Combustion Chamber

Hava soğutmalı tek silindirli olarak planlanan model uçak motorununun boyut ve termodinamik hesaplamaları yapılmış ve boyut analizlerine bağlı kalarak Solidworks programıyla tasarımı ve montajı yapılmıştır. Tasarımı yapılan motorun daha sonra yanma odası tasarımı yapılarak ANSYS programı ile yanma odası akış analizi yapılmıştır. Analiz sonucuna göre optimizasyon çalışması yapılarak en optimum tasarım bulunmuştur.

In this paper, the procedure of designing a gas turbine combustion chamber test rig test section operating at atmospheric conditions is described. This test rig can be used to evaluate the effects of geometric variations on the performance of the combustion chamber, as well as determining the flammability, stability and ignition maps, exhaust gas composition and temperature profile, and liner wall temperature. This rig has the potentiality of performing combustion tests with a maximum airflow rate of 800m3/h and preheated air up to 1000K, as well as different types of liquid or gas fuels.

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2020 The Authors. Energy Science & Engineering published by the Society of Chemical Industry and John Wiley & Sons Ltd. Department of Mechanical Engineering, University of Mazandaran, Babolsar, Iran

Aim: To evaluate the performance of a single cylinder, four–stroke, water cooled, 3.68 kW direct–injection diesel engine at a speed of 1500 rpm with different versions of the combustion chamber with tobacco seed oil biodiesel and to make comparative studies with data of pure diesel operation working on similar conditions. Study Design: Different versions of the low heat rejection (LHR) combustion chamber such as LHR–1 (ceramic coated cylinder head), LHR–2 (air gap insulated piston and air gap insulated liner) and LHR–3 (ceramic coated cylinder head, air gap insulated piston and air gap insulated liner); Various injector opening pressures such as 190 bar, 230 bar and 270 bar. Methodology; Performance parameters of brake thermal efficiency (BTE), brake specific energy consumption (BSEC), exhaust gas temperature (EGT), coolant load and volumetric efficiency at different values of brake mean effective pressure (BMEP) of the engine, Brief Results: At recommended injection timing of 27o bTDC and recommended injector opening pressure of 190 bar, conventional engine (CE) showed comparable performance, while different versions of LHR combustion chamber showed improved performance with biodiesel operation, when compared with conventional engine with pure diesel operation (standard diesel operation).

In this study, hydroxy gas (HHO) was produced by the electrolysis process of different electrolytes (KOH(aq), NaOH(aq), NaCl(aq)) with various electrode designs in a leak proof plexiglass reactor (hydrogen generator). Hydroxy gas was used as a supplementary fuel in a four cylinder, four stroke, compression ignition (CI) engine without any modification and without need for storage tanks. Its effects on exhaust emissions and engine performance characteristics were investigated. Experiments showed that constant HHO flow rate at low engine speeds (under the critical speed of 1750 rpm for this experimental study), turned advantages of HHO system into disadvantages for engine torque, carbon monoxide (CO), hydrocarbon (HC) emissions and specific fuel consumption (SFC). Investigations demonstrated that HHO flow rate had to be diminished in relation to engine speed below 1750 rpm due to the long opening time of intake manifolds at low speeds. This caused excessive volume occupation of hydroxy in cylinders which prevented correct air to be taken into the combustion chambers and consequently, decreased volumetric efficiency was inevitable. Decreased volumetric efficiency influenced combustion efficiency which had negative effects on engine torque and exhaust emissions. Therefore, a hydroxy electronic control unit (HECU) was designed and manufactured to decrease HHO flow rate by decreasing voltage and current automatically by programming the data logger to compensate disadvantages of HHO gas on SFC, engine torque and exhaust emissions under engine speed of 1750 rpm. The flow rate of HHO gas was measured by using various amounts of KOH, NaOH, NaCl (catalysts). These catalysts were added into the water to diminish hydrogen and oxygen bonds and NaOH was specified as the most appropriate catalyst. It was observed that if the molality of NaOH in solution exceeded 1% by mass, electrical current supplied from the battery increased dramatically due to the too much reduction of electrical resistance. HHO system addition to the engine without any modification resulted in increasing engine torque output by an average of 19.1%, reducing CO emissions by an average of 13.5%, HC emissions by an average of 5% and SFC by an average of 14%.

This study aims to model the methane partial oxidation process in the burner and combustion chamber of autothermal reactor. The numerical simulation based on this model offers a powerful tool that can assist in reactor design and optimization and scale up of the process saving expensive pilot work. The steady-state governing equations were solved using the SIMPLE algorithm and the effect of turbulence on the mean flow field was accounted for using the RNG k–ε model. A two-step reaction mechanism was used for the gas combustion with CO as the intermediate species. The reaction rates were modeled using an Eddy-Dissipation Model. In terms of the geometrical model, a 3D model for burner was developed while an axis-symmetric model for the combustion chamber was implemented to reduce the computational costs. The model formulated was validated against a currently operating autothermal reactor and then has been used to investigate different aspects of these reactors. Results show that effect of oxygen to methane ratio is more than that of feed temperature. It is demonstrated that a 60% increase in O2/CH4 ratio causes a 15.4% decrease and 42.7% increase in H2/CO ratio and methane conversion, respectively. In contrast, a 60% increase in feed temperature does not have a significant effect on the process.

