Analysis of the three-dimensional selective radiation field in a combustion chamber using mathematical modeling

1981 ◽  
Vol 41 (1) ◽  
pp. 762-768
Author(s):  
Yu. A. Zhuravlev ◽  
A. G. Blokh ◽  
I. V. Spichak
Keyword(s):  
Mathematical Modeling ◽  
Combustion Chamber ◽  
Radiation Field ◽  
Three Dimensional

scholarly journals Three-dimensional mathematical modeling of local scour

2005 ◽  
Vol 8 ◽  
pp. 803-812 ◽  
Author(s):  
Hao ZHANG ◽  
Hajime NAKAGAWA ◽  
Taisuke ISHIGAKI ◽  
Yasunori MUTO ◽  
Yasuyuki BABA
Keyword(s):  
Mathematical Modeling ◽  
Three Dimensional ◽  
Local Scour

A Stochastic Hierarchical Population System: Excitement, Extinction and Transition to Chaos

2021 ◽  
Vol 31 (14) ◽  
Author(s):  
Irina Bashkirtseva ◽  
Tatyana Perevalova ◽  
Lev Ryashko
Keyword(s):  
Mathematical Modeling ◽  
Food Chain ◽  
Analytical Method ◽  
Three Dimensional ◽  
Biological Parameters ◽  
Top Predator ◽  
Population System ◽  
Modeling And Analysis ◽  
Transition To Chaos ◽  
Random Fluctuations

A problem of the mathematical modeling and analysis of noise-induced transformations of complex oscillatory regimes in hierarchical population systems is considered. As a key example, we use a three-dimensional food chain dynamical model of the interacting prey, predator, and top predator. We perform a comparative study of the impacts of random fluctuations on three key biological parameters of prey growth, predator mortality, and the top predator growth. A detailed investigation of the stochastic excitement, noise-induced transition from order to chaos, and various scenarios of extinction is carried out. Constructive abilities of the semi-analytical method of confidence domains in the analysis of the noise-induced extinction are demonstrated.

The Mathematical Modeling of Utility Boilers at IST

2000 ◽  
Author(s):  
P. J. Coelho ◽  
J. L. T. Azevedo ◽  
L. M. R. Coelho
Keyword(s):  
Mathematical Modeling ◽  
Combustion Chamber ◽  
Difficult Problem ◽  
The Other ◽  
Utility Boilers ◽  
Coal Reburning ◽  
Physical Phenomena

Abstract The mathematical modeling of utility boilers is a difficult problem due to the multiplicity of physical phenomena involved and to the interaction between different phenomena. However, reliable models are extremely useful since they can be used to design new equipment, and to optimize and retrofit units in operation. In this paper a survey of the work carried out at Institute superior Técnico (IST) in Lisbon is reported. Only the work based on comprehensive models, i.e., those accounting for all the relevant physical phenomena taking place in the combustion chamber is addressed. The models employed are briefly outlined. Then, four examples of application are given, two of them for coal-fired boilers where the effect of low NOx burners and coal over coal reburning is investigated, and the other two for oil-fired boilers where parallelization of the code and simulation of the convection chamber are reported.

An Accurate Performance Prediction of Solid Fuel Ramjets Using Coupled Intake-Combustor-Nozzle Simulation

2020 ◽  
Vol 36 (6) ◽  
pp. 933-941
Author(s):  
A. M. Tahsini
Keyword(s):  
Combustion Chamber ◽  
Solid Fuel ◽  
Solid Phase ◽  
Three Dimensional ◽  
Flow Fields ◽  
Reacting Flow ◽  
Computational Domain ◽  
Regression Rate ◽  
Fuel Flow ◽  
Accurate Performance

ABSTRACTThe performance of the solid fuel ramjet is accurately predicted using full part simulation of this propulsion system, where the flow fields of the intake, combustion chamber, and the nozzle are numerically studied all together. The conjugate heat transfer is considered between the solid phase and the gas phase to directly compute the regression rate of the fuel. The finite volume solver of the compressible turbulent reacting flow is utilized to study the axisymmetric three dimensional flow fields, and two blocks are used to discretize the computational domain. It is shown that the combustion chamber's pressure is changed due to the fuel flow rate's increment which must be taken into account in predictions. The results demonstrate that omitting the pressure dependence of the regression rate and also the effect of the combustor's inlet profile on the regression rate, which specially exists when simulating the combustion chamber individually, under-predicts the solid fuel burning rate when the regression rate augmentation technique is applied to improve the performance of the solid fuel ramjets. It is also illustrated that using the inlet swirl to increase the regression rate of the solid fuel augments considerably the thrust level of the considered SFRJ, while the predictions without considering all parts of the ramjet is not accurate.

