Detonation generally caused by fuel with a low octane rating is the tendency for the fuel to preignite or autoignite in an engines combustion chamber. Detonation wave is a shock wave in a reactive medium that is sustained by energy released in chemical reactions that the shock itself triggers and sustains. Average overpressures recorded behind the first shock pressure peak varied between 1. Emulsion matrix is only detonable if it is sensitized generally by hollow microspheres. When new explosives are developed, their vod must be determined. The detonation velocity values presented here are typically for the highest practical density which maximizes achievable detonation velocity. The confined detonation velocity measures the speed at which the detonation wave travels through a column of explo sive within a borehole or other confined.
Detonation velocities and wave front curvatures were measured for bare cylindrical charges of irx4 and pbxn110 charges. If the curvaturenormal velocity relationship kdn is known for a high explosive, dd relation can be deduced by the following procedure. Pdf the effects of containment on detonation velocity. Deflagration and detonation are two ways energy may be released. Density dependence of detonation velocity for some. This allows increasing pressure by one or two orders inside of semiclosed volume.
Table of explosive detonation velocities wikimili, the. In this paper a blast performance assessment was conducted based on the results obtained from the steady state vod measurement of emulsion explosives hef100 and degree of blast fragmentation conducted on an open pit blast. In that method, the detonation velocity d is given by. The detonation parameters are derived from the hugoniot equation for the reacted gas mixture in equilibrium, and from the condition that the detonation velocity is the mini mum wave velocity of the possible velocities for the given state of the combustible gas.
Velocity indicating coherent integrator electronic countermeasure. The failure diameter of irx4 is between 25 and 33 mm. The detonation characteristics of hydrogenoxygen mixtures were com puted for the experimental range of conditions by the use of the elementary theory of detonation. The dynamics of the combustion products behind plane and. This theory pos tulates a planar discontinuity in pres sure, temperature, and composition moving at sonic velocity relative to the. Velocity determination is made by measuring the time required for the detonation wave to travel a measured. Supersonic high pressure shock front ahead of the reaction zone i. The results for the velocitydensity dependence may be summarized as follows.
Electromagnetic measurements of the particle velocity are performed in a situation when the detonation wave reaches the interface between a powdered high explosive he and a window made of an inert material plexiglas. In holes, the measurement of the velocity of detonation vod helps in comparing and evaluating relative performance of explosives. Military applications are excluded from this discussion. Explosive velocity, also known as detonation velocity or velocity of detonation vod, is the velocity at which the shock wave front travels through a detonated explosive. Detonation wave velocity and curvature of irx4 and pbxn110. Influence of density of emulsion explosives on its. The confined detonation velocity measures the speed at which the detonation wave travels through a column of explosive within a borehole or other confined space. The detonation velocity d and pressure p of the explosives are estimated by using the kamlet jacbos equation on the basis of the theoretical density and. Table of explosive detonation velocities wikipedia. Chno explosives, predicting the detonation velocity of.
The velocity of the anfo charges was measured using a continuous resistance wire and they were fired inside 25. In the frame of the wave, the fresh mixture enters the shock at speed d, starts burning in the reaction zone until completely. Temperatures range from 16503870oc and the velocity of detonation vod is so high 25008000 ms that the power of a single charge is around 25,000 mw. After a low velocity explosion, undecomposed explosive is often found. Calculations indicate that pressures in the detonation wave may run as high as 140,000 atmospheres and. Detonation occurs with a propagation of the combustion reaction to the unreacted material, whose speed is greater than the speed of sound in the unreacted material.
The detonations propagated with an average velocity between 1,512 to 1,863 ms. The relationship between the experimentallydetermined velocity of detonation of unconfined, cylindrical charges of rdxdriven pbxs and composite explosives, vd, and charge diameter, d, has been examined critically. The confined detonation velocity of commercial explosives varies from 5000 to 25,000 fps tables 21 through 26. Design and implementation of sensor for velocity of. The velocity of detonation vod is one of the most important properties of explosives. Design of new energetic materials based on derivatives of. A simole method for calculating detonation parameters of explosives. Pdf velocity of detonation vod measurement techniques.
A fifth equation is needed, and it is clear that this equation must in some way represent the reaction of the gas streaming away behind the front on the gas immediately behind it. The nonmonotonic dependence of the detonation velocity of a cylindrical charge on density for explosives of the 2nd type is due to the effect of the finite charge diameter and is related to an increase in the width of the reaction zone with a reduction in the porosity of the explosive. If the explosion moves outward at supersonic speeds faster than the speed of sound, its a detonation. This is defined as a transient change in the gas density, pressure, and velocity of the air surrounding an explosion point. The detonation velocities reported in table 1 are displayed in fig.
