Experimental Study On The Flow Of Droplets At Different Spray Pressures Using PIV

Spray flow field is extensively applied in many fields, such as daily life, industrial production and power equipment, etc. In the flow field of spray droplets, the organization of gas-liquid two-phase flow field is closely related to the flow structure characteristics of the spray flow field. Therefore, the experimental research of the spray flow field is conducive to quantitatively analyzing the spatial distribution of the characteristic parameters of the spray flow field, in order to build on the theoretical foundation for optimizing the organization of gas-liquid two-phase flow field.In the paper, the experimental visual model of the spray flow field was reconstructed, and the study object of the experiment was the atomized droplets. We conducted the droplet flow experiment under the following conditions: spray pressure 0.30?0.60MPa.The spray flow field was photographed by Particle Image Velocimetry (PIV), in order to acquire the instantaneous velocity information of the spray flow field at different spray pressures.According to the characteristics of PIV experimental data, such as multi-dimension and randomness, etc., we proposed the processing method of the combination of time-average and multi-scale spatial-average, and PIV data with random features was processed using the statistical analysis principle. Firstly, based on the summary of the calculation methods of the time-averaged values of the characteristic parameters of the spray flow field in the previous studies, the PIV experimental data was processed by time-average, including the time-averaged flow field, the time-averaged velocity, the time-averaged turbulent intensity, the time-averaged vorticity and the time-averaged shear strain rate. Then, the multi-scale spatial-average was introduced to further explore the method to obtain the spatial distribution of the characteristic parameters of the flow field on the basis of the time-averaged flow field, which aimed at obtaining the overall distribution of characteristic parameters of the spray flow field.The overall spatial distribution of the spray flow field characteristic parameters was successfully extracted based on experimental data of spray flow field at design pressure conditions, using the procedure of combining time-average and multi-scale spatial-average.And change rules of flow characteristics of the spray flow field under different spray pressure were discussed. Firstly, the influence of pressure changes on the velocity distribution of the spray flow field was analyzed. Then,the influence of pressure changes on the turbulent intensity distribution of the spray flow field was studied. After that, the influence of pressure changes on the vorticity distribution of the spray flow field was investigated. At last, the influence of pressure changes on the shear strain rate distribution of the spray flow field was researched.Meanwhile, the impact of pressure changes on distribution of the mainstream boundary line of the spray flow field was also explored. Ultimately, it revealed the systematic relationship between the continuous variation of pressure and the overall flow characteristics of the spray flow field.