零重力下建筑高分子材料燃烧过程外文文献

Contents lists available at ScienceDirect Acta Astronautica journal homepage Research of combustion process of construction polymeric materials in zero gravity Ivan Ardashevich Bolodyana Anatoliy Sergeevich Melikhova Leonid Timofeevich Tanklevskiyb Ivan Vyacheslavovich Istomina aFGBU VNIIPO EMERCOM of Russia VNIIPO District 12 Balashikha Moscow region 143903 Russia bDepartment of Fire Safety SPBSTU 65A Serdobolskaya Street Saint Petersburg 197342 Russia A R T I C L E I N F O Keywords Space Combustion Extinguishing Zero gravity Fire safety Spacecraft Inhabited compartment Polymeric material A B S T R A C T In order to provide fire safety of inhabited pressurized compartments of manned spacecraft hereinafter InPC SC a research of combustion process of construction polymeric materials in zero gravity conditions was carried out The research was practiced in a flying bench IL 76 in a free falling container in an experimental unit hereinafter EU Ploskiy kanal two dimensional duct where combustion conditions of polymeric materials were close to combustion conditions in zero gravity Such conditions were modeled via decrease of intensity of natural convection on the long term orbital station Mir on EU Skorost in an orbital flight On the basis of research results of the physical model of combustion process of polymeric materials in zero gravity were formed Previously unknown material combustion parameters introduced as fire danger indexes to practice of design of new means and methods of fire safety provision in InPC SC were discovered A fundamentally modern tech nology of fire suppression in InPC SC is presented Inhabited pressurized compartments of the Russian segment of the International space station are equipped with automatic fire extinguishing system designed on the basis of results of the research 1 Introduction Formation of cosmonautics has been always followed by accidents and catastrophes part of which developed into fires and explosions on the objects and on rocket and space equipment The problems of fire safety under microgravity conditions in the atmosphere inhabited pressurized compartments were widely discussed in this journal 1 6 Nowadays specialists in space area put fire danger in the list of the most dangerous factors of a space flight of manned spacecraft 7 Increased fire danger in InPC SC is caused by the following cir cumstances The atmosphere of InPC SC during their exploitation can be enriched with oxygen up to 40 Hereinafter concentrations of gas and steam components in the atmosphere InPC are given in volume In order to decrease the weight of spacecraft components large quan tity of polymeric materials is used However the problem of fire safety provision in InPC SC appears as the most part of polymeric materials have an intensive combustion in the atmosphere with the oxygen concentration up to 40 hereinafter Co Creation of polymeric materials which are not combustible in the atmosphere with the oxygen concentration increased up to 40 is extremely difficult that is why in InPC SC combustible materials are used In the beginning of the development of manned cosmonautics the difficulty of fire safety provision in InPC was in impossibility of im plementation of means and methods of fire safety provision traditional for that time because of strict limitations caused by ecological safety requirements in InPC SC 2 Practical necessity goals and objectives of carrying out researches of combustion of polymeric materials in zero gravity conditions In order to find new technologies of fire safety provision in InPC SC the research of space flight factors influence on combustion process of polymeric materials and methods of their extinguishing was carried out Theoretically and experimentally the following factors of influence on the combustion and extinguishing of polymeric materials were studied value of oxygen in the atmosphere of InPC in the range from 10 to 100 atmosphere pressure of the pressurized compartment in the range from 1 33 kP to 0 127 P which is defined by stand by and emergency modes of the atmosphere of InPC SC gravity acceleration value in the range from 4 10 2m s2to 15m s2 which happens during launching orbital flight landing of the spacecraft and also during its https doi org 10 1016 j actaastro 2019 01 044 Received 15 January 2019 Accepted 29 January 2019 Corresponding author E mail addresses ivanbolodyan yandex ru I A Bolodyan tanklevskiy gefest spb ru L T Tanklevskiy Acta Astronautica 163 2019 6 17 Available online 15 February 2019 0094 5765 2019 IAA Published by Elsevier Ltd All rights reserved T maneuvers on the orbit gas flow velocity in the range from 0 05 to 1 5 m s vibration in the range of this factor corresponding to ex ploitation conditions of manned transport vehicle MTV and long term orbital stations LOS 8 23 Considering a long duration of LOS and MTV on the low earth orbit and moreover in neutral points of different space systems 22 which can last for decades and in the future for hundred years special at tention was paid to the research of combustion and extinguishing processes of materials in conditions of zero gravity or microgravity The research of zero gravity combustion was started in the USSR in 1969 in connection with an urgent need of design fire safety provision measures of InPC SC starting with InPC of Soyuz 7K TM which was prepared for a joint Soviet American flight Soyuz Apollo in 1975 compartments of Salut series and the Mir station In this regard one of the tasks during carrying out of fundamental research of combustion polymeric materials in zero gravity was ob taining data allowing design methods and technical means of calcula tion of fire danger indexes of polymeric materials specific for zero gravity conditions On the first stage of examination of combustion process of poly meric materials in zero gravity conditions during the period from 1969 to 1989 a research was carried in a flying bench and in ground con ditions