2014 Vol. 34, No. 6
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2014, 34(6): 641-657.
doi: 10.11883/1001-1455(2014)06-0641-17
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Abstract:
This paper briefly reviews the development and application of the Hopkinson pressure bar experimental technique in China.The research works on the SHPB experimental techniques related to metal, polymer, composite, brittle material, concrete, soft material and foam material are presented.The results of the SHPB tests are discussed.
This paper briefly reviews the development and application of the Hopkinson pressure bar experimental technique in China.The research works on the SHPB experimental techniques related to metal, polymer, composite, brittle material, concrete, soft material and foam material are presented.The results of the SHPB tests are discussed.
2014, 34(6): 658-666.
doi: 10.11883/1001-1455(2014)06-0658-09
Abstract:
The finite element code, AUTODYN, was used to numerically simulate the propagation of the shock wave in the protective structure with holes under contact explosive loads.The overpressuretime curves were obtained for the shock waves around the orifice and in the center of the protective structure, respectively.The effects of the explosive charge weight and the blast center distance on the overpressure and impulse in the protective structures were analyzed.And based on the numerical calculation, the prediction formulas for the characteristic parameters were achieved by applying the dimensional analysis method.
The finite element code, AUTODYN, was used to numerically simulate the propagation of the shock wave in the protective structure with holes under contact explosive loads.The overpressuretime curves were obtained for the shock waves around the orifice and in the center of the protective structure, respectively.The effects of the explosive charge weight and the blast center distance on the overpressure and impulse in the protective structures were analyzed.And based on the numerical calculation, the prediction formulas for the characteristic parameters were achieved by applying the dimensional analysis method.
2014, 34(6): 667-672.
doi: 10.11883/1001-1455(2014)06-0667-06
Abstract:
Based on dynamic triaxial passive loading techniques, a new passive confined SHPB experiment technique was designed for measuring the responses of pressure and volume strain of materials with bulk modulus of giga pascal or less.In the experiment design, the dimensions of the specimens, encapsulated pads and confinement tube were determined as well as their matching.And the upper limit of pressure load was given.The pressure result from this design was validated by the deviation of equivalent pressure of LC4 aluminum alloy measured by the passive confined SHPB experiment and SHPB experiment.The volume strain result from this design is approximately equal to the axial strain measured by the SHPB experiment.And based on the analysis of experiment and numerical simulation, the radial strain can be omitted compared with the volume strain.Cerium was tested by the designed passive confined SHPB setup.The result shows the entire response of pressure and volume strain during the phase transition of gamma to alpha.The variety of volume strain during phase transition and the pressures of the beginning and ending of phase transition are similar to those by hydrostatic-pressure experiments.So the designed passive confined SHPB technique is feasible for measuring the pressure-volume strain relation of materials with low bulk modulus.
Based on dynamic triaxial passive loading techniques, a new passive confined SHPB experiment technique was designed for measuring the responses of pressure and volume strain of materials with bulk modulus of giga pascal or less.In the experiment design, the dimensions of the specimens, encapsulated pads and confinement tube were determined as well as their matching.And the upper limit of pressure load was given.The pressure result from this design was validated by the deviation of equivalent pressure of LC4 aluminum alloy measured by the passive confined SHPB experiment and SHPB experiment.The volume strain result from this design is approximately equal to the axial strain measured by the SHPB experiment.And based on the analysis of experiment and numerical simulation, the radial strain can be omitted compared with the volume strain.Cerium was tested by the designed passive confined SHPB setup.The result shows the entire response of pressure and volume strain during the phase transition of gamma to alpha.The variety of volume strain during phase transition and the pressures of the beginning and ending of phase transition are similar to those by hydrostatic-pressure experiments.So the designed passive confined SHPB technique is feasible for measuring the pressure-volume strain relation of materials with low bulk modulus.
