A wind-heated environment simulation device and a control method thereof

Abstract

The application discloses a wind heat environment simulation device and a control method thereof. The method is characterized in that a heating array composed of a flexible electric heating film and a one-to-one corresponding temperature sensor array are arranged on the surface of a heated object, and a wind speed sensor is arranged. A controller calculates the basic heating power of each heating unit according to a preset wind speed-power mapping relationship and a real-time wind speed value. Meanwhile, the power of each heating unit is independently closed-loop corrected according to the deviation between the actual temperature and the target temperature fed back by each point temperature sensor. After the feedforward value and the feedback correction value are superimposed, each heating unit is driven by a multi-loop PWM controller. The application realizes the instant response of the heating array to the change of the wind speed and the accurate control of the non-uniform temperature field on the surface, has the advantages of small thermal inertia, high control precision, low system complexity and easy expansion, and provides a reliable experimental platform for the research on the urban wind heat environment.

Description

Technical Field

[0001] This invention relates to the field of wind tunnel experimental environment simulation and control technology, specifically to a wind and heat environment simulation device and control method for the outer surface of an urban building model based on an electric heating film array. It is used to perform rapid, zoned, and precise closed-loop control of the temperature field of an object surface under dynamic airflow conditions, and is particularly suitable for simulating the non-isothermal and non-uniform wind and heat environment of the outer surface of an urban building model. Background Technology

[0002] In the process of urbanization, the heat capacity and heat absorption characteristics of artificial impermeable surfaces such as buildings, roads, and squares are much higher than those of natural surfaces, resulting in significantly higher air temperatures in urban areas compared to surrounding rural areas. This phenomenon is known as the urban heat island effect. In real urban environments, there are significant differences in surface temperature between different buildings, different facades of the same building (such as the sunny and shady sides), and different surface materials. This uneven surface heat source heats the air near the ground, thereby altering the vortex structure and turbulence intensity of the local wind field, forming a complex physical process in which wind and heat are coupled.

[0003] However, in current conventional wind tunnel tests of urban building canopy models in the atmospheric boundary layer, researchers mainly focus on the effects of wind speed, wind direction, and building geometry on airflow distribution. Therefore, the vast majority of experiments employ "isothermal" or "uniform temperature" conditions, meaning that the model surface is not actively heated, or the entire model surface is uniformly heated to a fixed temperature. The direct reason for this approach in reality is that traditional heating devices (such as constant-temperature heating plates and heating wires) have high thermal inertia and slow response, making it difficult to achieve multi-point, dynamic, and differentiated temperature control on the model surface. Therefore, researchers tend to avoid temperature variables. However, the main drawbacks of isothermal or uniform temperature wind tunnel tests are reflected in the following four aspects.

[0004] (1) It completely ignores the influence of thermal buoyancy on airflow structure. In real cities, heated walls and ground will cause air to rise, thereby changing the vortex shape and pollutant diffusion path in the street valley. However, under isothermal conditions, this thermally driven convection is completely eliminated, resulting in a deviation between the measured flow field and the actual situation.

[0005] (2) The physical coupling between wind speed and surface heat output is missing. In reality, the higher the wind speed, the faster the convective heat dissipation of the building surface, and the surface temperature will decrease dynamically. However, in the isothermal test, the change in wind speed will not cause any surface temperature response, which incorrectly simplifies the wind-heat process that should be mutually modulated into two independent variables.

[0006] (3) It cannot simulate the spatial inhomogeneity of urban heat islands. In real cities, the surface temperature difference between commercial areas, residential areas, parks, and water bodies can be more than 10°C. However, uniform heating will set all surfaces at the same temperature, which cannot reproduce the local heat island intensity differences. Therefore, it cannot provide meaningful validation data for urban-scale numerical models.

[0007] (4) Even in the few wind tunnel experiments that attempt to heat the surface, the use of large heat capacity heating devices means that it takes several minutes to change the surface temperature. Therefore, they cannot simulate the transient thermal response under dynamic scenarios such as sudden gusts, diurnal variations, or shadow movement, and can only remain at the steady-state or quasi-steady-state experimental level.

