Cellular flame structure and turbulent combustion

1982 ◽  
Vol 18 (1) ◽  
pp. 109-112 ◽  
Author(s):  
V. P. Karpov
Keyword(s):  
Turbulent Combustion ◽  
Flame Structure ◽  
Cellular Flame

Evaluation of CH4/NOx Reduced Mechanisms Used for Modeling Lean Premixed Turbulent Combustion of Natural Gas

1998 ◽  
Vol 120 (4) ◽  
pp. 703-712 ◽  
Author(s):  
H. P. Mallampalli ◽  
T. H. Fletcher ◽  
J. Y. Chen
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
Gas Turbine ◽  
Turbulent Combustion ◽  
Gas Turbines ◽  
Flame Structure ◽  
Computational Cost ◽  
Premixed Turbulent Combustion ◽  
Reduced Mechanism ◽  
Lean Premixed

This study has identified useful reduced kinetic schemes that can be used in comprehensive multidimensional gas-turbine combustor models. Reduced mechanisms lessen computational cost and possess the capability to accurately predict the overall flame structure, including gas temperatures and key intermediate species such as CH4, CO, and NOx. In this study, four new global mechanisms with five, six, seven, and nine steps based on the full GRI 2.11 mechanism, were developed and evaluated for their potential to model natural gas chemistry (including NOx chemistry) in gas turbine combustors. These new reduced mechanisms were optimized to model the high pressure and fuel-lean conditions found in gas turbines operating in the lean premixed mode. Based on perfectly stirred reactor (PSR) and premixed code calculations, the five-step reduced mechanism was identified as a promising model that can be used in a multidimensional gas-turbine code for modeling lean-premixed, high-pressure turbulent combustion of natural gas. Predictions of temperature, CO, CH4, and NO from the five-to nine-step reduced mechanisms agree within 5 percent of the predictions from the full kinetic model for 1 < pressure (atm) < 30, and 0.6 < φ < 1.0. If computational costs due to additional global steps are not severe, the newly developed nine step global mechanism, which is a little more accurate and provided the least convergence problems, can be used. Future experimental research in gas turbine combustion will provide more accurate data, which will allow the formulation of better full and reduced mechanisms. Also, improvement in computational approaches and capabilities will allow the use of reduced mechanisms with larger global steps, perhaps full mechanisms.

Development and Application of a Transported PDF Method on Unstructured Three-Dimensional Grids for the Prediction of Nitric Oxides

2013 ◽  
Author(s):  
Andreas Fiolitakis ◽  
Peter Ess ◽  
Peter Gerlinger ◽  
Manfred Aigner
Keyword(s):  
Nitric Oxide ◽  
Turbulent Combustion ◽  
Flame Structure ◽  
Hybrid Approach ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Nitric Oxides ◽  
Nitric Oxide Formation ◽  
No Formation ◽  
German Aerospace

The present work explores the capability of the transported PDF (probability density function) method to predict nitric oxide (NO) formation in turbulent combustion. To this end a hybrid finite-volume/Lagrangian Monte-Carlo method is implemented into the THETA code of the German Aerospace Center (DLR). In this hybrid approach the transported PDF method governs the evolution of the thermochemical variables, whereas the flow field evolution is computed with a RANS (Reynolds-Averaged Navier Stokes) method. The method is used to compute a turbulent hydrogen-air flame and a methane-air flame and computational results are compared to experimental data. In order to assess the advantages of the transported PDF method, the flame computations are repeated with the “laminar chemistry” approach as well as with an “assumed PDF” method, which are both computationally cheaper. The present study reveals that the transported PDF method provides the highest accuracy in predicting the overall flame structure and nitric oxide formation.

Measurement of Local Flame Structure for Turbulent Combustion Control

2002 ◽  
Vol 2002.7 (0) ◽  
pp. 75-76
Author(s):  
Shunsuke TSUKINARI ◽  
Toshihiko SAITO ◽  
Gyung Min CHOI ◽  
Mamoru TANAHASHI ◽  
Toshio MIYAUCHI
Keyword(s):  
Turbulent Combustion ◽  
Flame Structure ◽  
Combustion Control

Design of an optically accessible turbulent combustion system

2018 ◽  
Vol 233 (1) ◽  
pp. 336-349
Author(s):  
Mohammad A Hossain ◽  
Ahsan Choudhuri ◽  
Norman Love
Keyword(s):  
Gas Turbine ◽  
Turbulent Combustion ◽  
High Intensity ◽  
Flame Structure ◽  
Experimental Studies ◽  
Deep Understanding ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Operating Pressure ◽  
Combustion System

In order to design the next generation of gas turbine combustors and rocket engines, understanding the flame structure at high-intensity turbulent flows is necessary. Many experimental studies have focused on flame structures at relatively low Reynolds and Damköhler numbers, which are useful but do not help to provide a deep understanding of flame behavior at gas turbine and rocket engine operating conditions. The current work is focused on the presentation of the design and development of a high-intensity (Tu = 15–30%) turbulent combustion system, which is operated at compressible flow regime from Mach numbers of 0.3 to 0.5, preheated temperatures up to 500 K, and premixed conditions in order to investigate the flame structure at high Reynolds and Damköhler numbers in the so-called thickened flame regime. The design of an optically accessible backward-facing step stabilized combustor was designed for a maximum operating pressure of 0.6 MPa. Turbulence generator grid was introduced with different blockage ratios from 54 to 67% to generate turbulence inside the combustor. Optical access was provided via quartz windows on three sides of the combustion chamber. Extensive finite element analysis was performed to verify the structural integrity of the combustor at rated conditions. In order to increase the inlet temperature of the air, a heating section is designed and presented in this paper. Separate cooling subsystem designs are also presented. A 10 kHz time-resolved particle image velocimetry system and a 3 kHz planer laser-induced fluorescence system are integrated with the system to diagnose the flow field and the flame, respectively. The combustor utilizes a UNS 316 stainless steel with a minimum wall thickness of 12.5 mm. Quartz windows were designed with a maximum thickness of 25.4 mm resulting in an overall factor of safety of 3.5.

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