Zhicheng Shi

• Beijing Institute of Technology

There are few studies on the effect of turbulent jets on the combustion characteristics of passive pre-chamber (PC) gasoline engines, and their mechanism needs to be elucidated. Therefore, a 3-D simulation was performed using CONVERGE software. The results reveal that a modest expansion in the PC volume contributes to combustion due to the increase...

Piston damage is a frequent problem of engine durability and plays an important role in an engine’s performance design. Recently, a large amount of piston erosion has occurred in a series of heavy-duty diesel engines. To investigate the reason for the piston erosion, a study of the computational fluid dynamics (CFD) of the combustion process in the...

Spark ignition (SI) engines fueled with kerosene have broad application prospects in unmanned aviation vehicles. The knock phenomenon of kerosene in SI engines is a huge challenge, leading to a much lower power output than gasoline engines. In this context, the combustion characteristics of kerosene blending with hydrogen are analyzed numerically r...

To clarify the mechanism of destructive knock combustion and piston ablation in heavy-duty diesel engines operating at low temperatures, CONVERGE simulation and wall temperature measurement were performed. The results show that as the initial temperature (intake valve closing instant) decreases from 380K to 307K, the spray wet-wall ratio increases...

The effect of injection pressure on diesel ignition has been widely studied, but the conclusions are different or even contradictory. Thus, the 3-D simulation was conducted at injection pressures of 40–280 MPa under different spray wet-wall conditions. The results show that as the injection pressure increases, the fuel injection ends earlier, so th...

Given a lack of clarity on fuel-attached combustion and its effect on the wall heat load in diesel engines remain to be clarified. Therefore, visualization and wall temperature measurement experiments are carried out in a constant volume combustion chamber, while CONVERGE simulation is performed to make further explanation. The fuel film attached t...

The multiple-injection strategies can significantly improve the diesel engine startability at low-temperature conditions, but the processes are extremely complex due to the effect of various factors simultaneously. To find out how the pilot injection affects the main injection, the spray and ignition with different injection strategies at low tempe...

The two-stroke rod-less opposed pistons engine provides a new possibility to improve the energy conversion path by optimizing cam profile. Constrained by the optimization algorithms and profile control equations, previous research could not optimize the profile with a high-degree freedom under practical engine operating conditions. A thermodynamic...

The combustion of wall-impinging diesel spray of heavy-duty diesel engines deteriorates combustion quality under cold-start conditions, making it difficult to control soot emissions. To investigate the causes of soot increase in the combustion of wall-impinging spray at low temperature and low speed starting conditions, the effect of the starting f...

For diesel engines, the distance between the wall and the spray nozzle is an important feature for the matching of spray and combustion chamber geometry. In this study, the effects of the cold wall with different wall distance on the spray and ignition characteristics at low-temperature conditions are systematically analyzed. CFD simulations are us...

The effect of wall parameters on combustion and soot emission characteristics remains to be revealed so far, especially in the case of spray impingement at low temperatures. Therefore, the visualization experiments are carried out in a constant volume combustion chamber using the Mie scattering and direct photography techniques, and the two-color m...

Dimethyl ether (DME)/C1-C4 alkane mixtures are ideal fuel for homogeneous charge compression ignition (HCCI) engines. The comparison of ignition delay and multi-stage ignition for DME/C1-C4 alkane mixtures can provide theoretical guidance for expanding the load range and controlling the ignition time of DME HCCI engines. However, the interaction me...

The effect of diesel engine continuous strengthening on combustion and emission remains to be clarified. This study tested combustion and emission processes at different intake pressures on a single-cylinder diesel engine. The results show that the combustion of diesel engine after continuous strengthening is concentrated in diffusion and post-comb...

The knock combustion and pollutant emission of heavy-duty diesel engines at low temperatures are still unclear, especially under different injection timings. Therefore, this study illustrates the above issues through CONVERGE simulation. The results show that with the start of injection (SOI) sweeps from −7°CA to −32°CA, a large amount of liquid-ph...

In this paper, the heat transfer characteristics of spray-wall impingement on a high temperature wall were studied by using a transient thermocouple and a one-dimensional finite-difference conduction model to obtain variations of wall temperature and heat flux. Results showed that increasing the injection pressure and decreasing the ambient tempera...

The difference in impinging ignition characteristics of light- to heavy-duty diesel engines at low temperatures and the heating effect of fuel film combustion on the wall are still not well understood. Thus, visualization experiments are conducted in a constant volume combustion chamber using Mie-scattering and direct photography methods, and 3-D s...

SI engines are installed widely in small aircrafts as they have good fuel economy. Currently, these SI engines are fueled with gasoline, although their safety can be improved if kerosene is used. However, the combustion performance of kerosene cannot fulfil the requirements due to the differences in physicochemical properties. This study investigat...