Petn, rdx, and hmx with densities close to the natural bulk density are studied. The reaction rate of an explosive also called detonation velocity is the easiest parameter to measure, and also one of the most important in characterizing the process of detonation front. Rotating detonation engines are a novel device for generating thrust from combustion, in a highly efficient, yet mechanically simple form. Detonation velocity is one of the most important parameters in determining the explosives performance parameters. Velocity of detonation how is velocity of detonation. The low velocity detonation can be relatively stable, or it can change into a high velocity detonation. Most manufacturers, however, measure detonation velocity in an unconfined column of explosive 1 14 inches in diameter, although some measurements are made within the confinement of an iron pipe or using a different diameter. Detonation velocity may be expressed as a confined or unconfined value and is normally given in meter per second ms. In castings of density 1625 the maximum velocity is 6950 m. Detonation shock dynamics dsd is a detonation propagation methodology that replaces the detonation shock and reaction zone with a surface that evolves. Calculation of combustion, explosion and detonation characteristics.
It is essential that the explosive in the field condition detonates at its optimum rate and induces sufficient detonation pressure leading to good fragmentation. Pressure in the detonation reaction zone as it progresses along a charge, expressed in mpa. Steady detonation waves propagated in irx4 charges with diameters as small as 33 mm. An improved simple method is presented for calculation of the detonation velocity of chno and chnofcl explosives, as well as nonideal explosives containing. The effects of containment on detonation velocity wiley online. Turker et al velocity of detonation a mathematical model quantum chemical calculations at different levels were reported for the determination of detonation velocities mainly based on the method of kamlet and jacobs approach and using kistiakowskywilsons equation of state2529. The heat of detonation was evaluated using a detonation bomb calorimeter developed for drdcv19. Prediction of detonation pressure and velocity of xplosives 81 results and discussion the data reported shows that for nonideal explosives, detonation velocities are significantly different from those predicted by equilibrium, onedimensional and steadystate calculations. The measured detonation velocities and pressures are close to their corresponding theoretical chapmanjouguet cj detonation velocity d. We will see a combustion wave propagating down the tube with constant speed of less than one meter per second. In order to measure not only the averaged velocity profile, but also possible fluctuations at. V of d measured by triggering ionisation probes 8 off 25mm apart 6 firings carried out mean velocity of detonation of rf6743 1% above pbxn110 0. The value of the boundary diameter is a measure of the sensitivity to propaga tion.
It has been found that, for many formulations, the data can be fitted more satisfactorily to an elliptical. Pressure and velocity measurements on detonation waves in hydrogenoxygen mixtures volume 6 issue 4 d. The detonation velocity of an emulsion explosive containing hollow alumosilicate microspheres cenospheres as the sensitizer is measured. Methaneair detonation experiments at niosh lake lynn. The rate of velocity at which the shock waves travel upon the initiation of explosive charge is considered the most critical parameter during the detonation phenomenon. This is a compilation of published detonation velocities for various high explosive. Calculation of detonation velocity, pressure, and electric sensitivity. Now take away both ends cover rapidly and ignite the gas at one end. Pressure and velocity measurements on detonation waves in. Combustion burning is a process by which energy is released. The detonation velocity is found to depend only slightly on initial temperature and pressure.
During the detonation, the width of the optical spectrum is continuously reduced by the propagation of the wavefront. Determination of the velocitycurvature relationship for unknown front shapes scott i. Detonation velocity, impact and friction sensitivity, and also enthalpy of combustion of various tetrazole derivatives are presented in this section with emphasis on experimentally found values. This early before the spark plug fires ignition of fuel creates a shock wave throughout the cylinder as the burning and expanding fuelair mixture collides with the piston that is.
Calculation of combustion, explosion and detonation. If the combustion process propagates outward at subsonic speeds slower than the speed of sound, its a deflagration. The velocity of shock wave front relative to fuel components is supersonic. A generalized dependence of detonation velocity on charge diameter including low velocity detonation 3 curvature k, and flow in the reaction zone is weakly divergent 9. Dynamic measurements of shock and detonation velocities are performed using long chirped fiber bragg gratings cfbgs. Velocity of detonation unconfined test sample dimension 25. The data listed for a specific substance is usually a rough prediction based upon gas behavior theory citation needed see chapmanjouguet condition, as in practice it is difficult to measure citation needed. Detonation characteristics of hydrogenoxygen mixtures.
Calculated values of the detonation velocity for nitroglycerin, blasting gelatin and 60% gelatin dynamite are in approximate agreement with the experimentally determined values. It is used to derive a nonempirical equation for detonation velocity, which contain. Velocity of detonation, charge diameter and critical. Velocity of detonation vod is an important characteristic measure of explosive materials. Evaluation of new explosive composition is an important part of their development. The influence of ammonium particles size, structure and charge diameter on detonation velocity and distribution of parameters inside of the reaction zone has. Velocity of detonation measurement and fragmentation. Schematically, the detonation wave is shown in the figure here. The very high overpressure propagation is referred to as a shock wave.
Development of a shock and detonation velocity measurement. O explosives by means of artificial neural networks article pdf available march 2019. The composition, rheological structure and its detonation properties were presented in previous ict conferences. The high velocity of detonation is the limiting value of about 8000 metres per second and the low velocity of detonation is of the order of to 2000 metres per second.
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