the way for the systematic use of a high fidelity tool solution in design office constraints for combustion chamber development.

Application of Large-Eddy Simulation and the Multi-Scalar Flamelet Approach to a Methane-Hydrogen Mixed-Combustion-Type Industrial Gas-Turbine Combustor

2017 ◽  
Author(s):  
Ryosuke Kishine ◽  
Tenshi Sasaki ◽  
Nobuyuki Oshima ◽  
Saad Sibawayh ◽  
Kohshi Hirano ◽  
...  
Keyword(s):  
Large Eddy Simulation ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Flame Temperature ◽  
Simulation Method ◽  
Eddy Simulation ◽  
Development Costs ◽  
Large Eddy ◽  
Inflow Condition ◽  
Industrial Gas Turbine

In pursuit of a reduction in environmental loading, gas turbines equipped with lean premixed combustor technology that use a hydrogen-enriched fuel instead of pure methane have entered practical service. An accurate numerical simulation method is therefore needed to reduce product-development costs to a minimum. We performed a numerical analysis of an industrial combustor with a mixed methane-hydrogen fuel by large-eddy simulation and extending the 2-scalar flamelet approach to a multi-scalar one. The calculation object was the combustor of an L30A-DLE gas-turbine. Two calculations were conducted with different fuel compositions at the supplemental burner. In the first simulation, the inflow gas was composed of methane and air, whereas in the second simulation, the inflow gas was composed of methane, air, and hydrogen. The inlet boundary conditions were set so that both cases have the same adiabatic flame temperature at the outlet. The temperature distributions throughout the combustor were approximately equal in both cases. This study therefore suggests that equivalent performance can be obtained by setting the inflow condition at the supplemental burner so that the outlet adiabatic temperatures are equal for both monofuel combustion and mixed combustion.

Large eddy simulation of natural cavitating flows in Venturi-type sections

2010 ◽  
Vol 225 (2) ◽  
pp. 369-381 ◽  
Author(s):  
N M Nouri ◽  
S M H Mirsaeedi ◽  
M Moghimi
Keyword(s):  
Large Eddy Simulation ◽  
Preliminary Data ◽  
Cavitating Flow ◽  
Navier Stokes ◽  
Computational Time ◽  
Time Averaging ◽  
Cavitating Flows ◽  
Eddy Simulation ◽  
Wide Range ◽  
Large Eddy

Large eddy simulation (LES) is used here to model the cavitating flow at a Venturi-type section. Cavitating flows can occur in a wide range of applications. The flow is represented here by means of LES, which compared to Reynolds-averaged Navier—Stokes (RANS) has the advantage that in it the large, energy-containing structures are resolved directly, whereas most of these structures are modelled in RANS. This gives LES an improved fidelity over RANS, although, due to the time averaging, the required computational time is considerably lower for RANS than for LES. The conclusion of this work shows that the qualitative comparisons with earlier preliminary data and the simulated general cavitation behaviour correlate reasonably well with experimental observations and that the simulations have the ability to predict cavitation cycle in more detail.

scholarly journals Large eddy simulation of flows in industrial compressors: a path from 2015 to 2035

2014 ◽  
Vol 372 (2022) ◽  
pp. 20130323 ◽  
Author(s):  
N. Gourdain ◽  
F. Sicot ◽  
F. Duchaine ◽  
L. Gicquel
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Flows ◽  
Complex Geometry ◽  
Current Status ◽  
Navier Stokes ◽  
Future Research ◽  
Phase Lag ◽  
Eddy Simulation ◽  
Large Eddy ◽  
High Reynolds

A better understanding of turbulent unsteady flows is a necessary step towards a breakthrough in the design of modern compressors. Owing to high Reynolds numbers and very complex geometry, the flow that develops in such industrial machines is extremely hard to predict. At this time, the most popular method to simulate these flows is still based on a Reynolds-averaged Navier–Stokes approach. However, there is some evidence that this formalism is not accurate for these components, especially when a description of time-dependent turbulent flows is desired. With the increase in computing power, large eddy simulation (LES) emerges as a promising technique to improve both knowledge of complex physics and reliability of flow solver predictions. The objective of the paper is thus to give an overview of the current status of LES for industrial compressor flows as well as to propose future research axes regarding the use of LES for compressor design. While the use of wall-resolved LES for industrial multistage compressors at realistic Reynolds number should not be ready before 2035, some possibilities exist to reduce the cost of LES, such as wall modelling and the adaptation of the phase-lag condition. This paper also points out the necessity to combine LES to techniques able to tackle complex geometries. Indeed LES alone, i.e. without prior knowledge of such flows for grid construction or the prohibitive yet ideal use of fully homogeneous meshes to predict compressor flows, is quite limited today.