The impinging spray ignition has been widely studied, but the mechanism is unclear, especially at low temperatures. Thus, the 3-D simulation was conducted at ambient temperatures of 740–1200 K and wall temperature of 393 K. The results reveal that the fuel–air mixing and ignition processes of an impinging jet are approximately the same as that of a...

Wall-impinging ignition has been widely studied, but it is still poorly understood at low temperatures. Thus, visualization experiments are performed in a constant volume combustion chamber using direct photography methods. The results show that the injection pressure effect is highly sensitive to temperature, and increased injection pressure helps...

The effect of wall temperature on the ignition of vapor-phase spray impingement has been studied extensively, but the mechanism of the liquid-phase case is not clear. Thus, the visualization experiment was conducted at wall temperatures of 363–673 K using Mie-scattering, shadowgraph, and direct photography methods in a constant volume combustion ve...

The effect of injection pressure on impinging ignition at low temperatures is not systematic or even confusing. This work is to reveal the impinging ignition mechanism by the numerical method to further improve the success rate and thermal efficiency at cold-start conditions in a diesel engine. In which, n-dodecane was used as the diesel surrogate,...

In this paper, a free piston expander-linear generator (FPE-LG) test rig is established and the control strategy based on displacement is applied. The operation characteristic, output performance, and energy conversion efficiency of the FPE-LG are analyzed. The coefficient of equilibrium oscillation (C) is identified to evaluate the stability of th...

Although engines fueled with diesel/gasoline blends show excellent combustion and emission performance, its low-temperature flame development characteristics under cold-start conditions remain to be further verified. To clarify the details, experiments were conducted in an optical constant volume combustion chamber using Mie-scattering and direct p...

In the heavy-duty diesel engine, the unavoidable impinging spray and ignition during low-temperature ignition have a significant impact on engine performance. In this study, the effects of injection pressure on the impinging spray and ignition characteristics of the heavy-duty diesel engine with a 0.32 mm nozzle were measured visually in a constant...

Diesel engine plays a vital role in various fields, but it does suffer from the cold-start issue when operating in low-temperature environment. As an alternative fuel or emergency back-up fuel for diesel engine, kerosene was investigated to reveal the influences of its difference on physical and chemical properties from diesel on low-temperature ig...

Low temperature reaction process becomes more important for auto-ignition diesel spray with ambient temperature reducing. In order to reveal the effects of negative temperature coefficient (NTC), toluene was added to diesel with different ratios due to its non-NTC feature during investigating ignition and combustion characteristics of spray on an o...

The impact of ethane (C2H6) addition to ignition delay of dimethyl ether (DME) under high-temperature conditions is opposite to that of other small molecule alkanes, but the trend is still unclear under low-temperature conditions. Thus, ignition delays of DME/C2H6 mixtures (C2H6 blending ratio ranging from 0% to 70%) were measured at temperatures o...

Ignition delays of lean dimethyl ether (DME)/hydrogen mixtures with hydrogen mole fraction ranging from 0 to 85% were measured using a rapid compression machine with equivalence ratios from 0.3 to 0.5, temperatures from 621 to 852 K and pressures from 7 to 22 bar. Numerical analysis was performed based on the NUI Aramco Mech 2.0 and, in general, go...

Dimethyl ether (DME)/n-butane mixtures are ideal fuel for homogeneous charge compression ignition (HCCI) engine. Fundamental ignition delay data under engine-related conditions are essential to better understand HCCI combustion and to validate DME/n-butane models. However, there is a significant lack of ignition delay data of DME/n-butane mixtures...

Ignition delays of dimethyl ether and hydrogen (DME/H2) mixtures (hydrogen blending ratio ranging from 0% to 60%) were measured in a rapid compression machine at compressed temperatures ranging from 655 to 810 K and compressed pressures from 16.9 to 24.5 bar with an equivalence ratio range of 0.8–1.6. Experimental measurements are compared with res...

Experimental and numerical studies are conducted on the thermal, chemical and dilution effects of buffer gas composition on autoignition of dimethyl ether (DME). The buffer gases considered are nitrogen (N2), a mixture of N2 and argon (Ar) at a mole ratio of 50%/50% and a mixture of Ar and carbon dioxide (CO2) at a mole ratio of 61.2%/38.8%. Experi...

A rapid compression machine (RCM) test bench is developed in this study. The performance characterization and auto-ignition performance tests are conducted at an initial temperature of 293 K, a compression ratio of 9.5 to 16.5, a compressed temperature of 650 K to 850 K, a driving gas pressure range of 0.25 MPa to 0.7 MPa, an initial pressure of 0....