[0008] In existing wind tunnel testing techniques, even the few attempts to heat architectural models still have the following four significant drawbacks.

[0009] 1. Lack of dynamic mapping control between wind speed and surface heat output. Existing solutions typically treat wind speed as an independent boundary condition, with the heater output power remaining constant. When wind speed changes, the building surface temperature passively drifts due to changes in convective heat dissipation. Experimenters can only compensate by manually adjusting the heater, making it impossible to achieve automatic and synchronous adjustment of the heat source when wind speed changes.

[0010] 2. Lack of closed-loop feedback correction based on multi-point temperature array. Existing technology at most places one or two thermocouples on the model surface for monitoring, but does not feed the temperature signal back to the heating control loop in real time. Therefore, it is impossible to independently correct the temperature of each local heating area, resulting in uneven surface temperature distribution and deviation from the experimental set value.

[0011] 3. Heating elements have high thermal inertia and slow response speed. Traditional heating plates or heating wires require thicker heat-conducting and insulating layers, and it often takes several minutes to reach stability after changing the set temperature. They cannot simulate the transient thermal response process under dynamic scenarios such as gusts of wind, shadow movement, or diurnal variations.

[0012] 4. Systems with multi-point independent control are highly complex and expensive. To achieve different temperature control in multiple areas, traditional solutions require configuring an independent PID controller and power regulator for each area, resulting in cumbersome wiring, difficult debugging, and potential interference between multiple PID loops. Summary of the Invention

[0013] The objective of this invention is achieved through the following technical solutions.

[0014] To overcome the fundamental shortcomings of isothermal / uniform wind tunnel tests, this invention proposes an array-based heating control method based on multi-point wind speed and temperature feedback. Specifically, this invention deploys an array of ultra-thin, low-thermal-inertia electric heating film heating units on the surface of a building model, with each unit capable of independent and rapid temperature adjustment. Simultaneously, it introduces a real-time wind speed probe and a surface temperature probe array, establishing a feedforward control algorithm that maps wind speed to the target power of each heating unit, and superimposing multi-point temperature closed-loop feedback correction. This allows for the realistic reproduction of a non-isothermal, non-uniform urban thermal environment with real-time wind-heat coupling in wind tunnel tests, providing a reliable experimental platform for urban climate and wind environment research.

[0015] Specifically, this invention discloses a wind-heat environment simulation device, comprising:

[0016] The heating array includes multiple electrically heated film units for placement on the surface of a heated object, each of which can be independently controlled.

[0017] A temperature sensor array includes multiple temperature sensors that are configured one-to-one with the electric heating film unit, for detecting the surface temperature of the corresponding area of ​​each unit;

[0018] At least one wind speed sensor is used to collect the incoming wind speed;

[0019] A multi-loop PWM power controller is electrically connected to each electric heating film unit to independently adjust the heating power of each electric heating film unit;

[0020] A centralized controller is connected to the wind speed sensor, temperature sensor array, and multi-loop PWM power controller.

[0021] The centralized controller is configured as follows:

[0022] Based on the real-time wind speed collected by the wind speed sensor, and based on the pre-set mapping relationship between wind speed and basic heating power, the basic PWM duty cycle of each electric heating film unit is calculated simultaneously.

[0023] Based on the difference between the actual surface temperature fed back by each temperature sensor and the preset target temperature of the electric heating film unit, the corrected PWM duty cycle of each electric heating film unit is calculated independently.

[0024] The base PWM duty cycle of each unit is superimposed with the modified PWM duty cycle to generate the final PWM duty cycle, and the multi-loop PWM power controller is controlled to output the corresponding PWM signal to independently drive each electric heating film unit.

[0025] This invention also discloses a control method for a wind-heat environment simulation device, applied to a wind-heat environment simulation device consisting of multiple independently controlled electric heating film units, temperature sensors corresponding to each unit, at least one wind speed sensor, a multi-loop PWM power controller, and a centralized controller. The method includes the following steps:

[0026] Wind speed feedforward step: The centralized controller reads the real-time wind speed collected by the wind speed sensor, and calculates the basic PWM duty cycle of all electric heating film units synchronously based on the pre-established and stored mapping relationship between wind speed and basic heating power of each electric heating film unit.