2014, 34(6): 673-678.
doi: 10.11883/1001-1455(2014)06-0673-06
Abstract:
A new technique for testing dynamic spherical indentation of materials was proposed.It was implemented by putting a WC alloy ball between two specimens, one of which was bonded with the input bar and the other was bonded with the output bar.Then the two speciemens were pressed in the process of indentation.With this simple arrangement we can accomplish a very accurate measurment of force and displacement during the indentation.A finite element simulation was carried out by using the ABAQUS/Explicit software to evaluate this new experimental technique.The results show that the new method gives a more accurate result than other dynamic indent experimental methods.In addition, by testing the alumimum alloy materials, the curves of the indentation force and depth were gotten based on the new technique.The investigation diaplays that the technique proposed can porvide more accuate results and refect the indentation process more truely.
A new technique for testing dynamic spherical indentation of materials was proposed.It was implemented by putting a WC alloy ball between two specimens, one of which was bonded with the input bar and the other was bonded with the output bar.Then the two speciemens were pressed in the process of indentation.With this simple arrangement we can accomplish a very accurate measurment of force and displacement during the indentation.A finite element simulation was carried out by using the ABAQUS/Explicit software to evaluate this new experimental technique.The results show that the new method gives a more accurate result than other dynamic indent experimental methods.In addition, by testing the alumimum alloy materials, the curves of the indentation force and depth were gotten based on the new technique.The investigation diaplays that the technique proposed can porvide more accuate results and refect the indentation process more truely.
2014, 34(6): 679-684.
doi: 10.11883/1001-1455(2014)06-0679-06
Abstract:
Aimed to two kinds of TiNi alloy, that is, initial shape-memory effect TiNi alloy and pseudo-elastic TiNi alloy, the transient temperatures at the surfaces of the TiNi alloy specimens were measured during dynamic deformation in real time by using the compression split Hopkinson pressure bar device with an infrared detector system.And the corresponding temperature changes were calculated according to the experimental stress-strain curves.Temperature-measurement results indicate that significant temperature change was observed in the process of phase transformation.Specifically, during loading, the temperature increased with the increasing of the phase transformation strain, and reached its highest at the highest phase transformation strains.While during unloading, for the initial pseudo-elastic specimens, the temperature decreased significantly, in contrast, for the initial shape-memory effect specimens, the temperature kept the highest temperature constant or dropped, which is depended on the highest loading temperature.After a cycle of loading/unloading, the temperatures of the specimens with two initial states are higher than their initial ones.The calculated results show that the effect of transformation dissipation work on the temperature change can not be ignored.
Aimed to two kinds of TiNi alloy, that is, initial shape-memory effect TiNi alloy and pseudo-elastic TiNi alloy, the transient temperatures at the surfaces of the TiNi alloy specimens were measured during dynamic deformation in real time by using the compression split Hopkinson pressure bar device with an infrared detector system.And the corresponding temperature changes were calculated according to the experimental stress-strain curves.Temperature-measurement results indicate that significant temperature change was observed in the process of phase transformation.Specifically, during loading, the temperature increased with the increasing of the phase transformation strain, and reached its highest at the highest phase transformation strains.While during unloading, for the initial pseudo-elastic specimens, the temperature decreased significantly, in contrast, for the initial shape-memory effect specimens, the temperature kept the highest temperature constant or dropped, which is depended on the highest loading temperature.After a cycle of loading/unloading, the temperatures of the specimens with two initial states are higher than their initial ones.The calculated results show that the effect of transformation dissipation work on the temperature change can not be ignored.
