Patent Application
20170350681
The present disclosure relates generally to thermally-initiated venting systems, and more particularly, to detonation transfer assemblies.
Thermally-initiated venting systems may be implemented in energetic systems and configured to reduce the violence of the reaction of an energetic assembly in response to a known threat, for example, a propellant in a rocket motor exposed to an external heat source, such as a fire. Thermally-initiated venting systems may comprise a detonation transfer assembly configured to transfer a detonation or energy from one part of a thermally-initiated venting system to another, in order to cause a reaction, such as the ignition of an explosive material. Detonation transfer assemblies should be able to be exposed to fast cook-off (i.e., direct, immediate exposure to high heat, such as a fire) and/or slow cook-off (i.e., the exposure to gradually increasing temperature over an extended period of time) without ignition or detonation and without thermal degradation.
In various embodiments, a detonation transfer assembly may comprise an external casing comprising an input end and an output end axially opposite the input end, an explosive column spanning axially inside the external casing, a primary explosive disposed within the explosive column, and/or a secondary explosive disposed within the explosive column axially between the primary explosive and the output end. The primary explosive and/or the secondary explosive may thermally insensitive initiation material that may resist detonation and/or thermal degradation in response to a temperature increase rate of 3.3° C. per hour over at least twenty hours.
In various embodiments, the primary explosive may comprise lead azide and/or copper(I) 5-nitrotetrazolate. In various embodiments, the secondary explosive may comprise hexanitrostilbene and/or nonanitroterphenyl. In various embodiments, the primary explosive may comprise the same thermally insensitive initiation material as the secondary explosive. In various embodiments, the detonation transfer assembly may comprise a primer comprised within the external casing between the explosive column and the input end. In various embodiments, a column height of the explosive column may be less than one-third of a casing height of the external casing. In various embodiments, a column height of the explosive column may gradually increase from a first portion of the explosive column to a second portion of the explosive column.
In various embodiments, a thermally-initiated venting system may comprise a first stage pyrotechnic, a detonation transfer assembly coupled to the first stage pyrotechnic and configured to be actuated by the first stage pyrotechnic, and/or an energetic transfer line coupled to the detonation transfer assembly, wherein the energetic transfer line is configured to be ignited by the detonation transfer assembly. The detonation transfer assembly may comprise a primary explosive and a secondary explosive disposed axially-adjacent to the primary explosive. The primary explosive and/or the secondary explosive may comprise a thermally insensitive initiation material that resists detonation and/or thermal degradation in response to a temperature increase rate of 3.3° C. per hour over at least twenty hours. In various embodiments, the primary explosive and/or the secondary explosive may comprise a thermally insensitive initiation material that resists detonation and/or thermal degradation in response to a temperature increase rate of 3.3° C. per hour over at least 48 hours.
In various embodiments, the primary explosive may comprise lead azide and/or copper(I) 5-nitrotetrazolate. In various embodiments, the secondary explosive may comprise hexanitrostilbene and/or nonanitroterphenyl. In various embodiments, the primary explosive may comprise the same thermally insensitive initiation material as the secondary explosive.
In various embodiments, a method of igniting a thermally-initiated venting system may comprise igniting a first stage pyrotechnic, igniting a primary explosive in a detonation transfer assembly in response to the igniting the first stage pyrotechnic, igniting a secondary explosive in the detonation transfer assembly in response to the igniting the primary explosive, igniting an energetic transfer line in response to the igniting the secondary explosive, and/or damaging a vessel comprising a propellant in response to the igniting the energetic transfer line. The secondary explosive may comprise hexanitrostilbene and/or nanonitroterphenyl.
The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosure, however, may best be obtained by referring to the detailed description and claims when considered in connection with the drawing figures.
All ranges may include the upper and lower values, and all ranges and ratio limits disclosed herein may be combined. It is to be understood that unless specifically stated otherwise, references to “a,” “an,” and/or “the” may include one or more than one and that reference to an item in the singular may also include the item in the plural.
The detailed description of various embodiments herein makes reference to the accompanying drawings, which show various embodiments by way of illustration. While these various embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that logical, chemical, and mechanical changes may be made without departing from the scope of the disclosure. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected, or the like may include permanent, removable, temporary, partial, full, and/or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact.