via free falling containers 8 10 and also with the help of special EU Ploskiy kanal where combustion conditions of polymeric materials are reached via lowering intensity of natural convection during combustion of a material sample via regulation of the height of the two dimensional duct 11 12 Results of research on the first stage made it possible to formulate a physical model and mechanism of combustion process of polymeric materials in zero gravity Also previously unknown material combus tion parameters introduced as fire danger indexes to practice of design of new means and methods of fire safety provision in InPC SC were discovered Among them there were values of lower combustion limits depending on a flow velocity Vlimand on gravity acceleration here in after glim 8 10 which provided the basis for innovational technolo gies of fire safety provision of InPC SC The trigger of calculation a Vlim value of materials was its obvious physical sense as a fire danger index and also an opening prospective of its implementation in orbital flight conditions for fire suppression as well as for fire protection 24 27 Using a construction element in a pressurized compartment area where the flow velocity is less than of Vlimof material the possibility of its combustion can be prevented by lowering a ventilation flow velocity Vlimof materials fire extinguishing can be provided 3 Research methods of combustion process of polymeric materials in zero gravity conditions 3 1 Research method of combustion process of polymeric materials in zero gravity conditions in a flying bench IL 76 Taking into account the possibility of creating a considerably long 30s period of condition close to zero gravity experiments of studying combustion process of polymeric materials in a flying bench IL 76 were practiced The experimental unit consisted of hermetically closed vessel of 0 18m diameter and 0 8m length There was a bracket for installation of a cassette of and examined material inside the vessel The structure of the bracket allowed a fast change of samples of tested materials during the flight There were 5 samples of materials for tests in the air in the cassette of the bracket Experiments were carried out during the combustion of materials in the air There was a fan inside the vessel It was needed for ventilation of the vessel in order to filling the vessel with a fresh air from the cabin before combustion The ignition of a material sample was made via an electric coil Monitoring of all the elements of EU during the flight was practiced via a transportable test For the video and visual inspection the vessel had a window through which the record was done The method of testing was the following an electric coil with si multaneous switching on the camera and the backlight lamp had been switched 10s before the plane came into exploitation The operator who was near the desk near the EU supervised the combustion process of the material through the window A combustion process in zero gravity was examined in the plane with samples of such materials which have values of material com bustion limits depending on the oxygen concentration Climnot more than 16 organic glass capron fabric filter fabric cotton cloth Combustion of the whole sample of any material listed above without ventilation was practiced in air environment during the time not less than 30s and oxygen concentration decreased not more than 1 3 2 Research method of the combustion of polymeric materials in zero gravity conditions in a free falling container Considering technical difficulties of creating zero gravity with low residue acceleration level in a flying bench because of a high cost of experiments the research of the influence of different factors on the combustion process of polymeric materials in zero gravity conditions was carried out in free falling containers For reaching a high level of zero gravity an experimental unit was used where an internal con tainer used as a burning chamber was placed in external container which was a compensator of aero dynamic air resistance of the internal container of the EU 8 9 By these means the zero gravity level with a residue acceleration of not more than 2 10 3m s2was reached The free falling container with the help of which all the experiments were carried out on a quality level with a video fixation of the burning chamber had the internal container with volume of 0 02 m3 The ex ternal container with a spherical bottom part was 0 1m higher than the internal container which provided the falling of the internal container practically without aero dynamic air resistance by which a low rate of residue acceleration in the internal container during the free falling was reached One of the walls of both containers was transparent Through these walls the filming of the burning process via the camera with electric magnet starter was practiced Samples of fabric and sheet ma terials in the inner container could be placed in any position from horizontal to vertical The sample of material was inflamed in a pre set point via a high voltage discharge created between two electric diodes which were placed from two sides of the material The free falling container with the help of which experiments of studying the combustion process of materials on the quantitative level with calculation of velocity limit values of a gas flow for combustion of materials Vlimalso includes two containers An internal container was made in two versions During the calculation of Vlimvalues under flow velocity less than 0 15 m s 8 9 the system providing equal motion of the sample against the calm gas environment was used During the calculation of Vlimvalues under flow velocity less than 0 15 m s 8 9 the system providing equal motion of the gas environment against the burning fastened sample was used The sample represented a plate with the size 50 8 mm Experiments were practiced with samples if 1 2 3mm thick The burning process was filmed The free falling container