Research and development of hydrogen fuelled engines in China

Flow resistance characteristic is an important parameter in the design of solenoid valve. It not only affects the determination of structural parameters of valve, but also plays a decisive role in the selection of control method of valve. In this paper, the flow resistance characteristic curve of the solenoid valve is obtained based on a 3D steady-state CFD simulation.

https://iopscience.iop.org/article/10.1088/1742-6596/2441/1/012050/pdf

Analysis of flow resistance characteristics of solenoid valve based on numerical simulation

Acoustic stealth performance is an important performance index of Underwater Unmanned Aerial Vehicles. Due to equipment installation and other reasons, there will be a sea port on the bulkhead of the aircraft. Because the sea port destroys the flow field on the surface of the aircraft and produces noise, which affects the underwater communication of the aircraft. In this paper, the numerical simulation method is used to analyze the flow induced noise characteristics of the bulkhead of an underwater unmanned vehicle, and the main noise frequency characteristics at the bulkhead of the estuary are obtained, which provides data reference for the structural design of the estuary and the layout of the underwater communication system.

https://iopscience.iop.org/article/10.1088/1742-6596/2441/1/012060/pdf

Analysis of fluid excited noise characteristics of bulkhead opening of an Underwater Unmanned Vehicle

The geometrical size and motion characteristics of bubbles in water are the key parameters which affect the characteristics of gas-liquid two-phase flow and play a key role in engineering applications. There are few types of research on bubble formation by horizontal intake. This paper analyzes the effects of different gas velocities, gas hole diameters, and water temperature on bubbles' size and motion characteristics based on the BP(backpropagation) neural network and VOF(volume of fluid) model. The statistical data are trained by BP neural network to obtain the prediction model. The results show that the gas velocity and diameter are proportional to the bubble size and horizontal displacement amplitude, but the curvature decreases. The water temperature is inversely proportional to the bubble size, and the horizontal displacement amplitude has little change. The prediction model has a high degree of fit and good correlation and can predict bubble size and displacement quickly and accurately.

Simulation and Prediction of Bubble Size and Motion Characteristics of Underwater Horizontal Flow

The mechanical characteristics of the impeller are important indicators that determine the working characteristics of the pump. The pump is subjected to periodic hydraulic loads during the working process. This load will cause the dynamic deformation of the impeller and the impeller shaft, thereby further affecting the distribution of the fluid. Liquid-solid coupling is used. Method, the rated operating point of centrifugal pump is analyzed, and it is proved that the dynamic stress of the impeller and the impeller shaft meets the requirements, which lays a foundation for the formulation of the control strategy of the impeller.

https://iopscience.iop.org/article/10.1088/1742-6596/2441/1/012053/pdf

Dynamic Load Analysis of an Centrifugal Pump Axle using FSI Simulation

Fuel consumption was studied on a diesel engine by adding hydrogen into its air intake. Result shows that diesel fuel consumption can be reduced by 20%-30% with proper hydrogen addition. The reduction of diesel fuel consumption can save the exhausting petroleum reserve effectively. Fuel (energy) cannot be saved at high power with the addition of hydrogen, while at low power such as 4 kW, the saving rate of BSFC (brake specific fuel consumption) can reach 14% or more. When the initial temperature of hydrogen is raised to about 90-130 ℃, diesel fuel consumption can reduce about 3 g/(kW·h) , no matter diesel fuel or emulsified fuel is used. The experiment also shows that using emulsified fuel and hydrogen together can improve the saving rate of BSFC more effectively, It can be improved by about 3% when using emulsified fuel. Which is due to the fast vaporization of water. After the water vaporization, diesel droplets become much smaller and vaporize faster, so the combustion process finishes earlier.

Fu Wei

Papers

Effect of Hydrogen on Fuel Consumption of Diesel Engine