Large Eddy Simulation of Combustor and Complete Single-Stage High-Pressure Turbine of the FACTOR Test Rig

Author(s):  
Martin Thomas ◽  
Jerome Dombard ◽  
Florent Duchaine ◽  
Laurent Gicquel ◽  
Charlie Koupper

Abstract Development goals for next generation aircraft engines are mainly determined by the need to reduce fuel consumption and environmental impact. To reduce NOx emissions lean combustion technologies will be applied in future development projects. The more compact design and the absence of dilution holes in this type of engines shortens residence times in the combustion chamber and reduces mixing which results in higher levels of swirl, turbulence and temperature distortions at the exit of the combustion chamber. For these engines interactions between components are more important, so that the traditional engine design approach of component-wise optimization will have to be adapted. To study new lean burn architectures the European FACTOR project investigates the transport of hot streaks produced by a non-reactive combustor simulator through a single stage high-pressure turbine. In this work high-fidelity Large Eddy Simulation (LES) of combustor and complete high-pressure turbine are discussed and validated against experimental data. Measurement data is available on P40 (exit of the combustion chamber), P41 (exit of the stator) and P42 (exit of the rotor) and generally shows a good agreement to LES data.

Author(s):  
Martin Thomas ◽  
Antoine Dauptain ◽  
Florent Duchaine ◽  
Laurent Gicquel ◽  
Charlie Koupper ◽  
...  

With the goal of increasing the thermodynamic efficiency of aircraft engines, the temperature in the combustion chamber has risen to the point where the gas temperature is above the melting point of materials used in the chamber and cooling systems are mandatory. Today, most of the existing lean burn combustors rely on multiperforated liners to keep hot gases away from the walls. However, resolving all holes of the combustor in the CFD design phase remains beyond currently available computational resources, so the effusion cooling system is often modeled by homogeneously injecting air on the whole surface of the liner, especially in the context of Large Eddy Simulation (LES) based CFD. This paper investigates a novel approach to simulate the effect of jets emitted from discrete holes on the flow inside a combustion chamber. In this new modeling approach, jet diameters are treated to be resolvable by the grid while conserving the correct mass and momentum flow rate. LES are performed on the combustion simulator of the engine representative FACTOR test rig at two different operating points and compared to measurement data as well as previous simulations obtained using a homogeneous air injection modeling on liners. The new approach shows globally similar results as the well validated homogeneous injection model and is applicable on realistic industrial geometries at a negligible level of additional cost (+0.3%).


Author(s):  
Florent Duchaine ◽  
Jérôme Dombard ◽  
Laurent Gicquel ◽  
Charlie Koupper

To study the effects of combustion chamber dynamics on a turbine stage aerodynamics and thermal loads, an integrated Large-Eddy Simulation of the FACTOR combustion chamber simulator along with its high pressure turbine stage is performed and compared to a standalone turbine stage computation operated under the same mean conditions. For this specific configuration, results illustrate that the aerodynamic expansion of the turbine stage is almost insensitive to the inlet turbulent conditions. However, the temperature distribution in the turbine passages as well as on the stator vane and rotor blade walls are highly impacted by these inlet conditions: underlying the importance of inlet conditions in turbine stage computations and the potential of integrated combustion chamber / turbine simulations in such a context.


Author(s):  
Carlos Pérez Arroyo ◽  
Jérôme Dombard ◽  
Florent Duchaine ◽  
Laurent Gicquel ◽  
Nicolas Odier ◽  
...  

Abstract The design optimization of aviation propulsion systems by means of computational fluid dynamics is key to increase their efficiency and reduce pollutant and noise emissions. The recurrent increase in available computing power allows nowadays to perform unsteady high-fidelity computations of the different components of a gas turbine. However, these simulations are often made independently of each other and they only share average quantities at interfaces. In this work, the methodology and first results for a sectoral large-eddy simulation of an integrated high-pressure compressor and combustion chamber of a typical turbine engine architecture is proposed. In the simulation, the compressor is composed of one main blade and one splitter blade, two radial diffuser vanes and six axial diffuser vanes. The combustion chamber is composed of the contouring casing, the flame-tube and a T-shaped vaporizer. This integrated computation considers a good trade-off between accuracy of the simulation and affordable CPU cost. Results are compared between the stand-alone combustion chamber simulation and the integrated one in terms of global, integral and average quantities. It is shown that pressure perturbations generated by the interaction of the impeller blades with the diffuser vanes are propagated through the axial diffuser and enter the combustion chamber through the dilution holes and the vaporizer. Due to the high amplitude of the pressure perturbations, several variables are perturbed at the blade-passing frequency and multiples. This is also reflected on combustion where two broadband peaks appear for the global heat release.


Author(s):  
Solkeun Jee ◽  
Jongwook Joo ◽  
Gorazd Medic

It is important to be able to predict the state of the boundary layer on a high-pressure turbine vane with incoming turbulence. The laminar-to-turbulent transition significantly changes the heat transfer on the blade, which impacts the turbine performance and durability assessment. In this study, an experimental cascade with a high-pressure turbine vane was simulated with large-eddy simulation (LES). To incorporate the impact of turbulence from the freestream on the boundary layer, appropriate turbulence data sets were generated in separate direct-numerical simulation and fed into the LES inlet. The state of the boundary layer is reasonably well predicted for the test condition of the turbulence intensity of Tu=4%. Streamwise vortical structures and spanwise two-dimensional waves are observed in the transitional boundary layer. Discrepancy for the case with the higher turbulence intensity Tu=6% is discussed with the focus on the need for more detailed information about the freestream disturbances.


Author(s):  
S. Puggelli ◽  
D. Bertini ◽  
L. Mazzei ◽  
A. Andreini

During the last years aero-engines are progressively evolving toward design concepts that permit improvements in terms of engine safety, fuel economy and pollutant emissions. With the aim of satisfying the strict NOx reduction targets imposed by ICAO-CAEP, lean burn technology is one of the most promising solutions even if it must face safety concerns and technical issues. Hence a depth insight on lean burn combustion is required and Computational Fluid Dynamics (CFD) can be a useful tool for this purpose. In this work a comparison in Large-Eddy Simulation (LES) framework of two widely employed combustion approaches like the Artificially Thickened Flame (ATF) and the Flamelet Generated Manifold (FGM) is performed using ANSYS® Fluent v16.2. Two literature test cases with increasing complexity in terms of geometry, flow field and operating conditions are considered. Firstly, capabilities of FGM are evaluated on a single swirler burner operating at ambient pressure with a standard pressure atomizer for spray injection. Then a second test case, operated at 4 bar, is simulated. Here kerosene fuel is burned after an injection through a prefilming airblast atomizer within a co-rotating double swirler. Obtained comparisons with experimental results show the different capabilities of ATF and FGM in modelling the partially-premixed behaviour of the flame and provides an overview of the main strengths and limitations of the modelling strategies under investigation.


MTZ worldwide ◽  
2017 ◽  
Vol 78 (5) ◽  
pp. 50-57 ◽  
Author(s):  
Junmei Shi ◽  
Pablo Lopez Aguado ◽  
Noureddine Guerrassi ◽  
Gavin Dober

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