Air resistance loss assessment method and equipment based on exhaust cavity of cavity floor system

Abstract

The invention discloses an air resistance loss assessment method and equipment based on an exhaust cavity of a cavity floor system, and belongs to the field of cavity structure buildings. A cavity floor system exhaust channel is decomposed into combinations of eight types of cavity bodies, and all cavity body models are composed of the same cavities and concealed pipes; measuring points are arranged in the cavities and the concealed pipes, multiple groups of air velocity and pressure values measured by each type of cavities under different fan frequencies are obtained, and resistance loss obtained by pressure difference is calculated by considering the comparison of the sectional areas of the different cavities and the concealed pipes with the images of the air velocity and the pressure values; obtaining coefficients and indexes of air resistance loss in the eight types of cavities, and further obtaining a function relationship between resistance loss and flow velocity corresponding to the eight types of cavities; obtaining an optimized pressure loss fitting formula of each type of cavities; and evaluating the air resistance loss of each type of cavities. The method is simple in steps and convenient to use.

Description

Technical Field

[0001] This invention pertains to the field of cavity structure buildings, specifically proposing a method and device for assessing air resistance loss based on the exhaust cavity of a cavity floor slab. Background Technology

[0002] Currently, the calculation of resistance in traditional circular or rectangular pipes has formed a mature theoretical system (such as the Darcy-Weisberg formula). However, due to the complex geometry of hollow ventilation ducts (such as asymmetric cross-sections, built-in guide plates, and porous media filling), fluid flow exhibits complex phenomena such as vortices, separation, and secondary flow, making it difficult for existing theories to accurately predict their resistance characteristics. Furthermore, the development of computational fluid dynamics (CFD) and experimental measurement techniques (such as PIV particle image velocimetry and hot-wire anemometers) has provided technical support for in-depth research into the flow mechanism within hollow ventilation ducts, but further refinement of the research system based on practical engineering needs is still required.

[0003] 1. Limitations of theoretical models: Existing resistance calculation models are mostly based on simplifying assumptions (such as laminar flow and fully developed flow), which make it difficult to accurately describe the complex turbulent flow inside cavity ventilation ducts. In particular, for ventilation ducts with asymmetric cross-sections or complex turbulence structures, the lack of universal theoretical formulas leads to reliance on empirical parameters or conservative estimates in engineering design, resulting in design redundancy or insufficient performance.

[0004] 2. Complexity of Geometric Structure and Operating Conditions: Practical applications involve diverse structures of cavity ventilation ducts (e.g., irregular cross-sections, curved pipes, multi-stage branching), and operating conditions encompass variable flow rates, temperatures, and pressures. Current research primarily focuses on single structures or steady-state conditions, with insufficient attention paid to resistance characteristics under the coupled effects of multiple factors, making it difficult to meet the dynamic design requirements of engineering projects.

[0005] 3. Validation Gap Between Experiments and Simulations: Although CFD simulations can visually display flow field details, the selection of model parameters (such as turbulence models and boundary conditions) significantly affects the results. Existing studies have limited experimental validation sample sizes, resulting in limited engineering applicability of simulation results. Furthermore, experimental measurements of complex ventilation duct structures face challenges such as difficult sensor placement and flow interference, affecting data accuracy. Summary of the Invention

[0006] In view of the above problems, the present invention provides a method and device for assessing air resistance loss based on the air cavity of the cavity floor exhaust, which can quickly assess the air resistance loss of the cavity floor exhaust.

