阅读说明：本技术 一种热流计动态特性校准装置及方法 (Device and method for calibrating dynamic characteristics of heat flow meter ) 是由 田牧野 刘志鹏 徐强 马虎 于 2020-07-22 设计创作，主要内容包括：本发明属于传感器校准领域,具体涉及一种热流计动态特性校准装置及方法。包括爆震管,爆震管两端均设有端盖,一侧的端盖上设有用于点火的火花塞,相对的另一侧端盖上连接有相邻设置的待测热流计和标准热流计,在距离热流计最远处的端盖上安装有一个端口由膜片密封的长管作为泄压出口；所述爆震管可拆卸的连接有排气机构,燃气供给机构和氮气供给机构。本装置同时对热辐射和对流换热过程,进行研究和校准,既保证了瞬态热流传感器能获得可靠、准确的热流测试数据,同时也为热流传感器研制和性能评价提供可行的动态校准办法。(The invention belongs to the field of sensor calibration, and particularly relates to a device and a method for calibrating dynamic characteristics of a heat flow meter. The detonation tube comprises a detonation tube, end covers are arranged at two ends of the detonation tube, a spark plug for ignition is arranged on the end cover at one side, the end cover at the other opposite side is connected with a heat flow meter to be tested and a standard heat flow meter which are adjacently arranged, and a long tube with a port sealed by a diaphragm is arranged on the end cover at the farthest position away from the heat flow meter and serves as a pressure relief outlet; the detonation tube is detachably connected with an exhaust mechanism, a fuel gas supply mechanism and a nitrogen gas supply mechanism. The device simultaneously researches and calibrates the heat radiation and convection heat exchange processes, ensures that the transient heat flow sensor can obtain reliable and accurate heat flow test data, and provides a feasible dynamic calibration method for heat flow sensor development and performance evaluation.)

1. The utility model provides a heat flow meter dynamic characteristic calibrating device, its characterized in that, includes detonation tube (2), detonation tube (2) both ends all are equipped with the end cover, are equipped with spark plug (8) that are used for the ignition on the end cover of one side, are connected with the heat flow meter and the standard heat flow meter of awaiting measuring of adjacent setting on the relative other side end cover, install a port on the end cover of the farthest department apart from the heat flow meter and regard as pressure release export (9) by the sealed long tube of diaphragm.

2. The calibration device according to claim 1, wherein the detonation tube (2) is removably connected with exhaust means, gas supply means and nitrogen supply means;

the vacuumizing mechanism is used for vacuumizing the detonation tube (2), the fuel gas supply mechanism is used for supplying fuel gas to the detonation tube, and the nitrogen gas supply mechanism is used for replacing gas in the tube, cooling and protecting a heat flow meter.

3. The calibration device according to claim 2, wherein the detonation tube (2) is a copper tube having a diameter of 40-60 mm and a length of 1200-1500 mm.

4. A calibration device according to claim 2, wherein the exhaust means comprises a vacuum pump (1), the vacuum pump (1) being detachably connected to the detonation tube (2) by means of a manual valve.

5. The calibration device according to claim 4, characterized in that the gas supply means comprise a oxyhydrogen tank (4), the oxyhydrogen tank (4) being detachably connected to the detonation tube (2) in sequence through a manual valve, a flow-limiting throat, an anti-tempering valve and an explosion-proof solenoid valve.

6. The calibration device according to claim 5, wherein the nitrogen supply mechanism comprises a nitrogen tank (10), the nitrogen tank (10) is divided into two air pipes after being sequentially connected with a pressure reducing valve (11), a flow limiting throat and an electromagnetic valve, one air pipe is sequentially connected with an end cover where a fire-proof valve, a manual valve and a spark plug (8) are located, and the other air pipe is sequentially connected with one end, close to a heat flow meter, of a detonation pipe (2) through the fire-proof valve, the manual valve and the detonation pipe.

7. Calibration device according to claim 1, characterized in that the standard heat flow meter is a HFM-type heat flow sensor.