[0027] Temperature feedback correction step: The centralized controller reads the actual surface temperature collected by each temperature sensor, calculates the temperature difference between the actual surface temperature and the preset target temperature corresponding to each unit, and independently calculates and corrects the PWM duty cycle for each electric heating film unit;

[0028] Output superposition and driving steps: The basic PWM duty cycle of each electric heating film unit is added to the modified PWM duty cycle to obtain the final PWM duty cycle, and each final PWM duty cycle is sent to the multi-loop PWM power controller, which outputs the corresponding PWM signal to independently drive each electric heating film unit.

[0029] Dynamic cyclic steps: Repeat the wind speed feedforward step, temperature feedback correction step, and output superposition and driving step at a preset cyclic frequency to stabilize the temperature field of the heated object surface at the set target value under dynamic airflow environment.

[0030] The advantages of this invention are:

[0031] 1. It breaks through the limitations of traditional wind tunnel experiments that are isothermal or uniformly temperatured. It can simulate non-uniform temperature fields arbitrarily distributed on building and terrain surfaces, including the temperature difference between the windward and leeward sides, the temperature difference between the roof and the ground, and the differences in heat island intensity between different building types.

[0032] 2. Real-time dynamic coupling of wind speed and surface heat output was achieved. Through wind speed-temperature output mapping feedforward control, when the wind speed increases, the system automatically increases the heating power of the electric heating film to compensate for convective heat dissipation; when the wind speed decreases, it automatically reduces the power to avoid overheating. This feature enables wind tunnel experiments to realistically reproduce the physical process of wind and heat modulation, rather than treating them as independent variables.

[0033] 3. Surface temperature uniformity and control accuracy are significantly improved. The temperature at each point on the model surface can be stabilized within ±0.5℃ of the target value, while the standard deviation of traditional heating methods is usually above 2.0℃.

[0034] 4. Low system complexity and easy expansion. The system directly drives the electric heating film using PWM signals, eliminating the need for a separate PID controller for each circuit. All control algorithms run within the same PLC or embedded computer, simplifying wiring and facilitating debugging. When the number of heating units needs to be increased, only PWM output channels and temperature acquisition channels need to be added; the control program can be reused.

[0035] 5. High experimental repeatability and flexibility. The mapping function and PID parameters of this invention can be adjusted online according to different experimental needs, supporting the simulation of various urban morphologies (low-density villa areas, high-density commercial areas, different street width-to-height ratios) and various thermal boundary conditions (constant surface temperature, constant heat flux, temperature curves changing over time), providing a programmable and reproducible experimental platform for urban wind and thermal environment research. Attached Figure Description

[0036] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0037] Figure 1 A system technical flowchart of the array-type heating control method provided in an embodiment of the present invention.

[0038] Figure 2 This is a schematic planar view of a model with an electrically heated film unit arranged in an embodiment of the present invention.

[0039] Figure 3 This is a schematic elevation view of a model with an electrically heated film unit arranged in an embodiment of the present invention. Detailed Implementation

[0040] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0041] The purpose of this invention is to provide an array-based heating control method based on multi-point wind speed and temperature feedback. Specifically, the technical problem this invention aims to solve is how to achieve real-time dynamic response of building model surface temperature to wind speed changes in wind tunnel experiments, and how to achieve independent, rapid, and precise control of the temperature of multiple local areas on the model surface in a low-complexity and low-cost manner. The ultimate goal of this invention is to enable wind tunnel experiments to realistically reproduce the non-isothermal, non-uniform, and real-time wind-heat coupled urban canopy thermal environment, providing a reliable experimental platform for research on urban heat island effect, building ventilation, and pollutant diffusion.

