4337 Numerical Prediction of turbulent partially premixed combustion in a gas turbine combustor

2006 ◽  
Vol 2006.3 (0) ◽  
pp. 81-82
Author(s):  
Takuji TOMINAGA ◽  
Nobuyuki OSHIMA
Keyword(s):  
Gas Turbine ◽  
Numerical Prediction ◽  
Premixed Combustion ◽  
Gas Turbine Combustor ◽  
Partially Premixed Combustion ◽  
Partially Premixed

Large-Eddy Simulation With a New Flamelet Model for Partially Premixed Combustion in a Gas-Turbine Combustor

2017 ◽  
Author(s):  
Keisuke Tanaka ◽  
Tomonari Sato ◽  
Nobuyuki Oshima ◽  
Jiun Kim ◽  
Yusuke Takahashi ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Diffusion Flame ◽  
Premixed Combustion ◽  
Combustion Model ◽  
Gas Turbine Combustor ◽  
Flamelet Model ◽  
Eddy Simulation ◽  
Partially Premixed Combustion ◽  
Large Eddy ◽  
Partially Premixed

Turbulent combustion flows in the partially premixed combustion field of a dry low-emission gas-turbine combustor were investigated numerically by large-eddy simulation with a 2-scalar flamelet model. Partially premixed combustion was modelled with 2-scalar coupling based on the conservative function of the mixture fraction and the level set function of the premixed flame surface; the governing equations were then used to calculate the gas temperature in the combustion field with flamelet data. A new combustion model was introduced by defining a nondimensional equilibrium temperature to permit the calculation of adiabatic flame temperatures in the combustion field. Furthermore, a conventional G-equation was modified to include spatial gradient terms for the adiabatic flame temperature to facilitate smooth propagation of a burnt-state region in a predominantly diffusion flame. The effect of flame curvature was adjusted by means of an arbitrary parameter in the equation. The simulation results were compared with those from an experiment and a conventional model. Qualitative comparisons of the instantaneous flame properties showed a dramatic improvement in the new combustion model. Moreover, the experimental outlet temperature agreed well with that predicted by the new model. The model can therefore reproduce the propagation of a predominantly diffusion flame in partially premixed combustion.

Control of Lean Blowout in Partially Premixed Swirl-Stabilized Combustor Using a Fuel Rich Central Pilot Configuration

2019 ◽  
Author(s):  
Somnath De ◽  
Prasanna Mondal ◽  
Gourav Manohar Sardar ◽  
Rakin Bin Bokhtiar ◽  
Arijit Bhattacharya ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Premixed Flames ◽  
Premixed Combustion ◽  
Combustion Stability ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Lean Blowout ◽  
Partially Premixed Combustion ◽  
Partially Premixed

Abstract The main problem for using reliable and stable diffusion combustion in modern gas turbine engines is the production of NOx at a higher level which is not permissible for maintaining the healthy environment. Thus, combustion in lean premixed mode has become the most promising technology in many applications related to power generation gas turbine, industrial burner etc. Although the lean combustion minimizes NOx production, it suffers from an increased risk of lean blowout (LBO) when the requirement of thrust or load is low. It mainly occurs at the lean condition when the equilibrium between the flame speed and the unburnt air-fuel mixture velocity is broken. Current aircraft gas turbine engines operate fuel close to the combustion chamber which leads to the partially premixed combustion. Partially premixed combustion is also susceptible to lean blowout. Therefore, we have designed a swirl-stabilized dump combustor, where different lengths of fuel-air mixing are available. Our present work aims at improving the combustion stability by incorporating a secondary fuel injection through a pilot arrangement connected with the combustion chamber for premixed as well as partially premixed flames. Incorporation of the pilot system adds a small fraction of the total fuel into the combustion chamber directly. This investigation shows significant extension of the LBO limit towards leaner fuel-air mixture while the NOx emission in the combustion chamber is within the permissible limit. This result can be used for aircraft operators during the process of landing when fuel supply has to be decreased to reduce engine thrust or for power plants operating at low loads. The study of control is based on the colour variation of the flame which actually defines the changes in combustion characteristics. For early detection of LBO, the ratio between the intensity of red and blue colour obtained from flame images with a high speed camera is used. As LBO is approached, the ratio of red to blue intensity falls monotonically. When the ratio falls below a preset threshold, a small fraction of the total fuel is added to the central pilot line. This strategy allows the LBO limit to be shifted to a much lower equivalence ratio (maximum 20% and 11% for fully premixed and least premixed flames, respectively) without any significant increase in NOx production. The analysis includes a feedback control algorithm which is computed in MATLAB and the code is embedded in Labview for hardware implementation.

