Shock Wave Mitigation Research Articles

Investigation on shock wave mitigation performance of modified polyurea coated helmet

In recent years, traumatic brain injury caused by explosive blast has become the leading cause of death in current military conflicts. However, as for the existing battlefield protection equipment, most of them focus on how to protect against infered injury caused by high-speed shrapnel. Accordingly, there is a lack of systematic research based on shock wave protection. In this work, a new modified polyurea is designed by adding SiO2 nanoparticles filler firstly. The effects of different proportions of SiO2 nanoparticles on the thermodynamic, quasi-static and dynamic mechanical properties of matrix are investigated. Further, a test method of material shock wave protection is proposed, which eliminates the influence of boundary and diffraction coupling in the test of protective materials. The protection property of the material under shock wave is tested by the shock tube. Based on the above test results, the full-size shock wave protection test model of human head is developed, and the measurement of overpressure and acceleration peak of several key positions of head is realized. Finally, a new type of shock wave protection helmet is developed, which realizes efficient protection against shock wave. Under quasi-static loading conditions, the yield stress of PU-SiO2 decreases gradually with the increase of the content of SiO2 nanoparticles. Under high strain rate conditions, the strain hardening characteristic of PU-SiO2 increases gradually with the increase of SiO2 content. In the shock mitigation experiment, the peak overpressure and peak acceleration of shock wave decrease by 32.60 % and 50.90 %, respectively. The peak overpressure decreases again by 11.20 % when the protective material is PU-SiO2, indicating that the SiO2 particles can improve the shock mitigation of PU. In the brain protection experiment, the changes in peak overpressure and peak acceleration at the three monitoring sites of the prefrontal lobe, posterior skull, and head reflect the degree of protection of the new material against shock wave.

Shock wave mitigation and impact resistance response of kevlar fabric with novel shear-stiffening gel core

A novel shear thickening gel with micro-scale hard/soft interface structure and low reaction temperature was proposed in this article. The gel was named TH and used as core material within Kevlar fabrics. Storage modulus of TH was proved to increase by around two orders with increasing of shear frequency, and dynamic properties indicated that TH could dissipate or store more energy. TH can adhere with Kevlar fabrics well and satisfactorily fulfill the gap between fabrics. As a result, shock wave peak pressure and positive impulse decreased markedly. Wavelet decomposition analysis show that high frequency energy was filtered by protection materials. Meanwhile, impact resistance test suggested the existence of TH changed the stress propagation routes and avoided pulling out for Kevlar fabrics. Samples filled with TH demonstrated a better shock wave mitigation ability and impact resistance. Energy dissipation structures with TH have a promising prospect in the application of defending area.

Microcosmic mechanism of metal–organic framework enhanced thermoplastic polyurethane exposed to laser-induced shock wave

Incorporating nano-particles into polymer matrix has enabled improving shock wave mitigation (SWM) ability. Vast majority of researchers adopted inorganic nano-materials to enhance polymer matrix. Due to the incompatibility between inorganic nano-particles and polymers, complicated interface modification processes were often used. Metal–organic frameworks (MOFs) have good compatibility with polymers and show excellent SWM capabilities. However, they are brittle and experience lattice collapse after shock loading. Based on this, thermoplastic polyurethane (TPU) enhanced by zeolitic imidazolate framework-8 (ZIF-8) was proposed and prepared. The mixtures can not only improve the SWM ability of polymers, but also address the brittleness of MOFs. Additionally, scholars often use simulation methods to study energy dissipation mechanism of materials, rarely evidences of microstructural changes observed to support theoretical speculations. In this work, by analyzing surface morphology and molecular structural changes, energy dissipative mechanism was investigated. With addition amount of 5 wt% and 10 wt% ZIF-8 particles in TPU, the pressure can be reduced by 0.074 GPa and 0.1478 GPa than neat TPU. TPUM-10 had a stronger deformation resistance and SWM ability. Moreover, main chemical structures were remained unchanged after shock. The increased ability of SWM may relate to hydrogen bond forming process and delayed material failure.

