scholarly journals ПОВЫШЕНИЕ ТОЧНОСТИ РАСЧЕТА ПОЛЯ ТЕМПЕРАТУР ГАЗА НА ВЫХОДЕ ИЗ КАМЕРЫ СГОРАНИЯ ГТД МЕТОДОМ ТРЕХМЕРНОГО КОМПЬЮТЕРНОГО МОДЕЛИРОВАНИЯ

2020 ◽  
pp. 74-82
Author(s):  
Сергей Анатольевич Евсеев ◽  
Дмитрий Викторович Козел ◽  
Игорь Федорович Кравченко
Keyword(s):  
Numerical Experiment ◽  
Combustion Chamber ◽  
Turbulence Model ◽  
Schmidt Number ◽  
Temperature Pattern ◽  
Gas Temperature ◽  
Ansys Fluent ◽  
Maximum Value ◽  
Turbulent Schmidt Number ◽  
Initial Settings

The problem of numerical simulation of the gas flow with the combustion of atomized liquid fuel was solved (the equilibrium combustion model pdf was used along with the partially mixed mixture model) in the annular combustion chamber of a gas turbine engine. Numerical modeling was performed in Ansys Fluent calculation complex. The purpose of the calculations was to simulate the radial and circumferential unevenness of the gas temperature pattern at the outlet of the combustion chamber. As a result of the calculations, it was found that the accuracy of modeling the radial and circumferential unevenness of the gas temperature pattern at the outlet of the combustion chamber is unsatisfactory when using the k–e turbulence model with the initial settings for the Ansys Fluent calculation complex. Moreover, the maximum value of the radial non-uniformity of the gas temperature pattern at the outlet of the combustion chamber exceeded the value obtained in the experiment by 12.61 %, and the maximum value of the circumferential non-uniformity by 12.69 %. To improve the accuracy of modeling the temperature pattern non-uniformity at the outlet of the combustion chamber, a numerical experiment was conducted to study the effect of the degree of turbulent diffusion of gas components on the value of temperature pattern non-uniformity. To reduce the non-uniformity of the temperature pattern at the outlet of the combustion chamber, the degree of turbulent diffusion of gas components was increased with respect to the initial version of the calculation, performed using the k–e model of turbulence with the initial settings for the Ansys Fluent calculation complex, by reducing the turbulent Schmidt number Sc in the turbulence model. For the initial settings of the k–e turbulence model in the Ansys Fluent calculation complex, the turbulent Schmidt number Sc = 0.85. A numerical experiment was performed for the values of Sc = 0.6, Sc = 0.4, and Sc = 0.2. The results of a numerical experiment confirmed the influence of the turbulent Schmidt number Sc on the result of calculating the gas temperature pattern at the outlet of the combustion chamber; as the value of Sc decreases, the level of the circumferential and radial non-uniformities of the gas temperature pattern decreases. However, the degree of reduction of radial and circumferential irregularities with a decrease in Sc is different. Therefore, to ensure high accuracy in calculating both the circumferential and radial non-uniformities of the gas temperature pattern, it was proposed to use a variable value of the turbulent Schmidt number Sc depending on the gas temperature instead of a constant value. The functional dependence of the turbulent Schmidt number Sc on the gas temperature was implemented in the Ansys Fluent calculation complex using the user function (UDF). The results of modeling the gas temperature pattern using the proposed UDF function for the turbulent Schmidt number Sc are in satisfactory agreement with the experimental data for both radial and circumferential non-uniformities of the gas temperature pattern at the outlet of the combustion chamber.

scholarly journals Numerical Simulation of the Exit Temperature Pattern of an Aircraft Engine Using a Temperature-Dependent Turbulent Schmidt Number

2021 ◽  
Vol 2021 (3) ◽  
pp. 34-46
Author(s):  
Igor F. Kravchenko ◽  
Dmytro V. Kozel ◽  
Serhii A. Yevsieiev
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Temperature Dependence ◽  
Schmidt Number ◽  
Aircraft Engine ◽  
Temperature Pattern ◽  
Temperature Dependent ◽  
Ansys Fluent ◽  
Turbulent Schmidt Number ◽  
Exit Temperature

Abstract This paper presents a numerical simulation for predicting the combustor exit temperature pattern of an aircraft engine, developed using the commercial fluid simulation software Ansys Fluent, which assumes a shape probability density function for the instantaneous chemistry in the conserved scalar combustion model and the standard k-ε model for turbulence. We found the compliance of the radial and circumferential non-uniformities of the exit temperature with the experimental data to be insufficient. To achieve much more accurate result, the mixing intensity was enhanced with respect to the initial calculation due to using the reduced value of the turbulent Schmidt number Sc. Numerical simulation was performed for values of the turbulent Schmidt number from Sc = 0.85 (default) up to Sc = 0.2, with results confirming the reduction of radial and circumferential non-uniformities of exit temperature. However, correlation between radial and circumferential non-uniformities is not admissible for these cases. Therefore, we propose to use a temperature-dependent formulation of the turbulent Schmidt number Sc, accounting for the increase in Sc number with increasing gas temperature. A user defined function (UDF) was used to implement the Sc number temperature dependence in Ansys Fluent. The numerical results for the proposed Schmidt number Sc temperature dependence were found to be in acceptable agreement with the experimental data both for radial and circumferential non-uniformities of the exit temperature pattern.

