Rebound Height Research Articles

Experimental study of polyurethane rubber with half-sine waveform generator

Abstract Impact mechanics environmental testing technology is booming. Polyurethane rubber, as a typical semi-sinusoidal waveform generator, is particularly important to understand its stiffness performance. This paper presents an experimental investigation utilizing a pneumatic impact testing machine to evaluate the performance of polyurethane rubber waveform generators, varying in both hardness and height. By recording their compression under varying impact pressures, as well as the rebound height of the table and the corresponding velocity changes, we observed that the data generated by the 60mm thick waveform generator exhibited greater regularity. Notably, these data adhered to the principle that increased hardness correlates with decreased compression and reduced rebound height of the table. Additionally, we successfully designed an initial prototype of a rebound collision acceleration amplifier, which, under an impact pressure of merely 0.038MPa, achieved an impressive impact acceleration of nearly 2700g, accompanied by a smoother half-sine waveform curve.

Coalescence and Rebound Dynamics in Two Droplets Train Impacting on a Heterogeneous Wettability Surface.

Droplets that can be steered and rebound off surfaces are fundamentally interesting and important due to their promising potential in numerous applications, such as anti-icing and -fogging, spray coating, and self-cleaning. Heterogeneous wettability surfaces have been shown to be an effective means of droplet manipulation. This paper combines numerical simulation with theoretical analysis to investigate the dynamics of two droplets training impacting on and bouncing off a heterogeneous surface (superhydrophobic substrate decorated with a hydrophilic strip). First, the time evolutions of the droplet morphology and velocity vectors are examined to explore the particular dynamic behaviors. At different ratios of the impact velocity, three distinct rebound patterns are observed, and a regime diagram is established. After that, the effects of the impact conditions and surface wettability on the rebound performance of the coalesced droplet are studied systematically. Special attention is paid to the variations of the rebound height and the lateral transportation distance with the Weber number of two droplets and the distance between the impacting point and the hydrophilic stripe. Moreover, a theoretical analysis of two droplets' impact is performed based on the energy conservation. The obtained scaling laws match well with the numerical data in the trend. Our research may strengthen the understanding of the interactions between droplets, which is valuable for the manipulation of multiple droplets in related fields.

Investigation on dynamic characteristics of droplet impact on surfaces with different rough microstructures based on lattice Boltzmann method

Constructing microstructures on smooth surfaces is significant for 3D printing technology and surface self-cleaning effects in engineering applications. This paper uses the lattice Boltzmann method (LBM) to study the droplet impact behavior on different microstructured surfaces: right-triangle, semicircular, and rectangular microstructures. The formulas for calculating the surface wetting characteristics of different microstructures are derived theoretically, the difference between simulation results and those from theoretical analyses is less than 5 %. The increase of the microstructure column height h may eventually lead to the disappearance of the Wenzel mode. The droplet impact on the microstructured hydrophilic surface can accelerate the droplet to the stable stage and reduce the excessive impact effect. The droplet impacts on the superhydrophobic microstructured surface can accelerate the rebound separation and shorten the time to reach the stable stage. When droplets impact the superhydrophobic surface of the right-triangle microstructure, a secondary separation phenomenon will occur, resulting in the maximum rebound height and the maximum reduction of the near-wall density. The superhydrophobic right-triangle microstructured surface can more effectively promote self-cleaning.

The difference of dynamic elasticity characteristics and stroke effect between two types of new material seamed plastic table tennis ball

The diameter and weight of different brands of table tennis ball will affect the ball’s elasticity and stroke. The purpose of this study is to analyze the difference of the dynamic elasticity and stroke effect between the two brands of new plastic ball. A self-made experiment was designed to test the dynamic elasticity characteristics of DHS D40 + and Nittaku 40+. Table tennis players (N = 18) were randomly selected from the China Table Tennis College (Mage = 15.16 ± 2.41; Mheight = 1.59 ± 0.32 m; Mweight = 45.72 ± 5.17 kg). Each participant was righthand shake-hands grip. A speedometer was used to record the ball speed and a high-speed camera was used to measure the spin speed. Data normality was verified by using the Kolmogorov-Smirnov test. The independent t-test was conducted to assess the differences of the dynamic elasticity and stroke effect between the two types of plastic ball. Results showed that the rebound speed and decrement rate of DHS D40 + and Nittaku 40 + both increased with the increased falling speed, respectively. When falling at high speed, there was a significant difference of dynamic elasticity between DHS D40 + and Nittaku 40+ (p < 0.01). There was also a significant difference in the ball speed and spin speed between the two types of new material seamed plastic ball during the backhand backspin stroke (p = 0.041, p = 0.022, respectively), and the ball speed and spin speed of DHS D40 + were higher than that of Nittaku 40 + ball. Compared with the DHS D40+, the Nittaku 40 + has a faster rebound speed, higher rebound height, and better dynamic elasticity. Therefore, under same striking conditions, when hitting the Nittaku 40 + ball, players need to increase the swing distance and hit the ball with more strength to improve the ball speed and rotation speed; increase the spin and decrease the ball’s rebound height of the serve.