8. The calibration device of claim 6, further comprising a data collector for collecting data.

9. A method of calibrating the dynamics of a heat flow meter using the calibration device of any one of claims 1-8, the method comprising the steps of:

step (1): the vacuum pump vacuumizes the interior of the detonation tube (2), and when the pressure in the tube meets the requirement, the tube is closed by the manual valve (3);

step (2): injecting mixed gas of hydrogen, oxygen and nitrogen into the detonation tube through a flow-limiting throat, arranging a one-way valve in a pipeline connecting a hydrogen-oxygen tank and the detonation tube to prevent backfire, closing an electromagnetic valve after the pressure in the detonation tube meets the requirement, and separating the pipeline;

and (3): in the experiment, a spark plug (8) is ignited to generate pulse type detonation waves, the pulse type detonation waves are discharged from a pressure relief outlet (9), and a heat flow meter measures data;

and (4): meanwhile, nitrogen is slowly injected into the detonation tube through a pressure reducing valve (11), so that on one hand, gas in the detonation tube is replaced, and on the other hand, a heat flow meter is cooled and protected;

and (5): after the experiment is finished, the two heat flow meters compare data and are automatically calibrated by transient calibration software.

10. The method of claim 9, wherein the transient calibration software is calibrated using a comparative method, specifically using the following formula:

in the formula: c-coefficient of calibrated heat flow sensor

C₀-coefficients of standard heat flow sensors

q-heat flow density

E-output potential of calibrated heat flow sensor

E₀Output of a standard heat flow sensorAnd (4) discharging the potential.

Technical Field

The invention belongs to the field of sensor calibration, and particularly relates to a device and a method for calibrating dynamic characteristics of a heat flow meter.

Background

With the development of science and technology, people increasingly require measuring dynamic non-electricity or non-electricity during exercise. For example, measurement of transient temperatures and pressures of certain parts of aeronautical and aerospace vehicles, weighing of objects during handling or in motion; the magnitude and variation of cutting force are detected, the pressure in the bore of the gun, the heat flow of the engine knocking, the measurement of temperature transients and the like. If the dynamic performance of the sensor is not good, the measured change cannot be reflected quickly and accurately.

Sensor dynamics refer to the relationship between the output value measured by the sensor and the measured input value increment. A sensor with good dynamic characteristics, the output of which changes along with time, can simultaneously reproduce the input change along with time, namely, the same time function, which is an ideal requirement for the sensor in dynamic measurement. But in practice the output signal will not have exactly the same time function as the input signal except for the ideal scaling characteristic, and this difference between the output and input is known as the dynamic error. Any measurement system or device has an "intrinsic factor" that affects its dynamic behavior, except in a different form and degree of its behavior. For example, when a thermocouple is placed in water at 60 degrees celsius, the reading does not rise to this value immediately but gradually. At this stage of the rise, the difference between the thermocouple reading and the actual temperature is the dynamic error. This is because the thermal balance of the hot junction of the thermocouple and the water temperature requires a process. The improvement measure for reducing the measurement error by researching the dynamic characteristic of the sensor can reduce the phenomenon that the output is inconsistent with the input as much as possible and obtain the accurate rule of the change of the output along with the time.

The demand for transient heat flow meters is derived from the recognition of the urgent need for heat flow density under particular conditions. Researching the influence of aerodynamic force and thermal effect of the aircraft; in the experimental study considering the coupling effect of the aerodynamic thermal environment characteristics such as chemical unbalance and high-temperature gas effect and the thermal response of the material structure; the change process of instantaneous heat flow under special conditions (such as high overload, high pressure, high temperature and the like) needs to be mastered in the research of special fire behaviors, the evaluation of the problem of transient gas jet ablation in conventional weapons, the transient warm-pressing damage effect and the thermal safety of energetic materials, so that new requirements are provided for representing heat transfer, damage and protection efficiencies under the special conditions by adopting heat flow density, and higher requirements are provided for the aspects of dynamic performance, impact resistance, ablation resistance and the like of a heat flow sensor, which is a basic link of heat flow measurement. Due to the particularity of the temperature field and the transient variation of the temperature, the actual response time of the sensor is greatly different from a calibration value, and great difficulty is brought to the study of the temperature distribution rule of an unknown temperature field. For example, for a flame temperature field accompanied by high temperature, high pressure and high impact, such as detonation combustion, the temperature measuring environment is extremely complex, and it is obviously not feasible to describe the temperature change rule of the detonation process by only theoretical calculation. In recent years, most researchers have focused on the study of test methods and measuring devices in the explosion temperature test. However, some good conclusions have not yet been drawn and are only directed to the heat radiation process.