2014, 34(6): 685-690.
doi: 10.11883/1001-1455(2014)06-0685-06
Abstract:
In order to investigate the influence of the transition layer on the shear strength of the Zr/steel explosive clad plate and obtain the rational impact parameters of explosive welding, the difference of the Zr/steel and Zr/Ti/steel clad plates was compared by the explosive welding experiments at small angles.The interfacial wave parameters were measured by a metallographic microscope, and the impact velocities and impact angles were calculated by the smoothed particle hydrodynamics meshfree method.The shear strengths of the explosive and the annealed samples from the clad plates were measured according to the national standard (GBT 6396-2008).The results indicate that titanium as the transition layer can increase the shear strength of the Zr/steel interface and annealing treatment can decrease the shear strength.When the impact velocity is 734-805 m/s and the impact angle is 19.8°-20.8°, the shear strength of the Zr/Ti interface can be higher than 140 MPa.When the impact velocity is 803-904 m/s and the impact angle is 19.5°-20.5°, the shear strength of the Ti/steel interface can also be higher than 140 MPa.
In order to investigate the influence of the transition layer on the shear strength of the Zr/steel explosive clad plate and obtain the rational impact parameters of explosive welding, the difference of the Zr/steel and Zr/Ti/steel clad plates was compared by the explosive welding experiments at small angles.The interfacial wave parameters were measured by a metallographic microscope, and the impact velocities and impact angles were calculated by the smoothed particle hydrodynamics meshfree method.The shear strengths of the explosive and the annealed samples from the clad plates were measured according to the national standard (GBT 6396-2008).The results indicate that titanium as the transition layer can increase the shear strength of the Zr/steel interface and annealing treatment can decrease the shear strength.When the impact velocity is 734-805 m/s and the impact angle is 19.8°-20.8°, the shear strength of the Zr/Ti interface can be higher than 140 MPa.When the impact velocity is 803-904 m/s and the impact angle is 19.5°-20.5°, the shear strength of the Ti/steel interface can also be higher than 140 MPa.
2014, 34(6): 691-700.
doi: 10.11883/1001-1455(2014)06-0691-10
Abstract:
Aimed at the whipping response of submarines to underwater explosion, the later approximation of the second－order doubly－asymptotic approximation(DAA2)based on the wave equation was deduced in time domain, and the inner field problem of the double cylindrical shell structure was solved by combining DAA2with the acoustic－structure interaction method.Then coupled with the explicit finite element, a fluid－structure interaction method was established for analyzing the underwater shock of submarines.The numerical method established was validated by comparing its results with the analytical ones of a simple case that is about a water－filled elastic spherical shell subjected to a planar step wave.At last, by using the numerical method, the whipping responses of double cylindrical shell structures to underwater explosion were analyzed and the influences of period ratios and explosion distance ratios were explored.
Aimed at the whipping response of submarines to underwater explosion, the later approximation of the second－order doubly－asymptotic approximation(DAA2)based on the wave equation was deduced in time domain, and the inner field problem of the double cylindrical shell structure was solved by combining DAA2with the acoustic－structure interaction method.Then coupled with the explicit finite element, a fluid－structure interaction method was established for analyzing the underwater shock of submarines.The numerical method established was validated by comparing its results with the analytical ones of a simple case that is about a water－filled elastic spherical shell subjected to a planar step wave.At last, by using the numerical method, the whipping responses of double cylindrical shell structures to underwater explosion were analyzed and the influences of period ratios and explosion distance ratios were explored.
2014, 34(6): 701-708.
doi: 10.11883/1001-1455(2014)06-0701-08
Abstract:
Primary waves were chosen as the study object, then an analytical solution for the dynamic response of tunnels with composite lining in infinite media under blasting seismic waves was deduced based on the wave function expansion method.According to the solution, the sensitivity of dynamic stress concentration factors to parameters was analyzed with the tunnel group excavation at Nanjing Hongshan South Road.By curve fitting, the regression equations were obtained for the hoop dynamic stress concentration factors of the surrounding rock and inner lining varied with the kinetic and geometrical parameters, respectively.The analysis result show that the elastic moduli of the surrounding rock and secondary lining and the Poisson's ratio of the surrounding rock have more impact on the hoop dynamic stress at the observation points and the effect of the elastic modulus of the primary lining is negligible.The lining thickness change has greater influence on the hoop dynamic stress of the surrounding rock than on the inner lining.Increasing the lining thickness can balance the stress states of the tunnel structures in designs and constructions, but the effect by the thicker inner lining is not as well as that by the thicker secondary lining.
