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Underwater Energetics

1. Experimental Research of Underwater Energy of Explosive Containing Boron/Metal
FENG Xue-song,ZHAO Sheng-xiang,DIAO Xiao-qiang,DAI Zhi-xin
Xi'an Modern Chemistry Research Institute,Xi'an 710065,China)

Abstract: By underwater experiment,the underwater energy of explosives containing boron and combustible metals,including aluminum,magnesium,magnesium-aluminum,magnesium titanium and magnesium zirconium,is tested and compared with aluminum-containing explosive.Results show that the overall energy of HMX-based explosives containing 20%boron-magnesium and 20% boron-magnesium-aluminum is 40% more than that of HMX-based explosive with 20% boron.The energy of 20% boron-aluminum-containing HMX-based explosive is 7% more than that of 20% aluminum-containing HMX-based explosive.The RDX-based explosives containing 20% boron-aluminum,20% boron-magnesium and 20% boron-magnesium-aluminum have higher overall energy than 20% aluminum-containing RDX based explosive,9% higher with boron-magnesium.The overall energy of RDX-based explosive becomes higher with the increase of the content of boron-aluminum.When the content reaches 35%,the overall energy reaches tiptop,almost 7% higher than 35% aluminum-containing explosive.When the content reaches 40%,the overall energy becomes lower.When boron is blended with aluminum,its oxidizing efficiency and overall energy of metalized explosive can be improved.

2. Numerical Simulation of TNT Charge Underwater Explosion
PANG Jun
Military Representative Office of Missile Device,Xi'an 710068,China

Abstract: TNT charges underwater explosion models by different initiating mode were simulated by AUTODYN software,and numerical results were verified by experiments.In the charge centre initiation,end center-point initiation and end surface initiating circumstances,the change trends of the underwater shock wave pressure peak at different charge azimuths with the distance were analyzed by numerical results.The results showed that in end initiation state,the shock wave pressure peak at the charge radial azimuth are greater than the end azimuths,and in centre initiation state,the shock wave pressure peak at the charge end azimuths is greater than the radial azimuth in a certain distance.Changing the initiation mode made the underwater directed destruction of explosion shock wave actualize,and the energy efficiency of a particular azimuth improve.

3. Current Situation of Underwater Chemical-propellant
ZHAO Xiao-feng
Military Representative Office of Missle Device,Xi′an 710065,China)

Abstract: The variety,performance,application of underwater chemical-propellant are reviewed.Pointing out that the liquid monopropellant and liquid multi-component propellant have been widely used for high energy and good stability.Stored chemical energy propulsion system is one of development direction.Suggesting that research of underwater chemical-propellant should be strengthened,with 17 references.

4. Application of PVDF Sensor in Underwater Explosive Shock Wave Measurement at Near-Field
ZHAO Ji-bo,TAN Duo-wang,ZHANG Yuan-ping,SUN Yong-qiang,GONG Yan-qing
Laboratory for Shock Wave and Detonation Physics Research Institute of Fluid Physics,China Academy of Engineering Physics,Mianyang Sichuan 621900,China)

Abstract: In order to gain the pressure section curve and peak pressure attenuation rule of shock wave with transmitting distance in a certain extent filed under water explosion,an experiment is designed to validate the feasibility of PVDF which measure the pressure of shock wave,according to laying four PVDF sensors on the initial axes of explosive and scanning the shock track on axes of explosive on the same experimental condition.The results show that PVDF can be used to test the shock pressure in the near field and peak pressure of shock can be gained precisely in the testing scope of PVDF.Pressure attenuation course and section curves in near-field of shock wave can be gained if intension of shock is below 4 GPa,it is important to evaluate the anti-exploding performance of naval ship.

5. Underwater Shock Wave Characteristics of RDX-based Aluminized Explosives in Near-field Range
HU Hong-wei,WANG Jian-ling,XU Hong-tao,GUO Wei,REN Song-tao
Xi′an Modern Chemistry Research Institute,Xi′an 71065,China)

Abstract: Shock wave peak pressure,impulse and shock wave energy of RDX-based aluminized explosives were obtained at different scaled distance by underwater explosion test.The result indicated that shock wave peak pressure was not influenced with Al contents of 10%-20% in the scaled distance range smaller than 1.5 m/kg1/3.Shock wave peak pressure was nearly constant by Al contents up to 30% in the scaled distance range larger than 1.5 m/kg1/3.Impulse was not influenced with Al contents of 20%-30% in the measured scaled distance range.Shock wave energy decreased with the increase of scaled distance in the scaled distance range smaller than 1.0 m/kg1/3.Shock wave energy was nearly constant in the scaled distance range larger than 1.0 m/kg1/3.The utilization ratio of shock wave energy was only about 25% in the scaled distance 0.79 m/kg1/3(18 times radii of charge),initial shock wave energy lost nearly 1/2-3/5.

