Constant-temperature constant-speed water tank and effective working area calibration method thereof

Abstract

The application discloses a constant-temperature constant-speed water tank and an effective working area calibration method thereof, relates to the technical field of dynamic response calibration of temperature sensors, and comprises a rack, a speed-regulating motor, a plane bearing, an annular cylinder, a temperature controller and a precision slip ring. The annular cylinder is located on a gasket of the plane bearing and is fixedly connected with the speed-regulating motor through a flange coupling. The precision slip ring is connected with an electric heater on a rotating cylinder bottom plate and the temperature controller, so that the electric heating of a medium in the rotating cylinder is realized, the stability and uniformity of a flow field of the constant-temperature constant-speed water tank are ensured, and the rapid heating of the water tank is realized. The reflective strips are arranged on the outer wall surface of the inner ring of the annular cylinder, the rotating speed of the annular cylinder is measured, the flow speed at a certain position of the water tank is traced to the product of the rotating speed of the annular cylinder and the radius of the position, and the uncertainty of the measurement result is effectively reduced. The application provides metrological support for the calibration of the dynamic response of the temperature sensor by using the constant-temperature constant-speed water tank.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of temperature sensor dynamic response calibration, in particular to a constant-temperature constant-speed water tank and an effective working area calibration method thereof. BACKGROUND

[0002] When a contact temperature sensor measures the temperature of a fluid with rapid temperature change, it generally cannot immediately respond to the measured temperature and needs a certain time to reach a thermal equilibrium state. Only when the temperature sensor and the measured fluid reach thermal equilibrium, the temperature value responded by the sensor is the temperature of the measured fluid. The dynamic response characteristic of the sensor refers to the relationship between the temperature of the temperature sensor and the temperature increment of the measured medium. In actual calibration, the response time is often used to describe the response of the temperature sensor to the step temperature. The response time refers to the time required for the output temperature of the temperature sensor to change to a certain percentage of the step amount of the fluid temperature when the temperature of the fluid appears a step change. The time required to reach 63.2% of the step temperature amount is called the time constant.

[0003] The temperature sensor dynamic response calibration, i.e. the sensor response time calibration process mainly includes: generating a stable calibration working condition (a stable speed field and a temperature field); making the temperature sensor receive a temperature step excitation; collecting the response signal of the calibrated sensor to the step by the test system, and calculating the response time.

[0004] Generating a stable calibration environment condition is the basis for temperature sensor dynamic response calibration. Generally, the water flow is heated to be higher than the ambient temperature, and the stability of the water flow temperature is better than ±1.0% of the temperature step amount within 30 minutes. In addition, the uniformity of the water flow speed in the direction of the calibrated temperature sensor insertion is better than 10%, and the water flow speed fluctuation range at the measurement position is (0.4±0.05) m / s or (1.0±0.15) m / s.

[0005] The constant-temperature constant-speed water tank is a device for realizing a stable water flow calibration environment condition. The existing technology, such as the water flow environment calibration device in the “JJF1049-1995 Temperature Sensor Dynamic Response Calibration Specification”, uses a ring-shaped rotating container to realize a stable flow field and uses a high-power heating lamp to realize water flow heating. Since the heating lamp uses a non-contact method to first heat the inner wall of the ring-shaped rotating container and then heat the water flow, the heating rate is slow. The existing technology, such as the constant-temperature constant-speed water tank in the invention patent CN110617906B “Temperature Sensor Dynamic Response Calibration Device and Step Time Measurement Method”, includes a rotating cylinder and a stationary cylinder, and a rubber sealing strip is arranged at the connection between the two. After the device operates for a period of time, the sealing strip is worn and aged, and needs to be replaced frequently, otherwise leakage accidents are likely to occur. Therefore, it can be known that the existing technology cannot achieve the simultaneous realization of the flow field stability, uniformity and rapid heating of the constant-temperature constant-speed water tank.

[0006] In addition, long-term operation of the constant-temperature constant-speed water tank causes aging of parts, and the flow rate and temperature performance thereof need to be calibrated regularly to ensure that the parameters meet the technical requirements and guarantee the effectiveness of the dynamic response measurement results of the temperature sensor. The temperature performance can be calibrated according to the JJF1030 constant-temperature tank technical performance test specification, but it is not completely applicable to the constant-temperature constant-speed water tank. Moreover, there is no reference specification method for the flow rate performance calibration at present.

