Method for forecasting instantaneous detonation state after detonation of C4 charging center

Abstract

The invention discloses an instantaneous detonation state forecasting method after detonation of a C4 charging center, and relates to the field of explosive detonation reaction numerical forecasting. According to the method, the distance between a detonation wave front and a detonation point after a one-dimensional plane C4 charging center is detonated is utilized to construct a dimensionless normalized distance between any position and the detonation point at any moment after detonation in a computational domain, and a quantitative forecasting function based on the normalized distance is provided. The quantitative forecasting function is combined with CJ detonation parameters of C4, so that forecasting results of the density, the radial speed, the pressure and the unit mass internal energy of any position in a computational domain at any moment can be quickly and quantitatively calculated, a complex detonation calculation model does not need to be introduced any more, the calculation complexity and the calculation amount are small, and the forecasting speed is high. And the precision of quantitative forecasting can reach the same level as the forecasting precision of a detonation calculation model, and the method can be used for quantitative high-precision forecasting of far and near fields in a detonation scene of a one-dimensional plane C4 charging center.

Description

Technical Field

[0001] The invention relates to the field of numerical prediction of explosive detonation reaction, in particular to a method for predicting the instantaneous detonation state after central detonation of a C4 charge. Background Art

[0002] When numerically predicting underwater explosions, two main approaches are currently used to simulate the ignition and detonation processes of high-energy explosives. The first involves the introduction of complex detonation computational models, which can provide a detailed prediction of the detonation chemical reactions starting from the detonation point, primarily involving the generation and propagation of the detonation wave. Common detonation computational models, such as the "ignition-growth" reaction model proposed by Lee and Tarver, enable quantitative and refined predictions of the detonation process with high computational accuracy. Because they can describe the generation, development, and propagation of the detonation wave, as well as the coupling effects between the detonation wave and the surrounding flow field, they are applicable to scenarios that consider the near-field effects of the explosion. However, existing detonation computational models require a large number of input parameters. For some special charge types (such as C4), determining the specific values ​​of the reaction rate parameters in the reaction model is difficult, and the computational process is relatively complex.

[0003] The second approach ignores the specific detonation process of the explosive, that is, it disregards the details of the detonation process and simplifies the impact of the explosive on the surrounding environment to the effect of a mass of hot gas expanding. This approach assumes that the detonation of the explosive is instantaneous, and the detonation product gases become a mass of high-temperature, high-density, and high-pressure gas, thus constructing a simplified instantaneous detonation model. Compared to the first approach, this method simplifies the calculation process and is easier to implement in engineering. However, because it does not consider the details of the detonation process, it can only be used for qualitative engineering estimates in scenarios where the far-field effects of the explosion are considered. It is not applicable when the near-field effects of the explosion need to be considered or when quantitative, high-precision predictions are required. As can be seen, the two commonly used existing detonation state prediction methods have their own shortcomings and cannot meet the needs of actual academic research and engineering applications of C4 charge detonation states. Summary of the Invention

[0004] In response to the above-mentioned problems and technical needs, the inventors have proposed a method for predicting the instantaneous detonation state of a C4 charge after central detonation. This method utilizes a basic solver for condensed matter charge detonation reactions based on the ZND (Zeldovich, Von Neumann, Doering) theory. By analyzing the propagation characteristics of the detonation wave of a centrally symmetric ideal C4 charge after central detonation, it is found that the detonation wave has good similarity within the charge. Based on a quantitative prediction function, this method summarizes the normalized, high-precision instantaneous detonation state prediction results for the C4 charge, including prediction results for density, radial velocity, pressure, and unit mass internal energy at any location within the computational domain at any time. The specific technical solution is as follows:

[0005] A method for predicting the instantaneous detonation state after the central detonation of a C4 charge comprises the following steps:

[0006] Using the propagation position of the detonation wave front at any time t after the detonation of the center of the one-dimensional plane C4 charge, the distance r between any position Q in the calculation domain and the detonation point is normalized to obtain the normalized distance between position Q at time t

[0007] according to Calculate the normalized density at position Q at time t Combined with the relevant CJ detonation parameters of C4 charge, the density prediction result d at position Q at time t is obtained t (r);

[0008] according to The normalized radial velocity at position Q at time t is calculated as Combined with the relevant CJ detonation parameters of C4 charge, the radial velocity prediction result u at position Q at time t is obtained t (r);

[0009] according to Calculate the normalized pressure at position Q at time t Combined with the relevant CJ detonation parameters of C4 charge, the pressure prediction result p at position Q at time t is obtained t (r);

[0010] according to Calculate the normalized unit mass internal energy at position Q at time t Combined with the relevant CJ detonation parameters of C4 charge, the unit mass internal energy prediction result e at position Q at time t is obtained t (r).