Primary waves were chosen as the study object, then an analytical solution for the dynamic response of tunnels with composite lining in infinite media under blasting seismic waves was deduced based on the wave function expansion method.According to the solution, the sensitivity of dynamic stress concentration factors to parameters was analyzed with the tunnel group excavation at Nanjing Hongshan South Road.By curve fitting, the regression equations were obtained for the hoop dynamic stress concentration factors of the surrounding rock and inner lining varied with the kinetic and geometrical parameters, respectively.The analysis result show that the elastic moduli of the surrounding rock and secondary lining and the Poisson's ratio of the surrounding rock have more impact on the hoop dynamic stress at the observation points and the effect of the elastic modulus of the primary lining is negligible.The lining thickness change has greater influence on the hoop dynamic stress of the surrounding rock than on the inner lining.Increasing the lining thickness can balance the stress states of the tunnel structures in designs and constructions, but the effect by the thicker inner lining is not as well as that by the thicker secondary lining.
2014, 34(6): 709-715.
doi: 10.11883/1001-1455(2014)06-0709-07
Abstract:
Based on two-dimensional Euler equations associated with chemical reactions, gaseous detonation of 2H2/O2/Ar mixture propagating through a T-tube was investigated numerically.The second-order additive semi-implicit Runge-Kutta methods and the fifth-order weighted essentially non-oscillatory (WENO) scheme were used to discretize the time derivative term and the space derivative term, respectively.The nine-specie and 48-elementary-reaction model was applied to describe detonation chemical reaction processes.The distribution of pressure, temperature and H mass fraction as well as numerical cellular patterns were obtained.Results show that, in the flowing mixture, the wave surface has an oblique detonation structure on windward side, while the wave on downwind side has a structure of leading shock wave decoupled from the reaction zone which is the same as the structure of waves on both side in quiescent mixture.After undergoing a series mach reflection incident, waves eventually form detonation waves propagating to left and right.In the flowing system, the whole cellular structure takes shape markedly further downstream.The emergence of transverse detonation has a key role for detonation reinitiation.
Based on two-dimensional Euler equations associated with chemical reactions, gaseous detonation of 2H2/O2/Ar mixture propagating through a T-tube was investigated numerically.The second-order additive semi-implicit Runge-Kutta methods and the fifth-order weighted essentially non-oscillatory (WENO) scheme were used to discretize the time derivative term and the space derivative term, respectively.The nine-specie and 48-elementary-reaction model was applied to describe detonation chemical reaction processes.The distribution of pressure, temperature and H mass fraction as well as numerical cellular patterns were obtained.Results show that, in the flowing mixture, the wave surface has an oblique detonation structure on windward side, while the wave on downwind side has a structure of leading shock wave decoupled from the reaction zone which is the same as the structure of waves on both side in quiescent mixture.After undergoing a series mach reflection incident, waves eventually form detonation waves propagating to left and right.In the flowing system, the whole cellular structure takes shape markedly further downstream.The emergence of transverse detonation has a key role for detonation reinitiation.
2014, 34(6): 716-722.
doi: 10.11883/1001-1455(2014)06-0716-07
Abstract:
Based on the impact dynamics and the basic theory of explosive welding, the material point method was applied to study the wave formation at the compounded interface by explosive welding, and the corresponding three－dimensional numerical simulations were presented.The interfacial wave formation and plasticity flowing deformation were explored, and the simulated results by the material point method were compared with the explosive welding experiments.The above investigations display that the formation of the interfacial wave in explosive welding result from melting of the metal material and flowing of the eddy at the impact point.Furthermore, the material point method presents an outstanding advantage in the numerical simulation for the interfacial wave formation in explosive welding.