Tailoring Stress-Strain Curves of Flexible Snapping Mechanical Metamaterial for On-Demand Mechanical Responses via Data-Driven Inverse Design.

By incorporating soft materials into the architecture, flexible mechanical metamaterials enable promising applications, e.g., energy modulation, and shape morphing, with a well-controllable mechanical response, but suffer from spatial and temporal programmability towards higher-level mechanical intelligence. One feasible solution is to introduce snapping structures and then tune their responses by accurately tailoring the stress-strain curves. However, owing to the strongly coupled nonlinearity of structural deformation and material constitutive model, it is difficult to deduce their stress-strain curves using conventional ways. Here, a machine learning pipeline is trained with the finite element analysis data that considers those strongly coupled nonlinearities to accurately tailor the stress-strain curves of snapping metamaterialfor on-demand mechanical response with an accuracy of 97.41%, conforming well to experiment. Utilizing the established approach, the energy absorption efficiency of the snapping-metamaterial-based device can be tuned within the accessible range to realize different rebound heights of a falling ball, and soft actuators can be spatially and temporally programmed to achieve synchronous and sequential actuation with a single energy input. Purely relying on structure designs, the accurately tailored metamaterialsincrease the devices' tunability/programmability. Such an approach can potentially extend to similar nonlinear scenarios towardspredictable or intelligent mechanical responses.

Experimental study of the collision behavior between moving and sessile droplets on curved surfaces

In this study, we used pure water droplets to investigate the collision interactions of two droplets on curved surfaces. We captured the collision dynamics at different droplet impact velocities with the use of a high-speed camera. We observed three main modes during droplet collisions: deformation, coalescence, and rebound. We also plotted a collision regime map for different surfaces using the Weber number We and presented the critical We value for coalescence and rebound. With the increases of curvature radius, the critical We variates around 6.7 to 12.3 and presenting the tendency of increases first and then decreases. Furthermore, we quantitatively analyzed the transformation laws of droplet rebound height and compression value. Our main findings describe how the surface curvature radius influences droplet interactions, thus affecting the contact time, compression value and droplet deformation factor. The outcomes of droplet collisions on curved surfaces contribute to the development of technologies related to droplet manipulation and their applications in chemical and industrial processes.

A Novel Method to Characterize the Damping Capacity of EPDM/CIIR Blends Using Vibrating Rubber Balls.

An experimental device fixed with a laser displacement sensor was assembled to investigate the rebound behaviors and damping mechanism of rubber balls prepared with ethylene-propylene-diene monomer (EPDM)/chlorinated butyl rubber (CIIR) blends. The result showed that a prediction model was proposed to characterize the damping capacity by using the rebound height of the rubber balls. The lower rebound height corresponded to better damping capacity. A modified equation relating to the rebound height has been obtained from the theoretical derivation on the basis of the dynamic mechanical analysis, showing that the rebound height was affected by the deformation frequency, the external excitation, and the nature of rubber blends. Furthermore, the energy dissipation rate (EDR), defined by the ratio of the height loss to the rebound time, was proposed to further characterize the damping capacity. The EDR value was shown to be highest for the pure CIIR and lowest for the pure EPDM, exhibiting a decreasing trend with the increase in EPDM content in the rubber blends. It can be expected that the damping capacity of the EPDM/CIIR blends decreases with the decrease in external excitation, the conclusion of which plays a key role in the formulation design of viscoelastic damping rubber materials.

