Patent Application
20120032526
The present specification generally relates to methods, systems and devices for energy conversion and, more specifically, to methods, systems and devices for dissipating kinetic energy from a shock wave.
Energy is frequently generated and applied to various applications by converting one type of energy to another type of energy. For example, shields may dissipate kinetic energy and protect assets from the deleterious effect of explosively generated shock waves. Shields typically comprise robust and massive deflectors. The deflectors may be pre-emplaced heavy blast doors made of concrete, steel, or other shock absorbing materials. Such blast doors are subject to damage when utilized to deflect a shock wave and require maintenance before re-use. Additionally, due to their size and weight, heavy blast doors deploy slowly relative to the propagation rate of a shock wave generated by an explosion.
In addition to deflecting a shock wave, it may be desirable to intentionally generate the shock wave and utilize the shock wave as an energy source in lieu of other energy sources. For example, capacitors may convert electrical energy stored in batteries to high power microwave energy. The high power microwave energy may be utilized in various high power microwave systems such as, for example, radar imaging, communications, radar detection, and weapons that disable equipment and electronic devices. However, the batteries commonly require a large volume to produce enough power for the effective operation of the high power microwave systems. Effective operation may be facilitated by producing the necessary amount of power with a volume of explosive material that is smaller than the volume of the batteries by dissipating the energy of a shock wave generated by the explosive material with an electrical load.
Accordingly, a need exists for alternative methods, systems and devices for dissipating kinetic energy from a shock wave with electrical loads.
In one embodiment, a method for dissipating kinetic energy from a shock wave may include: applying a magnetic flux across a shock wave disposed within a channel, wherein the channel includes substantially constant dimensions as the shock wave propagates through the channel; transforming kinetic energy from the shock wave to electrical energy; applying a high potential electrode to the electrical energy; applying a low potential electrode to the electrical energy; and coupling an electrical load conductively with the high potential electrode and the low potential electrode to dissipate the kinetic energy from the shock wave.
In another embodiment, a system for dissipating kinetic energy from a shock wave may include: an electronic control unit including a processor and an electronic memory; a channel enclosing a fluid; a high potential electrode in contact with the fluid, wherein the high potential electrode includes an initiation surface; a low potential electrode in contact with the fluid, wherein the low potential electrode includes a termination surface facing the initiation surface; an electrical load conductively coupled to the high potential electrode and the low potential electrode; a north pole magnetic source communicatively coupled to the electronic control unit; and a south pole magnetic source communicatively coupled to the electronic control unit. The electronic control unit executes machine readable instructions to generate a magnetic flux across a shock wave propagating through the fluid, such that the magnetic flux induces an electric field between the initiation surface and the termination surface.
In yet another embodiment, a device for dissipating kinetic energy from a shock wave may include: a channel enclosing a fluid and defining a direction of propagation of a shock wave; a high potential electrode in contact with the fluid; a low potential electrode in contact with the fluid; a load conductively coupled to the high potential electrode and the low potential electrode; a north pole magnetic source coupled to the channel, wherein the north pole magnetic source includes a flux directing surface that faces the fluid; a south pole magnetic source disposed across from and substantially parallel to the north pole magnetic source, wherein a magnetic flux direction is substantially normal to the flux directing surface and substantially orthogonal to the direction of propagation; and an explosive, wherein a shock wave propagates along the direction of propagation upon a detonation of the explosive.
These and additional features provided by the embodiments described herein will be more fully understood in view of the following detailed description, in conjunction with the drawings.
The embodiments set forth in the drawings are illustrative and exemplary in nature and not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:
Referring now to
The channel 110 is a structure, tunnel, or adit that defines an outer boundary of an at least partially enclosed fluid 120 and constrains the motion of the fluid 120 such that the motion can be guided along one direction. In one embodiment, the channel 110 comprises a rectangular cross-section that is formed by insulators 112, a high potential electrode 130 and a low potential electrode 134. However, it is noted that the channel 110 may comprise any shape as a cross-section such as, for example, a circle, an oval, a polygon, a natural shape, or an irregular shape. Additionally it is noted, the channel 110 is generally depicted in
Furthermore, it is noted that the channel 110, as described herein, may be formed of any of the elements described herein that are capable of forming a fluidic boundary that is robust enough to contain and allow for the propagation of a shock wave within the bounded fluid. Therefore, by maintaining “substantially constant dimensions,” the channel is rigid enough to collimate the shock wave. Collimation assists in the transformation of shock wave kinetic energy to electrical energy by maintaining the kinetic energy within the shock front while it passes through a magnetic field. For the purpose defining and describing the present disclosure, it is noted that the term “fluid” as used herein means a substance, such as a liquid or a gas, that is capable of flowing and that changes its shape when acted upon by a force tending to change its shape. Thus, the embodiments described herein may be especially useful to protect assets from exterior events designed to collimate and project a shock wave toward the asset. An example is the detonation of explosives within an opened door of a subway car that collimates and projects a shock wave towards passengers at a loading station.