[0007] To achieve the above technical objectives, a method for assessing air resistance loss based on the exhaust cavity of a cavity floor slab is disclosed, the steps of which are as follows: Step 1: Decompose the cavity floor exhaust duct into a combination of eight types of cavities. All cavity models are composed of the same cavities and concealed pipes. Step 2: Set up measuring points in the cavity and the duct to obtain multiple sets of air velocity and pressure values ​​for each type of cavity at different fan frequencies. At the same time, consider the image of air velocity and pressure values ​​compared with the cross-sectional area of ​​different cavities and ducts, and calculate the resistance loss obtained by the pressure difference. Step 3: Utilize duct resistance loss With flow rate power function relationship The coefficients of air resistance loss in eight types of cavities were obtained through fitting. Sum of Indices This leads to the drag loss corresponding to eight types of cavities. With flow rate Functional relationship: Step 4: Calculate the optimization index and optimization coefficients The optimized fitting formulas for pressure loss of various types of cavities are obtained: Step 5: By using the optimized pressure loss fitting formulas for various types of cavities, the air resistance loss of the entire cavity floor exhaust channel can be calculated by evaluating the air resistance loss of various types of cavities.

[0008] Furthermore, based on the combination of cavities and concealed pipes and the direction of airflow movement, eight types of cavities are constructed: straight cavity, right-angle turning cavity, flat-angle confluence cavity, right-angle confluence cavity, exhaust cavity, flat-angle split cavity, right-angle split cavity, and ventilation cavity. Among them: the straight cavity body has two hidden pipes set on the two sides facing each other. The fluid enters from one side of the hidden pipe and exits from the other side of the hidden pipe. The right-angle turning cavity has concealed pipes installed on two adjacent sides of the cavity, with the two concealed pipes forming a 90-degree angle. Fluid enters from one concealed pipe and exits from the other concealed pipe. The flat-angle confluence cavity is equipped with concealed pipes on three adjacent sides of the cavity. Fluid enters through two oppositely arranged concealed pipes and exits through the third concealed pipe. The right-angle confluence cavity has concealed pipes on three adjacent sides of the cavity. Fluid enters through two adjacent concealed pipes and exits through the third concealed pipe. The exhaust port cavity is a cavity connected to a concealed pipe, and an air inlet is opened on the cavity. Fluid enters from the air inlet and exits from the concealed pipe. The flat-angle split cavity has concealed pipes on three adjacent sides of the cavity. Fluid is discharged through two oppositely arranged concealed pipes and enters through the third concealed pipe. The right-angle split cavity has concealed pipes on three adjacent sides of the cavity. Fluid enters through one of the two oppositely arranged concealed pipes and exits from the other two concealed pipes. The ventilation cavity is a cavity connected to a concealed pipe, and an air outlet is opened on the cavity. Fluid enters the cavity from the concealed pipe and exits from the air outlet.

[0009] Furthermore, measuring points, including QDF-6 hot-wire anemometers and DP2000 differential pressure gauges, were arranged in the cavities of the eight types of hollow bodies and in the concealed pipes. The specific steps and methods are as follows: For each type of cavity, a fan was used to generate simulated airflow. The fan frequency was adjusted to 10Hz, 20Hz, 30Hz, 40Hz, and 50Hz to obtain different initial airflow velocities. Three measuring points were arranged inside all the concealed pipes and at the cross-section of the exhaust outlet for each type of cavity. Three points were selected as six equal divisions along the cross-sectional length of the concealed pipe as measuring points. The average value of the three measuring points was calculated as the airflow velocity inside the concealed pipe. At the exhaust outlet, one measuring point was set at the middle, side, and corner of the exhaust outlet. The average value was calculated as the airflow velocity of the exhaust outlet. The exhaust outlet is the main duct where the airflow is discharged to the outside at the confluence of the concealed pipe system.

[0010] Furthermore, consider the impact of different cavity and concealed pipe cross-sectional areas on air velocity and pressure values: Let the vertical cross-sectional area of ​​the cavity be a rectangle A1, and the vertical cross-sectional area of ​​the concealed pipe be a rectangle A2; use the local resistance loss within the cavity to represent the overall resistance loss. Since the overall resistance loss is related to the cross-sectional ratio of the concealed pipe cross-sectional area A2 and the cavity vertical cross-sectional area A1, based on experimental experience, we give... Values ​​are selected to form various cross-sectional ratios; the ratio of the cross-sectional area of ​​the concealed pipe to the vertical cross-sectional area of ​​the cavity is set in eight types of cavities. The drag loss data of each type of cavity under different airflow velocities at five different cross-sectional scales were simulated using the shear stress transfer turbulence model SST k-ω. The drag loss data of each type of cavity under different airflow velocities at five different cross-sectional scales: 0.1, 0.2, 0.3, 0.4 and 0.5 were simulated using the SST k-ω model.