Force coefficient characterization in machining of UD-CFRP using numerical-analytical approach

A numerical-analytical approach was utilized to construct a predictive model of cutting force for machining unidirectional carbon fiber reinforced polymer (UD-CFRP) laminates. The force coefficients in the model, which include friction angle, shear plane angle, shear strength, and rebound height, can be characterized by the fiber orientations ranging from 0° to 180°. The accuracy of the model was confirmed through experimental verification. The results indicate good agreement between the predicted and experimental values, with relative errors below 14.8%, except for the thrust force at 90°. Additionally, the study examined the influence of rake angle and flank angle on the cutting force, revealing two critical points in the predicted cutting force curve throughout the fiber orientation. These turning points shifted with changes in the rake angle. For instance, the value of the first critical point changes from 60° to 45° when the rake angle range shifts from [0°, 5°] to [10°, 15°]. This indicates that a larger rake angle facilitated an earlier transformation of chip formation mode, leading to a decrease in cutting force. Furthermore, the cutting force decreased as the rake angle increased between the two turning points. The impact of the flank angle on the cutting force was determined to be minimal, and the turning points’ positions remained consistent as the flank angle increased.

Spreading dynamics of a droplet upon impact with a liquid film containing solid particles.

This study examines how a deionized water droplet behaves when it centrally collides with a liquid film containing TiO2 nanoparticles at low impact velocities, aiming to understand how nanoparticles affect droplet spreading, in particular its maximum spreading diameter. Typically, we found that both the spreading velocity and dynamic contact angle of the droplet would be similarly affected by increasing TiO2 nanoparticle concentration. During retraction, the droplet's dimensionless spreading diameter oscillates, with more pronounced oscillations at higher nanoparticle concentrations. Moreover, both the droplet's maximum dimensionless rebound height and dynamic contact angle show similar trends with increasing TiO2 nanoparticle concentration. Interestingly, we proved that the influence of the solid-liquid interaction (Stokes force) on the fluid during the spreading process accounts for less than 2% of the surface energy when the droplet reaches its maximum spreading diameter, indicating a negligible effect on droplet spreading. We hypothesize that the droplet's initial energy is fully converted into surface energy and viscous dissipation at maximum spreading diameter, which involves viscous dissipation both between the fluid and the solid wall surface and the fluid and solid particle surface. Based on this, we developed a model for predicting the droplet's maximum spreading diameter that includes parameters associated with the solid particles. Compared to models in the literature that do not consider the effect of solid particles, our model aligns more closely with experimental data. The results indicate that adding solid particles leads to increased viscous dissipation, which in turn reduces the droplet's maximum spreading diameter.

ANALYSIS OF THE DYNAMICS AND FREEZING OF WATER DROPLETS ON METAL SURFACES

This article investigates the effects of substrate temperature, tilt angle, and droplet size on droplet impact dynamics and freezing using a Motionpro high-speed camera and a DSA-30 droplet surface analyzer. The temperature of the substrate was changed from the ambient temperature of 21&amp;deg;C to -13&amp;deg;C, and three droplet sizes (&lt;i&gt;D&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt; &amp;#61; 2.57, 3.02, and 3.54 mm) were studied. The results show that some air gets trapped under the liquid film during the impact process due to insufficient escape time, resulting in the interior of the droplet being in an unstable state. Simultaneously, due to the low surface energy of the substrate, liquid droplets exhibit a rebound effect upon impact with the ambient temperature substrate, reaching their maximum height and forming a dumbbell-like shape. Furthermore, the rebound height decreases rapidly with the decrease in substrate temperature. A change in substrate temperature had no significant effect on the droplet spreading process, but decreasing substrate temperature increased the viscous forces, thereby suppressing the droplet retraction and oscillation processes, ultimately leading to longer droplet freezing times. Additionally, at low Weber numbers (&lt;i&gt;We &lt;/i&gt;&amp;#60; 250), the droplet dimensionless parameters exhibited a similar trend with respect to dimensionless time or temperature.