[0007] Therefore, a constant-temperature constant-speed water tank and an effective working area calibration method thereof are provided. SUMMARY

[0008] To solve the above technical problems, the application provides a constant-temperature constant-speed water tank and an effective working area calibration method thereof.

[0009] To achieve the above object, the application provides the following technical scheme.

[0010] A constant-temperature constant-speed water tank comprises a rack, a speed-regulating motor, a plane bearing, an annular cylinder, a temperature controller and a precision slip ring.

[0011] The speed-regulating motor, the plane bearing and the annular cylinder are all installed inside the rack, and the precision slip ring is installed on the upper plate of the rack. The speed-regulating motor is installed on a second support, the plane bearing is installed on a first support, and the second support and the first support are both fixedly installed on the bottom plate of the rack.

[0012] The speed-regulating motor is fixedly connected with the bottom surface center of the annular cylinder through a flange coupling, and the annular cylinder is fixedly connected with the upper gasket of the plane bearing. An electric heater is installed on the bottom surface of the annular cylinder, the power line of the electric heater is located in the inner ring of the annular cylinder and is electrically connected with the precision slip ring, the precision slip ring is electrically connected with the temperature controller through a power line, the inner wall of the inner ring and the outer wall of the outer ring of the annular cylinder are both arranged with heat preservation cotton, a fast-response platinum resistance thermometer is arranged in the annular channel of the annular cylinder, the fast-response platinum resistance thermometer is fixed on the upper plate of the rack, the fast-response platinum resistance thermometer is electrically connected with the input end of the temperature controller, and the output end of the temperature controller is electrically connected with the precision slip ring. The speed-regulating motor is electrically connected with a speed regulator. A reflective strip for measuring the rotating speed is attached to the outer wall surface of the inner ring of the annular cylinder.

[0013] As a further scheme of the application, the annular cylinder and the plane bearing are coaxially arranged.

[0014] As a further scheme of the application, the temperature controller is arranged to set the upper limit of the water temperature in the annular cylinder to not more than 95℃.

[0015] The application discloses a calibration method for an effective working area of a constant-temperature constant-speed water tank, which comprises a water tank flow speed calibration method and a water tank temperature calibration method.

[0016] S1, setting the rotating speed of the constant-temperature constant-speed water tank through a speed regulator, and waiting until the rotating speed reaches a set value and is stable;

[0017] S2, fixing the calibrated flow speed meter on a mechanical arm, locating the measuring end of the flow speed meter at the midpoint of the upper horizontal plane of the working area of the constant-temperature constant-speed water tank, and recording the fluctuation and average value of the output value of the flow speed meter within 30 minutes;

[0018] S3, adjusting the mechanical arm to respectively locate the measuring end of the flow speed meter at the midpoint of the middle horizontal plane and the midpoint of the lower horizontal plane of the working area of the constant-temperature constant-speed water tank, and respectively recording the fluctuation and average value of the output value of the flow speed meter within 30 minutes;

[0019] S4, taking the flow speed meter off the mechanical arm, resetting the mechanical arm, and calculating the uniformity of the average flow speed of the upper, middle and lower horizontal planes of the working area;

[0020] The water tank temperature calibration method comprises the following steps:

[0021] SS1, setting the temperature of the constant-temperature constant-speed water tank through a temperature controller, setting the rotating speed of the constant-temperature constant-speed water tank through a speed regulator, and waiting until the temperature and the rotating speed reach a set value and are stable;

[0022] SS2, fixing the calibrated fine-diameter platinum resistance thermometer on the mechanical arm, locating the temperature measuring end of the fine-diameter platinum resistance thermometer at the left point and the right point of the upper horizontal plane of the working area of the constant-temperature constant-speed water tank in sequence, and recording the fluctuation and average value of the temperature output value of the fine-diameter platinum resistance thermometer within 30 minutes through a data collector;

[0023] SS3, adjusting the mechanical arm to locate the temperature measuring end of the fine-diameter platinum resistance thermometer at the left point and the right point of the lower horizontal plane of the working area of the constant-temperature constant-speed water tank, and recording the fluctuation and average value of the temperature output value of the fine-diameter platinum resistance thermometer within 30 minutes through the data collector;

[0024] SS4, taking the fine-diameter platinum resistance thermometer off the mechanical arm, resetting the mechanical arm, and recording the distance from the water surface or the upper surface of the bottom plate of the working area of the constant-temperature constant-speed water tank.

