The Investigation Of Flow Field And Unsteady Drag Force While Shock Wave Loads On Unit Cell Of Ball Array

The investigation of the interaction between a shock wave and solid particles is an important subject in the field of supersonic gas-solid two-phase flows.and its research results have important applications in aerospace,medical and health,safety control and other fields.So the further study on the interaction mechanism between shock wave and solid particles is helpful to the development and improvement of supersonic gas-solid two-phase flow theory and the improvement of industrial production technology.The numerical simulation was carried out to study the flow field and the unsteady state resistance of the spherical array of three periodic boundary element models under shock loading.Through synchronous comparison on pressure contours and non-steady-state resistance coefficient of the changing curve,the mechanism and variation law of the unsteady resistance of the Unit cell model ball matrix were presented.The main conclusions of this thesis are as follows:1?The drag coefficient curves of different balls in the unit were compared and analyzed,It is found that the variation law of the drag coefficient in the element has stability and similarity,and proved that The feasibility of extending the drag coefficient model to the particle swarm.2?For a single pellet in the target unit body,the change law of the resistance coefficient is affected by the wave structures formed by the interaction of the incident shock wave,the front row pellet diffraction shock wave,the reflection of the same row of balls and the back row of balls,and the shock wave-shock wave.So than it is much more complex than single ball,double ball,four ball and other models in forces.The change law of drag coefficient first increases sharply to the peak value,and monotonically decreasing to a valley value,and then continues to increase to the second peak,then fluctuation decreases to appear a minimum value trough,finally shocked in the vicinity of zero and gradually stabilized.3?In the stage of Interaction between incident shock and element,the changing trend of drag coefficient is determined by the relative position of incident shock wave front and the ball in the unit,that is,when the shock front is in front of the ball to the equatorial position,the drag coefficient increased,the drag coefficient decreases when the shock front is at the equator to the posterior stagnation point.4 ? For unit A,the peak of the drag coefficient decreases with increasing void ratio(dimensionless spacing),and the larger the void ratio,the resistance coefficient tends to be stable after the interaction between the incident shock and the unit.5?For three units of A,B,C,the drag coefficient decreases with the increase of Mach number,the larger the Mach number,the resistance coefficient tends to be stable after the interaction between the incident shock and the unit.6?The influence of the front and back balls(perpendicular to the shock flow direction)on the flow field and shock wave structure in the model ball array is larger than that in the same row of adjacent balls.7?Under all operating conditions,the second wave crest of the change curve of resistance coefficient of the unit body is higher than the first wave crest,the main reason of this phenomenon is due to the secondary reflection of shock wave.