was placed at the height of 3 2m from shock receiving device placed on the floor The time of zero gravity during the free falling was 0 72 s Experiment method was the following the system of two containers was hung via releaser The internal container was filled with nitro oxygen environment with a specified oxygen concentration The sample was inflamed and the filming was started After reaching a steady combustion of the sample the releaser was turned on and the container during 0 72 s was in zero gravity The camera the electric motor of the system having provided the motion of the sample and the releaser were switched on in necessary moments of time via electric magnetic ac tuation units I A Bolodyan et al Acta Astronautica 163 2019 6 17 7 3 3 Research method of combustion process of polymeric materials in conditions imitating zero gravity on the experimental unit Ploskiy kanal Research of the combustion process in zero gravity is connected with considerable technical difficulties and material costs That is why the design of methods imitating combustion of materials in zero gravity in conditions of gravitation action without creating zero gravity conditions was currently important The studies carried out in this direction found that the most prospective method is when the com bustion process is implemented in a flat horizontal movable gas layer which lies between these two planes In works 28 29 it was shown that the decrease of a flat horizontally orientated gas layer made it possible to practice a heat transfer process equal to conductive which means that it practically excludes natural convection This provision makes it possible to practically absolutely reduce a vertical movement of the gas environment in a flame zone in a flat horizontally orientated moving gas layer and study the combustion process of materials in conditions imitating zero gravity 11 12 There are to circumstances which made it possible to calculate the height of horizontally or ientated two dimensional duct under which the combustion of samples of materials under gravity proceeds in the same way as in zero gravity Firstly it was determined 14 20 that on the limit conditions of polymeric materials combustion in nitro oxygen mix under oxygen concentration from 15 to 100 and pressures from 0 001 to 0 1 MPa maximum temperature in a fire zone is practically a constant value and does not depend on the type of material Secondly relative efficiency of a lifting force causing natural convection movement of the environment during the combustion in the zone of a limited size is characterized by Grashof number If gravity acceleration maximum temperature in the fire area and environment viscosity of under the maximum temperature in the fire area are considered as constant values the intensity of nat ural convection will be defined by the height of the horizontally or iented two dimensional duct Basing on the results of comparison of Vlimvalues of different materials calculated in the free falling container and 8 9 and in horizontally orientated two dimensional duct of dif ferent height 11 12 it was determined that Vlimvalues of polymeric materials are coincided under the height hkof the two dimensional duct calculated from the equation hk 0 49 Cox 0 3P 0 5 1 where Cox is a volume ration of oxygen in the gas environment Pen o component characterizing the pressure of the gas en vironment o atmosphere pressure Pen MPa gas environment pressure during the experiment MPa The found correlation subsequently was confirmed by results of comparison of Vlimvalues of materials with different physical chemical and physical mechanical properties defined in horizontally orientated two dimensional duct and on EU Skorost on the Mir station 11 In order to decrease the error of calculation of Vlimvalues of poly meric materials for zero gravity conditions on EU Ploskiy kanal this method and EU itself were improved The idea of the method was in equal movement of the burning sample of the material against the calm gas environment in opposition to initial device EU Ploskiy kanal with motion of gas environment movement against the fixed sample EU Ploskiy kanal is protected by the patent 12 The work of calculation Vlimvalue via the proposed device was carried out as follows Climof material under the given environment pressure was calculated With the help of the EU described in the paper 14 Climvalue of the material was calculated under the given en vironmental pressure Vlimvalue of the material was calculated if Clim value was of lower oxygen concentration under which the material would be used in InPC SC Depending on Coxand Penspecified in the experience the height of the burning chamber hkwas calculated ac cording to the formula 1 Samples of monolithic materials were made in the form of plate of 60 x8x 1 3 mm size Samples of fabrics and films were made in the form sheets of 60 30mm size Nitrogen oxygen mix with the specified concentration of oxygen and pressure was created The end face of the sample moved in the two dimensional duct after its ignition from the electric coil The moving sample was filmed The camera recorded the form and the size of the flame and also the condition of the burning sample of the material deformation melting etc The value of Vlimwas specified as the average index between the moving velocity of the burning sample under which the burning of the sample continued during the time it crossed the whole length of the burning chamber or if the sample burnt not less than 20s and the moving velocity of the sample of 10 less than the one under which the combustion of the sample was stopped during moving in the duct or for the time less 20 s 3 4 Research method of the combustion process of polymeric materials in zero gravity conditions on the experimental unit Skorost on the Mir orbital space station In order to confirm research results obtained on the first stage of work in the given direction and to specify the efficiency of new tech nologi