[0025] As a further scheme of the application, the working area during the flow speed calibration is the effective working area obtained by the last calibration of the constant-temperature constant-speed water tank or the effective working area indicated on the factory instruction, the fluctuation of the measured flow speed and the uniformity of the insertion direction in the working area should meet the limit value of the metrology technical specification, otherwise the space range of the working area should be reduced and recalibrated until the requirement is met.

[0026] As a further scheme of the present application, the temperature of the constant-temperature constant-speed water tank is set at a lower limit value and an upper limit value respectively during the temperature calibration, and the flow rate is set at a lower limit value.

[0027] As a further scheme of the present application, the working area during the temperature calibration is the effective working area obtained during the flow rate calibration, and when the measured temperature fluctuation and average value exceed the limit value of the metrological specification, the temperature controller should be adjusted or the working area space range should be reduced for recalibration until the requirement is met.

[0028] As a further scheme of the present application, the constant-temperature constant-speed water tank should be calibrated for the flow rate field first, and then calibrated for the temperature field, and the effective working area after calibration is the working area in which the flow rate fluctuation, the uniformity of the flow rate in the insertion direction and the temperature fluctuation all meet the requirements of the metrological specification.

[0029] Compared with the prior art, the present application has the following beneficial effects:

[0030] The present application realizes the electric heating of the medium in the rotating cylinder by connecting the electric heater on the bottom plate of the rotating cylinder and the temperature controller through a precision slip ring, which not only ensures the stability and uniformity of the flow field of the constant-temperature constant-speed water tank, but also realizes the rapid heating of the constant-temperature constant-speed water tank.

[0031] The present application also realizes the measurement of the rotating speed of the annular cylinder by the light-reflecting strips arranged on the outer wall surface of the inner circle of the annular cylinder, and traces the flow rate at a certain position of the constant-temperature constant-speed water tank to the product of the rotating speed of the annular cylinder and the radius at the position, which effectively reduces the uncertainty of the measurement result.

[0032] The calibration method of the effective working area of the constant-temperature constant-speed water tank of the present application provides a traceability basis for ensuring the effectiveness of the results of the dynamic response calibration of the temperature sensor using the constant-temperature constant-speed water tank. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The figure is a structural schematic diagram of the present application;

[0034] Figure 2 The figure is a calibration result of the flow rate fluctuation of a constant-temperature constant-speed water tank in the present embodiment;

[0035] Figure 3 The figure is a calibration result of the temperature fluctuation of a constant-temperature constant-speed water tank in the present embodiment;

[0036] Figure 4 The figure is a schematic diagram of the effective working area obtained by calibration of a constant-temperature constant-speed water tank in the present embodiment.

[0037] In the figure: 1, adjustable caster; 2, bottom plate; 3, side plate; 4, rack; 5, first support; 6, second support; 7, speed regulating motor; 8, plane bearing; 9, thermal insulation cotton; 10, annular cylinder; 11, electric heater; 12, fast response platinum resistance thermometer; 13, upper plate; 14, temperature controller; 15, precision slip ring; 16, reflective strip; 17, flange coupling; 18, speed regulator. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0039] Embodiment 1

[0040] Please refer to Figure 1 The present application provides a technical solution: a constant-temperature and constant-speed water tank, comprising a rack 4, a speed regulating motor 7, a plane bearing 8, an annular cylinder 10, a temperature controller 14 and a precision slip ring 15; the rack 4 comprises a bottom plate 2, a side plate 3 and an upper plate 13, and the annular cylinder 10 is coaxially arranged with the plane bearing 8;

[0041] The speed regulating motor 7, the plane bearing 8 and the annular cylinder 10 are all installed inside the rack 4, and the precision slip ring 15 is installed on the upper plate 13 of the rack 4; the speed regulating motor 7 is installed on the second support 6, the plane bearing 8 is installed on the first support 5, and the second support 6 and the first support 5 are both fixedly installed on the bottom plate 2 of the rack 4;

