阅读说明：本技术 火箭发动机内气-液两相热流密度测量工装 (Tool for measuring density of gas-liquid two-phase heat flow in rocket engine ) 是由 关轶文 于 2020-07-14 设计创作，主要内容包括：本发明提出一种火箭发动机内气-液两相热流密度测量工装,该测量工装包括测温基体材料和周向绝热材料,测温基体材料嵌入到周向绝热材料内；在测温基体材料内预埋多个热电偶作为测点,热电偶的埋设方向垂直于火箭发动机内气流传热方向,相邻热电偶相向错开布设且等间隔,所有热电偶的工作端处在一条直线上。本发明基于集总电容思路,设计了一种用于动态实时测量固体火箭发动机内部气-液两相热流密度的测量工装,将测温基体材料嵌入到周向绝热材料内,在测温基体材料内预埋多个热电偶作为测点,将其用在火箭发动机内颗粒冲刷或沉积位置处,可以实现在发动机高温高压等残酷恶劣环境中长时间生存的目的。(The invention provides a measuring tool for gas-liquid two-phase heat flux density in a rocket engine, which comprises a temperature measuring base material and a circumferential heat insulating material, wherein the temperature measuring base material is embedded into the circumferential heat insulating material; a plurality of thermocouples are pre-buried in the temperature measurement base material to serve as measuring points, the burying direction of the thermocouples is perpendicular to the airflow heat transfer direction in the rocket engine, the adjacent thermocouples are oppositely arranged in a staggered mode at equal intervals, and the working ends of all the thermocouples are located on the same straight line. The invention designs a measuring tool for dynamically measuring gas-liquid two-phase heat flow density in a solid rocket engine in real time based on a lumped capacitor thought, a temperature measuring base material is embedded into a circumferential heat insulating material, a plurality of thermocouples are embedded into the temperature measuring base material to serve as measuring points, and the measuring points are used at positions of particle scouring or deposition in the rocket engine, so that the purpose of long-time survival in harsh environments such as high temperature and high pressure of the engine can be realized.)

1. A tool for measuring the density of gas-liquid two-phase heat flow in a rocket engine is characterized by comprising a temperature measuring base material and a circumferential heat insulating material, wherein the temperature measuring base material is embedded into the circumferential heat insulating material;

a plurality of thermocouples are pre-buried in the temperature measurement base material to serve as measuring points, the burying direction of the thermocouples is perpendicular to the airflow heat transfer direction in the rocket engine, the adjacent thermocouples are oppositely arranged in a staggered mode at equal intervals, and the working ends of all the thermocouples are located on the same straight line.

2. The rocket engine internal gas-liquid two-phase heat flow density measurement tool of claim 1, wherein the distance from the closest measurement point to the temperature measurement substrate surface is 1-6mm from the temperature measurement substrate surface.

3. A rocket engine internal gas-liquid two-phase heat flux density measuring tool as recited in claim 1, wherein said measuring tool is disposed at a location of particle erosion or deposition in the rocket engine.

4. The tool for measuring the density of the gas-liquid two-phase heat flow in the rocket engine according to claim 1, wherein an epoxy resin adhesive layer is arranged on the periphery of the temperature-measuring base material, a hole is formed in the center of the circumferential heat-insulating material so that the temperature-measuring base material is embedded in the hole in the center of the circumferential heat-insulating material in an interference manner, and a lead of the thermocouple is arranged along the inner wall of the temperature-measuring base material and is finally led out through a sealing plug at the position where.

5. The rocket engine internal gas-liquid two-phase heat flow density measurement tool of claim 1, wherein the temperature measurement substrate material is high temperature resistant graphite; the circumferential heat-insulating material is made of EPDM heat-insulating material; the thermocouple is a thin wire type K-type thermocouple.

Technical Field

The invention relates to a heat flow measurement technology, in particular to a tool for measuring the density of gas-liquid two-phase heat flow in a rocket engine.

Background

In the working process of the solid rocket engine, the violent combustion of the propellant can generate 2500-3900K high-temperature and high-speed gas flow, and the heat flow generated by the high-temperature gas seriously ablates the heat protection material of the engine. Meanwhile, condensed phase particles in the combustion products can cause serious erosion and scouring to the submerged section and the convergent section of the spray pipe, so that the heat load of the engine is greatly increased. In order to ensure that the rocket engine can maintain normal operation under severe thermal environment conditions and the spacecraft cannot be burnt out due to external heating environment in the process of ascending and reentry, various thermal protection materials are required to absorb and dissipate various heating effects. As one of the root problems of thermal protection of solid rocket engines, heat flow measurement is a common means for mastering the wall thermal environment.

