In order to improve combustion characteristic of swirl chamber diesel engine, a simulation model about a traditional cylindrical flat-bottom swirl chamber turbulent combustion diesel engine was established within the timeframe of the piston motion from the bottom dead centre (BDC) to the top dead centre (TDC) with the fluent dynamic mesh technique and flow field vector of gas in swirl chamber and cylinder; the pressure variation and temperature variation were obtained and a new type of swirl chamber structure was proposed. The results reveal that the piston will move from BDC; air in the cylinder is compressed into the swirl chamber by the piston to develop a swirl inside the chamber, with the ongoing of compression; the pressure and temperature are also rising gradually. Under this condition, the demand of diesel oil mixing and combusting will be better satisfied. Moreover, the new structure will no longer forma small fluid retention zone at the lower end outside the chamber and will be more beneficial t...

Improvement of Swirl Chamber Structure of Swirl-Chamber Diesel Engine Based on Flow Field Characteristics

Based on the design principles of connecting passage, the article first proposed the idea of dual channel insert with expansion angle and designed three solutions which differed in the expansion angle between channel A and B by 0°& 0°, 5°& 10°, and 10°& 5°. Furthermore, the economic and emission characteristics of the swirl chamber were determined by conducting a bench test. Results indicate that the geometry of dual channel can promote the development of swirl, and a proper increase in the expansion angle of the channel has a positive effect on the development of the swirl in the swirl chamber. When the expansion angles of channel A and B are 10° and 5°, respectively, the swirl characteristic is relatively good, but experimental results show that the oil consumption rates of the Scheme at both the low and heavy load being at their least, which, respectively, are 3% and 3.2% lower than that of the original engine; and the corresponding exhaust transmission coefficients are also 72% and 9.7% lower than that of the original engine, respectively. And the economy and emission characteristics of the other two dual-channel schemes are also improved in some degree. The research results provide certain reference for the performance improvement of swirl chamber air-cooled diesel engine and are beneficial to the further design and optimization. © 2016 American Institute of Chemical Engineers Environ Prog, 2016

Analysis on working performance of the swirl chamber diesel engine with a dual channel and an expansion angle

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.

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

In order to improve the performance of a mini-type air-cooled diesel engine in terms of the overall efficiency and engine emissions, a swirl chamber of a variable cross-section dual-channel model was developed. This study proposed nine turbulent swirl chambers with a variable cross-section for a dual-channel combustion solution, which applied a dual-channel cross-section to the insert between the original swirl chamber and the main chamber. Model-based design, simulation and experiments were applied as a feasible approach to address this issue to find out the influence of the dual-channel inclination angle and divergence angle on the swirl rate in the swirl chamber, the power and the emissions performance, including the fuel efficiency. By comparing the tests, the performance of the diesel engine with a variable cross-section dual-channel swirl chamber was superior to the original one with a single channel in terms of the swirl rate, fuel consumption rate and emissions.

The Performance of an Air-Cooled Diesel Engine with a Variable Cross-Section Dual-Channel Swirl Chamber

Numerical simulation was carried out to clarify three-dimensional air motion in the swirl chamber of a diesel engine. Simulations have been performed spherical swirl chambers with different sorts of connecting ports. The results obtained are as follows. (1)Toward the end of the compression stroke, the swirling flow becomes strong. On the other hand, the flow normal to the swirling surface becomes comparatively weak. (2)According to the jet of a subconnecting port, the swirling flow in the end stage of the compression stroke becomes weak in the central part. (3)The spatial distribution of strong turbulent intensities corresponds to the strong flow field and the shear force field based on inlet flow.

Hiroyuki Uramachi

Papers

Numerical Simulation of Air Motion in the Swirl Chamber of a Diesel Engine : Effect of Connecting Port in Air Motion

Numerical simulation of air motion in the swirl chamber of a diesel engine. Effect of connecting port in air motion.