[0011] Furthermore, the power function relationship between cavity resistance loss and flow velocity is... Taking the logarithm of both sides yields the drag loss. With flow rate Functional relationship: ,make The formula simplifies to: Simulated values ​​of total resistance loss for all types of cavities under different cross-sectional proportions. and flow rate Substitute them separately Then, the coefficients of air resistance loss for cavities of different types and cross-sectional proportions were obtained by fitting using the least squares method. Sum of Indices : , In the formula, n is the total number of sets of numerical simulation data; i is the sequence number of the numerical simulation data.

[0012] Furthermore, the ratio of cross-sectional area of ​​the eight types of cavities... For five cross-sectional ratios (0.1, 0.2, 0.3, 0.4, and 0.5), the coefficients of air resistance loss for different types and cross-sectional ratios of cavities were obtained by least squares fitting. Sum of Indices According to the formula: The coefficient of air resistance loss Sum of Indices Represented as: Fully straight cavity model: , Right-angle turning cavity: , Flat-angle confluence cavity: , Right-angle straight pipe confluence cavity: , Right-angle tube confluence cavity: , Exhaust vent cavity: , Flat-angle split cavity: , Right-angle straight pipe split cavity: , Right-angle tube splitter cavity: , Ventilation cavity: , When a right-angle confluence cavity or a right-angle split cavity serves as the terminal of a cavity floor exhaust system, and the duct connecting the right-angle confluence cavity and the right-angle split cavity is a straight duct, it is further subdivided into a right-angle straight duct confluence cavity and a right-angle straight duct split cavity. When the duct connecting the right-angle confluence cavity and the right-angle split cavity is a bend, it is further subdivided into a right-angle corner duct confluence cavity and a right-angle corner duct split cavity.

[0013] Furthermore, the arithmetic mean was used to solve for the five exponents in the same set of formulas for each type of cavity. The number is used as a conventional truth value: the exponent in the five fitted formulas in the same group of formulas. The optimization index was obtained by averaging the values. Set different airflow rates Utilizing optimization index and airflow speed This can be substituted into the formulas for the resistance loss of various types of cavities to obtain the coefficients. Correction coefficient : Fully straight cavity: , Right-angle turn cavity: , Flat-angle confluence cavity: , Exhaust vent cavity: , Flat-angle split cavity: , Ventilation cavity: , Right-angle straight pipe confluence cavity: , Right-angle tube confluence cavity: , Right-angle straight pipe split cavity: , Right-angle tube splitter cavity: .

[0014] Furthermore, due to the coefficient Follow The changes occur with the changes in the cavity system, and numerical simulations are used to analyze the numerical values ​​of various types of cavity systems. and the corresponding cross-sectional area ratio By merging and analyzing line segments with similar slopes in the numerical simulation curves, we can proceed according to... The rate of change divides the numerical simulation curve into segments, and the criterion for segmentation is... Follow To determine whether the increase is amplification or decrementalization, and whether there are sudden changes in the rate of change, linear fitting is sequentially performed on each segment of the simulated curve after segmentation to obtain... and Function expressions between ; Various types of hollow bodies The fitting formula is as follows: Fully straight cavity: , Right-angle turn cavity: , Flat-angle confluence cavity: , Right-angle straight pipe confluence cavity: , Right-angle tube confluence cavity: , Exhaust vent cavity: , Flat-angle split cavity: , Right-angle straight pipe split cavity: , Right-angle tube splitter cavity: , Ventilation cavity: .

[0015] A computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program adapted to be loaded and executed by a processor, the method for assessing air resistance loss based on the exhaust cavity of a cavity floor slab.

