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1

Two-zone simulation of an axial vane rotary engine cycle

Mirzaei M., Hashemi S. M., Saranjam B., Binesh A.

International Journal of Applied Mechanics and Engineering

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2021

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Vol. 26, no. 2

143--159

EN

An axial vane rotary engine (AVRE) is a novel type of rotary engines. The engine is a positive displacement mechanism that permits the four “stroke” action to occur in one revolution of the shaft with a minimum number of moving components in comparison to reciprocating engines. In this paper, a two-zone combustion model is developed for a spark ignition AVRE. The combustion chamber is divided into burned and unburned zones and differential equations are developed for the change in pressure and change in temperature in each zone. The modelling is based on equations for energy and mass conservation, equation of state, and burned mass fraction. The assumption is made that both zones are at the same pressure P, and the ignition temperature is the adiabatic flame temperature based on the mixture enthalpy at the onset of combustion. The developed code for engine simulation in MATLAB is applied to another engine and there is a good agreement between results of this code and results related to the engine chosen for validation, so the modelling is independent of configuration.

2

Modeling of the burning process in the piston engines with various concepts of the working proces

Natriashvili Tamaz, Kavtaradze Revaz, Glonti Merab

Transport Problems

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2020

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T. 15, z. 1

39--48

EN

In this paper, the results of modeling of the burning process in the piston engines whose working process is realized on the basis of various conceptual approaches are presented: in diesel with direct injection of the fuel; in a gas engine with spark ignition; and in a two-fuel engine (in the gas-diesel), where the mixture of natural gas and air ignites with the help of the fuse dose of the diesel fuel. The models of burning based on the different in-principle approaches are analyzed and used. Verification of the models is performed by a comparison of the results of modeling with the experimental diagrams. The specific values of the empirical coefficients, used in modeling of the burning proces in the engines under study, are determined. The practical recommendations on the choice of the burning model depending on the working process conception are given.

3

Research on combustion mode of methanol micro-reciprocating piston internal combustion engine

Tang Gang Zhi, Wang Shuai Bin, Zhang Li, Shang Hui Chao

Diagnostyka

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2020

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Vol. 21, No. 1

97--103

EN

Constrained by the micro-space structure, it is proposed to use platinum wire incandescent ignition combustion mode to achieve the operation of internal combustion engine. However, the combustion test of the platinum wire incandescent ignition in miniature piston internal combustion engine shows: the combustion mode of micro-space platinum wire incandescent ignition has a poor combustion characteristic, low heat release rate, long combustion duration, and low combustion pressure. Therefore, a homogenous charge compression ignition mode is proposed to realize the operation of miniature internal combustion engine. However, it is found that the compression combustion cannot be come true in the cold start-up state of the micro engine. And the compression combustion in the first cycle was realized by the way of increasing the temperature of the cylinder block and platinum wire appropriately. The results show that: The maximum heat release rate is obviously improved and the combustion duration shortened by 28.6ºCA, and pmi increased by 76%. So, a novel hybrid combustion mode of in-cylinder compression combustion supported by the platinum wire incandescent ignition is put forward, through the way of adjusting the temperature of platinum wire, and this combustion mode is regarded as the ideal combustion mode of micro reciprocating piston internal combustion engine.

4

Predicting chemical flame lengths and lift-off heights in enclosed, oxy-methane diffusion flames at varying O2/CO2 oxidizer dilution ratios

Krishnamoorthy G., Ditaranto M.

Journal of Power Technologies

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2017

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Vol. 97, nr 4

370--377

EN

Experiments have shown reactor confinement, wall temperatures and radiative transfer to influence the flame length and lift-off characteristics of oxy-methane flames. In this study, the performances of the Shear Stress Transport (SST) k-ω turbulence model, a skeletal methane combustion mechanism (16 species and 41 reactions) and two weighted sum of gray gas models (WSGGM) towards capturing these flame characteristics are evaluated against measurements obtained from oxy-methane flames across a wide range of oxidizer O2/CO2 ratios and fuel Reynolds numbers. Gas composition, gas and wall temperatures, flame length measurements and inferences of lift-off heights from OH* chemiluminescence imaging are employed in the assessment. The corresponding numerical estimate of flame length and lift-off heights were made by determining the flame shape by the locus of points at which the CO concentrations reduce to 1% of their peak values within the flame. The predicted gas temperatures and compositions compared reasonably well against measurements. The criterion for defining the flame shape based on CO concentrations appears promising since the trends in chemical flame length and lift-off height predictions agreed reasonably well with the measurements across the range of oxidizer concentrations and fuel Reynolds numbers. Flame length prediction sensitivities to the wall temperatures and the WSGGM model were also assessed.