[0042] The innovation of this invention lies in:

[0043] (1) An array-type diaphragm temperature control method based on wind speed feedforward. The method is characterized by arranging multiple flexible thin-film heating units on the outer surface of the heated object to form a two-dimensional or three-dimensional distributed heating array; by real-time acquisition of the incoming wind speed signal, the controller calculates the basic heating power or basic PWM duty cycle of each heating unit based on the preset wind speed-power mapping relationship and outputs it to all heating units at the same time, so as to realize the real-time feedforward adjustment of the total output power of the heating array when the wind speed changes.

[0044] (2) An independent closed-loop feedback correction method based on a multi-point temperature array. The method is characterized by combining the heating area requirements of the control unit with the placement of a temperature sensor on or near the surface of each heating area unit, forming a temperature feedback array corresponding to the heating array. The controller reads the actual temperature value of each temperature sensor and compares it with its corresponding target temperature to obtain the independent temperature deviation of each heating unit. Based on this deviation, the corrected heating power or corrected PWM duty cycle of each heating unit is independently calculated. The base value obtained from the feedforward is superimposed with the corrected value obtained from the feedback to serve as the final control quantity for each heating unit, thereby achieving independent, parallel, and closed-loop precise control of the three-dimensional temperature distribution on the surface of the heated object.

[0045] (3) A dynamic adaptive adjustment algorithm based on wind speed-temperature joint mapping. The algorithm is characterized by pre-establishing a mathematical model of the target temperature or target power of each heating unit under different incoming wind speeds in the controller; during operation, the algorithm simultaneously executes the following three loops at an update frequency of not less than 10Hz: ① reading the real-time wind speed value and dynamically updating the basic control quantity of each heating unit; ② reading the real-time values ​​of all temperature sensors and calculating the temperature deviation at each point; ③ independently correcting the final control quantity of each heating unit according to the deviation; the three loops work together to ensure that the three-dimensional temperature field of the heated object surface remains stable at the set value under dynamic changes in wind speed and environmental disturbances.

[0046] Specifically, this invention provides an array-based heating control method based on multi-point wind speed and temperature feedback, suitable for distributed temperature control of multiple independent heating units on an object or terrain surface in a dynamic airflow environment. The hardware configuration used in this method includes multiple independent flexible thin-film heating units (such as PI films) arranged on the outer surface of the object or terrain, a temperature sensor corresponding to each heating unit, one or more wind speed sensors, a multi-loop PWM power controller, and a programmable centralized controller. This invention does not limit the specific structure of the above hardware; its control method includes the following steps:

[0047] (1) Step 1: Establish a mapping model between wind speed and the basic output of each heating unit.

[0048] A set of mapping functions or mapping tables, denoted as Di0=fi(V), is pre-stored in the controller, where V represents the incoming wind speed, i represents the i-th heating unit, and Di0 represents the base PWM duty cycle of that unit. The mapping function f_i for different heating units can be set to different forms according to their location (e.g., windward side, leeward side, top) to simulate the different response characteristics of different locations to wind speed. This mapping model can be obtained through theoretical calculations or pre-calibrated experiments.

[0049] (2) Step 2: Real-time wind speed acquisition and feedforward calculation

[0050] Within each cycle of the control loop, the controller reads the current wind speed value Vcurrent from the wind speed sensor. Based on the mapping model in step one, the controller simultaneously calculates the basic PWM duty cycle Di0 = fi(Vcurrent) for all heating units. This calculation process is completed within minutes.

[0051] (3) Step 3: Real-time acquisition of the surface temperature of each heating unit and calculation of the deviation.

[0052] Within the same control cycle, the controller reads the actual temperature value Tiactual from the temperature sensor corresponding to each heating unit, compares it with the preset target temperature value Titarget for that unit, and calculates the temperature deviation ei=Titarget-Tiactual.

[0053] (4) Step 4: Calculate the correction output of each heating unit independently based on the temperature deviation.

[0054] The controller independently runs a correction algorithm (e.g., proportional-integral-derivative PID algorithm) for each heating unit, calculating the corrected PWM duty cycle ΔDi based on the temperature deviation ei. When the actual temperature is lower than the target value, ΔDi is positive; when the actual temperature is higher than the target value, ΔDi is negative.

[0055] (5) Step 5: Superimpose the feedforward and feedback values ​​to obtain the final output and drive the heating unit.