Three-dimensional numerical study of two drops impacting on a heated solid surface by smoothed particle hydrodynamics

This paper presents a numerical study of a pair of water drops simultaneously and non-simultaneously impacting on a heated surface using smoothed particle hydrodynamics (SPH). The present SPH method is validated qualitatively and quantitively with available experiment results for the impact of single, simultaneous, and non-simultaneous drops on the solid surface. Numerical simulations are performed at the Weber number in the range of 20–117, surface temperature in the range of 25–250 °C, and pressure in the range of 1–20 bar. In the simulations, the coalescence, breakup, and evaporation of the drops are considered. After the collision of the two drops, the hydrodynamic behavior of the uprising sheet height and spreading areas are investigated by considering the horizontal and vertical distances between the two drops, Weber number, surface temperature, and elevated pressure. The numerical results indicate that the Weber number and horizontal distance significantly influence the height of the rising sheet and the spreading area. Conversely, the vertical spacing does not affect the rising sheet height or spreading area. The drop rebound height increases with the wall temperature in the film boiling regime for high boiling point liquids at atmospheric pressure. The effect of ambient pressure on drop rebound height is investigated for simultaneous and non-simultaneous impacts. According to the numerical results, the pressure increase causes a decrease in droplet rebound height.

Investigation of high-energy impact system using a physical model

The aim of the experimental research is to validate the theoretical findings obtained from a mathematical model of a two-mass impact system. The research object is a physical model of a two-mass impact system, designed to prevent the transfer of the reactive component to the tool carrier. The model includes a housing, inertial mass, elastic member and impact part. In the operating position, a compressed elastic member is placed between the inertial mass and the impact part, held together by dogs. The height at which the impact part detaches from the inertial mass is determined by the position of the clamp, which separates the moving impact part and inertial mass during free fall. The study involved the fundamental principles of similarity theory, planning theory and data processing. The height at which the impact part detaches from the inertial mass and the impact part is taken as an independent factor, while the energy of a single impact serves as the response function, determined by the diameter of the cone impression delivered by the impact part onto a wooden base. Based on the analysis of physical laws, similarity criteria for the impact mechanism were established, along with dependent and independent indicators, and transfer equations from real parameters to model parameters were derived. The research findings indicate that the total area of air holes should be at least half of the cross-sectional area of the housing for a physical model. The relationship between the diameter of the cone impression on the wooden base and the impact energy was determined. The adequacy of the mathematical model describing the processes in the impact device was confirmed, with a maximum discrepancy of 18% between the results of mathematical and physical modelling of the operating process for the impact mechanism characterised by an increased energy of a single impact. Therefore, the research results validate the results obtained from the mathematical model of the impact mechanism. Further studies should focus on refining the physical model to record the rebound height of the inertial mass as a function of the parameters of the impact mechanism.

Effects of surface temperature and Weber number on the dynamic and freezing behavior of impacting water droplets on a superhydrophobic ultra-cold surface

The dynamic and freezing behavior of a water droplet impacting a superhydrophobic cold surface is worthy of investigation. In this study, experiments are conducted to examine the impact and freezing of a water droplet on a cold superhydrophobic surface whose temperature changes in a wide range between −10 °C and −60 °C. A numerical model that introduces a continuous energy balance equation is developed to investigate the process numerically. The effects of surface temperature, Weber number, and initial droplet temperature on the droplet morphology, spread factor, contact time, and rebound height are investigated. The droplet exhibits three different behaviors as the surface temperature decreases: full rebound, partial rebound, and full adhesion. For the full rebound case, the results indicate that the growth rate of the contact time with decreasing surface temperature increases as the Weber number decreases. For the full adhesion case, the variation in the surface temperature minimally affects the dynamic behavior of the droplet impacting on an ultracold superhydrophobic surface (below −40 °C). The effect of surface temperature on the maximum spread factor is more pronounced at higher Weber numbers. Additionally, the ice nucleation rate is analyzed theoretically. The results show that the nucleation rate of droplets impacting an ultracold surface remains almost constant regardless of the surface temperature and surface roughness. Moreover, a regime map showing the different droplet morphologies correlating with the surface temperature and Weber number is established. The critical surface temperatures for different droplet morphologies of supercooled and room-temperature droplets are analyzed. This study allows us to better understand the dynamic and heat transfer mechanisms involved in the impact and freezing of a water droplet on a superhydrophobic surface.