Disclosure of Invention

The invention aims to provide a device and a method for calibrating the dynamic characteristics of a heat flow meter, which are used for calibrating the heat flow meter to be calibrated by utilizing gas jet of a pulse detonation engine and the calibrated heat flow meter, and solve the problems that the conventional calibrating tool has a complex structure and high requirements on environment, the calibration process is mainly manually operated, the calibration precision is low, and the working efficiency is low.

The technical solution for realizing the purpose of the invention is as follows: the utility model provides a heat flow meter dynamic characteristic calibrating device, includes the detonation pipe, the detonation pipe both ends all are equipped with the end cover, are equipped with the spark plug that is used for the ignition on the end cover of one side, are connected with the heat flow meter and the standard heat flow meter that await measuring of adjacent setting on the relative other side end cover, install a port on the end cover apart from the heat flow meter furthest and export as the pressure release by the sealed long tube of diaphragm.

Further, the detonation tube is detachably connected with an exhaust mechanism, a fuel gas supply mechanism and a nitrogen gas supply mechanism;

the vacuumizing mechanism is used for vacuumizing the detonation tube, the fuel gas supply mechanism is used for supplying fuel gas to the detonation tube, and the nitrogen gas supply mechanism is used for replacing gas in the tube, cooling and protecting a heat flow meter.

Furthermore, the detonation tube is a copper tube with the diameter of 40-60 mm and the length of 1200-1500 mm.

Further, the exhaust mechanism comprises a vacuum pump which is detachably connected with the detonation pipe through a manual valve.

Furthermore, the fuel gas supply mechanism comprises an oxyhydrogen tank, and the oxyhydrogen tank is detachably connected with the detonation tube sequentially through a manual valve, a flow-limiting throat, an anti-tempering valve and an explosion-proof electromagnetic valve.

Furthermore, the nitrogen gas supply mechanism comprises a nitrogen gas tank, the nitrogen gas tank is divided into two air pipes after being sequentially connected with a pressure reducing valve, a flow limiting throat and an electromagnetic valve, one air pipe is connected with an end cover where a spark plug is located sequentially through a tempering prevention valve, a manual valve and the detonation pipe, and the other air pipe is connected with one end, close to the heat flow meter, of the detonation pipe sequentially through the tempering prevention valve, the manual valve and the detonation pipe.

Further, the standard heat flow meter is an HFM type heat flow sensor.

Furthermore, the system also comprises a data collector for collecting data.

A method for calibrating the dynamic characteristics of a heat flow meter by adopting the calibration device specifically comprises the following steps:

step (1): the vacuum pump vacuumizes the detonation tube, and the detonation tube is closed by a manual valve when the pressure in the detonation tube meets the requirement;

step (2): injecting mixed gas of hydrogen, oxygen and nitrogen into the detonation tube through a flow-limiting throat, arranging a one-way valve in a pipeline connecting a hydrogen-oxygen tank and the detonation tube to prevent backfire, closing an electromagnetic valve after the pressure in the detonation tube meets the requirement, and separating the pipeline;

and (3): during the experiment, a spark plug is ignited to generate pulse type detonation waves, the detonation waves are discharged from a pressure relief outlet, and a heat flow meter measures data;

and (4): meanwhile, nitrogen is slowly injected into the detonation tube through a pressure reducing valve, so that on one hand, gas in the detonation tube is replaced, and on the other hand, a heat flow meter is cooled and protected;

and (5): after the experiment is finished, the two heat flow meters compare data and are automatically calibrated by transient calibration software.