[0011] A further technical solution is to obtain the normalized spacing of position Q at time t include:

[0012] According to the detonation velocity D = 8193 m / s of C4 charge, the distance R0(t) = D × t between the propagation position of the detonation wave front and the detonation point at any time t after the detonation of the center of the one-dimensional plane C4 charge is determined, and the normalized distance at position Q at time t is obtained by normalization.

[0013] A further technical solution is that the CJ detonation parameters of the C4 charge include the detonation product density d CJ =2180kg / m 3 , radial velocity of detonation products u CJ =2160m / s, detonation pressure p CJ = 28.5 GPa and the internal energy per unit mass of the detonation products e CJ =10.25e6 J / kg;

[0014] Get the density prediction result d at position Q at time t t (r), radial velocity prediction result u t (r), pressure prediction result p t (r) and the predicted result of unit mass internal energy e t (r) includes calculation according to the following formula:

[0015]

[0016] The beneficial technical effects of the present invention are:

[0017] The present invention discloses a method for predicting the instantaneous detonation state after central detonation of a C4 charge. The method uses the distance between the propagation position of the detonation wave front and the detonation point to construct a dimensionless normalized distance between any position in the calculation domain and the detonation point at any time after detonation, and provides a quantitative prediction function based on the normalized distance. The quantitative prediction function provided by the application, combined with relevant CJ detonation parameters of the C4 charge, can quickly and quantitatively calculate the predicted results of density, radial velocity, pressure and unit mass internal energy at any position in the calculation domain at any time without introducing a complex detonation calculation model. The calculation complexity and amount of calculation are relatively small, and the accuracy of the quantitative prediction can reach the same level as the prediction accuracy of the detonation calculation model. Therefore, the method can improve the calculation accuracy and efficiency of C4 charge detonation, and can provide key technical support for shock waves, bubble motion and load propagation under near-field and far-field explosions of C4 charges in underwater environments. It has important significance and value both in academic research and engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a flow chart of the method for predicting the instantaneous detonation state after the central detonation of C4 charge provided by this application.

[0019] Figure 2 The figure is a time history curve comparison diagram of the prediction result obtained by the method of the present application and the calculation result of the AUTODYN software in a calculation example, wherein: (a) is a density time history curve comparison diagram, and (b) is a pressure time history curve comparison diagram.

[0020] Figure 3 The diagram is a schematic diagram of the state prediction results at different times in the target prediction area after central detonation obtained by quantitatively predicting the state quantitative prediction method of the present application in a simulation example, wherein: (a) is the predicted density distribution curve, (b) is the predicted velocity distribution curve, (c) is the predicted pressure distribution curve, and (d) is the predicted internal energy distribution curve. DETAILED DESCRIPTION

[0021] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0022] One embodiment of the present application discloses a method for predicting the instantaneous detonation state after central detonation of a C4 charge. This method is targeted at the application scenario of central detonation of a one-dimensional planar C4 charge, where the detonation point is located at the center of the one-dimensional planar C4 charge. This method can be used to quickly and quantitatively predict the detonation state of a one-dimensional planar charge structure filled with C4 after central detonation, thereby quickly and quantitatively calculating the state parameter prediction results at any position Q in the computational domain at any time t after central detonation. The quantitative prediction method includes:

[0023] Please combine Figure 1 The method flow diagram shown in the figure first uses the detonation wave front propagation position at any time t after the center of the one-dimensional plane C4 charge is detonated to normalize the distance r between any position Q in the calculation domain and the detonation point, and obtains the normalized distance r between position Q at time t after the center detonation. In one possible embodiment, the distance R0(t)=D×t between the propagation position of the detonation wave front and the detonation point at any time t after the detonation of the center of the one-dimensional plane C4 charge is determined based on the detonation velocity D=8193m / s, and then normalized to obtain the normalized distance at the position Q at time t.