scholarly journals Расчетная оценка влияния неравномерности распыла топлива на поле температур газа на выходе из камеры сгорания ГТД

2021 ◽  
pp. 25-34
Author(s):  
Сергей Анатольевич Евсеев
Keyword(s):  
Numerical Simulation ◽  
Numerical Modeling ◽  
Temperature Field ◽  
Combustion Chamber ◽  
Combustion Model ◽  
Fuel Injector ◽  
Gas Temperature ◽  
Ansys Fluent ◽  
Turbulent Schmidt Number ◽  
Design Documentation

This paper presents the results of numerical simulation of a gas flow with the combustion of atomized liquid fuel (the equilibrium combustion model pdf was used along with the model of a partially mixed mixture) in an annular combustion chamber of a gas turbine engine. Numerical modeling was carried out in the ANSYS Fluent computational complex. The purpose of the calculations was to assess the influence of the unevenness of the fuel spray specified in the design documentation and the coking of the parts of the front-line device on the radial and circumferential unevenness of the gas temperature field at the exit from the combustion chamber. The simulation used the previously verified turbulence model k-e with the functional dependence of the turbulent Schmidt number Sc on the gas temperature, which was implemented in the ANSYS Fluent computational complex using the user function (UDF). Since the fuel injector and the swirler represent a rather complex spraying scheme, which does not allow calculating the amount of fuel entering through the holes in the swirler cap, an installation was made and tests were carried out to determine the amount of the fuel-air mixture distributed over the holes in the swirler cap. The experimental values of the distribution of the air-fuel mixture through the holes in the swirler cap were further used to perform numerical simulation of combustion in the combustion chamber. Numerical modeling was carried out with sector non-uniformity equal to 0 %, 50 % (the maximum allowable according to the design documentation), and during coking of the swirler cap holes. As a result of the calculations, it was found that the sector irregularity of 50 % has an insignificant effect concerning the sector irregularity of 0 % on the radial irregularity of the gas temperature field at the exit from the combustion chamber, while the circumferential irregularity at the exit from the combustion chamber increased by 1.6 %. to the sectorial unevenness 0 %. When coking the holes of the swirler cap, the value of the radial diagram at the outlet from the combustion chamber increases by 1.2%, and the value of the circumferential irregularity increases by 4%.

scholarly journals Computational Fluid Dynamics Analysis of Compressible Flow Through a Converging-Diverging Nozzle using the k-ε Turbulence Model

2020 ◽  
Vol 10 (1) ◽  
pp. 5180-5185 ◽  
Author(s):  
M. W. Khalid ◽  
M. Ahsan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Combustion Chamber ◽  
Turbulence Model ◽  
High Velocity ◽  
Chemical Potential ◽  
Low Velocity ◽  
Ansys Fluent ◽  
Computational Fluid Dynamics Analysis ◽  
Flow Through

The thrust produced by a rocket motor is mainly dependent upon the expansion of the product gases through a nozzle. The nozzle is used to accelerate the gases produced in the combustion chamber and convert the chemical-potential energy into kinetic energy so that the gases exit the nozzle at very high velocity. It converts the high pressure, high temperature, and low-velocity gas in the combustion chamber into high-velocity gas of lower pressure and low temperature. The design of a nozzle has particular importance in determining the thrust and performance of a rocket. In recent years, it has received considerable attention as it directly impacts the overall performance of the rocket. This paper aims to analyze the variation of flow parameters like pressure, Mach number, and velocity using Finite Volume Method (FVM) solver with the standard k-ε turbulence model in Computational Fluid Dynamics (CFD). The simulation of shockwave inside the divergent nozzle section through CFD is also investigated. In this regard, a nozzle has been designed using Design Modeler, and CFD analysis of flow through the nozzle has been carried out using ANSYS Fluent. The model results are compared with theoretically calculated results, and the difference is negligible.