[0042] In this embodiment, the adjustable caster 1 is a heavy-duty Foma wheel with adjustable height, the frame of the rack 4 is built by 3030 industrial aluminum profiles, the bottom plate 2, the side plate 3 and the upper plate 13 of the rack 4 are made of 304 stainless steel plates, and the bottom plate 2 is provided with reinforcing ribs to effectively support the load on the first support 5 and the second support 6;

[0043] The first support 5 and the second support 6 are also built by 3030 industrial aluminum profiles, the size of the plane bearing 8 on the first support 5 is φ260xφ320x45mm, the ear-type speed regulating motor 7 is installed on the first support 5, the reduction ratio of the ear-type speed regulating motor 7 is 20, and the maximum rotating speed is 65r / min; the annular cylinder 10 is fixedly installed on the plane bearing 8 through a washer, the wall thickness of the annular cylinder 10 is 3mm, the outer diameter of the annular cylinder 10 is 600mm, the inner diameter of the annular cylinder 10 is 200mm, the height of the annular cylinder 10 is 400mm, and the water injection depth of the annular cylinder 10 is 300mm.

[0044] The speed-regulating motor 7 is fixedly connected with the annular cylinder 10 through the flange coupling 17, and the annular cylinder 10 is fixedly connected with the upper gasket of the plane bearing 8; the electric heater 11 is installed on the bottom surface of the annular cylinder 10, the power line of the electric heater 11 is electrically connected with the precision slip ring 15 in the inner ring of the annular cylinder 10, the precision slip ring 15 is electrically connected with the temperature controller 14 through the power line, the inner wall of the inner ring and the outer wall of the outer ring of the annular cylinder 10 are both arranged with the heat preservation cotton 9; the fast-response platinum resistance thermometer 12 is arranged in the annular channel of the annular cylinder 10, the fast-response platinum resistance thermometer 12 is fixed on the upper plate 13 of the rack 4, the fast-response platinum resistance thermometer 12 is electrically connected with the input end of the temperature controller 14, and the output end of the temperature controller 14 is electrically connected with the precision slip ring 15; the speed-regulating motor 7 is electrically connected with the speed regulator 18; the reflective strip 16 for measuring the rotating speed is attached to the outer wall surface of the inner ring of the annular cylinder 10.

[0045] The temperature controller 14 sets the upper limit of the water temperature in the annular cylinder 10 to not more than 95 DEG C, and the nominal value of the flow rate at a certain position of the constant-temperature constant-speed water tank is calculated by the product of the rotating speed measured through the reflective strip 16 and the radius at the position.

[0046] It should be noted that the maximum flow rate at the position of the annular channel of the annular cylinder 10, that is, the position with a radius of 200 mm, can reach 1.36 m / s, which fully meets the range of 0.4 m / s to 1.0 m / s generally required in the specifications and standards (JJF 1049-1995 Temperature Sensor Dynamic Response Calibration, GB / T 30429-2013 Industrial Thermocouple).

[0047] In the embodiment, the precision slip ring 15 is of a two-way structure, each way can bear a current of not less than 16 A, the precision slip ring 15 is fixedly installed on the upper plate 13 of the rack 4, one end of the precision slip ring 15 is connected with the temperature controller 14 through the power line, the other end is connected with the electric heater 11 through the power line, and the temperature controller 14 can realize the non-overshoot and undershoot of the temperature of the constant-temperature constant-speed water tank based on the self-adjusting PID parameters; the electric heater 11 is fixedly installed on the annular cylinder 10, has a power of 3.5 kW, and rotates with the annular cylinder 10; the heat preservation and insulation cotton is installed on the outer wall of the outer ring and the inner wall of the inner ring of the annular cylinder 10.

[0048] Specifically, the precision slip ring 15 is adopted to avoid the winding problem caused by the direct connection of the rotating electric heater 11 with the temperature controller 14, and the water temperature is tested at the center point 107, in the embodiment, the water temperature is heated from 20 DEG C to 75 DEG C in about 30 min, which has a significant efficiency improvement compared with the traditional heating lamp heating; the fluctuation of the water temperature in 30 min is within the range of 75 DEG C ± 0.2 DEG C, for example, Figure 2As shown, the water temperature fluctuation is better than the temperature step of ±1% / 30min; the speed of the annular cylinder 10 is 46.50r / min, which is measured by the reflective strip 16 pasted on the outer wall of the inner ring of the annular cylinder 10 through the non-contact tachometer, and the flow rate at the radius of 200mm is 0.974m / s, as shown in Figure 3 As shown, the flow rate 150mm underwater is in the range of 0.962m / s to 0.978m / s, which is measured by the micro Doppler flowmeter, better than the requirement of 1m / s±0.15m / s, and also better than the requirement of 1m / s±0.05m / s; the flow rates obtained by the two methods are consistent, which shows that the flow rate of the water in the annular cylinder 10 can be traced back by the method of speed and radius multiplication.