5

The theoretical investigation on influence the fuel spray geometry on the combustion and emission characteristic of the marine diesel engine

Kowalski J.

Combustion Engines

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2017

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R. 56, nr 2

101--107

EN

The paper presents an analysis of the influence of the fuel spray geometry on the combustion and emission characteristic of the marine 4-stroke Diesel engine. Presented analysis was prepared based on computational fluid dynamic model (CFD). Initial and boundary conditions of the model as well as data used to model validation were collected during the laboratory study. Calculations were conducted for two different fuel injectors with changed nozzle holes diameters, the number of nozzle holes and the angle between holes axis. The increase of the fuel nozzle holes diameter causes the decrease of the fuel spray tip penetration, but simultaneously the decrease of holes number causes that auto-ignition delay is not changed. The increase of the angle between holes axis from 150° to 158° causes fuel ingintion near cylinder head wall. Result of this is the increase of CO fraction. The deterioration of fuel combustion causes the decrease of NOx mass fraction in the cylinder also.

6

Influence of fuel injector holes diameter on parameters of combustion process in the cylinder of the marine 4-stroke Diesel engine

Kowalski J.

Journal of Polish CIMEEAC

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2016

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Vol. 11, no 1

95--102

EN

The paper presents an analysis of the influence of the fuel injector nozzle holes diameter on parameters of the brake-up, evaporation and combustion process in the cylinder of the marine 4-stroke Diesel engine. Presented analysis was prepared in the basis on computational fluid dynamic model. Initial and boundary conditions of the model as well as data used to model validation were collected during the laboratory study. Calculations were conducted for nominal fuel holes diameter equals 0.375mm and diameters increased and decreased by 50μm and 100μm respectively. According to presented results the increase of the diameter of fuel nozzle holes causes the increase of fuel Sauter’s mean diameter in the initial stage of the injection process and the decrease of fuel process evaporation. The result of this phenomenon is the slowdown of the initial stage of the combustion process and the decrease of both pressure and temperature of combustion.

7

The analysis of the ECFM-3Z combustion model in the marine 4-stroke engine for the exhaust gas composition

Kowalski J.

Journal of Polish CIMAC

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2014

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Vol. 9, no 1

95--102

EN

The paper presents ECFM-3Z combustion model analysis in the marine, 4-stroke diesel engine. The purpose of the modeling was to determine the composition of the exhaust gas. This composition depends on the composition of the combustible mixture, combustion time and thermodynamic conditions prevailing in the engine cylinder during the working process. Mentioned parameters are variable in time and space, and therefore require the use of 3-dimensional model based on the finite volume method, taking into account the fuel injection, brake-up and evaporation, mixing with air, auto-ignition and combustion. All models presented in the literature are adapted to the parameters of relatively small engines. Different marine engine parameters require significant modifications taking into account the heat exchange with the structural elements of the engine, leakage through piston rings and energy losses by riction. It should also be noted that dimensions of the marine engine require careful optimization of spatial moving meshes according to computation time and quality of results. Paper presents influence of mixing time, start of injection and autoignition delay on modeling results of the exhaust gas composition.

8

Model of waste combustion on the grate

Jaworski T.

Architecture Civil Engineering Environment

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2009

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Vol. 2, no. 4

125-130

EN

The algorithm describing mass transport on the reciprocal moving and drum grates have been presented. Three main processes are taken into account: combustion of a single fuel particle, porous structure of the fuel layer and fuel transport on the grate and their mutual relations were analyzed. Each process is described by its own model: reactor, fuel particle, heat transfer and chemical reaction. The model describing the grate is designed as similar to the chemical reactor and the cascade of batch reactors simulates the transport on the grate.

PL

W pracy przedstawiono algorytm opisujący transport masy na rusztach posuwistych, posuwisto – zwrotnych i walcowych. Struktura modelu oparta jest na trzech głównych blokach zagadnień do których należą: spalanie pojedynczego ziarna paliwa, przestrzeń porowata w warstwie oraz analiza ruchu ziaren na ruszcie. Określono system powiązań parametrycznych w/w zagadnień. Każde z zagadnień wymaga opisu za pomocą podmodeli, są nimi: podmodel reaktora, paliwa (odpad/cząstka), transportu ciepła oraz reakcji. Zastosowano podobieństwo modelu rusztu do modelu reaktora chemicznego. Użyto kaskadę reaktorów zbiornikowych w dyskretyzacji warstwy.