Analysis of Solid Particle Ingestion and Dynamics in a Turbomachine Using Large-Eddy Simulation

2019 ◽  
Author(s):  
Benjamin Martin ◽  
Martin Thomas ◽  
Jérôme Dombard ◽  
Florent Duchaine ◽  
Laurent Gicquel
Keyword(s):  
Large Eddy Simulation ◽  
Gas Turbine ◽  
Solid Particle ◽  
Turbine Blades ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Lagrangian Formalism ◽  
Eddy Simulation ◽  
Wide Range ◽  
Large Eddy

Abstract Erosion of compressor and turbine blades operating in extreme environment fouled with sand particles, ash or soot is a serious problem for gas turbine manufacturers and users. Indeed, operation of a gas turbine engine in such hostile conditions leads to drastic degradation of the aerodynamic performance of the components, mostly through surface roughness modification, tip clearance height increase or blunting of blade leading edges. To evaluate associated risks, the computation of particle trajectories and impacts through multiple turbomachinery stages by Computational Fluid Dynamics (CFD) seems a decent path but remains a challenge. The numerical prediction of complex turbulent flows in compressors and turbines is however necessary in such a context and validations are still required. Recently, Large-Eddy Simulation (LES) has shown promising results for compressor and turbine configurations for a wide range of operating conditions at an acceptable cost. With this in mind, this article presents the assessment of a LES solver able to treat turbomachine configurations to predict solid particle motion. To do so, the governing equations of particle dynamics are introduced using the Lagrangian formalism and are solved to compute locations and conditions of impact, namely particle velocity, angle and radius. The fully unsteady and coupled strategy is applied to blade geometries for studying the main areas and conditions of impacts obtained with LES. For comparison, a one-way coupling computation based on a mean steady flow field where only the Lagrangian particles are advanced in time is performed to evaluate the gain and drawbacks of both methods.

Application of Large-Eddy Simulation to Pressurized Thermal Shock Problem

2009 ◽  
Author(s):  
M. S. Loginov ◽  
E. M. J. Komen ◽  
A. K. Kuczaj
Keyword(s):  
Large Eddy Simulation ◽  
Life Span ◽  
Thermal Shock ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Complex Flow ◽  
Eddy Simulation ◽  
Pressurized Thermal Shock ◽  
Large Eddy ◽  
Flow Phenomena

Life span assessment is a very important issue for the nuclear community. A serious threat to the life span of a Reactor Pressure Vessel (RPV) is an occurrence of the Pressurized Thermal Shock (PTS) during an Emergency Core Coolant (ECC) injection in a loss-of-coolant accident. Traditional system codes fail to predict the complex three-dimensional flow phenomena resulting from such an ECC injection. Improved results have been obtained using Computational Fluid Dynamics (CFD) analysis based on the Reynolds-Averaged Navier-Stokes (RANS) equations. However, it has been shown also that current transient RANS approaches are less capable to predict complex flow features in the downcomer of the RPV. More advanced CFD methods like Large-Eddy Simulation (LES) are required for modeling of these complex flow phenomena in the downcomer. The current paper addresses the feasibility of the application of LES for single-phase PTS. Furthermore, the required grid resolution for such LES analyses is identified by evaluation of solutions on different meshes. A buoyancy-driven PTS experiment has been considered. This experiment has been performed in the 1:5 linear scale Rossendorf Coolant Mixing Model (ROCOM) facility. In the applied numerical model, the incompressible Navier-Stokes equations are solved in the LES formulation, with an additional transport equation for a scalar, which is responsible for driving the embedded buoyancy term in the momentum equations. Instantaneous mixing characteristics are investigated based on evaluation of the scalar concentration. The analysis presented in this paper indicates that the application of LES is feasible nowadays. It is demonstrated that the mixing in the downcomer is quite sensitive to small turbulent disturbances at the ECC inlet, i.e., two simulations performed with slightly different fluctuations at inlet result in substantially different flow in the downcomer. This complicates the analysis of the data from simulations and suggests that validation against experimental data should not be performed using single physical experiment.