Validation of a Partially-Premixed Combustion Model for Gas Turbine Applications

2006 ◽  
Author(s):  
L. Caracciolo ◽  
P. A. Rubini
Keyword(s):  
Numerical Simulation ◽  
Gas Turbine ◽  
Computational Efficiency ◽  
Premixed Combustion ◽  
Experimental Results ◽  
Combustion Model ◽  
Gas Turbine Combustor ◽  
Accurate Representation ◽  
Combustion Models ◽  
Partially Premixed Combustion

The principal requirements of industry, with respect to the numerical simulation of gas turbine combustors, are computational efficiency and algorithm robustness, together with an accurate representation of the complex fundamental processes. This paper examines the performance of the premixed combustion models implemented in the commercial CFD package Fluent™, in order to validate the ability to model combustion in the context of a premixed gas turbine combustor. The predictions of the model are found to compare well with the experimental results available, demonstrating robustness and computational efficiency.

Large Eddy Simulation of a Gas-Turbine Combustor Using 2-Scalar Flamelet Approach

2007 ◽  
Author(s):  
Takuji Nakashima ◽  
Nobuyuki Oshima
Keyword(s):  
Large Eddy Simulation ◽  
Gas Turbine ◽  
Turbulent Combustion ◽  
Numerical Prediction ◽  
Premixed Combustion ◽  
Combustion Reaction ◽  
Combustion Model ◽  
Gas Turbine Combustor ◽  
Eddy Simulation ◽  
Large Eddy

To investigate the ability of a numerical prediction method in a practical combustor system, we have conducted a numerical simulation of partially premixed turbulent combustion within a gas-turbine combustor geometry. A combination of Large-Eddy simulation and the 2-scalar flamelet approach are used to simulate unsteady turbulent combustion in modeling turbulent and combustion reaction phenomena and their interactions. With the successful simulation of both the premixed and non-premixed combustion states including the effects of turbulence, the predicted distributions of time-averaged temperature and the O2 mole fraction are found to essentially correspond to the experimental data. In an analysis of the predicted results, the weights of resolved and unresolved phenomena in the numerical prediction are estimated in order to discuss the effects of the turbulent combustion model applied to a practical combustion flow. The analysis determines the effect of turbulence on a Grid Scale that accelerates the premixed combustion reaction, while the modeled effect of turbulence caused by combustion acceleration as shown on a Sub-grid Scale is about twice of the effect as that seen on the Grid Scale.

Effects of porous media on partially premixed combustion and heat transfer in meso-scale burners fuelled with ethanol

Energy ◽  
2021 ◽  
pp. 120191
Author(s):  
Xinjian Chen ◽  
Junwei Li ◽  
Dan Zhao ◽  
Muhammad Tahir Rashid ◽  
Xinyuan Zhou ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Premixed Combustion ◽  
Partially Premixed Combustion ◽  
Partially Premixed ◽  
Meso Scale

Effects of Different Type of Gasoline Fuels on Heavy Duty Partially Premixed Combustion

2009 ◽  
Vol 2 (2) ◽  
pp. 71-88 ◽  
Author(s):  
Vittorio Manente ◽  
Bengt Johansson ◽  
Per Tunestal ◽  
William Cannella
Keyword(s):  
Premixed Combustion ◽  
Heavy Duty ◽  
Partially Premixed Combustion ◽  
Partially Premixed

Characterization of Partially Premixed Combustion With Ethanol: EGR Sweeps, Low and Maximum Loads

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Vittorio Manente ◽  
Bengt Johansson ◽  
Pert Tunestal
Keyword(s):  
High Efficiency ◽  
Pressure Rise ◽  
Premixed Combustion ◽  
Maximum Pressure ◽  
Pressure Rise Rate ◽  
Start Of Injection ◽  
Partially Premixed Combustion ◽  
Rise Rate ◽  
Partially Premixed ◽  
Gas Recirculation

Exhaust gas recirculation (EGR) sweeps were performed on ethanol partially premixed combustion (PPC) to show different emission and efficiency trends as compared with diesel PPC. The sweeps showed that when the EGR rate is increased, the efficiency does not diminish, HC trace is flat, and CO is low even with 45% of EGR. NOx exponentially decreases by increasing EGR while soot levels are nearly zero throughout the sweep. The EGR sweeps underlined that at high EGR levels, the pressure rise rate is a concern. To overcome this problem and keep high efficiency and low emissions, a sweep in the timing of the pilot injection and pilot-main ratio was done at ∼16.5 bars gross IMEP. It was found that with a pilot-main ratio of 50:50, and by placing the pilot at −60 with 42% of EGR, NOx and soot are below EURO VI levels; the indicated efficiency is 47% and the maximum pressure rise rate is below 10 bar/CAD. Low load conditions were examined as well. It was found that by placing the start of injection at −35 top dead center, the efficiency is maximized, on the other hand, when the injection is at −25, the emissions are minimized, and the efficiency is only 1.64% lower than its optimum value. The idle test also showed that a certain amount of EGR is needed in order to minimize the pressure rise rate.

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