Referring to
In various embodiments, thermal sensor 110 may be any thermally-sensitive ignition device that reacts at an actuation temperature (e.g., chemically reacts), and in response, actuates and/or ignites first stage pyrotechnic 120. In various embodiments, thermal sensor 110 may comprise a melting alloy, which gives an output energy in response to achieving an actuation temperature. The output energy may ignite first stage pyrotechnic 120. In various embodiments, thermal sensor 110 may comprise a shape memory alloy. The shape memory alloy may comprise titanium (Ti), Nickel (Ni), Zirconium (Zr), Hafnium (Hf), Palladium (Pd), Gold (Au), Platinum (Pt), Aluminum (Al), Niobium (Nb), and/or Tantalum (Ta). For example, the shape memory alloy may comprise a Ti—Ni alloy, a (Ti—Zr)—Ni alloy, a (Ti—Hf)—Ni alloy, a Ti—(Ni—Pd) alloy, a Ti—(Ni—Au) alloy, a Ti—(Ni—Pt) alloy, a Ti—Al alloy, a Ti—Nb alloy, Ti—Pd alloy, and/or a Ti—Ta alloy. The shape memory alloy may be configured to transition from a first geometry to a second geometry, or from the second geometry to the first geometry, in response to the shape memory alloy achieving an actuation temperature. Therefore, the actuation temperature may cause thermal sensor 110 to change geometry, in response to thermal sensor 110 comprising a shape memory alloy, which may ignite first stage pyrotechnic 120. In various embodiments, thermal sensor 110 may be a reactive material configured to give an output energy in response to reaching an actuation temperature, and the output energy be configured to ignite first stage pyrotechnic 120.
In various embodiments, first stage pyrotechnic 120 may be ignited by the energy produced by thermal sensor 110. First stage pyrotechnic 120 may comprise any reactive material capable of being ignited by the energy output of thermal sensor 110, and capable of creating an output energy from the reactive material. For example, first stage pyrotechnic 120 may comprise black powder and/or boron potassium nitrate (BKNO3). The output energy from first stage pyrotechnic 120 may ignite detonation transfer assembly 200. In various embodiments, the output energy from first stage pyrotechnic 120 may comprise heat, expanding gases, a shock wave, and/or any other energy capable of actuating and/or igniting detonation transfer assembly 200. For example, first stage pyrotechnic 120 may chemically react and produce expanding gas. The expanding gas may mechanically act on an ignition device, such as a firing pin, causing the firing pin to strike and actuate, initiate, and/or ignite detonation transfer assembly 200.
In various embodiments, with combined reference to
In various embodiments, detonation transfer assembly 200 may be configured to withstand slow cook-off without primary explosive 210 and/or secondary explosive 220 igniting, detonating, or otherwise actuating, and/or without primary explosive 210 and/or secondary explosive 220 thermally degrading. Thermal degradation may entail a material, such as primary explosive 210 and/or secondary explosive 220, degrading in response to exposure to heat such that the material will no longer actuate, ignite, and/or detonate when desired and/or triggered. Slow cook-off is the exposure to gradually increasing temperature over an extended period of time. Slow cook-off may comprise a temperature, starting at 50° C. (122° F.), and a temperature increase rate of 3.3° C. (5.9° F.) per hour for at least 20 hours. In various embodiments, the slow cook-off may comprise a temperature increase rate of 3.3° C. (5.9° F.) per hour for at least 40 hours or 48 hours. In various embodiments, the slow cook-off may comprise a temperature increase rate of 3.3° C. per hour for at least 60 hours. Accordingly, primary explosive 210 and/or secondary explosive 220 may comprise thermally insensitive initiation materials, which are materials having the chemical stability to withstand mechanical or energetic shocks, the rapid and/or slow increase in temperature, and/or impact by a physical object, without igniting, detonating, and/or actuating. More specifically, primary explosive 210 and/or secondary explosive 220 may comprise thermally insensitive initiation materials capable of resisting detonation, ignition, and/or thermal degradation in response to exposure to slow cook-off, and/or prolonged exposure to temperatures ranging from 116° C. (240° F.) to 177° C. (350° F.). In various embodiments, primary explosive 210 and/or secondary explosive 220 may comprise thermally insensitive initiation materials capable of withstanding prolonged exposure to temperatures ranging from 116° C. (240° F.) to 204° C. (400° F.), or temperatures ranging from 177° C. (350° F.) to 204° C. (400° F.).
In various embodiments, primary explosive 210 may comprise lead azide (molecular formula: Pb(N3)2), a lead-free alternative to lead azide such as copper(I) 5-nitrotetrazolate, which is know in industry as “DBX-1” (molecular formula: C2Cu2N10O4), and/or any other suitable primary explosive 210 that can withstand slow cook-off in conjunction with secondary explosive 220. Lead azide has an auto-ignition temperature of 300° C. (572° F.). The auto ignition temperature is the temperature at which a reactive material will spontaneously ignite under normal atmospheric conditions without an external source of ignition, such as a spark. The chemical structure of DBX-1 is show in Diagram 1 below, which has an auto-ignition temperature of about 340° C. (644° F.) to 360° C. (680° F.). As used only in this context, the term “about” refers to plus or minus 10° C. (18° F.). Therefore lead azide and DBX-1 do not have a risk of igniting without an external ignition source until temperatures reach about 300° C. (572° F.) or above, wherein the term “about” as used in this context only, means plus or minus 10° C.