Based on the impact dynamics and the basic theory of explosive welding, the material point method was applied to study the wave formation at the compounded interface by explosive welding, and the corresponding three－dimensional numerical simulations were presented.The interfacial wave formation and plasticity flowing deformation were explored, and the simulated results by the material point method were compared with the explosive welding experiments.The above investigations display that the formation of the interfacial wave in explosive welding result from melting of the metal material and flowing of the eddy at the impact point.Furthermore, the material point method presents an outstanding advantage in the numerical simulation for the interfacial wave formation in explosive welding.
2014, 34(6): 723-729.
doi: 10.11883/1001-1455(2014)06-0723-07
Abstract:
According to the analysis of the tandem warhead characteristics, we proposed a new tandem shaped charge structure composed of two explosively-formed projectile charges with the same structure.By using the finite element software LS-DYNA, the effect of different explosion-proof bodies and different delay control on the forming process of the postpositive EFP charge were analyzed.Based on the above results, we conducted experiments for tandem EFP penetration with different delay time.The experimental results show that the penetration depth of the optimized tandem EFP charge can reach 96.7 percent of the sum depth that penetrated by a single EFP charge at twice.The penetration ability of the postpositive EFP charge is greatly improved.
According to the analysis of the tandem warhead characteristics, we proposed a new tandem shaped charge structure composed of two explosively-formed projectile charges with the same structure.By using the finite element software LS-DYNA, the effect of different explosion-proof bodies and different delay control on the forming process of the postpositive EFP charge were analyzed.Based on the above results, we conducted experiments for tandem EFP penetration with different delay time.The experimental results show that the penetration depth of the optimized tandem EFP charge can reach 96.7 percent of the sum depth that penetrated by a single EFP charge at twice.The penetration ability of the postpositive EFP charge is greatly improved.
2014, 34(6): 730-735.
doi: 10.11883/1001-1455(2014)06-0730-06
Abstract:
The three explosion events recorded by Mudanjiang and Baijitong sesimic stations on October 9, 2006, May 25, 2009 and Feburary 12, 2013 were analyzed, respectively.Both the stations belong to Global Sesimic Network.The energy ratios of the three events were estimated by comparing the maximum P-phase amplitudes and the power spectrum densities, and the correlation coefficients of the three explosion events were determined.The phases were compared to determine the relative location of these explosion events.Comparison between the 2013 event and the 2009 event displays that the mean ratios of the maximum amplitudes and the power spectrum densities are about 2.3 and 2.7, respectively.The results for the 2013 event and the 2006 event displays that the mean ratio of the maximum amplitudes is about 10.1 and the mean ratio of the power spectrum densities is about 13.5.It indicates that the energy released by the 2013 event is about 11.8 times as much as that released by the 2006 event and 2.5 times as much as that released by the 2009 event.The maximum cross correlations were 0.90 and 0.99 for the 2013, 2006 events and the 2013, 2009 events in 2-4 Hz, respectively.These results mean that the 2013 event is highly correlated to the 2006 and 2009 events in the frequency band which the main energy concentrated, and this shows that the relative distances of the three events are not long.The analysis on the relative locations of these three events can explain that the 2013 event lies to the southeast of the 2009 events.
The three explosion events recorded by Mudanjiang and Baijitong sesimic stations on October 9, 2006, May 25, 2009 and Feburary 12, 2013 were analyzed, respectively.Both the stations belong to Global Sesimic Network.The energy ratios of the three events were estimated by comparing the maximum P-phase amplitudes and the power spectrum densities, and the correlation coefficients of the three explosion events were determined.The phases were compared to determine the relative location of these explosion events.Comparison between the 2013 event and the 2009 event displays that the mean ratios of the maximum amplitudes and the power spectrum densities are about 2.3 and 2.7, respectively.The results for the 2013 event and the 2006 event displays that the mean ratio of the maximum amplitudes is about 10.1 and the mean ratio of the power spectrum densities is about 13.5.It indicates that the energy released by the 2013 event is about 11.8 times as much as that released by the 2006 event and 2.5 times as much as that released by the 2009 event.The maximum cross correlations were 0.90 and 0.99 for the 2013, 2006 events and the 2013, 2009 events in 2-4 Hz, respectively.These results mean that the 2013 event is highly correlated to the 2006 and 2009 events in the frequency band which the main energy concentrated, and this shows that the relative distances of the three events are not long.The analysis on the relative locations of these three events can explain that the 2013 event lies to the southeast of the 2009 events.