Thermochemical properties and the internal geometric configuration of the propellant affect the internal pressure in the
combustion chamber of a solid propellant rocket motor. An algorithm based on the finite difference method is formulated to predict
the comportment of the pressure during the fast combustion of the propellant grain, for a motor design whose geometry and grain
composition are previously established. Two geometry cases are compared and analyzed: (1) cylindrical grain with radial burning,
and (2) cylindrical grain with longitudinal burning. The performance from different propellants compositions can be compared with
this model. At the end, the calculated pressure and equations for isentropic flow in nozzle give the thrust-time curve which is useful
to determine the viability of each configuration in a the rocket mission, as well the performance of the motor. This work presents the
development of a numerical solution based on finite differences applied in both, end and radial burning.

A numerical work has been performed to analyze the heat transfer and fluid flow in a pent-roof type combustion chamber. Dynamic mesh model was used to simulation piston intake stroke. Revolution of piston (1000 ≤ n ≤ 5000) is the main governing parameter on heat ...

The purpose of this paper is to study the influence of the composition of the flue gases on the thermal radiation inside the combustion chamber of a three-stage regenerative oxidizer that neutralizes gaseous pollutants for a given plant capacity. This composition is expressed by the corresponding partial pressure of each constituent gas. It is assumed that the flue gases are gray and obey Lambert's law, so that the gas mixture is assumed to be composed of water vapor and carbon dioxide plus a neutral one. Accurate estimates of each gaseous component emissivity were calculated from the experimental data charts provided by H. Hottel by employing regression analysis. The total emissivity coefficients of the gaseous mixture are evaluated with the help of the above emissivities and they are incorporated into the energy conservation equation that relates the heat exchange among the chamber walls.

This paper investigates the validity of the method of zones proposed by H. Hottel and R. J. Tucker for enclosures with surfaces exposed to significant thermal radiation. The analysis is focused on a specific combustion chamber in a three-bed regenerative oxidizer and calculates the temperatures and the corresponding thermal flux exchanges among the hot wall surfaces of the chamber. The temperature distribution and the initial composition of the gaseous mixture at the inlet plane were assumed known.

Auto-igniting n-heptane sprays have been studied experimentally in a high pressure, high temperature constant volume combustion chamber with optical access. Ignition delay and the total pressure increase due to combustion are highly repeatable whereas the ignition location shows substantial fluctuations. Simulations have subsequently been performed by means of a first-order fully elliptic Conditional Moment Closure (CMC) code. Overall, the simulations are in good agreement with the experiment in terms of spray evolution, ignition delay and the pressure development. The sensitivity of the predictions with respect to the measured initial conditions, the spray modelling options as well as the chemical mechanism employed have been analysed. Strong sensitivity on the chemical mechanism and to the initial temperature on the predicted ignition delay is reported. The primary atomisation model did not affect strongly the predicted auto-ignition time, but a strong influence was found on the ignition location prediction.

This paper investigates the validity of the LECKNER relationsproposed to calculate the emissivity of mixture of gas combustion in comparation by H. Hottel and R. J. Tucker method for enclosures with surfaces exposed to signi icant thermal radiation. The analysis is focused on a speci ic combustion chamber in a threebed regenerative oxidizer and calculates the coef icient of absorption and the corresponding thermal irradiation lux exchanges among the hot wall surfaces of the chamber. The temperature distribution and the initial composition of the gaseous mixture at the inlet plane were assumed known.

The power can be generated in the combustion chamber of an automobile. The combustion chamber is the place where the charge burns in. The charge i.e. air and fuel at various proportions depending upon the accelerations made is sent through carburettor which is compressed inside the combustion chamber with to and fro moments of piston within the top and bottom dead centres. After the combustion, the burnt charge exerts a lot of force on the piston. The piston plays various roles in compressing the charge and in transferring the produced power to the crankshaft. During this process, always the piston is in contact with the charge. The burnt charge has temperature about 12000C. The heat flows into the piston. So the piston should have sufficient mechanical strength to with stand the force acting by the explosion and the piston should be thermally stable to with stand the heat flow into the piston. The piston is cooled by providing cooling fins external to the surface of Combustion Chamber. In this paper the thermal analysis of the piston is done by modelling the piston with aluminium alloy. The thermal analysis was analysed using software ANSYS. It is found that, the aluminium alloy piston is having the sufficient thermal stability to with stand the high temperatures.