Fire extinguishers – Processes – Of extinguishing fire
Reexamination Certificate
2000-10-12
2001-11-06
Scherbel, David A. (Department: 3752)
Fire extinguishers
Processes
Of extinguishing fire
C169S052000, C169S053000
Reexamination Certificate
active
06311780
ABSTRACT:
FIELD OF THE ART
A group of inventions is related to fire fighting techniques and aviation engineering, namely, it concerns fire fighting aviation means applied for extinguishing the fire sites on the inaccessible territories, in multistory buildings or in cases when the supply of fire extinguishing means is required from rather a great height.
PRIOR STATE OF THE ART
At present are known different methods and devices to extinguish fires by way of releasing liquid from special vessels on board an aircraft, preferably airplanes.
Thus, e.g., from Patent PL 127704 a device is known designed for fire extinguishing with the help of airplanes, which houses vessels for liquid storage, two liquid drain throats, an air inlet connected with the upper part of the vessels and controlled drain valves.
Utilization of two holes for liquid drain gives and opportunity to have different liquid consumption depending on combination of valve openings. This allows, in its turn, to extinguish fire on a large territory or create long closed zones of liquid dropping around the dire site. The prior art device employs the incoming air flow for liquid expulsion from the vessels and represents itself a detachable unit, which can be fixed on board a multi-purpose airplane.
A prior art method of liquid drain from an aircraft (Patent FR 2610894) is known, which includes a liquid drain through a branch pipe coming out of the airplane body in the direction opposite to the flight direction. The liquid drain in the prior art decision takes place both under force of gravity and excessive pressure of about 0.5 bar created by a pressurization system in the liquid vessel.
Another prior art method of liquid drain from an airplane (Patent CA 975733) is also known, which consists in liquid drain through a hole in the tank bottom. During the drain process there takes place the liquid atomization into drops, while it is passing through a profiled grid arranged in the outlet section of a drain hole.
The analog of a device claimed is the one of fire extinguishing with the aid of an aircraft (Application RU 94012947A1). The prior art device includes liquid drain in the form of a directed jet parallel to the incoming air flow, within the range of an aircraft angle of incidence, in the direction opposite to the flight direction. At the boundary of a free jet the direct proximity of the outlet section exit of a drain branch pipe a pressure area is produced, which is excessive in relation to air pressure overflowing the rest part of the jet and increasing with boundary distance from the jet axis. The air flow incoming onto the frontal surface of a liquid jet is inclined downwards, thus reducing the air flow component perpendicular to the jet. On account of this an impulse decrease imparted to a frontal jet surface and a jet deformation decrease, i.e. a directed liquid flow control, are achieved This effect is materialized in the prior art design with the aid of special aerodynamic surfaces placed in front of the jet below a drain branch pipe or with the aid of a profiled annular wing embracing the jet.
The analog of a device claimed if the one of fire extinguishing with the aid of an aircraft (Application RU 94012947A1). The prior art device comprises a drain unit with a branch pipe of a round section directed in parallel to the aircraft body opposite to the flight direction and placed outside the aircraft. The drain unit structure also comprises an annular wing connected with the branch pipe by means of pylons. Being in the air flow a circular wing embraces a free liquid jet and creates an excessive pressure area on its boundary in relation to the air flow pressure overflowing the rest part of the jet. In its bottom the wing has an S-type profile, on account of which the air flow incoming onto the frontal surface of the jet declines downwards. It results in impulse reduction transferred to the frontal surface of the jet and, hence, its deformation. The profited wing allows to control a directed liquid flow in this manner.
The most closely analogous method to the one claimed is a method of fire extinguishing with an aircraft applied described in U.S. Pat. No. 3,604,509. The prior art method includes liquid dispersion in a gas flow, acceleration of a generated dual-phase flow in a gas-dynamics nozzle, and a directed supply of an accelerated gas-droplet stream to the fire site from the aircraft board. A foam-generating fluid is used as a liquid meant for fire extinguishing in the prior art design, which determines a mixing chamber and nozzle configuration, with the help of which a directed dropping of generated foam from an aircraft board to the fire site is reduced to practice. The choice of foam-generating fluid and gas parameters fed into the flow mixing chamber as well as that of nozzle dimensions in the prior art design depends on a desired foam ball size and the required foam consumption.
The most closely analogous device to the one claimed is a fire extinguishing device with the aid of an aircraft described in U.S. Pat. No. 3,604,509. This prior art device includes a liquid vessel designed for fire extinguishing, a mixing chamber of liquid and gas connected via a pipeline with the vessel and a gas flow supply system, a means of foam-generating fluid dispersion fed into the mixing chamber, a gas-dynamics nozzle to supply a gas-droplet stream into a fire-site, and a directed gas-droplet stream control system. In this device a foam-generating fluid is used as a working fluid and a problem of generating a foam flow with a ball size control is being solved. The foam balls generated at the nozzle exit during an operating process have a negligible initial velocity but a large external surface, which does not allow to produce a 50 m range directed dual-phase flow stable in relation to external effect factors.
The said analogs of the inventions claimed serve for extinguishing substance concentration increase with a directed supply from board an aircraft. However, these designs only partially eliminate the incoming air flow effect and do not allow to control a gas-droplet stream in a wide range of directions, neither they compensate inertia forces acting on the jet from the aircraft side. That is, the prior art analogs do not allow to completely compensate distributing factors, first and foremost, the aerodynamic forces acting on a directed flow of fire extinguishing fluid and, hence, have a limited fire extinguishing efficiency.
The main factors having an influence on fire extinguishing efficiency are: extinguishing substance consumption, a flow of which is directed to the fire site, the size and velocity of extinguishing substance drops at the fire site approach. The fire extinguishing efficiency increases with extinguishing fluid consumption and its drop velocity increase, as well as with the drop size decrease.
In prior art designs a liquid jet spray takes place at a relatively low gas-droplet stream speed supply from board an aircraft, therefore the drop velocity approaching a fire site proves to lie rather low (comparable with the rain drop speed) and the effect on a gas-droplet stream of a high-speed air flow result in its dispersion and deviation from a desired direction. The said factors mainly determine a relatively low fire extinguishing efficiency with the prior art devices and fire extinguishing methods applied with the aid of an aircraft.
SUMMARY OF THE INVENTION
The inventions patented are based on the problem of increasing a fire extinguishing efficiency with, an aircraft application, which is solved on account of generating a high-speed finely dispersed dual-phase flow with a high concentration of extinguishing substance, which shows stability under the effect of disturbing forces as well as the incoming air flow. The properties of a dual-phase flow are provided under certain conditions due to a desired flow structure and its longer range, i.e. in maintaining a sufficiently high speed of liquid flow drops at the distance of more than 50 m.
This technical result is achieved by the fact that in reducing to practice a
Karpyshev Alexandr Vladimirovich
Lepeshinsky Igor Aleksandrovich
Zuev Jury Vladimirovich
Hwu Davis
Nauchno-Issledovatelsky Inst. Nizkikh Temperatur Pri Mai
Rothwell Figg Ernst & Manbeck
Scherbel David A.
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