[0056] The controller calculates the final PWM duty cycle Difinal=Di0+ΔDi for each heating unit and sends Difinal to the multi-loop PWM power controller, which then outputs the corresponding PWM signal to drive each heating unit.

[0057] (6) Step Six: Repeat steps two to five to achieve dynamic real-time control.

[0058] The above steps are executed cyclically at a frequency of no less than 10Hz, so that the output power of each heating unit can be synchronously fed forward and adjusted according to the change of the incoming airflow speed, and can also be independently closed-loop corrected according to their local temperature deviation, so that the three-dimensional temperature field of the object surface is stabilized at the target set value under dynamic airflow environment.

[0059] The core features of this invention are: ① It adopts a composite control structure with multi-point wind speed and temperature feedback, wherein wind speed feedforward enables all heating units to respond synchronously and rapidly to changes in wind speed, and temperature feedback enables independent and precise correction for each unit. ② Each heating unit has an independent target temperature and an independent feedback loop, supporting the setting and maintenance of arbitrary non-uniform temperature distribution on the object surface. ③ The feedforward mapping function Fi(V) can be set separately according to the positional differences of different units, allowing different areas of the same object surface to have different power response characteristics to wind speed.

[0060] This control method can be applied to any situation where rapid, zoned, and precise temperature control of an object's surface is required in a dynamic airflow environment, including but not limited to surface thermal simulation of building models or complex terrain models in wind tunnel experiments, anti-icing / de-icing heating control of the outer surface of aircraft or vehicles, and material surface temperature regulation in industrial hot air convection environments.

[0061] The basic principle of this invention is to use a scaled-down model of an urban building complex as the experimental object in a controlled wind tunnel environment. By arranging electric heating film units on the outer surface of the buildings and the urban surface, the surface heat source formed after the impermeable materials such as buildings and roads in the real city absorb heat is simulated, thereby reproducing the coupling process of wind speed field and temperature field in the urban canopy area in the wind tunnel.

[0062] The core idea of ​​this device is to distribute heat sources across the building surfaces and ground surfaces of a city model, enabling different local areas to generate varying heat outputs according to experimental needs. Existing technologies often employ constant-temperature plates or simple heating devices, which suffer from high thermal inertia, slow response, and difficulty in dynamically and precisely adjusting the temperature. Furthermore, traditional wind tunnel experiments often treat wind speed as an independent boundary condition, with heat source output not dynamically adjusted according to wind speed changes, making it difficult to accurately simulate the wind-heat coupling urban environment. This invention, however, uses electric heating films as thin heating elements, leveraging their low thermal inertia and fast response to form zoned and adjustable planar heat sources on the building's exterior surface and the ground surface. Each temperature-regulating unit consists of multiple electric heating films, and each film within the unit can be independently adjusted via control signals, thereby improving the spatial resolution and dynamic response capability of the heat distribution on the building surface.

[0063] In terms of control principle, the system acquires wind speed information in real time through wind speed probes arranged on the side of the wind tunnel and feeds this information back to the PLC controller. The central control computer is used to write and run control programs, controlling the PLC to adjust the heating output according to wind speed changes and experimental settings. The PLC works in conjunction with a multi-loop programmable PWM power controller, which outputs PWM control signals to each electric heating film heating unit, enabling independent control of the heating power of the electric heating film on different building surfaces and different ground areas. Wind speed is no longer a separately set boundary condition, but participates in the adjustment process of heat source output, creating a real-time linkage between changes in incoming wind speed and heat source output on the building surface.

[0064] Simultaneously, the temperature probes in each electric heating film unit collect the surface temperature of the corresponding area of ​​each heating unit in real time. The temperature collection results are used for feedback control, enabling the control system to adjust the heating output of the electric heating film according to the actual temperature conditions, avoiding problems such as local overheating, uneven heat distribution, or response lag caused by relying solely on open-loop settings.