[0016] Beneficial effects: This invention simulates the resistance of fluid passing through eight types of cavities under different cross-sectional area ratios of concealed pipes and flow velocities. Then, based on the least squares method and the law of large numbers, the parameters are fitted to derive a general fitting formula for the resistance of various types of cavities. Error analysis is also performed, solving the problems of large errors in the calculation of resistance loss of assembly box cavities for straight cavities, right-angle confluence cavities, and exhaust vent cavities, as well as the complex and cumbersome calculation process and the results being smaller than the experimental values, which cannot guarantee the normal use of the design results in actual engineering. This invention makes the resistance fitting of cavities more accurate and the design more reasonable. Attached Figure Description

[0017] Figure 1 The diagram shows the structure of eight types of cavities in this embodiment of the invention. In the diagram, a is a straight cavity, b is a right-angle turning cavity, c is a horizontal merging cavity, d is a right-angle merging cavity, e is an exhaust cavity, f is a horizontal splitting cavity, g is a right-angle splitting cavity, and h is a ventilation cavity.

[0018] Figure 2 This is a schematic diagram of the arrangement of measuring points on the cross-section of the concealed pipe in an embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of the arrangement of exhaust port measuring points in an embodiment of the present invention. Detailed Implementation

[0020] The embodiments of the present invention will be further described below with reference to the accompanying drawings: This invention provides a general fitting formula for the resistance loss of various cavities under different operating conditions in a pipeline system based on a cavity floor exhaust cavity. Using Fluent software, the resistance of fluid passing through various cavity structures, such as straight cavities and angled split cavities, under different duct cross-sectional area ratios and flow velocities is simulated and recorded. Then, parameters are fitted using the least squares method and the law of large numbers to derive a general fitting formula for the resistance of various cavities. Error analysis is performed; given enough data at different flow velocities, the coefficients and exponents in the formula can be calculated using the least squares method to obtain the resistance calculation formula for the duct of that cavity diameter. In actual engineering, the assembly box cavity consists of two parts: the cavity and the concealed duct. The length of the concealed duct is the same as the rib beam, typically 150 mm to 200 mm. The cavity and its upstream and downstream half-length concealed ducts are considered as a single component. Substituting multiple sets of flow velocity and resistance loss data, an independent formula is fitted for each type of cavity.

[0021] This invention discloses a method for assessing air resistance loss based on the exhaust cavity of a cavity floor slab. The steps are as follows: The exhaust duct of the cavity floor slab is decomposed into a combination of eight types of cavities, all of which consist of identical cavities and concealed ducts; measuring points are arranged in the cavities and concealed ducts to obtain multiple sets of air velocity and pressure values ​​for each type of cavity at different fan frequencies; simultaneously, considering the image of air velocity and pressure values ​​relative to the cross-sectional areas of different cavities and concealed ducts, the resistance loss obtained from the pressure difference is calculated; and the air resistance loss is then assessed using the duct resistance loss method. With flow rate power function relationship The coefficients of air resistance loss in eight types of cavities were obtained through fitting. Sum of Indices This leads to the drag loss corresponding to eight types of cavities. With flow rate Functional relationship: Calculate the optimization exponent and optimization coefficients The optimized pressure loss fitting formulas for various types of cavities are obtained. By using the optimized pressure loss fitting formulas for various types of cavities, the air resistance loss of the entire cavity floor exhaust channel can be completed by evaluating the air resistance loss of various types of cavities.

[0022] like Figure 1As shown, eight types of cavity test models capable of forming cavity floor ventilation systems are constructed based on the combination of cavities and concealed ducts and the direction of airflow movement. These include: a straight cavity, a right-angle turn cavity, a horizontal-angle confluence cavity, a right-angle confluence cavity, an exhaust vent cavity, a horizontal-angle split cavity, a right-angle split cavity, and a ventilation vent cavity. To more accurately detect wind speed, the length of the concealed duct in these cavity test models is extended. In actual cavity floor ventilation systems, the concealed duct length is only a few centimeters. However, if the concealed duct length in the test models is too short, the measurement by the testing equipment will be inaccurate. Therefore… Figure 1 The concealed pipes in the eight types of cavity test models are all idealized modifications, and their test results will not affect the actual calculation of air resistance loss of the cavity floor ventilation system.

