Non-Reacting and Reacting Flow Analysis in an Aero-Engine Gas Turbine Combustor Using CFD

Author(s):  
V. Ganesan
Author(s):  
S. James ◽  
M. S. Anand ◽  
B. Sekar

The paper presents an assessment of large eddy simulation (LES) and conventional Reynolds averaged methods (RANS) for predicting aero-engine gas turbine combustor performance. The performance characteristic that is examined in detail is the radial burner outlet temperature (BOT) or fuel-air ratio profile. Several different combustor configurations, with variations in airflows, geometries, hole patterns and operating conditions are analyzed with both LES and RANS methods. It is seen that LES consistently produces a better match to radial profile as compared to RANS. To assess the predictive capability of LES as a design tool, pretest predictions of radial profile for a combustor configuration are also presented. Overall, the work presented indicates that LES is a more accurate tool and can be used with confidence to guide combustor design. This work is the first systematic assessment of LES versus RANS on industry-relevant aero-engine gas turbine combustors.


1999 ◽  
Vol 121 (2) ◽  
pp. 243-248 ◽  
Author(s):  
D. M. Costura ◽  
P. B. Lawless ◽  
S. H. Fankel

A dynamic combustor model is developed for inclusion into a one-dimensional full gas turbine engine simulation code. A flux-difference splitting algorithm is used to numerically integrate the quasi-one-dimensional Euler equations, supplemented with species mass conservation equations. The combustion model involves a single-step, global finite-rate chemistry scheme with a temperature-dependent activation energy. Source terms are used to account for mass bleed and mass injection, with additional capabilities to handle momentum and energy sources and sinks. Numerical results for cold and reacting flow for a can-type gas turbine combustor are presented. Comparisons with experimental data from this combustor are also made.


Author(s):  
S. Suresh Kumar ◽  
V. Ganesan

This paper is concerned with the prediction of flow and flame characteristics behind complex flame stabilizer used in aero gas turbine afterburners. The numerical calculation is performed using SIMPLE algorithm with unstructured grid arrangement in which time averaged transport equation for mass, momentum, turbulence and energy are solved using finite volume method. The turbulence effects are simulated using RNG κ-ε model. Flow analysis has been carried out for the non-reacting and reacting conditions. Meshing of the flow domain is done in GAMBIT. A detailed analysis of non-reacting flow in a 60°sector afterburner from inlet to exit of the afterburner is carried out in FLUENT solver code. The various thermodynamic properties are analyzed and presented along the length of the afterburner. Three different combustion models viz. prePDF, eddy dissipation and finite rate/eddy dissipation model are used in order to predict the reacting flow. An experimental investigation of the three-dimensional confined flow fields behind a “V” shaped complex flame stabilizer in an isothermal model of an afterburner is carried out to validate the CFD code. From the present study it is concluded that the prediction procedure adopted especially for non-reacting flow can be used with confidence in the development of an afterburner at a lower cost. Since measurements were not possible under reacting conditions no attempt has been made for reacting flow validation.


Author(s):  
Daero Joung ◽  
Kang Y. Huh

This study is concerned with 3D RANS simulation of turbulent flow and combustion in a 5 MW commercial gas turbine combustor. The combustor under consideration is a reverse flow, dry low NOx type, in which methane and air are partially mixed inside swirl vanes. We evaluated different turbulent combustion models to provide insights into mixing, temperature distribution, and emission in the combustor. Validation is performed for the models in STAR-CCM+ against the measurement data for a simple swirl flame (http://public.ca.sandia.gov/TNF/swirlflames.html). The standard k-ε model with enhanced wall treatment is employed to model turbulent swirl flow, whereas eddy break-up (EBU), presumed probability density function laminar flamelet model, and partially premixed coherent flame model (PCFM) are tried for reacting flow in the combustor. Independent simulations are carried out for the main and pilot nozzles to avoid flashback and to provide realistic inflow boundary conditions for the combustor. Geometrical details such as air swirlers, vane passages, and liner holes are all taken into account. Tested combustion models show similar downstream distributions of the mean flow and temperature, while EBU and PCFM show a lifted flame with stronger effects of swirl due to limited increase in axial momentum by expansion.


Author(s):  
Kitano Majidi

In the present study numerical calculations are used to solve reacting flow in a gas turbine combustor. A 3-D Favre-Averaged Navier-Stokes solver for a mixture of chemically reacting gases is applied to predict the flow pattern, gas temperature and fuel and species concentrations in the entire combustor. The complete combustor geometry with all important details such as air swirler vane passages and secondary holes are modeled. The calculations are carried out using three different turbulence models. Comparisons are made between the standard k-ε model, RNG k-ε model and a Reynolds stress transport model. To provide a closure for the chemical source term the Eddy Dissipation model is used. A lean direct injection of a liquid fuel is employed. Furthermore the influence of radiation will be investigated.


Author(s):  
Srinivasan Karuppannan ◽  
Bhirud Mehul ◽  
Gullapalli Sivaramakrishna ◽  
Raju D. Navindgi ◽  
N. Muthuveerappan

Swirl cups (hybrid atomizers) are being widely employed in aero gas turbine engine combustors for their established merits in terms of achieving satisfactory atomization over the entire combustor operating regime. Even though several investigators have worked on development of these swirl cups, there is a scanty data reported in literature relevant to their design. In the present study, flow behavior in a swirl cup assembled in a confined chamber similar to a gas turbine combustor has been analyzed. Flow analysis has been carried out using ANSYS Fluent and turbulence has been modeled using Realizable k-ϵ model. Six swirl cup configurations have been analyzed; mass flow ratio between primary and secondary swirler and venturi converging area ratio have been varied. The effect of these parameters on downstream flow field has been studied by analyzing the profiles of axial, tangential and radial velocities downstream of swirl cup. The size and shape of the recirculation zone has been analyzed and reported for all configurations. Also, the mass flow recirculated by swirl cup has been estimated and compared amongst the configurations analyzed. Data thus generated is very useful in designing such swirl cups of gas turbine combustors.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Lei Sun ◽  
Yong Huang ◽  
Zhilin Liu ◽  
Shaolin Wang ◽  
Xiaobo Guo

Abstract The lean blowout (LBO) limit is crucial for gas turbine combustor in the aero engine. The effect of atomization of liquid fuels on the LBO limit is needed to be further studied. On the other hand, the effects of atomization on the LBO limit can be neglected if gas fuels are utilized in a combustor. Thus, the comparative experiment between liquid fuel and gas fuel can be utilized to study the effects of atomization performance of liquid fuels on the LBO limit. In this paper, the LBO limit for a gas turbine combustor utilizing methane is studied experimentally. Seven kinds of combustor configurations are chosen for the experimental test. The LBO limits are obtained for all the chosen combustors. The variation of the LBO limit with the combustor configuration for both methane and aviation kerosene exhibits the similar tendency, i.e., the LBO limits utilizing methane are slightly larger than those utilizing aviation kerosene for the same combustor. Further, the atomization performance has little effects on the LBO limits for the present combustor configurations at the present operating conditions where the SMD for the fuel atomizer utilizing aviation kerosene is about 10 μm.


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