Further, the transient calibration software is calibrated by a comparison method, specifically by the following formula:

in the formula: c-coefficient of calibrated heat flow sensor

C₀-coefficients of standard heat flow sensors

q-heat flow density

E-output potential of calibrated heat flow sensor

E₀-output potential of a standard heat flow sensor.

Compared with the prior art, the invention has the remarkable advantages that:

(1) the pulse detonation is that a mixture of fuel and oxidant is injected into a combustion chamber at low pressure, then a proper ignition source is used for detonating the mixture, and in a very short time, detonation waves and high-temperature and high-pressure fuel gas are discharged out of a tail nozzle to generate thrust; it can produce 3X 10⁶Pa～1×10⁷The peak value pressure rise of Pa, the speed of mach number Ma 5 ~ 6 and the temperature of 2000 degrees, this kind of high temperature high pressure high speed environment convection heat transfer occupies very big proportion in the heat transfer, and this device can be simultaneously to heat flow meter calibration under heat radiation and the convection heat transfer environment, improves the dynamic characteristic of heat flow meter.

(2) The pneumatic pipeline is a detachable pneumatic pipeline, so that the experiment is safer and more reliable.

(3) After the experiment table is built, manual operation is not needed, the whole process is automatic, manual errors are reduced, and experimental data are more accurate and reliable.

Drawings

FIG. 1 is a schematic diagram of a calibration apparatus according to the present invention.

Description of reference numerals:

1-vacuum pump, 2-detonation tube, 3-manual valve, 4-oxyhydrogen gas tank, 5-flow-limiting throat, 6-tempering-preventing valve, 7-electromagnetic valve, 8-spark plug, 9-pressure-relief outlet, 10-nitrogen tank, 11-pressure-reducing valve and 12-heat flow meter.

Detailed Description

The present invention is described in further detail below with reference to the attached drawing figures.

A transient heat flow sensor dynamic characteristic calibration system based on pulse detonation engine gas jet. As shown in figure 1, the detonation tube comprises a copper tube with the diameter of 40-60 mm and the length of 1200-1500 mm, an engine fixing frame, a oxyhydrogen gas tank 4, a nitrogen tank 10, a vacuum pump 1, a spark plug 8, an air valve, a pneumatic channel, an HFM type heat flow sensor, a data acquisition unit and a notebook computer.

The oxyhydrogen gas tank 4: hydrogen and oxygen according to a ratio of 2: 1 proportion loading as fuel for a pulse detonation engine. The gas tank 4 is connected with the flow-limiting throat, the electromagnetic valve, the anti-backfire valve, the manual valve and the combustion chamber in sequence. The flow-limiting throat is used for controlling the gas flow velocity of the pipeline to be less than 10m/s, and the experimental safety is ensured. The anti-flashback valve prevents hydrogen flashback after ignition, and the solenoid valve must be explosion-proof for safety.

The detonation tube 2: the detonation combustion is generated in a copper pipe with the diameter of 40-60 mm and the length of 1200-1500 mm. The combustion chamber is actually a detonation tube and brings detonation wave incoming flow for testing. The head end is sealed by a flange end cover, and the tail end is sealed by a membrane. A spark plug ignition device is arranged at the flange end cover. The head end of the combustion chamber is provided with two air inlet pipelines and an exhaust pipeline: the two air inlet pipelines are respectively hydrogen-oxygen mixed gas and nitrogen, and the exhaust pipeline is used for exhausting by the vacuum pump. Besides the pressure relief outlet, the tail end of the combustion chamber is also provided with a heat flow sensor to be measured and a standard heat flow sensor.

The spark plug 8: and the ignition device is positioned on the end cover of the detonation tube 2 and is controlled to ignite by a computer remote online. The rapid ignition forms a pulse detonation wave to provide a pulse signal for the heat flow sensor.

Engine mount: and the device is used for fixing the whole engine and the calibration system.

Vacuum pump 1: before the fuel gas is injected, the air in the pipe is firstly pumped out, so that the hydrogen mixed with the air is prevented from exploding. The manual valve is connected with the combustion chamber, and the combustion chamber is detached before ignition.

