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Ammonium dinitramide (ADN) monopropellant is currently the most promising among all ‘green propellants’. In this paper, the decomposition and combustion process of liquid ADN-based ternary mixtures for propulsion are numerically studied. The R–R distribution model is used to study the initial boundary conditions of droplet distribution resulting from spray hit on a wire mesh based on PDA experiment. To simulate the heat-transfer characteristics between the gas–solid phases, a two-temperature porous medium model in a catalytic bed is used. An 11-species and 7-reactions chemistry model is used to study the catalytic and combustion processes. The final distribution of temperature, pressure, and other kinds of material component concentrations are obtained using the ADN thruster. The results of simulation conducted in the present study are well agree with previous experimental data, and the demonstration of the ADN thruster confirms that a good steady-state operation is achieved. The effects of spray inlet mass flux and porosity on monopropellant thruster performance are analyzed. The numerical results further show that a larger inlet mass flux results in better thruster performance and a catalytic bed porosity value of 0.5 can exhibit the best thruster performance. These findings can serve as a key reference for designing and testing non-toxic aerospace monopropellant thrusters.

Fuel-air mixing process is one crucial key to determine the performance of a diesel engine, and it is crucially determined by swirl within cylinder. For generating strong swirl within the cylinder, a new device named swirler has been propounded. In the present paper, four swirlers have been employed to experimentally study the performance on both the discharge capability and swirl generation capability. The steady flow test bench was employed to study the both capabilities in macro-level. Then, a water-flow model was employed to observe the flow motion within the cylinder via the tested swirlers. The results indicate that adopting swirler with a suitable configuration could generate strong swirl without remarkable discharge capability loss.

Ample intake charge and suitable intake flow motion can improve the combustion quality in diesel engine for it can promote the mixing process between air and fuel. But enough air charge is more difficult to reach for high blower engine. The stead flow test method under naturally aspirated condition is usually used to obtain the flow characteristics of engine intake port. But it may over-evaluate the flow ability when the intake port is used for a high blower engine. The characteristics of intake flow under supercharging condition have rarely been studied in past. Therefore, it is necessary to make study on the relation between the supercharging pressure and intake flow characteristics for supercharging diesel engine. In this paper, the authors have completed experiments under supercharging condition. The test data showed that the flow coefficient and swirl ratio is reduced with pressure difference increase between inlet and outlet of the port, and the flow coefficient and swirl ratio increases with intake pressure increase.

Swirl is an important flow pattern of air motion, it not only affects the fuel-air mixing and combustion processes in diesel engine, but also has a significant impact on heat transfer, combustion quality, and engine-raw emissions. For generating swirl efficiently, many researches have been performed, however, almost the methods have more or less crucial disadvantages. For overcoming these shortcomings and generating more efficient swirl during the intake process, the authors design a new device, swirler, to induce intake swirl in non-swirl intake port diesel engine. In this paper, the authors design four types of swirler including one straight-shaped swirler and three arc-shaped swirlers. In order to research the fundamental characteristics of swirler, the authors make series of experiments researches. The total researches can be divided into three stages: in the first stage, steady flow tests are carried for researching the swirl capability and the discharge capability of swirler from the macro-level, in the second stage, flow fields in the cylinder are measured by Particle Image Velocimetry (PIV) technique in the water analog tests for researching the swirl performance from the micro-level, at last stage, the tested swirler is installed on a certain type of actual diesel engine for studying whether swirler can improve the engine operation performance noticeably. The results show that this new device can induces intake swirl efficiently and can improve fuel economy at on an optimized swirl ratio.

Double swirl combustion system, which is abbreviated to DSCS, is a new combustion system. For its noticeable effect on improving the fuel-air mixing process and reducing raw emissions, it has been accepted and applied widely. Double swirl combustion chamber, as one of the most important components of the DSCS, plays an important role to affect the fuel-air mixing processes and the fuel-air mixture quality which controls the combustion processes. Hence, make the further researches on the DS combustion chamber and design an optimized DS combustion chamber is very necessary and important. However, there has no reports about the researches on the configuration parameters of DS chamber have been published. Therefore, the authors make the research on parametric design of DS combustion chamber, to find out the main configuration parameters of DS chamber, and then explore how those configuration parameters affect the performance of DS chamber. In this paper, the authors make analysis on the configuration structure detailedly, and determine the crucial configuration parameters of DS chamber, and then, the authors make series of simulation researches on those parameters to reveal their effect rules, and indicate the design direction of DS chamber based on those results.