Numerical Simulation as Design Optimization Tool for Gas Turbine Combustion Chambers

Author(s):  
Digvijay B. Kulshreshtha ◽  
S. A. Channiwala ◽  
Saurabh B. Dikshit

In present study an attempt has been made through CFD approach using CFX 11 to analyze the flow patterns within the combustion liner and through different air admission holes, namely, primary zone, intermediate zone, dilution zone and wall cooling, and from these the temperature distribution in the liner and at walls as well as the temperature quality at the exit of the combustion chamber are predicted. The design optimization is carried out using the CFD results with validation using experimental investigations.

Author(s):  
Digvijay B. Kulshreshtha ◽  
S. A. Channiwala ◽  
Jatin R. Patel

The combustion chamber of gas turbine unit is one of the most critical components to be designed. The study of literature review reveals that much work is available pertaining to design and performance of combustion chamber. However, the systematic approach and optimized liner wall configuration is not easily traceable in the literature. This is particularly true for small capacity units. Hence there is a need for experimental optimization of combustion chamber in small capacity range. The present work aims at the experimental optimization of liner wall configuration. Four different types of combustion chambers with primary zone equivalence ratios of 0.5, 0.7, 0.9 and 1.1 are designed, developed and experimented based on which an optimal configuration is recommended. It is worth to mention that the present work clearly focuses the combustion chamber with equivalence ratio in primary zone as 0.9 as the optimal combustion chamber.


Author(s):  
Marek Dzida ◽  
Krzysztof Kosowski

In bibliography we can find many methods of determining pressure drop in the combustion chambers of gas turbines, but there is only very few data of experimental results. This article presents the experimental investigations of pressure drop in the combustion chamber over a wide range of part-load performances (from minimal power up to take-off power). Our research was carried out on an aircraft gas turbine of small output. The experimental results have proved that relative pressure drop changes with respect to fuel flow over the whole range of operating conditions. The results were then compared with theoretical methods.


Author(s):  
Washington Orlando Irrazabal Bohorquez ◽  
João Roberto Barbosa ◽  
Rob Johan Maria Bastiaans ◽  
Philip de Goey

Currently, high efficiency and low emissions are most important requisites for the design of modern gas turbines due to the strong environmental restrictions around the world. In the past years, alternative fuels have been considered for application in industrial gas turbines. Therefore, combustor performance, pollutant emissions and the ability to burn several fuels became of much concern and high priority has been given to the combustor design. This paper describes a methodology focused on the design of stationary gas turbines combustion chambers with the ability to efficiently burn conventional and alternative fuels. A simplified methodology is used for the calculations of the equilibrium temperature and chemical species in the primary zone of a gas turbine combustor. Direct fuel injection and diffusion flames, together with numerical methods like Newton-Raphson, LU Factorization and Lagrange Polynomials, are used for the calculations. Diesel, ethanol and methanol fuels were chosen for the numerical study. A computer code sequentially calculates the main geometry of the combustor. From the numerical simulation it is concluded that the basic gas turbine combustor geometry, for some operating conditions and burning diesel, ethanol or methanol, are of similar sizes, because the development of aerodynamic characteristics predominate over the thermochemical properties. It is worth to note that the type of fuel has a marked effect on the stability and combustion advancement in the combustor. This can be seen when the primary zone is analyzed under a steady-state operating condition. At full power, the pressure is 1.8 MPa and the temperature 1,000 K at the combustor inlet. Then, the equivalence ratios in the primary zone are 1.3933 (diesel), 1.4352 (ethanol) and 1.3977 (methanol) and the equilibrium temperatures for the same operating conditions are 2,809 K (diesel), 2,754 K (ethanol) and 2,702 K (methanol). This means that the combustor can reach similar flame stability conditions, whereas the combustion efficiency will require richer fuel/air mixtures of ethanol or methanol are burnt instead of diesel. Another important result from the numerical study is that the concentration of the main pollutants (CO, CO2, NO, NO2) is reduced when ethanol or methanol are burnt, in place of diesel.


2019 ◽  
pp. 86-90
Author(s):  
Sergey Serbin

The appliance of modern tools of the computational fluid dynamics for the investigation of the pulsation processes in the combustion chamber caused by the design features of flame tubes and aerodynamic interaction compressor, combustor and turbine is discussed. The aim of the research is to investigate and forecast the non-stationary processes in the gas turbine combustion chambers. The results of the numerical experiments which were carried out using three-dimensional mathematical models in gaseous fuels combustion chambers reflect sufficiently the physical and chemical processes of the unsteady combustion and can be recommended to optimize the geometrical and operational parameters of the low-emission combustion chamber. The appliance of such mathematical models are reasonable for the development of new samples of combustors which operate at the lean air-fuel mixture as well as for the modernization of the existing chambers with the aim to develop the constructive measures aimed at reducing the probability of the occurrence of the pulsation combustion modes. Keywords: gas turbine engine, combustor, turbulent combustion, pulsation combustion, numerical methods, mathematical simulation.