The magnetic sources 150, 160 generate magnetic fields across the fluid 120. Referring now to
Referring now to
Referring again to
Referring now to
The electronic control unit 170 comprises a processor for executing machine readable instructions and a memory for electronically storing machine readable instructions and machine readable information. The processor may be an integrated circuit, a microchip, a computer or any other computing device capable of executing machine readable instructions. The memory may be RAM, ROM, a flash memory, a hard drive, or any device capable of storing machine readable instructions. In the embodiments described herein, the processor and the memory are integral with the electronic control unit 170. However, it is noted that the processor and the memory may be discrete components communicatively coupled to one another such as, for example, modules distributed throughout the system 200 without departing from the scope of the present disclosure. Furthermore, it is noted that the phrase “communicatively coupled,” as used herein, means that components are capable of transmitting data signals with one another such as, for example, electrical signals via a conductive medium, electromagnetic signals via air, optical signals via optical waveguides, and the like.
The shock sensor 172 is a device for measuring indicia of a shock or explosive event. In one embodiment, the shock sensor 172 senses the indicia and transmits a signal indicative of the shock or explosion to the electronic control unit 170. For example, the shock sensor 172 may sense an overpressure and transmit information indicative of the overpressure to the electronic control unit 170. Embodiments of the shock sensor 172 may measure indicia of a shock or explosion such as, for example, light, temperature, pressure, ionization, and the like. It is noted that the term “sensor,” as used herein, means a device that measures a physical quantity and converts it into an electrical signal, which is correlated to the measured value of the physical quantity, such as, for example a transducer, a transmitter, an indicator, a piezometer, a manometer, an accelerometer, and the like. Furthermore, the term “signal” means an electrical waveform, such as DC, AC, sinusoidal-wave, triangular-wave, square-wave, and the like, capable of traveling along a conductive medium.
Referring now to
A shock wave 122 will be generated by the detonation of the explosive 180. For example, the detonation may initiate a driving pressure that is greater than a hundred atmospheres and increase the temperature to an ionizing temperature. The driving pressure and the ionizing temperature serve as sources of kinetic energy that cooperate to form the shock wave 122. The shock wave 122 may be dense (on the order of about several hundred micrometers thick) and may travel along a direction of propagation x within a fluid 120 disposed within the channel 110 at a high velocity. The high velocity is a function of the driving pressure (i.e., the higher the driving pressure, the higher the velocity) and may be from about 1 km/s to about 25 km/s for conventional explosives. However, it is noted that the embodiments described herein may operate with explosives with higher driving pressure such as, for example, non-conventional explosives or explosions produced extra-terrestrially. As the shock wave 122 forms a pressure discontinuity, or shock front, the ionizing temperature forms a sheet-like ionized zone of several mean free paths of the detonation product at the shock front. The ionized zone comprises free charge and forms a thin conductive zone, which is analogous to a conductor traveling with the shock wave 122. The system 200 contains high kinetic energy, which may be utilized to power an electrical load 140 according to the embodiments described herein.
A magnetic curtain can be erected to dissipate the kinetic energy from the shock wave 122 relatively rapidly via the electrical load 140 when the channel length is relatively short such as a window well or a door frame. Referring again to
A magnetic flux density B0 can be generated between north pole magnetic source 150 and a south pole magnetic source 160 to fill a portion of the fluid 120 in front of the shock wave 122 to form a magnetic curtain. As the ionized shock front of the shock wave 122 impinges on the magnetic flux density B0 along the direction of propagation x, kinetic energy from the shock wave 122 is converted to electrical energy as an electric field density E. The electric field density E is generated along the electric field direction (depicted in
An exemplary mathematical model describing the conversion of the kinetic energy from the shock wave 122 may be formulated by combining a model describing fluid dynamics with adjustments from a model describing electrodynamics. Specifically, the mathematical model may be utilized for analytic computations by considering: the conservation of mass, the conservation of momentum, the conservation of energy, and the gas state equations. From the conservation of mass it may be inferred that the matter that goes into a plane fully exits the plane. From the conservation of momentum it may be inferred that the velocity drop and accompanying momentum change must be transferred to an electron particle and charged molecule. From the conservation of energy it may be inferred that the kinetic energy decrease as result of retardation of plasma velocity must be made up by the increase in electrical and/or joule heating energy. And finally, the gas state equations provide a relationship between temperature, pressure and volume. Thusly, the mathematical model may be solved for pressure, temperature, plasma velocity, and density to provide a descriptive tool regarding plasma deceleration as a function of channel length or flow down a channel when given material properties, initial conditions, and boundary conditions. It is noted that the exemplary mathematical models described herein are provided for clarity, and should not be interpreted as limiting or requiring the present disclosure to any particular theory. Therefore, the exemplary mathematical models are merely descriptive of the physical phenomena inherent to the embodiments described herein.