2014, 34(6): 736-741.
doi: 10.11883/1001-1455(2014)06-0736-06
Abstract:
The failure mechanism of throttling rings in gun recoil brakes was experimentally researched from the micro level.In the experimental research, the scrapped throttling rings and recoil solutions from a repair facility were chosen as the research objects.The experimental research was carried out on the basis of metal corrosion abrasion theories and microscopic analysis technologies.The microscopic analysis technologies involved a metallurgical microscope, a scanning electron microscopy and an energy dispersive spectrometer, as well as micro-hardness measurement, inductively coupled plasma mass spectrometry and flame atomic absorption spectrometry.The above research shows that as one of vital components in a recoil brake, the failure of the throttling ring results from the combined action of impact wear, chemical corrosion and cavitation damage.
The failure mechanism of throttling rings in gun recoil brakes was experimentally researched from the micro level.In the experimental research, the scrapped throttling rings and recoil solutions from a repair facility were chosen as the research objects.The experimental research was carried out on the basis of metal corrosion abrasion theories and microscopic analysis technologies.The microscopic analysis technologies involved a metallurgical microscope, a scanning electron microscopy and an energy dispersive spectrometer, as well as micro-hardness measurement, inductively coupled plasma mass spectrometry and flame atomic absorption spectrometry.The above research shows that as one of vital components in a recoil brake, the failure of the throttling ring results from the combined action of impact wear, chemical corrosion and cavitation damage.
2014, 34(6): 742-747.
doi: 10.11883/1001-1455(2014)06-0742-06
Abstract:
To examine the rate-dependent properties of aluminum foams, three-dimensional random spherical cell models were constructed to simulate the microstructures of aluminum foams, and the dynamic deformations of aluminum foams at the strain rates of 10-10 000 s-1 were calculated by using the ANSYS/LS-DYNA commercial code.Obtained results show that at moderate and low strain rates, the rate-dependent properties of aluminum foams originate mainly from the strain-rate sensitivities of their matrix materials.At high strain rates, the rate-dependent properties of aluminum foams are dominated by the combining action of the strain rate sensitivity of cell materials and the microstructure inertia of cells, and the microstructure inertia effects are more remarkable for aluminum foams with low relative density than for those with high relative density.
To examine the rate-dependent properties of aluminum foams, three-dimensional random spherical cell models were constructed to simulate the microstructures of aluminum foams, and the dynamic deformations of aluminum foams at the strain rates of 10-10 000 s-1 were calculated by using the ANSYS/LS-DYNA commercial code.Obtained results show that at moderate and low strain rates, the rate-dependent properties of aluminum foams originate mainly from the strain-rate sensitivities of their matrix materials.At high strain rates, the rate-dependent properties of aluminum foams are dominated by the combining action of the strain rate sensitivity of cell materials and the microstructure inertia of cells, and the microstructure inertia effects are more remarkable for aluminum foams with low relative density than for those with high relative density.
2014, 34(6): 748-753.
doi: 10.11883/1001-1455(2014)06-0748-06
Abstract:
To predict the peak pressure in the explosion－vented vessel with a venting duct, the influencing factors on the peak pressure were abstracted from the experimental data in literatures.The abstracted factors were deployed as the inputs to the support vector machine(SVM), and the corresponding peak pressures were used as the outputs.Thereby, the SVM model was developed.The validity of the SVM model was checked by comparing the predictive capacities between the SVM model and the empirical formula.The results show that the SVM model has a better predictive capacity than the empirical formula.