[0023] Fully straight cavity: Two concealed pipes are installed on the two sides of the cavity facing the Class 8, and the fluid enters from one concealed pipe and exits from the other concealed pipe. Right-angle turning cavity: The cavity has concealed pipes on two adjacent sides, with the two concealed pipes forming a 90-degree angle. Fluid enters from one concealed pipe and exits from the other concealed pipe. Flat-angle confluence cavity: The cavity has concealed pipes on three adjacent sides, through which fluid enters through two oppositely arranged concealed pipes and exits through the third concealed pipe; Right-angle confluence cavity: The cavity has concealed pipes on three adjacent sides, through which fluid enters through two adjacent concealed pipes and exits through the third concealed pipe; Exhaust vent cavity: The cavity is connected to a concealed pipe, and an air inlet is opened on the cavity. Fluid enters from the air inlet and exits from the concealed pipe. Flat-angle split-flow cavity: The cavity has concealed pipes on three adjacent sides, through which fluid is discharged through two oppositely arranged concealed pipes and enters through the third concealed pipe; Right-angle split-flow cavity: The cavity has concealed pipes on three adjacent sides, through which fluid enters through one of the two oppositely arranged concealed pipes and exits through the other two concealed pipes; Ventilation cavity: The cavity is connected to a concealed pipe and has an air outlet. Fluid enters the cavity from the concealed pipe and exits from the air outlet.

[0024] Measuring points, including QDF-6 hot-wire anemometers and DP2000 differential pressure gauges, were arranged in the cavities and concealed pipes of eight types of cavities. Specifically: For each type of cavity, a fan was used to generate simulated airflow. The fan frequency was adjusted to 10 Hz, 20 Hz, 30 Hz, 40 Hz, and 50 Hz to obtain different initial airflow velocities. Three measuring points were arranged inside all concealed pipes and at the exhaust outlet cross-section of each type of cavity. Three equally divided points were selected along the cross-sectional length of the concealed pipe as measuring points, and the average value of the three measuring points was calculated as the airflow velocity inside the concealed pipe. At the exhaust outlet, one measuring point was set at the middle, side, and corner of the exhaust outlet; the average value was calculated as the airflow velocity of the exhaust outlet. The exhaust outlet is the confluence point of the concealed pipe system, where the airflow is discharged to the outside in the main duct. Figure 2 and Figure 3 As shown.

[0025] The power function relationship between cavity resistance loss and flow velocity Taking the logarithm of both sides yields the drag loss. With flow rate Functional relationship: ,make The formula simplifies to: Simulated values ​​of total resistance loss for all types of cavities under different cross-sectional proportions. and flow rate Substitute them separately Then, the coefficients of air resistance loss for cavities of different types and cross-sectional proportions were obtained by fitting using the least squares method. Sum of Indices : , In the formula, n is the total number of sets of numerical simulation data; i is the sequence number of the numerical simulation data.

[0026] Consider the impact of different cross-sectional areas of cavities and concealed pipes on air velocity and pressure values: Let the vertical cross-sectional area of ​​the cavity be a rectangle A1, and the vertical cross-sectional area of ​​the concealed pipe be a rectangle A2; use the local resistance loss within the cavity to represent the overall resistance loss. Since the overall resistance loss is related to the cross-sectional ratio of the concealed pipe's cross-sectional area A2 to the cavity's vertical cross-sectional area A1, based on experimental experience, we give... Values ​​are selected to form various cross-sectional ratios; the ratio of the cross-sectional area of ​​the concealed pipe to the vertical cross-sectional area of ​​the cavity is set in eight types of cavities. The drag loss data of each type of cavity under different airflow velocities at five different cross-sectional scales were simulated using the SST k-ω model. The SST k-ω model was also used to simulate the drag loss data of each type of cavity under different airflow velocities at five different cross-sectional scales: 0.1, 0.2, 0.3, 0.4, and 0.5. The cross-sectional area ratios of the eight types of cavities were also analyzed. For five cross-sectional ratios (0.1, 0.2, 0.3, 0.4, and 0.5), the coefficients of air resistance loss for different types and cross-sectional ratios of cavities were obtained by least squares fitting. Sum of Indices According to the formula: The coefficient of air resistance loss Sum of Indices Represented as: Fully straight cavity model: , Right-angle turning cavity: , Flat-angle confluence cavity: , Right-angle straight pipe confluence cavity: , Right-angle tube confluence cavity: , Exhaust vent cavity: , Flat-angle split cavity: , Right-angle straight pipe split cavity: , Right-angle tube splitter cavity: , Ventilation cavity: ;

