Method of determining spatial distribution of temperature in heat-shield structures

FIELD: measuring technique.

SUBSTANCE: method comprises heating the heat-shield structure from one side up to a high temperature, cooling the structure, applying marker dots on the section of the outer surface under study, cutting the axisymmetric specimens of the heat-shield structure, applying marker dots on the side of the specimen at a given distance from the inner surface, cutting the specimen over the planes perpendicular to its longitudinal axis and passing through the marker dots into pieces, subsequent heating of the pieces in the atmosphere of an inert gas, recording the change of weight of the pieces, recording the temperature of the beginning of the decrease of weight of each piece, and judging on the spatial temperature distribution from data obtained.

EFFECT: expanded functional capabilities.

5 dwg

 

This invention relates to the field of temperature measurement, in particular, to determine the spatial temperature distribution in the heat-shielding structures subjected to high temperature one-sided heating, and can be used when developing thermal protection re-entry spacecraft.

Composite materials based on thermosetting polymers are textolite with a layered filler in the form of, for example, asbestos cloth or fiberglass different types of weaving, impregnated as a binder resin, such as epoxy, epoxy-novolak, phenol, phenol-held polymerization for formation. The efficiency of heat structures made of composite materials based on thermosetting polymers associated with low heat conductivity, and absorption of heat input due to thermal effects thermal decomposition of the binder. Due to the irreversibility of the process of thermal decomposition of the heat shield is disposable and not used again. When experimental development of disposable heat structures made of composite materials based on thermosetting polymers is the problem of determining the spatial distribution of temperature after high-temperature heating when room is different, for example, if the entry of space vehicles into the dense layers of the atmosphere or bench trials. The task is usually solved by installing temperature sensors such as thermocouples between the layers of glass(Asbo)fabrics in forming the heat-shielding design by pressing. Coordinates at the mounting location of thermocouples in the formed heat-shielding design known with low precision, and the presence of thermoelectrodes between layers of heat-shielding design leads to a distortion of the field temperature. The influence of these factors increases the accuracy of determining the spatial temperature distribution in the heat-shielding design. In addition, the introduction of termoelektrodnye wire violates the integrity and structure of the heat-shielding design that can result in operational terms, to the delamination of the material during heating and simultaneous loading and, in the case of monitoring thermal performance of standard products to the need to upgrade its canals measure and record the temperature.

In connection with the foregoing, the determination of the spatial temperature distribution in the heat-shielding structures subjected to unilateral high-temperature heat without compromising their integrity and structure during fabrication is relevant.

There is a method of measuring spatial is raspredeleniya temperature (patent RF №2194956 IPC 7: G 01 K 7/00, 2002), which consists in applying on the analyzed heated object controlled points, the location of many temperature-sensitive sensors, the reading of which is judged on the spatial temperature distribution in the object.

The disadvantage of this method is the impossibility of determining the spatial temperature distribution in the heat-shielding structures from composite materials based on thermosetting polymers without compromising their integrity and structure in manufacturing.

There is also known a method of determining the spatial temperature distribution in the heat-shielding structures from composite materials based on thermosetting polymers, adopted for the prototype ("thermal deformation of non-metallic destructively materials", Hinterlaces, Ligacheva, publishing house "Naukova Dumka", 1983, str-121), which consists in applying to the sample heat-shielding design of controlled points, high temperature heating of the sample, during which measure the temperature in the controlled points allocated to them by the sensors, the readings of which are judged on the spatial temperature distribution in the sample heat-shielding design.

The disadvantage of this method is the impossibility of determining the spatial distribution and the Oia temperatures in heat structures made of composite materials based on thermosetting polymers without compromising their integrity and structure in manufacturing.

The technical result of the invention is the ability to determine the spatial temperature distribution in the heat-shielding structures from composite materials based on thermosetting polymers without compromising the integrity and structure in their manufacture.

The technical result is achieved in that in the method of determining the spatial temperature distribution in the heat-shielding structures from composite materials based on thermosetting polymers, consisting of high-temperature heating of the sample heat-shielding design and the application to it of controlled points, after cooling in heat structures subjected to high temperature one-sided heating, put the finer points of interest the area of the external surface of the heat-shielding design, cut across the whole width of axisymmetric specimens, the longitudinal axes of which are controlled through the point and perpendicular to the surface of the heat-shielding design, then the finer points applied on the lateral surface of each cut sample at a given distance from the inner surface of the heat-shielding design, cut each sample on the sample on the planes perpendicular to its longitudinal axis and passing through the finer points, cereno heated each sample in inert gas, by registering the change in her weight, record the temperature of the beginning weight of each sample, they will judge sought the spatial distribution of temperatures.

The essence of the method is illustrated presents drawings. Figure 1 schematically shows a frontal section of a product with a pre-installed heat-shielding design and shows the direction of influencing the heat flux q. Figure 2 schematically presents a view of the left heat structures subjected to high temperature one-sided heating. Figure 3 presents one of the samples cut the entire thickness of the heat-shielding design. Figure 4 presents, for one sample, depending on the temperature relative weight change in weight - G/G0, where G is the weight of the sample during heating, G0- the weight of the sample before heating. Figure 5 presents, for one sample, the temperature distribution through the thickness (Z-axis).

Product 1 set heat-proof design 2. Interesting plot 3 the surface of the heat-shielding design 2 applied controlled point 4. Axisymmetric samples 5 cut the entire thickness of the heat-shielding design 2, on the side surface of each cut sample caused the finer points 6 at a given distance Z1Z2Z3...Z8from what nutrena the surface of the heat-shielding design 7. Sample 5 is cut along the plane 8 perpendicular to its longitudinal axis Z and passing through the finer points 6, in sample 9.

