Mixture In Combustion Chamber Research Articles

Analysis of Hydrocarbon Mixture Performance of a Dual-Channel Swirl Engine

In order to understand and improve the oil and gas mixing performance of a dual-channel vortex chamber diesel engine, the BH175F dual-channel vortex chamber combustion system was used as the research foundation, and the oil-gas mixture process of the combustion system was numerically analyzed. By analyzing the cylinder temperature, cylinder pressure, mixing process and combustion process of the combustion system, the mixture performance of the combustion system was studied. Results indicated that: The mixture of the compression Top Dead Center (TDC) started to enter the main combustion chamber through the start-up hole; when the piston reached 4° After Top Dead Center (ATDC), the mixture started to enter the main combustion chamber through the connecting channels A and B, and the high-concentration mixture entered the main combustion from the start-up hole; when the piston continued running down to 20° and 25° ATDC, it could be seen that the main combustion chamber mixture was already relatively uniform; besides, when the equivalence ratio was between 0.8 and 1, the air-fuel mixture was unevenly distributed in the main combustion chamber. It provides guidance for further improvement of the combustion system.

Numerical investigation into the fuel evaporation and mixture formation characteristics of a free-piston diesel engine

The free-piston engine generator becomes a new-type potential substitute for the conventional crankshaft combustion engine. This article presents a simulation to study the fuel spray and mixing characteristics of a diesel free-piston engine generator by comparing a corresponding crankshaft combustion engine. A full-cycle model which couples with piston dynamics, combustion, and gas exchange is developed to simulate the fuel spray, atomization, and mixing in the free-piston engine generator. The result indicates that compared with the crankshaft combustion engine, the free-piston engine generator provides a higher temperature and pressure for fuel spray and mixing during the ignition delay, but its ignition delay lasts shorter. The free-piston engine generator shows a shorter spray penetration and more fuel impingement due to its smaller combustion chamber volume during the injection process. The free-piston engine generator exhibits a lower level of air utilization and worse uniformity of fuel–air mixture in combustion chamber. In addition, the shorter ignition delay of free-piston engine generator makes the time of atomization, evaporation, and mixing of fuel shorter, and the mixing effect of free-piston engine generator is worse, resulting in less combustible mixture formed during the ignition delay. In addition, some guiding suggestions have been proposed to improve the fuel spray and fuel–air mixing characteristics of free-piston engine generator.

Numerical simulation of plasma-assisted combustion of methane-air mixtures in combustion chamber

A two-dimensional mathematical model was developed to investigate the effects of dielectric barrier discharge (DBD) plasma on CH4-air mixtures combustion at atmospheric pressure. Considering the physical and chemical processes of plasma-assisted combustion (PAC), plasma discharge, heat transfer and turbulent were simultaneously coupled into simulation of PAC. This coupling model consists of DBD kinetic model and methane combustion model. By comparing simulations and the original reference’s results, a high-accuracy of this model was validated. In addition, the effects of PAC actuation parameters on combustion characteristics were studied. Numerical simulations show that with an inlet airflow velocity of 10 m s−1, a CH4-air mixtures’ equivalence ratio of 0.5, an applied voltage of 10 kV, a frequency of 1200 kHz, compared to conventional combustion (CC), the highest flame temperature rises by 32 K; outlet temperature distribution coefficient drops by 2.3%; the maximum net reaction rate of CH4 and H2O increase by 11.22% and 12.80% respectively; the maximum CO emission index decreases by 14.61%; the mixing region turbulence mixing time reduces by 89 ms.

Applying artificial neural networks (ANN) to the estimation of thermal contact conductance in the exhaust valve of internal combustion engine

Exhaust valve temperature increases significantly due exhaust hot gases obtained from combustion fuel-air mixture in combustion chamber of internal combustion engine. In order to avoid the damage of the combustion chamber and the engine itself, heat must be taken away from the valve. This can be done when the valve in contact with the seat and the periodic contact heat transfer takes place. Therefore study of heat transfer contact between the valve and its seat is important and necessary. In this study back propagation neural (BPN) network has been used to estimate two parameters to determine the heat transfer rate through the valve and its seat due the complexity of thermal contact problem between the valve and its seat. This thermal contact problem is solved to obtain the required information for design the neural network using inverse heat transfer method (conjugate gradient method using a two search step sizes). The results show that, between the different algorithms, Levenberg Marquardt algorithm is produced the best model for estimating the unknown parameters.

C121 直噴ガソリンエンジンの噴霧挙動可視化

We developed new technique to visualize the condition of fuel-air mixture in combustion chamber of the direct injection gasoline engine clearly in real time.In this technique, a micro CCD TV camera, optical fiber for illumination, a set of lenses and an observation window are put in spark plug and we can observe through spark plug hole.So it is not necessary to provide with a particular observation window in an engine as before and this technique is characterized by the possibility of rapid visualization at the same time.