[0027] When a right-angle confluence cavity or a right-angle divergence cavity serves as the terminal of a cavity floor exhaust system, and the exhaust duct is connected to an external duct, if the duct connected to the right-angle confluence cavity and the right-angle divergence cavity is a straight duct, it is further subdivided into a right-angle straight duct confluence cavity and a right-angle straight duct divergence cavity. If the duct connected to the right-angle confluence cavity and the right-angle divergence cavity is a bend, it is further subdivided into a right-angle corner duct confluence cavity and a right-angle corner duct divergence cavity.

[0028] Solve the five exponents in the same set of formulas for each type of cavity using the arithmetic mean. The number is used as a conventional truth value: the exponent in the five fitted formulas in the same group of formulas. The optimization index was obtained by averaging the values. Set different airflow rates Utilizing optimization index and airflow speed This can be substituted into the formulas for the resistance loss of various types of cavities to obtain the coefficients. Correction coefficient : Fully straight cavity: , Right-angle turn cavity: , Flat-angle confluence cavity: , Exhaust vent cavity: , Flat-angle split cavity: , Ventilation cavity: , Right-angle straight pipe confluence cavity: , Right-angle tube confluence cavity: , Right-angle straight pipe split cavity: , Right-angle tube splitter cavity: .

[0029] Due to the coefficient Follow The changes occur with the changes in the cavity system, and numerical simulations are used to analyze the numerical values ​​of various types of cavity systems. and the corresponding cross-sectional area ratio By merging and analyzing line segments with similar slopes in the numerical simulation curves, we can proceed according to... The rate of change divides the numerical simulation curve into segments, and the criterion for segmentation is... Follow To determine whether the increase is amplification or decrementalization, and whether there are sudden changes in the rate of change, linear fitting is sequentially performed on each segment of the simulated curve after segmentation to obtain... and Function expressions between ; Various types of hollow bodies The fitting formula is as follows: Fully straight cavity: , Right-angle turn cavity: , Flat-angle confluence cavity: , Right-angle straight pipe confluence cavity: , Right-angle tube confluence cavity: , Exhaust vent cavity: , Flat-angle split cavity: , Right-angle straight pipe split cavity: , Right-angle tube splitter cavity: , Ventilation cavity: .

[0030] By decomposing the cavity floor exhaust vent into cavities, the air resistance loss can be evaluated using the optimized pressure loss fitting formulas for each type of cavity.

[0031] The above description is merely one embodiment of the present invention and is not intended to limit the present invention. Any minor modifications, equivalent substitutions, and improvements made to the above embodiment based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for assessing air resistance loss based on the exhaust cavity of a cavity floor slab, characterized in that, The steps are as follows: Step 1: Based on the structural characteristics of the cavity floor exhaust duct, it is divided into eight types of cavities. All cavities are composed of the same cavities and concealed pipes. Step 2: Set up measuring points in the cavity and the duct to obtain multiple sets of air velocity and pressure values ​​for each type of cavity at different fan frequencies. At the same time, consider the image of air velocity and pressure values ​​compared with the cross-sectional area of ​​different cavities and ducts, and calculate the resistance loss obtained by the pressure difference. Step 3: Using the power function relationship between duct resistance loss and flow velocity, the coefficients of air resistance loss in the eight types of cavities are obtained through fitting. Sum of Indices This leads to the functional relationship between resistance loss and flow velocity for eight types of cavities: Step 4: Calculate the optimization index and optimization coefficients The optimized fitting formulas for pressure loss of various types of cavities are obtained: Step 5: Decompose the cavity floor exhaust vent to be evaluated into cavities, and then use the optimized pressure loss fitting formula for each type of cavity to evaluate the air resistance loss.