Experimental investigation on weak shock wave mitigation characteristics of flexible polyurethane foam and polyurea

In recent years, explosion shock wave has been considered as a signature injury of the current military conflicts. Although strong shock wave is lethal to the human body, weak shock wave can cause many more lasting consequences. To investigate the protection ability and characteristics of flexible materials and structures under weak shock wave loading, the blast wave produced by TNT explosive is loaded on the polyurethane foam with the density of 200.0 kg/m3 (F-200) and 400.0 kg/m3 (F-400), polyurea with the density of 1100.0 kg/m3 (P-1100) and structures composed of the two materials, which are intended for individual protection. Experimental results indicate that the shock wave is attenuated to weak pressure disturbance after interacting with the flexible materials which are not damaged. The shock wave protective capability of single-layer materials is dependent on their thickness, density and microscopic characteristics. The overpressure, maximum pressure rise rate and impulse of transmitted wave decrease exponentially with increase in sample thickness. For the same thickness, F-400 provides better protective capability than F-200 while P-1100 shows the best protective capability among the three materials. In this study, as the materials are not destroyed, F-200 with a thickness more than 10.0 mm, F-400 with a thickness more than 4.0 mm, and P-1100 with a thickness more than 1.0 mm can attenuate the overpressure amplitude more than 90.0%. Further, multi-layer flexible composites are designed. Different layer layouts of designed structures and layer thickness of the single-layer materials can affect the protective performance. Within the research range, the structure in which polyurea is placed on the impact side shows the optimal shock wave protective performance, and the thicknesses of polyurea and polyurethane foam are 1.0 mm and 4.0 mm respectively. The overpressure attenuation rate reached maximum value of 93.3% and impulse attenuation capacity of this structure are better than those of single-layer polyurea and polyurethane foam with higher areal density.

Experimental and Numerical Study on Perforated Plate Mitigation Capacity to Near-Field Blasts.

Based on the analysis of existing collective shockwave protection methods worldwide, this paper addresses the mitigation of shock waves by means of passive methods, namely the use of perforated plates. Employing specialized software for numerical analysis, such as ANSYS-AUTODYN 2022R1®, the interaction of shock waves with a protection structure has been studied. By using this cost-free approach, several configurations with different opening ratios were investigated, pointing out the peculiarities of the real phenomenon. The FEM-based numerical model was calibrated by employing live explosive tests. The experimental assessments were performed for two configurations, with and without a perforated plate. The numerical results were expressed in terms of force acting on an armor plate placed behind a perforated plate at a relevant distance for ballistic protection in engineering applications. By investigating the force/impulse acting on a witness plate instead of the pressure measured at a single point, a realistic scenario can be considered. For the total impulse attenuation factor, the numerical results suggest a power law dependence, with the opening ratio as a variable.

Transparent Films Thickness Mapping Highlighting the Viscosity Effect of Elastic Layers Made by Sol–Gel Process with an In-House Ellipsometer

New optical coatings are currently developed to mitigate the shockwave generated by nanosecond lasers in high-power laser systems such as the MegaJoule laser (LMJ). These shockwaves seem responsible for the damage growth observed on optical components. A possible solution for shockwave mitigation is using ormosil (organically modified silicate) coatings made by the sol–gel method with thicknesses of a few microns. Unfortunately, the sol–gel solution exhibits a viscous behavior, and thus, the deposited layers are heterogeneous in thickness. An experimental ellipsometer has been designed to measure this heterogeneity and highlight the viscoelastic properties of the layers responsible for self-healing effects that were observed when these layers were scratched. This ellipsometer allows us to know the refractive index of the coating and therefore its density. Density and thickness are the two essential parameters for determining the speed of sound and the modulus of elasticity of the layer, which indicate the ability of the layer to attenuate more or less elastic waves or shock waves.

Investigate of shock wave mitigation performance of nano‐carbon fillers modified epoxy composites

AbstractPolymer composites are considered to be the most effective materials in mitigating shock waves. Efforts are made in this work to improve shock wave mitigation performance of polymer composites. Epoxy resin (EP) with nano‐carbon fillers, including fullerene (FL), graphene (GP), and multi‐walled carbon nanotubes (CNT) were prepared through solution casting method. A variety of testing methods, including transmission electron microscope (TEM), X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), shock tube test, have been introduced to investigate the reaction process, dynamic mechanical properties and shock wave mitigation performance of epoxy composites. The results shown that different nano‐carbon fillers lead to differences of spatial and reactivity in EP matrix. The addition of nano‐carbon materials is conducive to improve the shock wave mitigation ability of EP. EP with GP fillers show the best enhancement for the shock wave mitigation in shock tube test. With same addition amount of nano‐carbon fillers, shock wave peak pressure of EP with FL fillers (EP‐FL), EP with CNT fillers (EP‐CNT), and EP with GP fillers (EP‐GP) decreased by 16.5%, 29.6%, and 31.7% in comparison with EP, respectively.