[0065] Supplementary explanation of the control algorithm:

[0066] During the k-th control cycle, for the i-th electric heating film unit, the controller first collects the incoming air velocity V(k) and filters it to obtain the effective air velocity Vf(k) = αV(k) + (1-α)Vf(k-1), where α is the equalization coefficient. Then, based on the preset wind speed-base duty cycle mapping relationship, calculate the feedforward output Di0(k)=fi[Vf(k),Tiset(k),Ta(k)]; simultaneously, collect the actual surface temperature Ti(k) of the corresponding area of ​​the unit, calculate the temperature deviation ei(k)=Tiset(k)-Ti(k), and calculate the corrected duty cycle ΔDi(k)=Kpi·ei(k)+Kii·∑ei(k)Ts+Kdi·[ei(k)-ei(k-1)] / Ts according to the feedback control law; finally, superimpose the wind speed feedforward output and the temperature feedback corrected output to obtain the PWM control quantity of the heating unit: Difinal(k)=sat[Di0(k)+ΔDi(k)], where sat[] indicates that the output is limited to the safe duty cycle range of Di,min≤Difinal(k)≤Di,max, i=1,2,…,N. Di,min represents the lower threshold, and Di,max represents the upper threshold.

[0067]

[0068] Variable definition:

[0069] V(k): The incoming wind speed value collected in the kth control cycle;

[0070] Vf(k): The effective wind speed value after filtering;

[0071] Ts: Represents the control cycle, which is the time interval between two consecutive executions of the control algorithm by the controller;

[0072] Ti(k): The actual surface temperature of the region corresponding to the i-th heating unit;

[0073] Tiset(k): The target temperature of the i-th heating unit;

[0074] Ta(k): represents the ambient air temperature collected in the kth control cycle;

[0075] ei(k): Temperature deviation of the i-th heating unit;

[0076] Kpi: Represents the proportional control coefficient of the i-th heating unit;

[0077] Kii: represents the integral control coefficient of the i-th heating unit;

[0078] Kdi: represents the differential control coefficient of the i-th heating unit;

[0079] Di0(k): The basic PWM duty cycle of the i-th heating unit, calculated from the wind speed feedforward;

[0080] ΔDi(k): The corrected PWM duty cycle of the i-th heating unit, calculated from temperature feedback;

[0081] Difinal(k): The final PWM duty cycle of the i-th heating unit;

[0082] fi(·): The wind speed-base duty cycle mapping function or mapping table of the i-th heating unit;

[0083] Dimin, Dimax: The minimum and maximum PWM duty cycles allowed for the i-th heating unit;

[0084] Therefore, the overall working process of this invention can be understood as follows: a wind tunnel provides a controllable incoming flow, an urban building complex model provides the geometric environment of the urban canopy, electrically heated film units form adjustable heat sources on building surfaces and the ground surface, temperature probes collect local thermal state data in real time, wind speed probes collect wind speed information within the wind tunnel in real time, and a PLC, under computer program control, integrates wind speed information, temperature feedback, and experimental objectives, dynamically adjusting the output of each electrically heated film unit through a multi-loop PWM power controller. This system can thus simulate complex urban thermal environments within a wind tunnel, including the urban heat island effect, local heat flux density variations, and temperature distribution changes under different wind speed conditions, providing a repeatable and controllable experimental platform for studying the wind-heat coupling law of urban building complexes and verifying the boundary conditions of numerical simulations.

[0085] Example 1: Simulation of wind and heat environment in a wind tunnel model of an urban street valley

[0086] This embodiment applies the method of the present invention to the heating control of an idealized two-dimensional street valley model consisting of two parallel buildings.

[0087] System hardware configuration:

[0088] Heated Objects and Heating Array: A 1:100 scale urban street canyon model. Twenty independent polyimide (PI) electric heating film units are arranged on the inner walls (windward and leeward sides), ground, and roof of the street canyon. Each unit has an effective heating area of ​​5cm × 5cm and a resistance of 10Ω. The heating units are numbered 1 to 20.

[0089] Temperature sensor array: 20 high-precision PT100 platinum resistance temperature sensors are attached to the center of the back of each heating film unit with thermally conductive adhesive for real-time measurement of the surface temperature of the unit.