C/C soft-hard mixed preform multi-units compression compaction viscoelastic rebound technique and optimization

To address the issue of non-uniform fiber volume fraction between layers in the compression compaction process of C/C soft-hard mixed preforms, a multi-unit variable duration cyclic compression compaction process based on the inter-laminar fiber compression viscoelastic deformation behavior is proposed. This process aims to gradually eliminate the rebound characteristics of inter-laminar fibers and reduce the error of inter-laminar fiber volume fraction. The mapping relationships between the number of units, holding duration, and compaction times with the rebound height of inter-laminar fibers are established using data fitting. The compression compaction process is determined using the Box Behnken response surface design method, and digital devices are utilized for preform compaction experiments. The micro-morphology of the preform is observed using an optical microscope, and the density of inter-laminar fibers before and after process optimization is compared. Experimental results indicate that when the number of units is 3, the holding duration is 57 s, and the compaction times is 2, the fiber volume fraction of the soft-hard mixed preform is 42.90%, which is 12.16% higher than before process optimization, and the error of inter-laminar fiber volume fraction is less than 6.5%.

Assessment of impact resistance recovery in Ultra High-Performance Concrete through stimulated autogenous self-healing in various healing environments

Ultra High-Performance Concrete (UHPC) is widely acknowledged for its remarkable mechanical properties, owing to its compact microstructure. The response of UHPC to impact forces plays a vital role in ensuring the safety and longevity of structures, specifically in protective buildings, high-performance pavements and offshore concrete structures. In this context, this paper reports on an experimental investigation aimed at assessing the effects of stimulated autogenous self-healing of UHPC on the recovery of its performance under impact loadings. Drop weight tests were performed on UHPC slabs, with a 10 kg heavy impactor dropped from the height of 1 m on the centre of the specimens. Specimens were pre-cracked by repeated impacts up to 40% of their predetermined capacity. Pre-cracked specimens were exposed to different healing conditions, water submersion, 95% ± 5% RH, and wet/dry cycling (12/12 h) either in water or in a NaCl solution. Self-healing was evaluated through rebound height, elastic stiffness recovery, natural frequency, and laser displacement measurements. High-speed cameras and Digital Image Correlation were used to capture rebound height and crack formation. Performance was assessed at time 0, pre-damaging, 1, 2, and 4 months. After the healing period, all specimens were tested to failure. Specimens exhibited an increasing healing efficiency when moving from 95% ± 5% RH, over wet/dry cycling, to submerged conditions. Specimens healed continuously under submerged conditions exhibited a complete closure of surface cracks (50–150 μm) and an 80% recovery in natural frequency. Furthermore, they showed a more than 10% increase in stiffness and energy dissipation capacity after four months of healing.

A modified dynamic contact angle model applied to double droplet impact curved surface

The microscopic processes involving droplet impact and interaction on spatially curved surfaces remain unclear. In this study, we implement a dynamic contact angle model with adjusted upper and lower limits into a simulation of droplet motion, constructing a three-dimensional numerical model to depict the dynamics and heat transfer characteristics of symmetric double droplets impacting plane, concave, and convex cylindrical, and concave and convex spherical surfaces. The processes of droplet spreading, retraction, rebound, splitting, and heat transfer are elaborated, revealing the role of surface curvature during impact. Our results show that different curvatures significantly affect the flow morphology of the flow dividing line. For the two main curvatures of the surface, the curvature in the direction of droplet arrangement predominates. Positive curvature promotes spreading and repels the liquid phase, while negative curvature promotes agglomeration and attracts the liquid phase. Extreme situations arise when both positive and negative curvatures occur simultaneously. Regarding heat transfer, the overall heat transfer rate is mainly determined by the spread area, and the heat transfer performance of convex surfaces is better than that of plane or concave surfaces. Residual bubbles increase heat transfer inhomogeneity, but different surfaces do not show significant variability. Additionally, the heat flow intensity in the central interaction region has the following relationship with its rebound height and is independent of the overall heat transfer intensity.

Performance of stringer sheet parts under static and dynamic load

The stringer sheet forming process chain enables the cost-effective production of components with significantly increased stiffness for mass markets such as the automotive sector. In the first process step, a stringer is added to a conventional sheet by laser welding. In the subsequent process step, the stringer sheet parts are formed by a deep drawing operation. Previous investigations of component performance focused in particular on the static stiffness of the stringer sheets. The behavior under dynamic load, such as in crash events, has not been systematically investigated to date. Static testing focused on the stringer height as the only influence on part performance. This study characterizes the crash performance of stringer sheet components by means of a drop hammer test. The energy absorption of the components is evaluated in the experiment based on the rebound height of the drop hammer, whereas the structural integrity is characterized based on the maximum dynamic as well as permanent deformation. Furthermore, a quasi-static compression test is carried out to obtain the static stiffness of the parts. In these tests, the geometric design of the stringer sheets as well as two forming process parameters are varied individually. The influence of these parameters on the static stiffness, energy absorption and structural integrity is assessed and discussed on their own and with regard to their influence on the part weight.