Deformation dynamics of h-BN reinforced polyethylene nanocomposite under shock/impact loading

The aim of this article was to reveal the dynamic and structural response of hexagonal boron nitride (h-BN) reinforced polyethylene (PE) nanocomposites under shock/impact loading. Micro and nano scale deformation dynamics of h-BN reinforced PE nanocomposites were captured using experimental and atomistic-based combined approaches. The experimental approach was adopted to investigate the effect of fabrication techniques and the concentration of boron nitride nanoplatelets (BNNP) on the impact behavior of PE-based nanocomposites. The impact strength of nanocomposites was studied with the help of differential scanning calorimetry in conjunction with the plastic deformation governing mechanism captured using the micrographs of scanning electron microscopy (SEM). It was reported from the experiments that the crystallinity of BNNP/PE nanocomposites is significantly affected by the fabrication technique. The BNNP/PE nanocomposites fabricated with the solvent blending method show superior impact strength as compared to samples fabricated using the colloidal solution method at the same BNNP weight concentration of 5%. It was also revealed from the SEM observations that the addition of BNNP to the PE matrix shifts the plastic deformation mechanism from a combination of craze and drawing of fibrils in pure PE to brittle failure in BNNP/PE nanocomposites. To complement the experimental observations, molecular dynamics-based simulations were performed to study the effect of orientation and distribution of boron nitride nanosheets (BNNS) on shock mitigation capabilities of BNNS/PE nanocomposite. It was predicted from MD simulations that a parallel oriented nanosheet remains longer in contact with the shock, which helps in dissipating energy from the shock wave. As compared to stacked, dispersed nanosheets have superior shock attenuation capabilities. These findings could be helpful to design a roadmap for shock wave mitigation through impedance mismatch and energy disruption across the multiple interfaces of BNNS and polymer matrix.

A Prospective Way to Achieve Ballistic Impact Resistance of Lightweight Magnesium Alloys

The ballistic impact resistance of lightweight magnesium alloys is an eye-catching material for the military and aerospace industries, which can decrease the cost of a project and the fuel consumption. The shockwave mitigation ability of a magnesium alloy is 100 times stronger than an aluminum alloy; nonetheless, ballistic impact resistance has still not been achieved against blunt and API projectiles. The major obstacles are the low hardness, low mechanical strength, basal texture and strain hardening ability under loading along the normal direction of the sheet. The high yield strength and ultimate strength can be achieved for a specific loading condition (tensile or compression) by adjusting the texture in magnesium alloys. The projectile impact along the normal direction in a strong basal-textured magnesium alloy can only produce a slip-induced deformation or minor twinning activity. Here, we propose a practical technique that can be valuable for altering the texture from c-axes//ND to c-axes//ED or TD, and can produce high strain hardening and high strength through a twinning and de-twinning activity. Subsequently, it can improve the ballistic impact resistance of magnesium alloys. The effect of the technique on the evolution of the microstructure and possible anticipated deformation mechanisms after ballistic impact is proposed and discussed.

Improvement of Accuracy of Temperature Measurement Method around Discharge Field Based on Shock Wave Velocity

The shock wave mitigation technique by using the electromagnetic energy is one of the promising methods. The baroclinic effect has the important role in this method. This effect has the possibility to apply to the generation the vortex phenomena in the compressible flow field. Therefore, the comprehension of the effect is inevitable for exploring the further vortex control- ing application in the supersonic flow field. Until now, the temperature distribution measurement has been conducted in order to the comprehension of the baroclinic effect by the interaction between the shock wave and the temperature modulated field due to the electric discharge energy, based on the shock wave velocity. However, the conventional method depends on the Mach number at the down stream region of the discharged field. This Mach number has a large impact on the temperature determination.Based on this background, in this study, we tried to improve the temperature determination method. As a result, the determination accuracy improved.