2. The method for assessing air resistance loss based on the exhaust cavity of a cavity floor slab according to claim 1, characterized in that, Eight types of cavities are manufactured based on the combination of cavities and concealed pipes and the direction of airflow: straight cavities, right-angle turning cavities, flat-angle confluence cavities, right-angle confluence cavities, exhaust vent cavities, flat-angle splitting cavities, right-angle splitting cavities, and ventilation vent cavities. The straight cavity has two concealed pipes installed on the two sides facing each other. Fluid enters from one concealed pipe and exits from the other concealed pipe. The right-angle turning cavity has concealed pipes installed on two adjacent sides of the cavity, with the two concealed pipes forming a 90-degree angle. Fluid enters from one concealed pipe and exits from the other concealed pipe. The flat-angle confluence cavity is equipped with concealed pipes on three adjacent sides of the cavity. Fluid enters through two oppositely arranged concealed pipes and exits through the third concealed pipe. The right-angle confluence cavity has concealed pipes on three adjacent sides of the cavity. Fluid enters through two adjacent concealed pipes and exits through the third concealed pipe. The exhaust port cavity is a cavity connected to a concealed pipe, and an air inlet is opened on the cavity. Fluid enters from the air inlet and exits from the concealed pipe. The flat-angle split cavity has concealed pipes on three adjacent sides of the cavity. Fluid is discharged through two oppositely arranged concealed pipes and enters through the third concealed pipe. The right-angle split cavity has concealed pipes on three adjacent sides of the cavity. Fluid enters through one of the two oppositely arranged concealed pipes and exits from the other two concealed pipes. The ventilation cavity is a cavity connected to a concealed pipe, and an air outlet is opened on the cavity. Fluid enters the cavity from the concealed pipe and exits from the air outlet.

3. The method for assessing air resistance loss based on the exhaust cavity of a cavity floor slab according to claim 2, characterized in that, Eight types of cavity test models were constructed. Measuring points, including a QDF-6 hot-wire anemometer and a DP2000 differential pressure gauge, were arranged in the cavities and concealed tubes of the eight types of cavity test models. The specific steps and methods are as follows: For each type of cavity, a fan was used to generate simulated airflow. The fan frequency was adjusted to 10 Hz, 20 Hz, 30 Hz, 40 Hz, and 50 Hz to obtain different initial airflow velocities. Three measuring points were arranged inside all the concealed pipes and at the cross-section of the exhaust outlet for each type of cavity. Three six-part points were selected along the cross-sectional length of the concealed pipe as measuring points, and the average value of the three measuring points was calculated as the airflow velocity inside the concealed pipe. At the exhaust outlet, one measuring point was set at the middle, side, and corner of the exhaust outlet, and the average value was calculated as the airflow velocity of the exhaust outlet. The exhaust outlet is the main duct where the airflow is discharged to the outside at the confluence of the concealed pipe system.

4. The method for assessing air resistance loss based on the exhaust cavity of a cavity floor slab according to claim 3, characterized in that, Consider the impact of airflow velocity and pressure values ​​on the cross-sectional areas of different cavities and concealed pipes: Let the vertical cross-sectional area of ​​the cavity be... For a rectangle, the vertical cross-sectional area of ​​the concealed pipe is... Rectangular; using the local resistance loss within the cavity to represent the overall resistance loss, since the overall resistance loss is related to the cross-sectional area of ​​the concealed pipe. and the vertical cross-sectional area of ​​the cavity The cross-sectional ratio is related, therefore, based on experimental experience, it is given... Values ​​are selected to form various cross-sectional ratios; the ratio of the cross-sectional area of ​​the concealed pipe to the vertical cross-sectional area of ​​the cavity is set in eight types of cavities. The drag loss data of each type of cavity under different airflow velocities at five different cross-sectional scales were simulated using the shear stress transfer turbulence model SST k-ω. The drag loss data of each type of cavity under different airflow velocities at five different cross-sectional scales: 0.1, 0.2, 0.3, 0.4 and 0.5 were simulated using the SST k-ω model.