[0090] Wind speed sensor: A hot-wire anemometer probe is installed in front of the model at a stable inflow section, about 50cm away from the model, to collect the reference wind speed of the inflow in real time.

[0091] Controller and Actuators: A PLC is used as the central controller, equipped with multiple analog input modules (connecting to the anemometer and PT100) and multiple PWM output modules. The PWM outputs are connected to a 24-channel DC PWM power controller to independently power each heating film unit. The controller program update frequency is set to 20Hz.

[0092] Control method implementation steps:

[0093] A mapping model was established: Through preliminary steady-state experiments, the basic PWM duty cycle required for each heating unit to maintain its target temperature under different constant wind speeds at a specific ambient temperature (25℃). For unit 1, located at the bottom of the windward side in the street valley, its mapping function is \(f_1(V)=15%+4%\timesV\); for unit 5, located on the roof, due to the significant influence of wind speed, its mapping function is \(f_5(V)=10%+8%\timesV\), where V is in m / s. The mapping tables for all units were stored in the PLC memory.

[0094] Set target temperatures: Based on experimental requirements, set non-uniform target temperatures for the 20 units. For example, the sun-facing roof should be 50°C, the sun-facing interior wall 45°C, the shaded interior wall 35°C, and the ground 40°C.

[0095] Control loop: The program executes the following loop at a frequency of 20Hz. In the k-th cycle:

[0096] Read the filtered wind speed value (V_f(k) = 4.5 m / s).

[0097] Based on the mapping function, calculate the base duty cycle of all cells, such as \(D_{10}(k)=f_1(4.5)=33%\), \(D_{50}(k)=f_5(4.5)=46%\).

[0098] Read the temperature values ​​of all 20 temperature sensors, such as the actual temperature of unit 1 (T_1(k) = 44.8℃), and calculate its deviation (e_1(k) = 45.0℃ - 44.8℃ = 0.2℃).

[0099] Run the PID algorithm to calculate the correction. For cell 1, \(\DeltaD_1(k)=K_p\times0.2+K_i\times\sume_1\timesT_s\). Assuming the PID parameters are tuned, \(\DeltaD_1(k)=1.5%\).

[0100] Calculate the final duty cycle and limit the amplitude, \(D^{final}_1(k)=sat[33%+1.5%]=34.5%\).

[0101] Twenty final duty cycle values, including 34.5%, are sent to the PWM power controller to drive each heating film.

[0102] Experimental effect test:

[0103] Dynamic response test: During a wind tunnel wind speed change from 2 m / s to 6 m / s, the system using the method of this invention was activated. The surface temperature of Unit 1 on the inner wall of the street valley recovered to the set value of 45 ± 0.3℃ within 8 seconds, with an overshoot of less than 0.5℃. In contrast, in the traditional mode with the feedforward channel closed and only PID feedback control used, the temperature of the same unit dropped by 1.8℃ and took 25 seconds to recover.

[0104] Spatial nonuniformity test: Under stable wind speed of 3 m / s, the surface temperature of the model was scanned using an infrared thermal imager. The results showed that the maximum deviation between the actual temperature at the 20 temperature measurement points after stabilization and their respective independent set values ​​was 0.4℃, and the standard deviation was 0.2℃, successfully simulating a temperature difference of up to 15℃ between the roof and the ground, and between the sun-facing and shaded sides.

[0105] Stability test: During 30 minutes of continuous operation, the wind speed fluctuated by ±1.0 m / s around 3.5 m / s, and the temperature fluctuation of all controlled units was within ±0.5℃ of their set value.