Air Plasma Mitigation of Shock Wave

Theory is presented to show that shock wave structure can be modified via interacting with an air plasma plume generated symmetrically in front of a shock wave generator. Electron jet in the plasma plume deflects the impinging airflow via momentum transfer collisions. Symmetrical deflection makes it easy to satisfy the conservation of transverse momentum between the airflow and plasma. The charge transfer between N2+ and N2 randomizes the impinging airflow to increase the deflection angle. The flow deflection increases the effective cone angle of the shock generator; as the effective cone angle exceeds a critical value, the shock becomes detached and faded.  Experiments were conducted in a Mach 2.5 wind tunnel to mitigate shock wave via air plasma deflection. A non-thermal air plasma was symmetrically generated, in front of a wind tunnel model by on-board 60 Hz periodic electric arc discharge, as a deflector for shock wave mitigation. The results show a transformation of the shock from a well-defined attached shock into a highly curved shock structure, which has increased shock angle and appears in diffused form. Shown in a sequence with increasing discharge intensity, the transformed curve shock in front of the model moves upstream to become detached with increasing standoff distance from the model and is eliminated when the discharge is near the peak. The steady of the incoming flow during the discharge cycle is manifested by the repetition of the baseline shock front. The experimental observations confirm the theory and efficacy of this air plasma mitigator.

Study on control of hypersonic aerodynamic force by quasi-DC discharge plasma energy deposition

This paper reports an active method for aerodynamic force control of a hypersonic spacecraft via shock wave mitigation with plasma energy deposition. The energy deposition was generated by quasi-direct current discharge at two positions in the streamwise direction on a flat plate upstream a compression surface. Wind tunnel experiments of visualizing a Mach 6 flow over a ramp with high-speed schlieren imaging were performed to verify the method's effect on diluting a shock wave. Meanwhile, the Reynolds averaged Navier-Stokes equations, with a source term of simulating plasma heating due to discharge, were solved to evaluate the method's control abilities. From the experimental results, low-density plasma layers can be formed by quasi-DC discharge, which were continuously weakening the shock wave induced by the ramp. The numerical results predicted flow topology under control well with the experimental schlieren images, with the corresponding force reduction rate as high as 58%, which mainly depends on the amount of energy injection, instead of arrangement of heating zones in this study.

Investigation on shear layer instabilities and generation of vortices during shock wave and boundary layer interaction

The interaction of a reflected shock with the boundary layer inside the shock tubes is an important engineering problem. Studies related to shock wave mitigation and attenuation are performed inside the shock tubes. A proper understanding of the flow behind the reflected shock and the separated zone involving multiple vortical structures is highly essential for estimating the effectiveness of the shock wave mitigation/ attenuation. Such complex flows consist of Lambda shock, shear layer originating from the triple point, multiple shocklets, Mach stems, and vortices. Experimentally the shock structures are obtained through optical techniques. The vortices present in the compressible flow can be obtained through numerical simulations. The complex flows consisting of the above- mentioned features have been simulated numerically so far for the Reynolds numbers up to 1000 [ Zhou G, Xu K, Liu F. Grid-converged solution and analysis of the unsteady viscous flow in a two-dimensional shock tube. Phys Fluids 2018;30(016102):1-21.]. In the present investigation, the shock-wave boundary-layer interaction is simulated for the Reynolds numbers of 1000 and 2500 using a 13th order hybrid scheme to discern the distinct flow features. First, the solver [Kundu A, De S. Navier-Stokes simulation of shock-heavy bubble interaction: Comparison of upwind and WENO schemes. Comput Fluids 2017;157:131-145.] was validated with the benchmark wall density data for a Reynolds number of 1000. Next, the simulations were performed using 50 and 109.5 million cells for the Reynolds number of 2500. The density gradients, vorticity, wall density, and Fourier spectra were used for comparing the flow field for the Reynolds numbers of interest. The Lambda shock, Kelvin-Helmholtz (K-H) vortices in the shear layer, shocklets, the height of lambda shock, and Mach stems were obtained using a grid-mesh of 109.5 million cells. It is observed that the number of vortices generated inside the separated flow region increased with the increase in Reynolds number from 1000 to 2500. Furthermore, the triple point height and the number of K-H vortices generated at the shear layer also increase with an increase in Reynolds number. The present simulations revealed the formation of vortices close to the wall at a Reynolds number of 2500. Such flow structures have an important role in shock / blast wave mitigation and the associated aeroacoustics.