6. Underwater Test and Analysis for Explosion Energy of Explosives
SHI Rui1,XU Geng-guang1,LIU De-run1,QIN Jian1,2
1.State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081,China
2.Graduate School of Navy Weaponry,Beijing 100073,China)

Abstract: The underwater testing method for explosion energy of explosives was introduced.The explosion properties of TNT and several aluminized explosives were studied through underwater explosion experiments. The underwater explosive performance of different explosives was compared.The results show that the performance parameters(shock wave peak pressures,impulse and energy flux) accord with explosion similar rules,and the explosion similar equation coefficient of these performance parameters for new formulation was obtained.The shock wave energy and bubble energy of these explosives were calculated and the method for calculating total energy was introduced.The detonation heat calculated by KHTR was compared with experimental total energy,showing that the experimental result is very consistent with the calculated one,the program KHTR to calculate detonation heat can be used.

7. Conversion Relation of Shock Wave Overpressure about Underwater Explosion and Air Blast
SONG Pu,XIAO Chuan,LIANG An-ding,YUAN Bao-hui,LI Guang-jia,FANG Hao
Xi′an Modern Chemistry Research Institute,Xi′an 710065,China)

Abstract: By the study of experience formula and simulated experiment,the shock wave overpressure conversion relation between air blast and underwater explosion was studied.The results show that the shock wave overpressure of air blast and underwater explosion has a quantitative relation when scaled distances r=R/W1/3 were varied within 1.5-2.5,and the conversion formula describing the relation was fit out.By theoretical analysis and empirical data analysis,the conversion method of TNT equivalent of shock wave overpressure of other charges was obtained,the conversion of TNT equivalent of shock wave parameters should be based on the shock wave energy of explosive underwater explosions.By contrast,it was certified that calculated results by experience formularevised with TNT equivalent of shock wave parameters meet the needs of precision engineering design.

8. A Method of Studying Bubble Pulses in a Confined Water Area
WANG Bin,WANG Yan-ping,ZHANG Yuan-ping
Laboratory for Shock Wave and Detonation Physics,Institute ofFluid Physics,CAEP,Mianyang Sichuan 621900,China)

Abstract: Dynamics of bubble pulses generated by PETN charge underwater explosions were studied in a 2m×2m×2m water tank.The wall of the water tank were equipped with a layer of material which can absorb shock waves.With this method,the bubble pulse did not influenced by shock waves reflected from the wall of water tank.The pressure and the explicit picture of bubbles were captured by piezoelectric pressure transducers and a digital high speed camera.To validate the experimental data,another experiment was carried out in a 8kg test pound of 48m in diameter and 23m in depth with the same PETN charge.The experiment data of bubble pulse from the water tank were compared with the water pound results.The maximal difference of the two experiment results is 4.8%.It can be considered that the result of underwater explosion in a water tank can be regarded as the result obtained from test pound.The method of studying bubble pulse presented in this paper is simple and efficient.

9. Effect of Different Initiating Modes on TNT Underwater Explosion
SONG Pu,XIAO Chuan,LIANG An-ding,YUAN Bao-hui
Xi′an Modern Chemistry Research Institute,Xi′an 710065,China)

Abstract: The energy output construction change laws of TNT underwater explosion were studied and compared by end surface point-initiating and centre point-initiating experiments in the pool.The results showed that the energy output construction about the shock wave peak pressure and specific impulse of charge varied explicitly by end surface point-initiating,and increased in the direction of near-detonation compared with other directions.The shock wave peak pressure and specific impulse of specific azimuth were about 10 percent increase in the state of end surface point-initiating than centre point-initiating.It was found that the energy output construction changes of specific azimuth could be obtained by changing initiating mode in condition of notchanging the shape of charge in the water.Additionally,the value for the shock waves specific impulse was gained with shaped structures in the distant area of the explosion.