Current heat flow measurement techniques commonly use the assumption of one-dimensional heat transfer, with heat being transferred in the wall normal or wall direction. According to the fourier law, when heat is transferred in the direction of the wall surface, a temperature gradient exists in the wall surface, and therefore the influence of the wall surface temperature on the heat flow cannot be studied. The heat flow measurement techniques that are transferred in the normal direction include transient measurement techniques and steady state measurement techniques. For long-time and high-heat-flow test measurement, the transient measurement technology cannot be applied. The steady-state heat flow measurement technology transmitted along the normal direction is divided into two types, 1) the water calorie calorimeter based on the energy balance principle, the response time of the water calorie calorimeter is usually from several seconds to tens of seconds, and the requirement of quick response cannot be met. 2) The thermal resistance type heat flow sensor generally forms thermocouple joints on two sides of a non-metal thermal resistance layer, and simultaneously measures the surface temperature and the heat flow. However, when the non-metal thermal resistance layer is connected with a metal water-cooling or heat sink structure, obvious thermal contact resistance exists, and the method is not suitable for megawatt square meter heat flow and long-time test when megawatt square meter heat flow is measured in a long-time test.

Some researchers in China explore the temperature and heat flow measurement in long-time tests based on the thermal resistance type heat flow test principle.

Research on the processes of radiation, heat conduction and boundary coupling convection heat transfer in a one-dimensional semitransparent plate is carried out by LisIntiman, Harbin Industrial university, and the like, and a method for inverting the incident radiation heat flow density of the other side boundary by the emergent radiation intensity of the one side boundary is provided. The Shuai Y and the like adopt MCM (Monte Carlo method) to research the radiant heat property of the spherical heat absorption cavity and provide the distribution rule of the heat flux density of the focal plane. Chen cheng zao etc. introduced lumped hot melt formula transient state radiation heat flow meter, and general radiation type heat flow meter adopts the design of thermal balance method, can not use in the thermal current that measures the change, lumped hot type heat flow meter is makeed the side head of heat flow meter by the thin copper sheet that the surface is scribbled black, and the copper sheet back is adiabatic, is influenced by test head hot melt, and its dynamic response characteristic is also relatively poor, consequently measurable transient state thermal radiation heat flux density.

In summary, related research work is carried out in the aspects of design of heat flow meters and measurement of heat flows at home and abroad, but the design of the heat flow meters and the measurement of the heat flows in the solid rocket engine are less, the test means are different greatly, influence factors are considered less, and the conclusion difference is larger.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a measuring tool for dynamically measuring the heat flux density under a gas-liquid two-phase scouring environment in the working process of a solid rocket engine in real time, in particular to the measurement of the heat flux density under the conditions of overload, deposition and the like caused by gas-liquid two-phase flow aggregation.

In order to solve the technical problems, the invention adopts the following technical scheme:

a measuring tool for the density of gas-liquid two-phase heat flow in a rocket engine comprises a temperature measuring base material and a circumferential heat insulating material, wherein the temperature measuring base material is embedded into the circumferential heat insulating material;

a plurality of thermocouples are pre-buried in the temperature measurement base material to serve as measuring points, the burying direction of the thermocouples is perpendicular to the airflow heat transfer direction in the rocket engine, the adjacent thermocouples are oppositely arranged in a staggered mode at equal intervals, and the working ends of all the thermocouples are located on the same straight line.

Preferably, the measuring point closest to the surface of the temperature measuring base material is 1-6mm away from the surface of the temperature measuring base material.

It is emphasized that the measurement tooling is located at a particle washout or deposit location within the rocket engine.

Specifically, an epoxy resin adhesive layer is arranged on the periphery of the temperature measuring base material, a hole is formed in the center of the circumferential heat insulating material, so that the temperature measuring base material is embedded in the hole in an interference mode, and a lead of a thermocouple is arranged along the inner wall of the temperature measuring base material and is finally led out through a sealing plug at the position where particles in the rocket engine are washed away or deposited.

Preferably, the temperature measurement substrate material is graphite; the circumferential heat-insulating material is made of EPDM heat-insulating material; the thermocouple is a thin wire type K-type thermocouple.