Directional shock diode behavior through the interaction of geometric voids in engineered polymer assemblies

With the advent of additive manufacturing (AM) techniques, a new class of shockwave mitigation and structural supports has been realized through the hierarchical assembly of polymer materials. To date, there have been a limited number of studies investigating the role of structure on shockwave localization and whether AM offers a means to tailor shockwave behavior. Of particular interest is whether the mesoscopic structure can be tailored to achieve shockwave properties in one direction of impact vs the other. Here, we illustrate directional response in engineered polymer foams. In situ time-resolved x-ray phase contrast imaging at the Advanced Photon Source was used to characterize these diode-like structures. This work offers a breakthrough in materials technology for the development of protective structures that require augmentation of shock in one direction while diminishing transmission in the opposite direction.

Shock wave mitigation using zig-zag structures and cylindrical obstructions

The present study focuses on the mitigation of shock wave using novel geometric passages in the flow field. The strategy is to produce multiple shock reflections and diffractions in the passage with minimum flow obstruction, which in turn is expected to reduce the shock wave strength at the target location. In the present study the interaction of a plane shock front (generated from a shock tube) with various geometric designs such as, 1) zig-zag geometric passage, 2) staggered cylindrical obstructions and 3) zig-zag passage with cylindrical obstructions have been investigated using computational technique. It is seen from the numerical simulation that, among the various designs, the maximum shock attenuation is produced by the zig-zag passage with cylindrical obstructions which is then followed by zig-zag passage and staggered cylindrical obstructions. A comprehensive investigation on the shock wave reflection and diffraction phenomena happening in the proposed complex passages have also been carried out. In the new zig-zag design, the initial shock wave undergoes shock wave reflection and diffraction process which swaps alternatively as the shock front moves from one turn to the other turn. This cyclic shock reflection and diffraction process helps in diffusing the shock wave energy with practically no obstruction to the flow field. It is found that by combining the shock attenuation ability of zig-zag passage (using shock reflection and diffraction) with the shock attenuation ability of cylindrical blocks (by flow obstruction), a drastic attenuation in shock strength can be achieved with moderate level of flow blocking.

Experimental and numerical study of the blast wave decrease using sandwich panel by granular materials core

Among the intrinsic properties of some materials, e.g., foams, porous materials, and granular materials, are their ability to mitigate shock waves. This paper investigated shock wave mitigation by a sandwich panel with a granular core. Numerical simulations and experimental tests were performed using Autodyn hydro-code software and a shock tube, respectively. The smoothed particle hydrodynamics (SPH) method was used to model granular materials. Sawdust and pumice, whose properties were determined by several compression tests, were used as granular materials in the sandwich panel core. These granular materials possess many mechanisms, including compacting (e.g., sawdust) and crushing (e.g., pumice) that mitigate shock/blast wave. The results indicated the ineffectiveness of using a core with low thickness, yet it was demonstrated to be effective with high thickness. Low-thickness pumice yielded better results for wave mitigation. The use of these materials with a core with appropriate core reduces up to 88% of the shock wave. The results of the experiments and numerical simulations were compared, suggesting a good agreement between the two. This indicates the accuracy of simulation and the ability of the SPH method to modeling granular material under shock loading. The effects of grain size and the coefficient of friction between grains have also been investigated using simulation, implying that increasing the grain size and coefficient of friction between grains both reduce overpressure.

Mechanochemistry of Metal-Organic Frameworks under Pressure and Shock.