Analysis of the Mixing and Emission Characteristics in a Model Combustor

2018 ◽  
Author(s):  
Shan Li ◽  
Shanshan Zhang ◽  
Lingyun Hou ◽  
Zhuyin Ren
Keyword(s):  
Gas Turbines ◽  
Schmidt Number ◽  
Numerical Study ◽  
Flame Temperature ◽  
Scalar Dissipation ◽  
Mixing Process ◽  
Nox Formation ◽  
Turbulent Schmidt Number ◽  
Wide Range ◽  
Air Mixing

Modern gas turbines in power systems employ lean premixed combustion to lower flame temperature and thus achieve low NOx emissions. The fuel/air mixing process and its impacts on emissions are of paramount importance to combustor performance. In this study, the mixing process in a methane-fired model combustor was studied through an integrated experimental and numerical study. The experimental results show that at the dump location, the time-averaged fuel/air unmixedness is less than 10% over a wide range of testing conditions, demonstrating the good mixing performance of the specific premixer on the time-averaged level. A study of the effects of turbulent Schmidt number on the unmixedness prediction shows that for the complex flow field involved, it is challenging for Reynolds-Averaged Navier-Stokes (RANS) simulations with constant turbulent Schmidt number to accurately predict the mixing process throughout the combustor. Further analysis reveals that the production and scalar dissipation are the key physical processes controlling the fuel/air mixing. Finally, the NOx formation in this model combustor was analyzed and modelled through a flamelet-based approach, in which NOx formation is characterized through flame-front NOx and its post-flame formation rate obtained from one-dimensional laminar premixed flames. The effect of fuel/air unmixedness on NOx formation is accounted for through the presumed probability density functions (PDF) of mixture fraction. Results show that the measured NOx in the model combustor are bounded by the model predictions with the fuel/air unmixedness being 3% and 5% of the maximum unmixedness. In the context of RANS, the accuracy in NOx prediction depends on the unmixedness prediction which is sensitive to turbulent Schmidt number.

Numerical Investigation of the Influence of Flow Parameters Nonuniformity at the Diffuser Inlet on Characteristics of the GTE Annular Combustion Chamber

2015 ◽  
Author(s):  
Sergey S. Matveev ◽  
Ivan A. Zubrilin ◽  
Mikhail Yu. Orlov ◽  
Sergey G. Matveev
Keyword(s):  
Combustion Chamber ◽  
Dynamic Pressure ◽  
Air Distribution ◽  
Gas Generator ◽  
Air Velocity ◽  
Degree Polynomial ◽  
Flow Dynamic ◽  
Ansys Fluent ◽  
Flow Parameters ◽  
Mode Of Operation

Parameters at a combustion chamber’s inlet significantly vary in an aircraft engine’s transient states of operation. At the same time, there is a significant spatial heterogeneity of flow parameters at a diffuser inlet of a combustion chamber, which is defined by nature of flow in a compressor and an individual for each mode of operation of a specific gas generator. In this paper presented a study of an influence of radial and circumferential nonuniformities of flow parameters on characteristics of a combustion chamber. Multi spray for annular combustion chamber with two rows of burner is considered. Z-shaped sector, which contains two nozzles of outer and two nozzles of inner row, was selected as the calculated domain. Calculations were carried out in ANSYS Fluent 14.5 software package with an implementation of cluster analysis. Nonuniformity at a diffuser inlet was set as fifth degree polynomial, which was derived from a numerical simulation of a compressor. As a result it was established, that radial nonuniformity of flow parameters at an inlet of a combustion chamber influences on characteristics of a combustion chamber. A stretched shape of velocity profile contributes to higher air flow dynamic pressure on dome than using uniform profile air velocity. At that, local equivalents ratio excess are changing, and consequently, sizes and location NOx production zones are changing as well. The residual rotation of flow from the compressor leads to a lesser effect on total pressure drop and air distribution in flame tube. The obtained results showed that, during a design of a combustion chamber, it is necessary to take into account nonuniformity of parameters’ distribution at its inlet.

scholarly journals Gas-solid and gas-liquid mass transfer: Effect of turbulent Schmidt number

2007 ◽  
Vol 13 (3) ◽  
pp. 167-168 ◽  
Author(s):  
Aleksandar Dudukovic ◽  
Rada Pjanovic
Keyword(s):  
Mass Transfer ◽  
Eddy Viscosity ◽  
Schmidt Number ◽  
Mass Transfer Rate ◽  
Transfer Effect ◽  
Transfer Coefficients ◽  
Mass Transfer Effect ◽  
Liquid Mass ◽  
Turbulent Schmidt Number ◽  
Liquid Mass Transfer

The scope of this paper is to explain effect of eddy viscosity and turbulent Schmidt number on mass transfer rate. New, theoretically based correlation for gas-liquid mass transfer coefficients are proposed.

scholarly journals Development and Bench Test of High-Temperature Combustion Chamber With Structural Ceramic Components

1991 ◽  
Author(s):  
A. V. Sudarev ◽  
J. I. Zakharov ◽  
G. N. Ljubchik ◽  
L. S. Butovsky ◽  
E. A. Granovskya
Keyword(s):  
Combustion Chamber ◽  
Turbine Unit ◽  
Bench Test ◽  
Gas Temperature ◽  
Structural Ceramic ◽  
Gas Turbine Unit ◽  
Operational Procedure ◽  
Ceramic Components ◽  
Temperature Combustion ◽  
High Temperature Combustion

The most effective method of increasing the thermal efficiency of a simple cycle gas turbine unit involves elevation of the gas temperature upstream of the turbine. This requires development of appropriate operational procedure principles and adequate combustion chamber design.

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