[0024] Based on the normalized distance at any position Q at time t The state parameters of the position Q predicted by the state quantitative prediction method provided in this application at time t include the density prediction result d t (r), radial velocity prediction result u t (r), pressure prediction result p t (r), prediction result of unit mass internal energy e t (r), are introduced as follows:

[0025] 1) Density prediction result d t (r)

[0026] First follow Calculate the normalized density at position Q at time t

[0027] Then, combined with the relevant CJ detonation parameters of the C4 charge, the density prediction result d at position Q at time t is obtained. t (r), the CJ detonation parameters used in this step include the detonation product density d of C4 CJ =2180kg / m 3 , then the density forecast result of position Q at time t is calculated as

[0028] 2) Radial velocity prediction result u t (r)

[0029] First follow The normalized radial velocity at position Q at time t is calculated as

[0030] Then, combined with the relevant CJ detonation parameters of the C4 charge, the radial velocity prediction result u at position Q at time t is obtained. t (r), the CJ detonation parameters used in this step include the radial velocity u of the detonation products of C4 CJ =2160m / s, then the radial velocity prediction result at position Q at time t is calculated as

[0031] 3) Pressure prediction result p t (r)

[0032] First follow Calculate the normalized pressure at position Q at time t

[0033] Then, combined with the relevant CJ detonation parameters of the C4 charge, the pressure prediction result p at position Q at time t is obtained. t (r), the CJ detonation parameters used in this step include the detonation pressure p of C4 CJ =28.5GPa, then the pressure forecast result at position Q at time t is calculated as

[0034] 4) Unit mass internal energy prediction result e t (r)

[0035] First follow Calculate the normalized unit mass internal energy at position Q at time t

[0036] Then, combined with the relevant CJ detonation parameters of the C4 charge, the unit mass energy prediction result e at position Q at time t is obtained. t (r), the CJ detonation parameters used in this step include the unit mass internal energy e of the detonation products of C4 CJ =10.25e6 J / kg, then the predicted result of unit mass internal energy at position Q at time t is

[0037]

[0038] It should be noted that in the quantitative prediction scenario of detonation state, the main focus is on the quantitative prediction of the state of the position of the internal area of ​​the detonation wave front. Therefore, the calculation domain referred to in this application is mainly the area between the initiation point and the detonation wave front. Therefore, the distance r between any position Q and the initiation point in the calculation domain does not exceed the distance R0(t) between the detonation wave front and the initiation point. The dimensionless normalized spacing of any position in the corresponding calculation domain at any time is But in fact, this method can also be used to quantitatively predict the state parameters in the area outside the detonation wave front. Any location within the area is:

[0039]

[0040] The present application provides a quantitative prediction function for the state parameters of any position Q within the calculation domain at time t after the central detonation of a one-dimensional plane C4 charge. Utilizing this quantitative prediction function in combination with the CJ detonation parameters of the C4 charge, the state parameter prediction results for any position within the calculation domain at any time can be quickly and quantitatively calculated without introducing a complex detonation calculation model. This improves the computational accuracy and efficiency, stability, and engineering applicability of the C4 instantaneous detonation state prediction.

[0041] In order to verify the accuracy of the instantaneous detonation wave calculation of C4 charge by the method of this application, the density and pressure prediction results of this application were compared with the calculation results of AUTODYN software. The calculation example was designed to calculate the propagation of the detonation wave after the center of the C4 charge was detonated in a three-dimensional closed space of a cube and the process of multiple reflections inside the solid wall. The cube has a side length of 20cm. At a distance of 10cm from the center of the cube, the flow field density time history curve obtained by the prediction results obtained by the method of this application and the calculation results of the AUTODYN software were compared. Figure 2 -(a) shows the pressure-time curve comparison. Figure 2 -(b), Figure 2The black dashed line in the middle is the calculation result of the AUTODYN software, and the red solid line is the forecast result obtained using the method of this application.