[0049] Example 2

[0050] Please refer to Figure 1 and Figure 4 An effective working area calibration method of a constant-temperature and constant-speed water tank, the calibration method comprises a water tank flow rate calibration method and a water tank temperature calibration method, wherein the specific steps of the water tank flow rate calibration method are as follows:

[0051] S1, set the speed of the constant-temperature and constant-speed water tank by the tachometer 18, and wait until the speed reaches the set value and is stable;

[0052] S2, fix the calibrated flowmeter on the mechanical arm, and the measurement end of the flowmeter is located at the midpoint of the upper horizontal plane of the working area of the constant-temperature and constant-speed water tank, and record the fluctuation and average value of the output value of the flowmeter within 30min;

[0053] S3, adjust the mechanical arm to respectively make the measurement end of the flowmeter located at the midpoint of the middle horizontal plane and the midpoint of the lower horizontal plane of the working area of the constant-temperature and constant-speed water tank, and respectively record the fluctuation and average value of the output value of the flowmeter within 30min;

[0054] S4, take the flowmeter off the mechanical arm, reset the mechanical arm, and calculate the uniformity of the average flow rate of the upper, middle and lower horizontal planes of the working area;

[0055] It should be noted that the working area during flow rate calibration is the effective working area obtained by the last calibration of the constant-temperature and constant-speed water tank or the effective working area indicated on the factory specification, and the fluctuation and insertion direction uniformity of the flow rate measured in the working area should meet the limit value of the metrology specification, otherwise the working area space range should be reduced and recalibrated until the requirements are met.

[0056] During the calibration process, it should be noted that the fluctuation of the flow rate of the constant-temperature and constant-speed water tank is mainly affected by the output stability performance of the speed regulating motor 7 and the tachometer 18, when the fluctuation of the flow rate exceeds the limit value of the metrology specification, the tachometer 18 or the speed regulating motor 7 should be considered for repair or replacement.

[0057] In this embodiment, please refer to Figure 4 , the flow velocity uniformity of the constant-temperature constant-speed water tank in the direction of the measured temperature sensor insertion is measured by a micro Doppler flowmeter, and the position points are selected at the middle surface of the annular cylinder 10 flow channel, i.e. the middle points of the upper, middle and lower horizontal planes of the working area; the flow velocity distribution in the radial direction of the working area can be calculated by the product of the rotation speed and the radius;

[0058] In the figure, 101 is an upper near point, 102 is an upper middle point, 103 is an upper far point, 104 is a lower near point, 105 is a lower middle point, 106 is a lower far point, and 107 is a center point;

[0059] In this embodiment, the radius of the middle surface of the annular cylinder 10 flow channel is 200 mm, in order to meet the technical requirement that the flow velocity deviation is within the range of 0.4 m / s±0.05 m / s or 1 m / s±0.15 m / s, the calculation result is that the width of the working area is 50 mm, which is uniformly distributed on both sides of the middle surface of the flow channel.

[0060] As further calibration of the water tank, the specific steps of the water tank temperature calibration method are as follows:

[0061] SS1, set the temperature of the constant-temperature constant-speed water tank through the temperature controller 14, and set the rotation speed of the constant-temperature constant-speed water tank through the speed regulator 18, and wait until the temperature and rotation speed reach the set value and are stable;

[0062] SS2, fix the calibrated fine-diameter platinum resistance thermometer on the mechanical arm, and sequentially locate the temperature measuring end of the fine-diameter platinum resistance thermometer at the left point and the right point of the upper horizontal plane of the working area of the constant-temperature constant-speed water tank, and record the temperature output value fluctuation and average value of the fine-diameter platinum resistance thermometer within 30 minutes through the data collector;