To predict the peak pressure in the explosion－vented vessel with a venting duct, the influencing factors on the peak pressure were abstracted from the experimental data in literatures.The abstracted factors were deployed as the inputs to the support vector machine(SVM), and the corresponding peak pressures were used as the outputs.Thereby, the SVM model was developed.The validity of the SVM model was checked by comparing the predictive capacities between the SVM model and the empirical formula.The results show that the SVM model has a better predictive capacity than the empirical formula.
2014, 34(6): 754-758.
doi: 10.11883/1001-1455(2014)06-0754-05
Abstract:
Small-scale chemical explosion simulation experiments were carried out to investigate the leakage time and percentage of CO gas from different-scale chemical explosions in rock.The different-scale chemical explosions meted a scaling relation.The researched results show as follows: (1) the beginning time and stopping time of gas leakage are approximately proportional to the two-third power of the explosive quantities in scaled explosion experiments in similar media; (2) some materials in a sealed blast chamber can decompose into non-condensable gas under high temperature caused by explosion; (3) the percentages of the leaked CO in smaller charge scale experiments are not less than those in the larger charge scale experiments.According to the researched results, one can estimate the gas leakage in larger charge scale underground explosion by the metrical results in smaller charge explosion.
Small-scale chemical explosion simulation experiments were carried out to investigate the leakage time and percentage of CO gas from different-scale chemical explosions in rock.The different-scale chemical explosions meted a scaling relation.The researched results show as follows: (1) the beginning time and stopping time of gas leakage are approximately proportional to the two-third power of the explosive quantities in scaled explosion experiments in similar media; (2) some materials in a sealed blast chamber can decompose into non-condensable gas under high temperature caused by explosion; (3) the percentages of the leaked CO in smaller charge scale experiments are not less than those in the larger charge scale experiments.According to the researched results, one can estimate the gas leakage in larger charge scale underground explosion by the metrical results in smaller charge explosion.
2014, 34(6): 759-763.
doi: 10.11883/1001-1455(2014)06-0759-05
Abstract:
The explosion of the high pressure, dense gas (SF6) in a circular shape was explored with the use of large eddy simulation (LES), the hybrid high-order schemes were employed to solve the LES equations.The simulated results show that while the shock wave exploding from SF6 gas to air, the incident shock bifurcates into the transmitted shock and the reflected rarefaction wave.The Richtmyer-Meshkov instabilities occur as the transmitted shock accelerates the gas interface, the rarefaction wave moves inward first and converges at the origin, this will generate a strong circular reflected shock which makes the flow field become fully turbulent.
The explosion of the high pressure, dense gas (SF6) in a circular shape was explored with the use of large eddy simulation (LES), the hybrid high-order schemes were employed to solve the LES equations.The simulated results show that while the shock wave exploding from SF6 gas to air, the incident shock bifurcates into the transmitted shock and the reflected rarefaction wave.The Richtmyer-Meshkov instabilities occur as the transmitted shock accelerates the gas interface, the rarefaction wave moves inward first and converges at the origin, this will generate a strong circular reflected shock which makes the flow field become fully turbulent.
2014, 34(6): 764-768.
doi: 10.11883/1001-1455(2014)06-0764-05
Abstract:
Aiming at the shortcoming that the measurement of part points can not acquire the propagation process of shock wave overall and the limitations of the empirical formulae for overpressure, this paper utilizes the weighted generalized inversion to inverse the velocity field of shock wave, acquires the overpressure distribution according to the relationship of peak overpressure and velocity.The inversion results are preferable to the empirical results by experimental confirmation in limitative area.
Aiming at the shortcoming that the measurement of part points can not acquire the propagation process of shock wave overall and the limitations of the empirical formulae for overpressure, this paper utilizes the weighted generalized inversion to inverse the velocity field of shock wave, acquires the overpressure distribution according to the relationship of peak overpressure and velocity.The inversion results are preferable to the empirical results by experimental confirmation in limitative area.