10. Underwater Energy of DNTF Based Boron-contained and Aluminum-contained Explosive
WANG Hao,WANG Qin-hui,JIN Dayong,HUANG Wen-bin
Xi′an Modern Chemistry Research Institute,Xi′an 710065,China)

Abstract: The explosion performance of DNTF based boron-contained and aluminum-contained explosive is calculated theoretically,and their energy characteristics are studied through determining the underwater energy and explosion heat.The results show that when the mass fraction of boron in the DNTF based boron-contained explosive is 15%,the underwater energy of this explosive arrive to 2.1 TNT-equivalent,revealing the maximum peak in the content of boron vs.TNT equivalent curve.With increasing the mass fraction of aluminum from 10% to 50%,the underwater energy of DNTF based aluminum-contained explosive raises.The maximum energy corresponding to the mass fraction of aluminum of 50% is 2.67 TNT-equivalent.When the content of comburant is less than 18%,the energy of boron-contained explosive is better than that of aluminum-contained explosive.If boron and aluminum are used together,better energy characteristics can be obtained.

11. Numerical Simulation of Energy Output Structure for Aluminized Explosive and Idealized Explosive in Underwater Explosion
XIN Chun-liang1,XU Geng-guang1,LIU Ke-zhong1,QIN Jian1,2
1.State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology,Beijing 100081,China
2.Graduate School of Navy Weaponry,Beijing 100073,China)

Abstract: Numerical simulation of energy output structure for an aluminized explosive and an idealized explosive in underwater explosion has been performed with AUTODYN software.Influence of artificial viscosity on simulation results has been discussed and comparisons of histories pressure profiles have been made.Aluminized explosive PBXN-105 can keep larger shock energy than PBX9010 in far-field because of combustion of aluminum powders.Numerical simulation of energy output structure for aluminized explosive can provide theoretical guide for designs of underwater explosives.

12. Research Development of Underwater Explosion Mechanism
XIAO Chuan,SONG Pu,LIANG Anding
Xi′an Modern Chemistry Research Institute,Xi′an 710065,China)

Abstract: The distinct characteristics of underwater explosion were expatiated compared with the characteristics of air blast.The research mechanisms of underwater explosion,including shock wave of underwater explosion,bubble pulse and dynamic response of targets,were analyzed and summarized.The research hot points and development trend,based on the above-mentioned development situations,were concluded that the underwater explosion damages and energy output form should be researched emphatically,and the near field dynamic response of underwater explosion of the target should be studied deeply,with 31 references.

13. Approximate Calculation of Underwater Explosion Shock Wave Propagation
LI Peng,XU Geng-guang
Beijing Institute of Technology,State Key Laboratory of Explosion Science and Technology,Beijing 100081,China)

Abstract: The underwater explosion shock wave propagation calculation is simplified by emperical expression from the energy flux density-time curve.The set of partial differential governing equations,made up of Lagrange form fluid dynamic equations,Hugoniot equation and the energy flux density-time relation are solved by simple numerical integration method.The shock wave peak value at different distance is calculated by initial data from a single point.The results show that the calculated results by this approximate method well agree with experiment data and law of similitude.By properly selecting initial value of calculating parameters,the shock wave propagation at the distance range out of 5 times of charge radius is accurately deduced.The calculating method fails in the immediate pressure field,in which the shock wave forms incompletely.The shock wave of various aluminized explosive is calculated,showing that the energy markedly influences the propagation character of shock wave.High energy inures to maintain high shock wave peak pressure.

14. The Energy and Impact Sensitivity of EAK Based Melt Cast Intermolecular Explosive
ZHAO Sheng-xiang, ZHANG Yi-an, WANG Xiao-feng
Xi′an Modern Chemistry Research Institute, Xi′an710065, China)

Abstract: The effect of RDX and HMX on the energy of EAK based melt cast intermolecular explosive was investigated by the underwater detonation energy testing which was carried out in a water pool with a diameter of 10 m and depth of 7 m, and the samples were about 300 g and set at 4 m under the water. The results indicated that all of RDX and HMX promoted the energy of EAK composition, but there was difference between aluminized and non-aluminized explosive composition systems. In the aluminized explosive compositions RDX was more effective on promoting underwater energy than HMX,but in the non-aluminized explosive compositions, HMX was more effective than RDX. The tests of detonation velocity and impact sensitivity for the EAK-RDX mixtures showed that ideality and propagation stability of detonation, and impact sensitivity all increased with increasing the content of RDX. The mixtures containing 20% and 30% RDX could come to a detonation velocity of 7 800 m/s and 8 000 m/s respectively, and their impact sensitivity both were less than 10%. The impact sensitivity increased sharply as the content of RDX was higher than 40%, while the detonation velocity just showed a smooth increasing. According to tradeoff between the energy and the impact sensitivity, the suitable content of RDX in the EAK composition was about 20% to 30%.