In various embodiments, secondary explosive 220 may comprise hexanitrostilbene (“HNS”), nonanitroterphenyl (“NONA”), and/or any other suitable secondary explosive 220 that can withstand slow cook-off in conjunction with primary explosive 210. HNS has an ignition onset temperature of about 320° C. (608° F.), which is preceded by an endothermic melt that occurs at about 317° C. (603° F.). NONA is very thermally stable, having a melting point of 440° C. (824° F.). As used only in this context, the term “about” refers to plus or minus 10° C. (18° F.). In various embodiments, primary explosive 210 and secondary explosive 220 may comprise the same thermally insensitive initiation material. In various embodiments, primary explosive 210 and secondary explosive 220 both may comprise, for example, lead azide, DBX-1, HNS, and/or NONA.
In various embodiments, energetic transfer line 130 may be configured to be actuated and/or ignited by transfer output energy 225 created by detonation transfer assembly. Energetic transfer line 130 may be, for example, a linear shape charge comprising an explosive material configured to weaken and/or rupture a metal casing coupled to the linear shape charge. For example, energetic transfer line 130, such as a linear shape charge, may be disposed adjacent to a motor 50, such as a rocket motor. In operation, energetic transfer line 130 may be actuated and/or ignited by transfer output energy 225, causing the explosive material in energetic transfer line 130 to detonate. Such a detonation may result in the damaging of, i.e., the weakening or destruction of, a portion of a vessel, such as a motor case, which may house a propellant. The propellant may be ignited by the explosion of the explosive material in energetic transfer line 130. In various embodiments in which the vessel is a motor case, the motor case may be weakened by the explosion of the explosive material in energetic transfer line 130, and the propellant within the motor case may ignite without an external ignition source, but instead, the propellant may ignite as a result of heat and pressure around the motor case. The detonation of the explosive material in energetic transfer line 130 may mitigate a potential hazard, such as exposure to a thermal threat such as a fire, by venting energy from the propellant to prevent the rocket or missile comprising the propellant from moving and/or exploding. Otherwise, the thermal threat may cause an explosion of the propellant, causing the rocket or missile comprising the propellant to be propelled in a direction or explode. In various embodiments, energetic transfer line 130 may transfer an energetic signal to another component within TIV system 150 or to a separate system.
In various embodiments, an explosive column 317A-317C in detonation transfer assemblies 300A-300C, respectively, may be disposed axially-adjacent to initiator 303 and span axially between initiator 303 and output end 302. In various embodiments, within explosive columns 317A-317C, there may be a column void 304A-304C, respectively, adjacent to initiator 303. A primary explosive 310A-310C may be disposed axially-adjacent to column voids 304A-304C, respectively, in explosive columns 317A-317C, respectively. A secondary explosive 320A-320C may be disposed axially-adjacent to primary explosives 310A-310C, respectively, and output end 302.
In various embodiments, explosive columns 317A-317C may comprise various dimensions depending on the explosive materials used as primary and/or secondary explosives. In various embodiments in which a primary and/or secondary explosive is used that has a detonation energy that is less than tradition explosive materials used in detonation transfer assemblies such as hexogen (C2H6N6O6) (“RDX”) or octogen (C4H8N8O8) (“HMX”), more of the primary and/or secondary explosive will be required to achieve the same detonation energy as the traditional explosive materials. For example, HMX has an energy of detonation of 10.87 KJ/cc, while HNS has an energy of detonation of 8.08 KJ/cc. Therefore, in order to achieve the same amount of detonation energy with HNS as would have been produced by HMX, a greater mass of HNS should be used than HMX in the explosive column, which is associated with an adjustment of the dimensions of explosive column 317A-317C. In various embodiments, a column height, such as column height 322A of explosive column 317A, may be uniform across the axial length of the explosive column. With reference to
Referring to
In various embodiments, the lengths 324A-324C of different sections of explosive columns 317A-317C, respectively, may vary. As depicted in
In various embodiments, primary explosives 310A-310C and/or secondary explosives 320A-320C may comprise thermally insensitive initiation materials, as described herein. For example, primary explosives 310A-310C may comprise lead azide, DBX-1, and/or any other suitable primary explosive. Secondary explosives 320A-320C may comprise, for example, HNS, NONA, and/or any other suitable secondary explosive.
In operation, with reference to
In various embodiments, referring back to
Referring to
Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the disclosure. The scope of the disclosure is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. Different cross-hatching is used throughout the figures to denote different parts but not necessarily to denote the same or different materials.
Systems, methods and apparatus are provided herein. In the detailed description herein, references to “one embodiment”, “an embodiment”, “various embodiments”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments.
Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112(f) unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises”, “comprising”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