On the Combination of Large Eddy Simulation and Phenomenological Soot Modeling to Calculate the Smoke Index From Aero-Engines Over a Large Range of Operating Conditions

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
J. Lamouroux ◽  
S. Richard ◽  
Q. Male ◽  
G. Staffelbach ◽  
A. Dauptain ◽  
...  
Keyword(s):  
Large Eddy Simulation ◽  
Gas Turbines ◽  
Soot Formation ◽  
Operating Conditions ◽  
Extended Model ◽  
Engine Exhaust ◽  
Eddy Simulation ◽  
Wide Range ◽  
Large Eddy ◽  
Aero Engines

Nowadays, models predicting soot emissions are neither able to describe correctly fine effects of technological changes on sooting trends nor sufficiently validated at relevant operating conditions to match design office quantification needs. Yet, phenomenological descriptions of soot formation, containing key ingredients for soot modeling exist in the literature, such as the well-known Leung et al. model (Combust Flame 1991). However, when blindly applied to aeronautical combustors for different operating conditions, this model fails to hierarchize operating points compared to experimental measurements. The objective of this work is to propose an extension of the Leung model over a wide range of condition relevant of gas turbines operation. Today, the identification process can hardly be based on laboratory flames since few detailed experimental data are available for heavy-fuels at high pressure. Thus, it is decided to directly target smoke number values measured at the engine exhaust for a variety of combustors and operating conditions from idling to take-off. A large eddy simulation approach is retained for its intrinsic ability to reproduce finely unsteady behavior, mixing, and intermittency. In this framework, The Leung model for soot is coupled to the thickened flame model (TFLES) for combustion. It is shown that pressure-sensitive laws for the modeling constant of the soot surface chemistry are sufficient to reproduce engine emissions. Grid convergence is carried out to verify the robustness of the proposed approach. Several cases are then computed blindly to assess the prediction capabilities of the extended model.

NUMERICAL STUDY OF DETONATION PROPAGATION IN VISCOUS TURBULENT FLOW IN A DUCT

2020 ◽  
Author(s):  
V. A. SABELNIKOV ◽  
◽  
V. V. VLASENKO ◽  
S. BAKHNE ◽  
S. S. MOLEV ◽  
...  
Keyword(s):  
Complex Geometry ◽  
Numerical Study ◽  
Navier Stokes ◽  
Detonation Waves ◽  
Detonation Propagation ◽  
Eddy Simulation ◽  
Detonation Structure ◽  
Classical Studies ◽  
Large Eddy ◽  
Physical Effects

Gasdynamics of detonation waves was widely studied within last hundred years - analytically, experimentally, and numerically. The majority of classical studies of the XX century were concentrated on inviscid aspects of detonation structure and propagation. There was a widespread opinion that detonation is such a fast phenomenon that viscous e¨ects should have insigni¦cant in§uence on its propagation. When the era of calculations based on the Reynolds-averaged Navier- Stokes (RANS) and large eddy simulation approaches came into effect, researchers pounced on practical problems with complex geometry and with the interaction of many physical effects. There is only a limited number of works studying the in§uence of viscosity on detonation propagation in supersonic §ows in ducts (i. e., in the presence of boundary layers).

On LES Methods Applied to Seal Geometries

2012 ◽  
Author(s):  
James Tyacke ◽  
Richard Jefferson-Loveday ◽  
Paul Tucker
Keyword(s):  
Maximum Error ◽  
Labyrinth Seal ◽  
Navier Stokes ◽  
Final Solution ◽  
Complex Flow ◽  
Eddy Simulation ◽  
Wide Range ◽  
Large Eddy ◽  
Rans Models ◽  
Flow Through

Nine Large Eddy Simulation (LES) methods are used to simulate flow through two labyrinth seal geometries and are compared with a wide range of Reynolds-Averaged Navier-Stokes (RANS) solutions. These involve one-equation, two-equation and Reynolds Stress RANS models. Also applied are linear and nonlinear pure LES models, hybrid RANS-Numerical-LES (RANS-NLES) and Numerical-LES (NLES). RANS is found to have a maximum error and a scatter of 20%. A similar level of scatter is also found among the same turbulence model implemented in different codes. In a design context, this makes RANS unusable as a final solution. Results show that LES and RANS-NLES is capable of accurately predicting flow behaviour of two seals with a scatter of less than 5%. The complex flow physics gives rise to both laminar and turbulent zones making most LES models inappropriate. Nonetheless, this is found to have minimal tangible results impact. In accord with experimental observations, the ability of LES to find multiple solutions due to solution non-uniqueness is also observed.

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