15. Amendment of Shock Wave Parameters of Underwater Explosion
SU Hua,CHEN Wang-Hua, WU Tao,GE Gui-lan,FAN Xiu-qin,LIU Rong-hai
School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing210094, China)

Abstract: Based on the underwater test results of TNT and desensitized RDX in a limited cylinder vessel and the characteristics of the pressure gauges, an amendment method to correct the shock wave parameters, including peak pressure and specific shock wave energy, is put forward. With the amendment, the corrected peak pressure is much close to the calculated value, the fraction of their specific shock wave energies of the two explosives to their total specific energies are at the round of 46% and 44% respectively, and the tested total specific energy of explosive is more than 95% of its explosion energy.

16. Configuration of Underwater Energy Output for Aluminized Explosive Mixtures
Zhou Lin,Xu Gengguang
Beijing Institute of Technology, Beijing100081, China)

Abstract: Underwater energy output characteristics of the different explosives has been indicatad through its parameters. The effect of aluminum on the underwater power of explosive mixtures was discussed. The result was proved that if the underwater shock wave energy can be close to the maximum Al/O ratio range for 0.35～0.40. When Al/O ratio is 1.00, the underwater bubble energy can reach to the highest. The method can make the underwater energy output structure of explosion device each other mates valnembility of explosion objeitive, the damage effect of underwater detonation can be raised.

17. The Shallow Water Explosion's Effect on the Destructive Radius
TIAN Yue hua, ZHANG Zhi cai
Yichang Testing Technique Research Institute, Yichang 443003, China)

Abstract: Underwater ordnance charge explodes near the water surface, due to the effect of the free surface, the effective destructive radius of its charge is reduced and destructive potency is dropped down. Now 1 kg TNT equivalent charge package were used in shallow water explosion test. The minimal binary multiplication, impulse equivalency, energy equivalency methods were used to process p(t) relational expression to get two kinds of calculation formula for the effective destructive radius as follows:R s=0.7636R+0.2603H;R s=0.9301R+ 0.1047H .

18. Determination of the Reasonable Depth of Explosives in Water to Measure Underwater Explosive Energy
WANG Jian Ling, ZHAO Dong kui, GUO Wei
Xi′an Modern Chemistry Research Institute, Xi′an 710065, China)

Abstract: The relationship between the depth of explosive samples in water and the period of the bubble pulsations was investigated. Through comparing the experimental and calculated values of the bubble period, the reasonable depth of explosive samples in limited water was determined.

19. The Cylinder Test and JWL Equation of State Detontion Product of Aluminized Explosives
CHEN Lang, FENG Chang gen, HUANG Yi min
Institute of Fluid physics, CAEP, Mianyang 621900, China)

Abstract: For understanding the detonation preferences of aluminized explosives under the strong confinement, the cylinder tests with diameter of 50mm were carried out. The detonation waves velocities of aluminized explosives were measured by electric pins. The cylinder expansion processes were recorded by rotating mirror streak camera. The photos of camera were analyzed by the computer image technique. With two dimensions numerical simulations of the cylinder tests, the parameters of JWL equation of state detonation product of the aluminized explosives were determined.

20. Effect of Thermite Content on Acoustic Radiation Characteristics of Pyrotechnic Composition Underwater Combustion
OuYang De-hua, Pan Gong-pei, Guan Hua, Fan Lei, Zheng Lei and Yang Sha, Chinese Journal of energetic materials, 2010, 18(1):55-57

Abstract: In order to discuss the effect of combustion heat of the products on acoustic radiation characteristics,the underwater combustion for different thermite contents of pyrotechnic compositions were studied with underwater acoustics system.Results show that acoustic energy can be increased significantly by adding the proper content of the thermite,and the optimal thermite content is 25%.Fifteen gram pyrotechnic composition with thermite content of 25% can produce the sound pressure level as high as 158.8 dB,and the acoustic frequency is mainly 0~5 kHz,then the acoustic energy decreases with the increasing of thermite content.