The rebound height of a capsule-shaped object

The bouncing process of an irregular object falling on the ground contains many interesting mechanical problems. The article investigated the bounce height of a capsule-shaped object when it falls on the ground. The variation of three physical quantities, namely the angle of the object, the linear velocity of the center of mass and the angular velocity relative to the center of mass when it fell on the ground are studied. According to the limit condition of friction, the three-dimensional phase diagram of the above three physical quantities was drawn when the fall height of the capsule-shaped object and the bounce height was equal. The movement of the capsule-shaped object is captured by using two cameras positioned perpendicular to each other. The trajectory was tracked by TRACKER software to obtain the fall height and bounce height of the capsule. When the bounce height was higher than the fall height, it was marked with a red dot. If both heights were equal, it was marked with a black dot. Otherwise, it was marked with a blue dot. Different types of experimental data points are plotted in the phase diagram. A large amount of random experimental data verifies the correctness of the theory.

Superhydrophobic Epoxy/Fluorosilicone/PTFE Coatings Prepared by One-Step Spraying for Enhanced Anti-Icing Performance

The icing of glass insulators is likely to cause faults such as insulator flashover, which poses a serious threat to the power system. Traditional deicing techniques have the disadvantage of being costly and inefficient. Herein, polytetrafluoroethylenes (PTFEs) as nanoparticles and epoxy and fluorosilicone resins as binders were blended to construct an anti-icing coating. The superhydrophobic (SHP) epoxy/fluorosilicone/PTFE coatings for anti-icing were successfully prepared on glass slides through one-step spraying. The effect of PTFE mass fraction on the microstructure, on the wettability and on the anti-icing properties of the coatings was investigated. The results showed that the coatings with different PTFE mass fractions had different microstructures. When the PTFE mass fraction was 47.2%, the SHP coating exhibited a uniform rough structure with an apparent contact angle as high as 164.7° and a sliding angle as low as 3.2°. Moreover, the water droplets can bounce back five times with a contact time of only 9.5 ms and a rebound height of 4.58 mm. In the low-temperature environment (−10 °C), the SHP coating displayed good anti-frosting, anti-icing and icephobic properties. The delayed frosting time (1499 s) and delayed freezing time (1295.3 s) of the SHP coating were three and five times longer than those of the glass, respectively. The SHP coating presented an ice-adhesion strength (39.8 kPa) that was six times lower than that of glass. The prepared SHP coating demonstrated potential applications for the anti-icing of glass insulators.

Comparative investigation on macroscopic and microscopic characteristics of impingement spray of gasoline and ethanol from a GDI injector under injection pressure up to 50 MPa

Particulate Matter (PM) emissions from passenger vehicles have attracted considerable interest over the last decade. In order to reduce PM emissions, improving maximum injection pressure has been a developing trend for new generation GDI engines. However, comparing gasoline and ethanol impingement spray characteristics from a GDI injector under high injection pressure is still unclear. In this paper, a comparative investigation on both the macroscopic and microscopic characteristics of impingement spray from a GDI injector fuelled with gasoline and ethanol was performed under injection pressure up to 50 MPa, providing new findings to promote a more homogeneous air–fuel mixture and reduce PM emissions. The experimental results show that under the same PI (injection pressure), rebound height of gasoline impingement spray is a bit higher than ethanol. AS (spray area) of gasoline is slightly higher than ethanol under PI=10MPa. However, under PI=30MPa and PI=50MPa, AS of gasoline is gradually exceeded by that of ethanol as time progresses. By increasing PI to 50 MPa, the difference in DN (diffusion distance of the near side) between gasoline and ethanol is greatly reduced, meantime DF (diffusion distance of the far side) becomes weaker than ethanol. For both gasoline and ethanol, with the increase PI from 10 MPa to 50 MPa, VN (average normal component of droplet velocity) and VT (average tangential component of droplet velocity) of incident droplets increase by around 1 m/s. Meantime, there is a slight decrease in the absolute value of VN and VT of reflected droplets. DSMD (Sauter mean diameter of droplets) presents a significant decreasing trend with the increase of PI. Besides, a smaller DSMD can be seen for the gasoline impingement spray compared to ethanol under the same PI.