EXPERIMENTAL STUDY ON THE MACRO-AND MICRO- CHARACTERISTICS OF THE SPRAY FROM A PRESSURE SWIRL NOZZLE

The experimental study on the macro and micro characteristics of the spray from a pressure swirl nozzle embraces the growth of surface unstable wave,disintegration process,spray angle,breakup length and so on.The effects of injection pressure,nozzle geometry and liquid properties on these characteristics are also discussed.The results are helpful to understand the underlying physics of the pressure swirl nozzle and serve as the basis for the practical design,usage and improvement of the nozzle.

An experimental study on microscopic characteristics of gas-bearing sediments under different gas reservoir pressures

Gas-bearing sediments are widely distributed in five continents all over the world.Most of the gases exist in the soil skeleton in the form of discrete large bubbles.The existence of gas-phase may increase or decrease the strength of the soil skeleton.So far,bubbles’structural morphology and evolution characteristics in soil skeleton lack research,and the influence of different gas reservoir pressures on bubbles are still unclear.The micro characteristics of bubbles in the same sediment sample were studied using an industrial CT scanning test system to solve these problems.Using the image processing software,the micro variation characteristics of gas-bearing sediments in gas reservoir pressure change are obtained.The results show that the number and volume of bubbles in different equivalent radius ranges will change regularly under different gas reservoir pressure.With the increase of gas reservoir pressure,the number and volume of tiny bubbles decrease.In contrast,the number and volume of large bubbles increase,and the gas content in different positions increases and occupies a dominant position,driving the reduction of pore water and soil skeleton movement.

Research on windmill starting characteristics of MTE-D micro turbine engine

Micro turbine engine （MTE） is an important kind of propulsion system for miniature unmanned aircraft or missiles, because of its better high-speed performance （than propeller propulsion） and higher propulsion efficiency （obviously than rockets）. Windmill start is a common air-starting mode used in micro turbine engine. The windmill starting characteristics are important to the practical use of micro turbine engine. In this paper, the windmill starting characteristics research for a 12 cm diameter （MTE-D） micro turbine engine is carried out by experiment and numerical simulation. The characteristic of rotor mechanical losses at low-speed condition is stud- ied, and the engine common working line of windmill starting process is obtained. Based on the engine windmill characteristics, the propane ignition characteristics under different inflow conditions are researched, and the envelope of propane ignition and propane flameout is determined. The experimental research of fuel supply and ignition characteristics is completed, and the envelope of fuel supply and ignition is obtained. The windmill stage, propane ignition stage, fuel ignition stage and acceleration process from idling-speed to 80% full speed of MTE-D micro turbine engine is optimized, and the optimization windmill starting parameters are collected. The successful wind-mill starting experiment under this condition with engine speed up to 80% full speed indicates that these starting parameters are reasonable. All the starting parameters of MTE-D micro turbine engine obtained in this work are dimensionless parameters, and the conclusions obtained in this study have some reference to other micro turbine engines with the similar structural form and starting process.