ConspectusMetal-organic framework solids (MOFs) are synthetic nanoporous materials that have drawn intense efforts in synthesis and characterization of chemical properties, most notably for their ability to adsorb liquids and gases. They are constructed as "node-spacer" nanostructured materials: metal centers (ions or clusters) connected by organic linkers (commonly containing carboxylate or imidazolate groups) to form crystalline, extended, often highly nanoporous structures. MOFs exhibit a variety of advantages over conventional porous materials: rationally designed synthesis of desired crystal structures and crystal engineering become feasible; great synthetic versatility and ease of incorporating different chemical functionalities are realized; and the use of lightweight organic linkers allows for ultrahigh surface area and porosity previously not accessible to conventional materials (i.e., zeolites and porous carbon). As a consequence, MOFs show great promise for a rapidly expanding collection of applications such as gas storage, separations, catalysis, sensing, and drug delivery.The mechanochemistry of MOFs and their response to shock waves, which we discuss in this Account, have been only partially explored. Mechanochemistry, the connection between the mechanical and the chemical worlds, has ancient origins. Rubbing sticks together to start a fire is mechanochemistry. Only in the past decade or so, however, has mechanochemistry gained a notable focus in the chemical community. In the following discussion, we present a general introduction to the complex mechanochemical behavior of MOFs both under quasi-static compression and under shock loading created by high-speed impact. During elastic deformation, MOFs undergo reversible structural or phase transitions. Plastic deformation of MOFs can result in mechanochemistry and can permanently modify the crystal structure, the pore dimensions and configuration, and the chemical bonding. The large energies required to induce bond rearrangement during plastic deformation suggest an interesting potential of MOFs for shock wave mitigation applications.MOFs are promising materials for shock energy dissipation because of the high density of nanopores which can absorb shock energy as they collapse. We have recently developed a platform to assess shock wave energy attenuation by MOFs and other powdered materials. It uses a tabletop laser-driven flyer plate to impact MOF samples at velocities of up to 2.0 km/s. The pressure of the shock waves that break out from the MOF sample can be measured by photon Doppler velocimetry. By measuring the shock profiles of MOF layers with different thicknesses, we can determine the shock pressure attenuation by the MOF layer. We have identified the two-wave structure of shocks in MOFs caused by nanopore collapse. Electron micrographs of recovered shocked MOFs show distinct zones in the shocked material corresponding to shock powder compaction, nanopore collapse, and chemical bond destruction.

Achieving an optimal shock-wave mitigation inside open channels with cavities for weak shock waves: A computational study

This paper deals with a numerical study of weak shock-waves propagation and their attenuation in channel flow having different heights and exhibiting a hollow circular cavities with different depths and diffraction angles inside. The effect of initial diffraction angle and cavity depth on the shock mitigation is investigated. A better shock attenuation is achieved with diffraction angle θw = 90° by a factor of approximately 17% in terms of shock-Mach number and 38% in terms of total energy. The obtained results show also, in addition to the initial diffraction angle and cavity depth, the importance of reducing the channel heights as well as the position of the reduced section in achieving an optimal shock-wave attenuation. The presence of a cavity inside the channel helps to attenuate faster the shock wave. The underlying physics relies on the shock diffraction phenomenon that generates large amount of vortical structures capable of dissipating part of the shock energy by inducing a pressure loss behind it. A subtle arrangement of channel position/height and a cavity location leads to an efficient pressure attenuation by approximately a factor of 57% for Ms = 1.6 and 16% for Ms = 1.1.

Impact of filler composition on mechanical and dynamic response of 3-D printed silicone-based nanocomposite elastomers

Cellular silicone reinforced with silica filler prepared using additive manufacturing (AM) have been used widely for vibrational damping and shockwave mitigation. The two most commonly printed cellular silicone structures, simple cubic (SC) and face-centered tetragonal (FCT) display distinctly different static and dynamic mechanical responses dependent upon structure. In this work, the relationship between filler size and composition with mechanical response is investigated using polydimethylsiloxane-based silicones filled with aluminum oxide, graphite, or titanium dioxide. SC and FCT structures of porous, periodic silicone pads were printed using new direct ink write (DIW) resin formulations containing up to 25 wt% of functional filler (TiO2, Al2O3, or graphite). All AM pads were characterized using mechanical techniques (DMA, compression). Dynamic compression experiments coupled with time-resolved X-ray phase contrast imaging were performed to obtain insights into role of filler interactions in the in situ evolution of shockwave coupling in these functional, periodic porous polymers.

Experimental and Numerical Investigation on the Shock Wave Structure Alterations and Available Energy Loss Variations With a Grooved Nozzle Vane

A passive shock wave control method, using a grooved surface instead of the original smooth surface of a gas turbine nozzle vane to alter a single shock wave into a multiple shock wave structure, is investigated in this paper, so as to gain insight into the flow characteristics of a multiple shock wave system and its variations with various grooved surface geometry parameters. With the combination of numerical and experimental approaches, the shock wave structure and the flow behavior in a linear turbine nozzle channel with different grooved surface configurations were compared and analyzed in details. The numerical and experimental results indicate that the multiple shock wave structure induced by the grooved surface is beneficial for mitigating the intensity of the shock wave, reducing the potential excitation force of the shock wave and decreasing the shock wave loss as well. It was also found that the benefits are related to the geometry of the grooved surface, such as groove width, depth, and number. However, the presence of the grooved surface inevitably causes more viscous boundary layer loss and wake loss, which maybe a bottleneck for general engineering application of such a passive shock wave mitigation method.