Author(s):  
Greg Pucher ◽  
William Allan ◽  
Pierre Poitras

The synthetic fuel industry is poised to experience large-scale growth and profoundly affect current aviation fuel infrastructure. New candidate technologies, such as Camelina oil-derived synthetic fuel have been demonstrated to not only provide satisfactory quasi drop-in characteristics for conventional fuels, but in life cycle analysis studies have also been shown to potentially offer positive improvements relative to conventional feedstocks with respect to economic, environmental, and land use considerations. As part of a multiyear study at the Royal Military College of Canada to evaluate combustion related parameters of fuel additives and alternative fuels for gas turbine applications, a Camelina-derived synthetic fuel blend was assessed to determine potential combustion related benefits as compared to conventional and other synthetic blends. The Combustion Chamber Sector Rig (CCSR) which houses a Rolls Royce T-56-A-15 combustion section was utilized for the evaluation of emissions and deposits. Following combustion testing, several combustion system components, including the combustion chamber, fuel nozzle, and igniter plug were analyzed for relative levels of deposit build-up. As with other Fischer Tropsch derived synthetic fuels, there were positive benefits found with Camelina blends in terms of emissions performance and deposit production tendencies.


2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Serhiy Serbin ◽  
Kateryna Burunsuz

AbstractInvestigations of the working process in a gas turbine combustion chamber with ecological and energy steam injection operating on liquid fuel are conducted. The mathematical model of the aerodynamic processes and liquid fuel combustion in similar burning devices based on the numerical solution of the system of conservation and transport equations for a multi-component chemically reactive turbulent system is developed. The influence of the relative steam mass flow rate (the ratio of the sum of the mass flow rates of ecological and energy steam to the fuel consumption) on the combustion chamber’s emission characteristics is determined. The obtained results can be used for parameter selection and optimization of promising high-temperature gas turbine combustion chambers with steam injection operating on liquid fuels.


Author(s):  
Jean-Michel Lourier ◽  
Axel Widenhorn ◽  
Berthold Noll ◽  
Michael Sto¨hr ◽  
Manfred Aigner

Acoustic measurements within combustion chambers are expensive due to high thermal loads applied on the measurement devices at operating conditions. As a more feasible substitute, pressure ducts can be used to lead acoustic waves from combustion chambers to externally mounted microphones. Since these pressure ducts are purged by nitrogen at atmospheric temperature, high thermal loads are avoided. However, the acoustic signal measured within the pressure ducts is altered compared to the signal within the combustion chamber. This change in the acoustic signal can be characterised by means of the acoustic transfer function of the pressure duct, which mainly depends on the pressure ducts geometry and the combustion chambers temperature distribution. The main subject of the present paper is to analyse the influence of the combustion chambers temperature distribution on the acoustic transfer function of pressure ducts. For this scope, experiments at standard conditions and transient CFD simulations for different temperature distributions have been carried out. The acoustic signal measured in the pressure duct is found to be amplified with increasing temperatures within the combustion chamber. Moreover this amplification grows with increasing frequency of the acoustic signals.


Author(s):  
Nicolas Noiray ◽  
Bruno Schuermans

This paper deals with the dynamics of standing and rotating azimuthal thermoacoustic modes in annular combustion chambers. Simultaneous acoustic measurements have been made at multiple circumferential positions in an annular gas turbine combustion chamber. A detailed statistical analysis of the spatial Fourier amplitudes extracted from these data reveals that the acoustic modes are continuously switching between standing, clockwise and counter-clockwise travelling waves. A theoretical framework from which the modal dynamics can be explained is proposed and supported by real gas turbine data. The stochastic differential equations that govern these systems have been derived and used as a basis for system identification of the measured engine data. The model describes the probabilities of the two azimuthal wave components as a function of the random source intensity, the asymmetry in the system and the strength of the thermoacoustic interaction. The solution of the simplified system is in good agreement with experimental observations on a gas turbine combustion chamber.


Author(s):  
N. Rasooli ◽  
S. Besharat Shafiei ◽  
H. Khaledi

Whereas Gas Turbines are the most important producers of Propulsion and Power in the world and with attention to the importance of combustion chamber as one of the three basic components of Gas Turbine, various activities in different levels have been done on this component. Because of the environmental limitations and laws related to the pollutants such as NOx and CO, Lean Premixed Combustion Chambers are specially considered in gas turbine industries. This study is part of a Multi-Layer simulation of the whole gas turbine cycle in MPG Company. In this work, the combination of a general 1D code and CFD is used for deriving appropriate performance curves for a 1D and 0D gas turbine design, off-design and dynamic cycle code. This 1D code is a general code which has been developed for different combustion chambers; annular, can-annular, can type and silo type combustion chambers. The purpose of generating this 1D code is the possibility of fast analysis of combustors in different operating conditions and reaching required outputs. This 1D code is a part of a general simulation 1D code for gas turbine and was used for a silo type combustor performance prediction. This code generates required quantities such as pressure loss, exit temperature, liner temperature and mass distribution through the combustion chamber. Mass distribution and pressure loss are analyzed and determined with an electrical analogy. Results derived from 1D code are validated with empirical data available for different combustors. There is appropriate agreement between these experimental and analytical results. Drag coefficients for liner holes are available from experimental data and for burner are calculated as a curve with CFD simulations. What differs this code from other 1D codes for gas turbine combustors is the advantage of using combustion efficiencies evolved from numerical simulation results in different loads. These efficiencies are determined with CFD simulations and are available as maps and inserted into the gas temperature calculation algorithm of 1D code. In other 1D codes in this field, empirical correlations are used for combustion efficiency determination. Combustion efficiency curves for design and off-design conditions in this study are achieved by 2D and 3D simulation of combustion chamber with application of EBU/Finite Rate model and 8 step reactions of CH4 burning. Diffusion flame in low loads and premixed flame in high loads are considered. Flame stability and Lean Blow Out charts are evolved from CFD simulation and Heat transfer is applied with empirical correlations.


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