The method consists in the following. It is known that composite materials based on thermosetting polymers in the temperature range thermal properties are characterized by having at each value of temperature equilibrium (marginal) density values (see Offchance "Thermal properties of glass-reinforced plastics", Moscow, publishing house "Chemistry", 1973, p.64-68). The decomposition thermosetting polymers occurs in the temperature range 250-950°C, and the density of the composite material decreases due to the intense release of gaseous products of decomposition and formation of coke residue. The equilibrium value of the density at each temperature is characterized by the number of decayed to coke residue material and is achieved by slow heating to this temperature or exposure at this temperature. Each layer heat-shielding design, slow cooling after high-temperature heating in conditions of full-scale or bench tests, reaches the equilibrium value of the density at the corresponding temperature. If a thin sample, subjected to preliminary uniform thickness heating to a predetermined temperature, to cool and then re-heat, when reaching this temperature will continue the process of destruction and the weight of the sample will begin to decrease. Thus, if the sample is cut on the entire thickness of the heat-shielding design, previously subjected to unilateral high-temperature heat, cut into thin layers with a known coordinate of each layer thickness of the sample and hold their re-heating with the temperature of the beginning of the weight change of each layer, it is possible to reconstruct the temperature distribution along the thickness of the heat-shielding design. Having the temperature distribution along the thickness of the heat-shielding design for a number of samples with known coordinates their longitudinal axes on the surface of the heat-shielding design, you can restore to select a part of the heat-shielding design spatial (three-axis), the temperature distribution.

The proposed method is implemented as follows.

After cooling applied to the product 1 heat-shielding design 2, subjected to high-temperature one-sided heating, put on interesting plot 3 the outer surface of the heat-shielding design 2 controlled point 4 with known coordinates. On the whole thickness of the heat-shielding design 2 cut axisymmetric, for example, cylindrical samples 5, the longitudinal axes of which pass through to strairway point 4 and perpendicular to the surface of the heat-shielding design 2. Samples cut out on the possibility of a smaller cross-section (diameter), so that when thermovacuum analysis of sub-samples to reduce the error in determining the temperature distribution along the Z axis, associated with the presence of a temperature gradient along the axes X and Y in the heat of the structure during in situ heating. Put the finer points 6 on the side surface of each cut sample 5 at a given distance from the inner surface of the heat-shielding design 7. Cut each sample 5 sample 9 by 8 planes perpendicular to its longitudinal axis Z and passing through the finer points 6. Turn heat up each of the investigated sample 9 in the chamber thermovision filled with an inert gas. It is not necessary to heat the entire sample 9 as a whole, it is enough to separate from her part in a plane parallel to the longitudinal axis of the sample 5 to the study material from the entire thickness of the sample 9 participated in thermovacuum analysis. The weight of the investigated part of the hinge 8 is selected based on the sensitivity thermovision, which is thermovisual the analysis, with the heating rate of the sample in the chamber dermavisu is chosen from the condition that the temperature difference across the thickness of the sample should not exceed 5°C. In practice, the heating rate should not exceed 1-2°C. the Requirement that heating of the sample was carried out in the environment inert the CSOs gas, due to the fact that in conditions of full-scale one-sided heating of the inner layers of thermal insulation material located in the environment of evolved gaseous products of thermal decomposition and are not in contact with atmospheric oxygen. Thermal-oxidative degradation during high-temperature heating of the investigated sample will lead to distortion of the results termolecular analysis that will make a significant error in determining the temperature of the beginning weight of the sample and, accordingly, in determining the spatial distribution of temperatures.

In the process of heating register the change in weight of the sample (part of the hinge) and record the temperature of the beginning of the reduction of its weight on the chart recording instrument weighing device, for example, in the coordinates of G/G0-T (Figure 4). So spend thermovisual analysis of each sample. Next, build the temperature distribution across the thickness of each sample is presented in figure 5. As for any thickness of the sample in terms of one-sided heating Z-axis existed temperature gradient, its decomposition when heated in the chamber thermovision will begin with a less heated in situ Foundation sample from the inner surface of the heat-shielding design. In this regard, the value of the fixed temperature at the start thermodestruction and for sample thickness Z 1refer to the coordinate Z=0, for a sample thickness Z2for Z1etc.

Having the temperature distribution along the thickness of the samples cut from the area of interest 3 heat-shielding design 2, the longitudinal axes of which pass through the finer points 4 with known coordinates on the surface of the heat-shielding design, determine the desired spatial temperature distribution.

Thus the task of determining the spatial temperature distribution in the heat-shielding structures from composite materials based on thermosetting polymers without compromising the integrity and structure in their manufacture.

The method of determining the spatial temperature distribution in the heat-shielding structures from composite materials based on thermosetting polymers, consisting of high-temperature heating of the sample heat-shielding design and the application to it of controlled points, wherein after cooling the heat-shielding design, subjected to high-temperature one-sided heating, put the finer points of interest the area of the external surface of the heat-shielding design, cut across the whole width of axisymmetric specimens, the longitudinal axes of which pass through the finer points and perpendicula what are the surface heat-shielding design, then put the finer points on the side surface of each cut sample at a given distance from the inner surface of the heat-shielding design, cut each sample to sample on the planes perpendicular to its longitudinal axis and passing through the finer points, alternately heating each sample in inert gas, registering the change in her weight, record the temperature of the beginning weight of each sample, they will judge sought the spatial distribution of temperatures.



 

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