Nitrogen tank 10: the nitrogen tank 10 is connected with the head end and the tail end of the combustion chamber, so that gas after detonation in the pipe is replaced on one hand, and the heat flow sensor is cooled and protected on the other hand. Because the high-pressure nitrogen is filled in the gas tank, the pressure and the flow rate of the pipeline are reduced through the reducing valve and the flow-limiting throat, and the pipeline is controlled by the electromagnetic valve. And meanwhile, the anti-tempering valve and the manual valve are arranged to ensure the safety of the experiment.

A data acquisition unit: the model is NI 9215, the product has high signal conditioning voltage (+/-60V), multiplexing of 800kS/s or synchronous sampling of at most 100kS/s, and simultaneously has various advanced functions such as the capability of an intelligent TEDS sensor, an anti-aliasing filter and thermocouple open circuit detection.

Amplification adapter: the heat flow sensor signal is a millivolt level voltage signal, and the potential is small and easily submerged in noise, thus losing a useful signal. The amplification adapter may function to low pass filter, amplify the signal.

A pneumatic channel: the hard copper pipe is adopted as a pneumatic pipeline, the copper pipe is good in sealing performance, firm, reliable and safe in experiment.

HFM type heat flow sensor: the HFM type commercial heat flow sensor provided by Vatell of America is also a thermal resistance type thin film thermopile heat flow sensor, which is also a sensor used by the inventor as a reference in the future, and the heat flow meter has good dynamic characteristics and high sensitivity coefficient. Considering the influence of the temperature of the sensing surface on the sensitivity coefficient of the sensor, the heat flow test data of the HFM type heat flow sensor satisfies the following relation:

in the formula: a, b-two coefficients to be calibrated, namely a + b × T) are the sensitivity coefficients of the sensor corrected by the temperature T; t-temperature of the sensing surface, T ≈ T₁+T₂) And/2, obtained by utilizing the calibration relation conversion between the resistance value change of the platinum resistor and the platinum resistor plated on the sensing surface and the temperature, the unit is as follows: DEG C.

Heat flow sensor transient calibration software: the software calibration principle is theoretically a comparative calibration. Calibrating the heat flow sensor by comparative methods is also similar to measuring the thermal conductivity of an insulating material by comparative methods. The heat flow sensor to be calibrated and the heat flow sensor calibrated by the absolute method as the standard are placed at the same position at the tail end of the combustion chamber. In each experiment, two heat flow meters simultaneously measure data, and standard heat flow sensing is utilizedCoefficient of device C₀And an output potential E₀The heat flow density q can be calculated and the coefficients of the heat flow sensor can be determined. The calibration accuracy of the method is mainly determined by the accuracy of the coefficient of the standard heat flow sensor.

In the formula: c-coefficient of calibrated heat flow sensor

C₀-coefficients of standard heat flow sensors

q-heat flow density

E-output potential of calibrated heat flow sensor

E₀Output potential of a standard heat flow sensor

The experimental process is as follows:

1. the vacuum pump (1) firstly vacuumizes the inside of the detonation tube (2), and when the pressure in the tube reaches the requirement, the tube is closed by the manual valve (3).

2. The mixed gas of hydrogen, oxygen and nitrogen (4) is injected into the pipe through the flow-limiting throat (5), a one-way valve (6) is arranged in the pipe to prevent backfire, after the pressure in the pipe reaches the requirement, the electromagnetic valve (7) is firstly closed, and then the separation pipe is used for ensuring safety.

3. In the experiment, a spark plug (8) is ignited to generate pulse type detonation waves, the pulse type detonation waves are discharged from a pressure relief outlet (9), and data are measured by a heat flow meter.

4. Meanwhile, nitrogen (10) is slowly injected into the tube through a pressure reducing valve (11), so that the gas in the tube is replaced on the one hand, and a heat flow meter (12) is cooled and protected on the other hand.

5. After the experiment is finished, the two heat flow meters compare data and are automatically calibrated by transient calibration software.