[0042] From the comparison results, it can be seen that the state parameter prediction results obtained by quantitative calculation of the quantitative prediction function provided by the present application are basically consistent with the state parameter prediction results obtained by using the detonation calculation model (AUTODYN software) within the error range, indicating that the accuracy of quantitative prediction using the method of the present application can reach the same level as the prediction accuracy of the detonation calculation model. Therefore, the method of the present application can be used for quantitative high-precision prediction of far and near fields, and from Figure 2 It can also be seen that the method of the present application is actually better than commercial software in capturing the peak pressure of the detonation wave.

[0043] The above method is used to simulate and verify the rapid prediction of the detonation zone state at any time after the center of the one-dimensional plane C4 charge is detonated. In a simulation example, assuming that the length of the C4 charge is [-0.1, 0.1] m, the detonation point is located at the center origin of the C4 charge, and the detonation velocity of C4 is 8193 m / s, then the distance between the coordinates of the detonation wave front and the detonation point at t = 1 μs after the central detonation is R0(t) = 8.193 mm, the distance between the coordinates of the detonation wave front and the detonation point at t = 3 μs after the central detonation is R0(t) = 24.58 mm, the distance between the coordinates of the detonation wave front and the detonation point at t = 5 μs after the central detonation is R0(t) = 40.97 mm, the distance between the coordinates of the detonation wave front and the detonation point at t = 7 μs after the central detonation is R0(t) = 57.35 mm, and the distance between the coordinates of the detonation wave front and the detonation point at t = 9 μs after the central detonation is R0(t) = 73.74 mm. The method provided by this application can be used to quickly and quantitatively predict the density d of the target forecast area at each time t = 1μs, t = 3μs, t = 5μs, t = 7μs, and t = 9μs after the central detonation. t (r), radial velocity u t (r), pressure p t (r) and the predicted result of unit mass internal energy e t (r) respectively as Figure 3 As shown in (a), (b), (c) and (d) in the figure.

[0044] The above description is only a preferred embodiment of the present application, and the present invention is not limited to the above embodiment. It is understood that other improvements and variations directly derived or imagined by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included in the scope of protection of the present invention.

Claims

1. A method for predicting the instantaneous detonation state after the central detonation of a C4 charge, characterized in that: The method comprises: Using the propagation position of the detonation wave front at any time t after the detonation of the center of the one-dimensional plane C4 charge, the distance r between any position Q in the calculation domain and the detonation point is normalized to obtain the normalized distance between position Q at time t according to Calculate the normalized density at position Q at time t Combined with the relevant CJ detonation parameters of C4 charge, the density prediction result d at position Q at time t is obtained t (r); according to The normalized radial velocity at position Q at time t is calculated as Combined with the relevant CJ detonation parameters of C4 charge, the radial velocity prediction result u at position Q at time t is obtained t (r); according to Calculate the normalized pressure at position Q at time t Combined with the relevant CJ detonation parameters of C4 charge, the pressure prediction result p at position Q at time t is obtained t (r); according to Calculate the normalized unit mass internal energy at position Q at time t Combined with the relevant CJ detonation parameters of C4 charge, the unit mass internal energy prediction result e at position Q at time t is obtained t (r).

2. The method for predicting the instantaneous detonation state after the central detonation of C4 charge according to claim 1 is characterized in that: The normalized distance between the positions Q at time t is obtained include: According to the detonation velocity D=8193m / s of the C4 charge, the distance R0(t)=D×t between the propagation position of the detonation wave front and the detonation point at any time t after the detonation of the center of the one-dimensional plane C4 charge is determined, and the normalized distance at the position Q at the time t is obtained by normalization.

3. The method for predicting the instantaneous detonation state after the central detonation of C4 charge according to claim 1 is characterized in that: The CJ detonation parameters of C4 charge include the detonation product density d of C4 CJ =2180kg / m 3 , radial velocity of detonation products u CJ =2160m / s, detonation pressure p CJ = 28.5 GPa and the internal energy per unit mass of the detonation products e CJ =10.25e6 J / kg; Get the density prediction result d at position Q at time t t (r), radial velocity prediction result u t (r), pressure prediction result p t (r) and the predicted result of unit mass internal energy e t (r) includes calculation according to the following formula:

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