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Traditional exhaust-gas turbocharging exhibits hysteresis under variable working conditions. To achieve rapid-intake supercharging, this study investigates the synergistic coupling process between the detonation and diesel cycles using gasoline as fuel. A numerical simulation model is constructed to analyze the detonation characteristics of a pulse-detonation combustor (PDC), followed by experimental verification. The comprehensive process of the flame’s deflagration-to-detonation transition (DDT) and the formation of the detonation wave are discussed in detail. The airflow velocity, DDT time, and peak pressure of detonation tubes with five different blockage ratios (BR) are analyzed, with the results imported into a one-dimensional GT-POWER engine model. The results indicate that the generation of detonation waves is influenced by flame and compression wave interactions. Increasing the airflow does not shorten the DDT time, whereas increasing the BR causes the DDT time to decrease and then increase. Large BRs affect the initiation speed of detonation in the tube, while small BRs impact the DDT distance and peak pressure. Upon connection to the PDC, the transient response rate of the engine is slightly improved. These results can provide useful guidance for improving the transient response characteristics of engines.

Herein, a diesel engine jet disturbance combustion system was proposed to achieve efficient and clean combustion under heavy load conditions in heavy-duty diesel engines. The key components of the combustion system were designed, and a research platform was constructed. Focusing on the internal combustion conditions of the disturbance chamber and the developmental path of high-speed jets, the design and comprehensive optimization of the jet disturbance combustion system were carried out. Following optimization, the peak internal heat release rate increased from 86 J/deg to 269 J/deg, and the cumulative heat release increased by 112 J, significantly enhancing the energy of the disturbance chamber jet. Then, considering combustion optimization and the heat transfer loss from the piston, it was determined that the optimal configuration for the disturbance chamber jet channel angles was 60 deg inter-channel angle and 10 deg channel incidence angle. This configuration allowed the disturbance chamber jet to precisely disturb the concentrated mixture area in the middle and late stages of combustion. The intervention of the disturbance chamber jet provided sufficient energy for the fuel–air mixing process and complicated the gas flow state in the main combustion chamber. Despite its low-momentum density, the residual mixture in the cylinder maintained a high mixing rate after the end of the fuel injection process. Single-cylinder engine test results showed that a diesel engine using this jet disturbance system and a 180 MPa common rail pressure fuel system achieved 52.12% thermal efficiency.

Excessive nitrogen fertilizer usage in agricultural often leads to negative ecological and production gains. Alterations in the physical and chemical properties and microbial community structure of agricultural soils are both the cause and consequence of this process. This study explored the perturbation of soil properties and microorganisms in agricultural soils by different nitrogen levels. Soil total nitrogen, total phosphorus, and total potassium decreased in the shallow soil layer with decreasing nitrogen. Changes in nitrogen affected soil organic matter, pH, bulk density, and water content. However, a moderate reduction in nitrogen did not cause significant yield loss; the increased nitrogen use efficiency was the main reason, attributed to the available phosphorus and potassium. Short-term changes in nitrogen had limited effects on soil microbial community structure. Bacteria were more susceptible to perturbation by nitrogen changes. Nitrogen reduction increased the relative abundance of MND1 (1.21%), RB41 (1.96%), and Sphingomonas (0.72%) and decreased Dongia (0.3%), Chaetomium (0.41%), and Penicillium (0.5%). Nitrogen reduction significantly increased the bacteria functional composition of aerobic ammonia oxidation (4.20%) and nitrification (4.10%) and reduced chemoheterotrophy (2.70%) and fermentation (4.08%). Available phosphorus specifically drove bacterial community structure variation in the shallow soil layers of moderate nitrogen reduction treatments. Steroidobacter, RB41, Gemmatimonas, Ellin6067, Haliangium, and Sphingomonas were the main component nodes in this community structure. These results provide insights into the study of nitrogen and microorganisms in agricultural soils.