[0063] SS3, adjust the mechanical arm to locate the temperature measuring end of the fine-diameter platinum resistance thermometer at the left point and the right point of the lower horizontal plane of the working area of the constant-temperature constant-speed water tank, and record the temperature output value fluctuation and average value of the fine-diameter platinum resistance thermometer within 30 minutes through the data collector;

[0064] SS4, remove the fine-diameter platinum resistance thermometer from the mechanical arm, reset the mechanical arm, and record the distance between the upper and lower horizontal planes of the working area of the constant-temperature constant-speed water tank and the water surface or the upper surface of the bottom plate 2;

[0065] It needs to be further explained that the working area during temperature calibration is the effective working area obtained during flow velocity calibration, when the measured temperature fluctuation and average value exceed the limit value of the measurement technical specification, the temperature controller 14 should be adjusted or the working area space range should be reduced for re-calibration until the requirements are met.

[0066] In this embodiment, when calibrating the temperature of the water tank, the temperature of the constant-temperature constant-speed water tank is set at the lower limit value and the upper limit value respectively, and the flow rate is set at the lower limit value. The constant-temperature constant-speed water tank should be calibrated for the flow rate field first, and then for the temperature field. The effective working area after calibration is: the working area in which the flow rate fluctuation, the flow rate uniformity in the insertion direction and the temperature fluctuation all meet the requirements of the metrology technical specification.

[0067] It should be noted that when the temperature fluctuation of the constant-temperature constant-speed water tank exceeds the limit value of the metrology technical specification, the parameters of the temperature controller 14 should be adjusted. The PID parameter self-adjusting function can be used for adjustment.

[0068] In summary, after the flow rate field and the temperature field are calibrated, the effective working area cross section of the constant-temperature constant-speed water tank is as shown in the diagonal line area in Figure 4 the effective working area is Figure 4 the area formed by rotating the effective working area cross section around the axis of the annular cylinder 10, Figure 4 the diagonal line area is 50 mm away from the upper surface of the bottom plate 2 of the annular cylinder 10, and 20 mm away from the water surface. The effective working area cross section is 50 mm wide, and the boundary distances from the central axis are 175 mm and 225 mm respectively.

[0069] Among them, the mechanical arm, flow rate meter, micro Doppler flow rate meter, fine diameter platinum resistance thermometer, data collector and the like used when calibrating the flow rate field and the temperature field of the constant-temperature constant-speed water tank are general equipment, and will not be described in detail.