After the gas-liquid two-phase heat flux density measuring tool in the rocket engine measures the temperature response values of N thermocouples in real time, wherein N is a natural number, the real-time heat flux density is obtained according to the following method;

and (3) calculating the heat flux density by using the temperature response value of the thermocouple:

q_Mheat flow density, q, representing M time steps^*For estimating the heat flow density value, the heat flow value is calculated by M-1 time step length, Y_k,MThe temperature response value of the kth node M in time step is obtained by thermocouple reading,

the estimated temperature value of the kth node M in time step is an assumed value and is obtained by inverse derivation, X_kRepresenting the sensitivity coefficient, X, of the kth measurement point_kIs between 0 and 1.

Compared with the prior art, the invention has the following technical effects:

1. the invention designs a measuring tool for dynamically measuring gas-liquid two-phase heat flow density in a solid rocket engine in real time based on a lumped capacitor thought, a temperature measuring base material is embedded into a circumferential heat insulating material, a plurality of thermocouples are embedded into the temperature measuring base material to serve as measuring points, and the measuring points are used at positions of particle scouring or deposition in the rocket engine, so that the purpose of long-time survival in harsh environments such as high temperature and high pressure of the engine can be realized.

2. The device can avoid the measurement error caused by material pyrolysis and ablation by using a high-temperature-resistant metal heating body and a heat flow measurement means of pre-burying a thermocouple inside the device, and meanwhile. The defect that the Gordan heat flow meter is easy to damage is overcome, and meanwhile, the structure is simple and the installation is realized. Is convenient to use.

3. The heat flow density value can be calculated by measuring the particle heat flow and the wall surface temperature, and an experimental basis is provided for establishing a thermal boundary condition in numerical calculation, so that the research on the ablation mechanism of the heat insulation layer is facilitated.

Drawings

FIG. 1 is a schematic view of a measurement tool of the present invention.

FIG. 2 is an assembly view of the measuring tool of the present invention.

FIG. 3(a) is the temperature response curve of the first 5 measuring points in the experiment of the present invention, and (b) is the temperature response curve of the second 5 measuring points in the experiment of the present invention.

Fig. 4 is a graph of heat flux density measured in experiment one and experiment two of the present invention.

In the figure, 1 is a graphite heat measuring body, 2 is a heat insulating material, 3 is a thermocouple, 4 is a tetrafluoro plug, and 5 is a thermocouple mounting hole.

The present invention will be explained in further detail with reference to examples.

Detailed Description

Specific examples of the present invention are given below, and it should be noted that the features of the examples and examples of the present invention may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. Any specific values in all examples shown and discussed herein are to be construed as exemplary only and not as limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

In the description of the present invention, it is to be understood that the orientation or positional relationship indicated by the directional terms such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal" and "top, bottom", etc., are generally based on the orientation or positional relationship shown in the drawings, and are used for convenience of description and simplicity of description only, and in the absence of any contrary indication, these directional terms are not intended to indicate and imply that the device or element so referred to must have a particular orientation or be constructed and operated in a particular orientation, and therefore should not be considered as limiting the scope of the present invention: the terms "inner and outer" refer to the inner and outer relative to the profile of the respective component itself.

Spatially relative terms such as "above … …", "above … …", "above … …", "above", "circumferential", and the like, may be used herein for ease of description to describe the spatial relationship of one device or feature to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

It should be noted that the terms "first", "second", and the like are used to define the components, and are only used for convenience of distinguishing the corresponding components, and the terms have no special meanings unless otherwise stated, and therefore, the scope of the present invention should not be construed as being limited.

The thermocouple of the invention is a common temperature measuring element in a temperature measuring instrument, directly measures temperature, converts a temperature signal into a thermal electromotive force signal, converts the thermal electromotive force signal into the temperature of a measured medium through an electric instrument (a secondary instrument), generally consists of main parts such as a thermode, an insulating sleeve protection tube, a junction box and the like, is usually matched with a display instrument, a recording instrument and an electronic regulator for use, and directly uses one end for measuring the temperature of the medium as a working end (also called a measuring end) and the other end as a cold end (also called a compensation end); the cold end is connected with a display instrument or a matched instrument, and the display instrument can indicate the thermoelectric force generated by the thermocouple.