The stall point, or critical velocity, is a free variable that sets a threshold velocity at which the shock wave 122 must traverse along the direction of propagation x in order to dissipate kinetic energy from the shock wave 122 via the electrical load 140. The critical velocity is a term that is equal to the ratio of the electric field density E to the magnetic flux density B0:
Therefore, the critical velocity may be set by modifying the magnetic flux B0 of the system in accordance with the electric field density E. In one embodiment, the electric field density E may be sensed or calculated real time and the magnetic flux can be altered via, for example, modifying the current supplied to an electromagnet. In another embodiment, the critical velocity may be designed into the physical dimensions of the system (e.g., adjusting the surface area of the electrodes 130, 134), the energy level of the explosion, or combinations thereof. Furthermore, it is noted that while the embodiments described herein are provided in relation to an x-y-z coordinate system, the arrangement of the elements of the embodiments described herein are to be interpreted as arranged in relation to one another and not to any fixed coordinate system.
The magnetic curtain may be utilized as a reusable magnetic blast shield that protects assets from the deleterious effects of shock waves. For example, if a rogue explosive event such as, but not limited to, the detonation of an IED, occurs within a subway tunnel which acts as a channel 110, a shock sensor 172 may sense an over pressure or an explosive flash indicative of the presence of a shock wave 122. The shock sensor 172 can transmit a signal indicative of the presence of the shock wave 122 to the electronic control unit 170. Then, a magnetic flux density B0 can be generated between north pole magnetic source 150 and a south pole magnetic source 160 away from the shock wave 122. Since electrons travel at the speed of light, the sensing of the shock wave 122 and initiation of the magnetic flux density B0 occurs prior to any significant movement of the shock wave 122 down the channel 110 and along the direction of propagation x. As the shock wave 122 travels along the direction of propagation x and orthogonally intersects with the magnetic flux B0, current flows through the electrical load 140 via the electrodes 130,134. Kinetic energy is dissipated from the shock wave 122 via a Lorentz Force 124 and electrical energy dissipated by the electrical load 140.
Additionally, since the shock wave 122 maintains an ionized state due to the ionizing temperature, the shock front will maintain its conductivity until the kinetic energy of the shock wave 122 becomes sub lethal, i.e. ionization is correlated with high temperature and pressure of the shock wave which may cause lethal effects for both personnel and equipment. A reduction in the shock front ionization has a commensurate reduction in lethality. Specifically, lack of ionization (i.e., stalling the system) may be accompanied by reduction in driving pressure and temperature of the shock wave such that a human sub-lethal environment would be created. For example, if a shock wave was generated by the detonation of an explosive in a subway tunnel, passengers in the tunnel would experience a very high wind, but not a collapse of their chest cavity, or production of free radicals within their biological system.
In one embodiment of the device 101, depicted in
In another embodiment, the electrical load 140 may comprise a circuit for generating an electromagnetic transmission. For example, the transmission power level can be scaled to the energy level of shock event giving instantaneous annunciation of rogue activity, and the level of threat. Since, the shock wave 122 powers the transmission circuit, no additional power source is required to signal the occurrence of rogue activity.
Still referring to
Referring now to
An embodiment of the system 201 for generating high power directed energy transmissions is depicted in
High power microwaves with power densities of greater than about 108 w/m3, such as, for example, power densities of about 1011 w/m3 or greater, can be produced from systems with a size of about 0.001 m3. Similarly, systems that generate about 15,000 J can be produced in packages with a cross-section of less than about 0.1 m2 with a length less than about 0.5 m. The high energy density allows the embodiments described herein to be suitable for many delivery systems that provide for extended standoff from a target such as, for example, rockets, missiles, or bombs. Therefore, the embodiments disclosed herein may be used as a power source for many applications associated with high power microwaves. For example, the embodiments described herein may be utilized as electromagnetic weapons, annunciation systems, early warning systems, and radar systems, such as, for example, bi-static targeting or bi-static imaging.
The embodiments described herein will be further clarified by the following example.
The embodiments described herein were analytically tested against theoretical solutions to shock waves propagating in a one-dimensional channel of nearly constant area. This allowed for the exploration of the shock wave structure and the extent of the effect of the electromagnetic field on the velocity and dynamic pressure behind the blast wave. The shock wave was computed over the detonation products mean free paths of thickness and the fluid assumed to be a conducting perfect gas that satisfies the standard compressible flow equations. The computation was run to simulate both a shock wave modified with an applied magnetic flux and a shock wave without an applied magnetic flux. The system was formulated by the partial differential equations of conservation of mass, momentum and energy. The state laws were utilized to close the system so that the number of variables equaled the number of equations. Finally, computer integrations were performed to describe a shock front jump over the thickness of the front for a theoretical system with a cross section of 0.0025 m2, a channel length of 0.5 m, a constant Mach number of 19, a specific heat ratio of 1.25, a magnetic flux density of 2.1 Wb/m2, an electric field density of 7,750 v/m, and a critical velocity of about 3.5 km/s.
The results of the analysis are schematically depicted in
It is noted that the terms “substantially” and “about” may be utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. These terms are also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue. Furthermore, these terms are also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference due to manufacturing tolerances or fabrication tolerances.
While particular embodiments have been illustrated and described herein, it should be understood that various other changes and modifications may be made without departing from the spirit and scope of the claimed subject matter. Moreover, although various aspects of the claimed subject matter have been described herein, such aspects need not be utilized in combination. It is therefore intended that the appended claims cover all such changes and modifications that are within the scope of the claimed subject matter.