[0106] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A wind-heat environment simulation device, characterized in that, include: The heating array includes multiple electrically heated film units for placement on the surface of a heated object, each of which can be independently controlled. A temperature sensor array includes multiple temperature sensors that are configured one-to-one with the electric heating film unit, for detecting the surface temperature of the corresponding area of ​​each unit; At least one wind speed sensor is used to collect the incoming wind speed; A multi-loop PWM power controller is electrically connected to each electric heating film unit to independently adjust the heating power of each electric heating film unit; A centralized controller is connected to the wind speed sensor, temperature sensor array, and multi-loop PWM power controller. The centralized controller is configured as follows: Based on the real-time wind speed collected by the wind speed sensor, and based on the pre-set mapping relationship between wind speed and basic heating power, the basic PWM duty cycle of each electric heating film unit is calculated simultaneously. Based on the difference between the actual surface temperature fed back by each temperature sensor and the preset target temperature of the electric heating film unit, the corrected PWM duty cycle of each electric heating film unit is calculated independently. The base PWM duty cycle of each unit is superimposed with the modified PWM duty cycle to generate the final PWM duty cycle, and the multi-loop PWM power controller is controlled to output the corresponding PWM signal to independently drive each electric heating film unit.

2. The wind-heat environment simulation device according to claim 1, characterized in that, The mapping relationship is set according to the different positions of the electric heating film unit on the surface of the heated object, so that the units located on the windward side, leeward side or top have different basic PWM duty cycles under the same wind speed.

3. The wind-heat environment simulation device according to claim 1, characterized in that, The centralized controller cyclically performs the calculation of the basic PWM duty cycle, the calculation of the corrected PWM duty cycle, and the generation and output of the final PWM duty cycle at a frequency of not less than 10 Hz.

4. The wind-heat environment simulation device according to claim 1, characterized in that, When calculating the corrected PWM duty cycle, the centralized controller executes a proportional-integral-derivative control algorithm to determine the correction amount based on the proportional, integral, and derivative terms of the temperature deviation.

5. The wind-heat environment simulation device according to claim 1, characterized in that, The centralized controller is also configured to limit the final PWM duty cycle, restricting it to a safe range between a preset minimum duty cycle and a maximum duty cycle.

6. The wind-heat environment simulation device according to any one of claims 1 to 5, characterized in that, The heated object is a scaled-down model of an urban building complex or a terrain model. The electric heating film unit is arranged on the outer surface of the building, the ground, or the roof of the model to simulate the non-uniform, non-isothermal urban canopy wind and heat environment.

7. A control method for a wind-heat environment simulation device, applied to a wind-heat environment simulation device consisting of multiple independently controlled electric heating film units, temperature sensors corresponding to each unit, at least one wind speed sensor, a multi-loop PWM power controller, and a centralized controller, characterized in that, The method includes the following steps: Wind speed feedforward step: The centralized controller reads the real-time wind speed collected by the wind speed sensor, and calculates the basic PWM duty cycle of all electric heating film units synchronously based on the pre-established and stored mapping relationship between wind speed and basic heating power of each electric heating film unit. Temperature feedback correction step: The centralized controller reads the actual surface temperature collected by each temperature sensor, calculates the temperature difference between the actual surface temperature and the preset target temperature corresponding to each unit, and independently calculates and corrects the PWM duty cycle for each electric heating film unit; Output superposition and driving steps: The basic PWM duty cycle of each electric heating film unit is added to the modified PWM duty cycle to obtain the final PWM duty cycle, and each final PWM duty cycle is sent to the multi-loop PWM power controller, which outputs the corresponding PWM signal to independently drive each electric heating film unit. Dynamic cyclic steps: Repeat the wind speed feedforward step, temperature feedback correction step, and output superposition and driving step at a preset cyclic frequency to stabilize the temperature field of the heated object surface at the set target value under dynamic airflow environment.

8. The control method according to claim 7, characterized in that, The mapping relationship is obtained through pre-calibration experiments, and for electric heating film units arranged at different positions on the heated object, the mapping relationship is set as different functions or data tables, so that different units obtain different basic PWM duty cycles under the same wind speed.

9. The control method according to claim 7, characterized in that, In the temperature feedback correction step, the corrected PWM duty cycle is calculated using a proportional-integral-derivative control algorithm; when the actual temperature is lower than the target temperature, the corrected duty cycle is positive; when the actual temperature is higher than the target temperature, the corrected duty cycle is negative.

10. The control method according to claim 7, characterized in that, Before the wind speed feedforward step, a low-pass filtering process is also included for the signal collected by the wind speed sensor to suppress the impact of wind speed turbulence fluctuations on the calculation of the basic PWM duty cycle.

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