Prediction of the Thermoacoustic Combustion Instabilities in Practical Annular Combustors

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Giovanni Campa ◽  
Sergio Mario Camporeale
Keyword(s):  
Combustion Chamber ◽  
Three Dimensional ◽  
Design Stage ◽  
Combustion Instabilities ◽  
Combustion Chambers ◽  
Stability Maps ◽  
Dimensional Finite Element ◽  
Practical Tool ◽  
The Stability ◽  
Three Dimensional Finite Element

A three-dimensional finite element code is used for the eigenvalue analysis of the thermoacoustic combustion instabilities modeled through the Helmholtz equation. A full annular combustion chamber, equipped with several burners, is examined. Spatial distributions for the heat release intensity and for the time delay are used for the linear flame model. Burners, connecting the plenum and the chamber, are modeled by means of the transfer matrix method. The influence of the parameters characterizing the burners and the flame on the stability levels of each mode of the system is investigated. The obtained results show the influence of the 3D distribution of the flame on the modes. Additionally, the results show what types of modes are most likely to yield humming in an annular combustion chamber. The proposed methodology is intended to be a practical tool for the interpretation of the thermoacoustic phenomenon (in terms of modes, frequencies, and stability maps) both in the design stage and in the check stage of gas turbine combustion chambers.

The Effect of Upstream Flow Conditions to Laminar Mixing in a Miniature Combustion Chamber

2003 ◽  
Author(s):  
Peter L. Woodfield ◽  
Kazuya Tatsumi ◽  
Kazuyoshi Nakabe ◽  
Kenjiro Suzuki
Keyword(s):  
Combustion Chamber ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Baffle Plate ◽  
Micro Gas Turbine ◽  
Laminar Mixing ◽  
Fuel Jet ◽  
Single Jet ◽  
Inlet Conditions ◽  
Volume Method

A three-dimensional unstructured finite-volume method is used to investigate laminar flow characteristics of a miniature chamber with a possible application to micro gas turbine combustor design. The chamber is cylindrical in shape and 20mm in diameter with the fuel stream entering via a single jet in the center of one end of the can. Oxidizer jets are generated by a circular baffle plate having six holes surrounding the fuel jet. Attention is given to the effect of the inlet conditions on the flow structure and mixing pattern inside the chamber. Computations are carried out with the calculation domain inlet being positioned at two different locations; (1) at the immediate entrance to the combustion chamber (2) one combustor diameter upstream of the baffle plate. Numerous inlet conditions are considered including ‘top-hat’, fully-developed, swirling, an annular backward facing step and some asymmetrically skewed profiles. The baffle plate is shown to have a significant smoothing effect on the inlet conditions for a Reynolds number of 100.

Simulation of Pollutant Emissions in a Small-Sized Combustion Chamber With a Gas Fuel for Various Regime Modes

2019 ◽  
Author(s):  
Nikita I. Gurakov ◽  
Ivan A. Zubrilin ◽  
Ivan V. Chechet ◽  
Vladislav M. Anisimov ◽  
Sergey S. Matveev ◽  
...  
Keyword(s):  
Experimental Data ◽  
Combustion Chamber ◽  
Equivalence Ratio ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Combustion Products ◽  
Pollutant Emissions ◽  
Eddy Simulation ◽  
Flamelet Generated Manifold ◽  
Combustion Processes

Abstract The study shows the results of the emission simulation in a small-sized combustion chamber. The influence of temperature and equivalence ratio on CO and CxHy in the combustion chamber was investigated. Experiments and calculations were carried out for the following modes: temperature at the inlet of the combustion chamber Tinlet = 323 ... 523 K; equivalence ratio φ = 0.2 ... 0.33; normalized flow rate at the inlet of the combustion chamber λ = 0.1 ... 0.3. The simulation of combustion of natural gas was carried out. The studies were conducted using CFD software and experimental methods. Measurements of the combustion products composition were carried out by the method of sampling collection and subsequent chromatographic analysis. The flow and combustion processes were simulated in a three-dimensional steady formulation using the Reynolds-averaged Novier-Stokes equations (RANS) and in a transient formulation using the Large Eddy Simulation (LES) method. The combustion processes were simulated by Flamelet Generated Manifold model in conjunction with the probability density function method (PDF). In addition to the above methods, the method of the reactor network model (RNM) was used to simulate the emission. As a result, a comparison of the calculated and experimental data of concentrations values of combustion products and emissions indices averaged over the combustion chamber outlet was conducted. According to the results of the calculated-experimental study obtained: - the simulated concentrations values of the main combustion products such as CO2 and H2O qualitatively and quantitatively coincide with the experimental data (the discrepancy is less than 5%) for all three approaches — RANS, LES, RNM; - when modeling CO emissions, the discrepancy between the calculated emission indices obtained by the RANS and LES methods is greatly underestimated relative to the experimental data, whereas the values calculated by the RNM method deviate from the experiment by less than 10%; - mass concentration values of unburned hydrocarbons obtained by the RANS method are overestimated relative to the experimental values, while using the LES with RNM methods, the discrepancy does not exceed 10%.

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