The invention selects the measuring tool parts according to the following principle:

1. selection of temperature measurement base material

The first thing to be faced when designing the temperature measurement component is the selection of the material of the heat measuring body. According to the design principle based on the lumped capacitance method, the difference of the thermal diffusivity of the calorimetric body and the temperature measuring element cannot be too large, and if the thermal diffusivity of the temperature measuring element is large and the thermal diffusivity of the calorimetric body is low, the temperature measuring element can generate large interference on heat transfer near a measuring point, so that large errors are introduced to the heat flow inversion calculation. In addition, the physical and chemical properties of the calorimetric body are relatively stable, the physical parameters cannot be changed greatly under high temperature conditions, and the calorimetric body cannot generate large heat absorption or heat release due to thermal decomposition or chemical reaction. The heat insulating material belongs to a carbonized material, thermal decomposition and carbonization can be generated when the heat insulating material is heated, the thermal decomposition and heat absorption can greatly influence temperature measurement, parameters such as density, heat conductivity coefficient and the like after carbonization can be greatly changed, the contact state of a temperature measuring element can be changed after carbonization, and the difference between the thermal diffusion coefficient of the heat insulating material and the temperature measuring element is large, so the heat insulating material is not suitable for being used as a heat measuring body. The graphite belongs to a non-carbonized material, has more stable physical and chemical properties, has the advantages of high temperature resistance and ablation resistance, and is more suitable to be used as a calorimetric body.

2. Circumferential thermal insulation design of temperature measurement base material

The heat flow inversion performed by the heat conduction inverse problem calculation method is based on the quasi-one-dimensional assumption, and the heat transfer of the side wall surface of the heat measurer brings large errors to the measurement result. The graphite heat measurer is embedded into the integral EPDM heat insulating material, so that the influence caused by lateral heat conduction is reduced to the maximum extent.

3. Selection of thermocouple

The choice of what temperature sensing element is critical to the overall temperature sensing process. From the analysis of the heat conduction inverse problem calculation principle, it can be known that the response rate of temperature measurement has a large influence on the final result, and therefore, the temperature measurement element is required to have a high temperature response rate. In addition, because the density of gas-liquid two-phase scouring heat flow in the solid engine is relatively high, and the thermal diffusion coefficient of the calorimetric body is relatively high, the temperature of a measuring point which is closer to the surface of the calorimetric body is higher, and the temperature measuring element is required to have a relatively large measuring range. Therefore, the experiment selects the thin-wire type K thermocouple with better temperature response characteristic as the temperature measuring element, and reduces the size of the thermocouple measuring point as much as possible on the premise of ensuring the stable and reliable work of the thermocouple. And a high-temperature-resistant heat-shrinkable tube is used for covering in the mounting process so as to prevent short circuit between thermocouple wires or with a graphite heat measurer.

4. Thermocouple measuring point arrangement design

From the theory of heat conduction inverse problem calculation, the surface heat flow can be calculated by inversion only by arranging a measuring point in the calorimeter, but the sensitivity analysis of the heat conduction inverse problem calculation shows that the sensitivity of the accuracy of the calculation result to the experimental measurement error is larger. Meanwhile, measurement errors caused by temperature measurement, heat loss, physical property parameter difference and the like are considered, and the heat flow error obtained by final inversion calculation is possibly very large. Therefore, researchers usually adopt a design form of arranging a plurality of temperature measuring points, and the invention arranges 5 measuring points. In addition, the position of the measuring point has certain influence on the measuring result, if the distance between the measuring point and the surface is too far, the temperature response in the working time is possibly very small, and therefore, the arrangement of the measuring point is close to the temperature measuring surface as far as possible under the condition that the temperature response does not exceed the range of the thermocouple. Meanwhile, the thermocouples are arranged at equal intervals, so that the calculation amount of later-stage heat flow inversion can be simplified, and finally determined measuring point positions are shown in fig. 1.

5. Thermocouple installation mode design

The installation mode of the thermocouple also has certain influence on the measurement result. If the thermocouple is arranged along the longitudinal direction (heat transfer direction), the longitudinal position of the thermocouple measuring point after installation can not be accurately ensured, and the thermocouple can bring heat conduction loss, so the invention adopts a transverse arrangement mode as shown in figure 1. The longitudinal position of the measuring point in the arrangement mode is limited by the aperture, and the aperture can be smaller during processing, so that the longitudinal position of the measuring point can be ensured accurately, and the longitudinal position deviation caused by vibration of an engine during working can be avoided. In addition, the thermocouples are arranged along the direction close to the isotherm, so that the heat conduction loss can be greatly reduced. After a thermocouple is installed in a graphite calorimetric body measuring hole, graphite powder is used for filling a gap in the measuring hole so as to reduce the influence of a tiny cavity on heat transfer of the calorimetric body and reduce the error of heat flow inversion.

Finally, the heat flux measuring device designed by the invention can finally obtain the heat increment of the point brought by gas-liquid two-phase scouring in the working process of the solid rocket engine.