21. Application of High-speed Photography in Bubble Oscillation at Underwater Explosion
WANG Bin ,ZHANG Guang-sheng ,GAO Ning ,WANG Yan-ping , chinese journal of energetic materials,2010,18(1):102~106,

Abstract: The explicit pictures of bubble oscillation at free field and water jet formed during bubble and boundary interaction at underwater explosion was captured by APX-RS digital high-speed camera with the frame rate of camera of 6000 s-1 by using Xe lamp. The wall of the water tank was equipped with a layer of acoustic-impedance materials,and the bubble oscillation was not influenced by shock waves reflected from the wall of water tank. The experimental data obtained by high speed camera agree with the experimental results of 8 kg test pound.

22. Numerical Simulation of Energy Output Structure for the Underwater Explosion
SHI Rui,XU Geng-guang,XU Jun-pei and LIU Ke-zhong, chinese journal of energetic materials,2009,17(2):147~151

Abstract: Energy output models for the ideal explosives and aluminized explosives were introduced. These models were used to calculate far-field UNDEX of TNT and PBXW-115 with AUTODYN software. Performance parameters such as peak pressure, time constant, impulse, energy flux density and shock wave energy were calculated. These parameters were compared with experimental data. The dynamic model of high pressure gas bubble in uncompressible liquid was achieved. The dynamic equations and JWL EOS (Equations of State) of the detonation products were both used to calculate bubble parameters. Bubble periods of 1 kg TNT and PBXW-115 are 0.213 s and 0.283 s. Bubble energy are 1.88 MJ•kg-1and 4.41 MJ•kg-1, respectively. Bubble parameters calculated are consistent with experimental data.

23. Characteristic of Energy Output of Underwater Explosion for Dual Explosive Charge
NIU Yu-lei,WANG Xiao-feng and YU Ran, chinese journal of energetic materials,2009,17(4):415~419

Abstract: By choosing two types of explosives GH-1 and GUHL-1, and two typical dual charge structures, the test samples were prepared. The characteristics of energy output of underwater explosion for dual explosive charge were studied and compared with that of the single explosive charge. The results show that under the same composition, the dual explosive charge can change the explosion load near the testing point, and decrease the energy loss of shock wave in the detonation propagation. By using dual explosive charge structure with a non-ideal explosive as an inner core surrounded by a high detonation velocity explosive, the bubble energy is increased by 22.4% compared with that of the single explosive charge, and also energy coupling exists in the two parts of the charge.

24. Effects of Ratios of Aluminum to Oxygen on Shock Wave of Cylindrical Charge at Underwater Explosive Close-field
ZHAO Ji-bo,LI Jin-he,TAN Duo-wang,SUN Yong-qiang and ZHANG Guang-sheng, chinese journal of energetic materials,2009,17(4):420~423

Abstract: Three kinds of cylindrical charges based on RDX with different ratios of aluminum to oxygen were tested through underwater explosion. Attenuation law of shock wave peak pressure versus transmission distance at close-field underwater explosion was resolved by high-speed scanning. The effects of Al/O ratios on initial shock wave peak pressure and attenuation were analyzed. Results show that the initial shock wave peak pressure achieves 18.95 GPa, 13.66 GPa and 8.35 GPa respectively when the Al/O ratios are 0, 0.4 and 0.7. The speed of peak pressure attenuation decreases with the increasing of aluminum content. The factors, such as the time of aluminum beginning to react and the degree of reaction,have remarkable effects on shock wave peak pressure at close-filed and attenuation of peak pressure.

25. Preparation and Performance of a New Powdery Ammonium Nitrate Fuel Oil Explosive
HUANG Wen-yao,YAN Shi-long,WANG Xiao-guang,YUAN Sheng-fang,WU Guo-qun and XU Peng, chinese journal of energetic materials,2010,18(2):222~225

Abstract: A new powdery ammonium nitrate fuel oil explosive was produced to solve the problems of complicated production process and low explosion energy. The explosive was made of ozocerite,surfactant,gelatinizer and water, which were made into slurry mixed solution at 105-110 ℃, and was dehydrated from -0.07 MPa to -0.09 MPa. The microstructure and sensitivity of the explosive were analyzed,and the effects of the charge density on detonation velocity and underwater explosion energy were also studied. Results show that the mixing uniformity of the components and safety are good. When the charge density is 0.91-0.94 g•cm-3,the detonation velocity is more than 4000 m•s-1, and the underwater explosion energy is more than 3700 kJ•kg-1,which is close to the theoretical calculation value.