[0070] Although embodiments of the present application have been shown and described, it is to be understood that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A constant temperature and constant speed water bath and a calibration method for its effective working area, characterized in that... The constant temperature and constant speed water bath includes a frame (4), a speed-regulating motor (7), a plane bearing (8), an annular cylinder (10), a temperature controller (14), and a precision slip ring (15); the frame (4) includes a base plate (2), a side plate (3), and an upper plate (13); The speed-regulating motor (7), the plane bearing (8), and the annular cylinder (10) are all installed inside the frame (4), and the precision slip ring (15) is installed on the upper plate (13) of the frame (4); the speed-regulating motor (7) is installed on the second bracket (6), the plane bearing (8) is installed on the first bracket (5), and the second bracket (6) and the first bracket (5) are both fixedly installed on the bottom plate (2) of the frame (4); The speed-regulating motor (7) is fixedly connected to the center of the bottom surface of the annular cylinder (10) via a flange coupling (17). The annular cylinder (10) is coaxially arranged with the plane bearing (8) and fixedly connected to the upper washer of the plane bearing (8). An electric heater (11) is installed at the lower part of the annular cylinder (10). The power line of the electric heater (11) is located in the inner ring of the annular cylinder (10) and electrically connected to the precision slip ring (15). The precision slip ring (15) is electrically connected to the temperature controller (14) via the power line. Insulation cotton (9) is arranged on both the inner wall of the inner ring and the outer wall of the outer ring of the annular cylinder (10). A fast-response platinum resistance thermometer (12) is arranged in the annular channel of the 10). The fast-response platinum resistance thermometer (12) is fixed on the upper plate (13) of the platform (4). The fast-response platinum resistance thermometer (12) is electrically connected to the input terminal of the temperature controller (14). The output terminal of the temperature controller (14) is electrically connected to the precision slip ring (15). The speed-regulating motor (7) is electrically connected to the speed regulator (18). A reflective strip (16) for speed measurement is attached to the outer wall of the inner ring of the annular cylinder (10). The flow velocity at a certain position in the annular cylinder (10) is the product of the rotational speed of the annular cylinder (10) and the radius of that position. A method for calibrating the effective working area of ​​a constant temperature and constant velocity water bath, characterized in that the calibration method includes a water bath flow rate calibration method and a water bath temperature calibration method, wherein the specific steps of the water bath flow rate calibration method are as follows: S1. Set the rotation speed of the constant temperature and constant speed water bath through the speed controller (18) until the rotation speed reaches the set value and stabilizes. S2. Fix the calibrated flow meter on the robotic arm. The measuring end of the flow meter is located at the midpoint of the upper horizontal plane of the working area of ​​the constant temperature and constant velocity water bath. Record the fluctuation and average value of the flow meter's output value within 30 minutes. S3. Adjust the robotic arm so that the measuring end of the flow meter is located at the midpoint of the middle horizontal plane and the midpoint of the lower horizontal plane of the working area of ​​the constant temperature and constant velocity water bath, respectively. Record the fluctuation and average value of the output value of the flow meter within 30 minutes. S4. Remove the flow meter from the robotic arm, reset the robotic arm, and calculate the uniformity of the insertion direction based on the average flow velocity at the midpoint of the upper, middle, and lower horizontal planes of the working area. The specific steps for calibrating the water tank temperature are as follows: SS1. Set the temperature of the constant temperature and constant speed water bath through the temperature controller (14), and set the speed of the constant temperature and constant speed water bath through the speed controller (18). Wait until the temperature and speed reach the set values ​​and stabilize. SS2. Fix the calibrated fine-diameter platinum resistance thermometer on the robotic arm. The measuring end of the fine-diameter platinum resistance thermometer is located at the near point and far point of the upper horizontal plane of the constant temperature and constant speed water bath working area. Record the temperature output value fluctuation and average value of the fine-diameter platinum resistance thermometer within 30 minutes through the data acquisition device. SS3. Adjust the robotic arm to position the measuring end of the fine-diameter platinum resistance thermometer at the near and far points of the lower horizontal plane of the constant temperature and constant speed water bath working area. Record the temperature output fluctuation and average value of the fine-diameter platinum resistance thermometer within 30 minutes using a data acquisition device. SS4. Remove the fine-diameter platinum resistance thermometer from the robotic arm, reset the robotic arm, and record the distances from the upper and lower horizontal planes of the working area of ​​the constant temperature and constant speed water tank to the water surface or the upper surface of the bottom plate (2). The calibration of the effective working area of ​​the constant temperature and constant velocity water bath should first calibrate the flow velocity field, and then calibrate the temperature field. During temperature field calibration, the temperature of the constant temperature and constant velocity water bath should be set to the lower and upper limits, respectively, and the flow velocity should be set to the lower limit. The calibrated effective working area is the working area in which the flow velocity fluctuation, the uniformity of the flow velocity in the insertion direction, and the temperature fluctuation all meet the requirements of the metrological technical specifications. The calibrated constant temperature and constant speed water bath should be used to calibrate the dynamic response time of the temperature sensor within its effective working area to ensure the validity of the calibration results.

2. The constant temperature and constant speed water bath and its effective working area calibration method according to claim 1, characterized in that... The temperature controller (14) is set to ensure that the water temperature inside the annular cylinder (10) does not exceed 95°C.

3. The constant temperature and constant speed water bath and its effective working area calibration method according to claim 1, characterized in that... The working area for flow rate calibration is the effective working area obtained from the last calibration of the constant temperature and constant velocity water bath or the effective working area specified in the manufacturer's instruction manual. The flow rate fluctuation and insertion direction uniformity measured within the working area should meet the limits of the metrological technical specifications. Otherwise, the working area should be reduced and recalibrated until it meets the requirements.

4. The constant temperature and constant speed water bath and its effective working area calibration method according to claim 1, characterized in that... The working area during temperature calibration is the effective working area obtained during flow rate calibration. When the measured temperature fluctuation and average value exceed the limits of the metrology technical specifications, the temperature controller (14) should be adjusted or the working area space range should be reduced, and recalibration should be performed until the requirements are met.

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