5. The method for assessing air resistance loss based on the exhaust cavity of a cavity floor slab according to claim 4, characterized in that, The power function relationship between cavity resistance loss and flow velocity Taking the logarithm of both sides yields the drag loss. With flow rate Functional relationship: ,make The formula simplifies to: Simulated values ​​of total resistance loss for all types of cavities under different cross-sectional proportions. and flow rate Substitute them separately Then, the coefficients of air resistance loss for cavities of different types and cross-sectional proportions were obtained by fitting using the least squares method. Sum of Indices The formula is as follows: ， In the formula, n is the total number of sets of numerical simulation data; the subscript i of X and Y is the sequence number of the numerical simulation data.

6. The method for assessing air resistance loss based on the exhaust cavity of a cavity floor slab according to claim 5, characterized in that, The ratio of cross-sectional area of ​​eight types of cavities For five cross-sectional ratios (0.1, 0.2, 0.3, 0.4, and 0.5), the coefficients of air resistance loss for different types and cross-sectional ratios of cavities were obtained by least squares fitting. Sum of Indices Then, according to the formula: Coefficient of air resistance loss Sum of Indices Represented as: Fully straight cavity model: , Right-angle turning cavity: , Flat-angle confluence cavity: , Right-angle straight pipe confluence cavity: , Right-angle tube confluence cavity: , Exhaust vent cavity: , Flat-angle split cavity: , Right-angle straight pipe split cavity: , Right-angle tube splitter cavity: , Ventilation cavity: ; When a right-angle confluence cavity or a right-angle split cavity serves as the terminal of a cavity floor exhaust system, and the duct connecting the right-angle confluence cavity and the right-angle split cavity is a straight duct, it is further subdivided into a right-angle straight duct confluence cavity and a right-angle straight duct split cavity. When the duct connecting the right-angle confluence cavity and the right-angle split cavity is a bend, it is further subdivided into a right-angle corner duct confluence cavity and a right-angle corner duct split cavity.

7. The method for assessing air resistance loss based on the exhaust cavity of a cavity floor slab according to claim 6, characterized in that, Solve the five exponents in the same set of formulas for each type of cavity using the arithmetic mean. The number is used as a conventional truth value: the exponent in the five fitted formulas in the same group of formulas. The optimization index was obtained by averaging the values. Set different airflow rates Utilizing optimization index and airflow speed This can be substituted into the formulas for the resistance loss of various types of cavities to obtain the coefficients. Correction coefficient : Fully straight cavity: , Right-angle turn cavity: , Flat-angle confluence cavity: , Exhaust vent cavity: , Flat-angle split cavity: , Ventilation cavity: , Right-angle straight pipe confluence cavity: , Right-angle tube confluence cavity: , Right-angle straight pipe split cavity: , Right-angle tube splitter cavity: .

8. The method for assessing air resistance loss based on the exhaust cavity of a cavity floor slab according to claim 7, characterized in that, Due to the coefficient Follow The changes occur with the changes in the cavity system, and numerical simulations are used to analyze the numerical values ​​of various types of cavity systems. and the corresponding cross-sectional area ratio By merging and analyzing line segments with similar slopes in the numerical simulation curves, we can proceed according to... The rate of change divides the numerical simulation curve into segments, and the criterion for segmentation is... Follow To determine whether the increase is amplification or decrementalization, and whether there are sudden changes in the rate of change, linear fitting is sequentially performed on each segment of the simulated curve after segmentation to obtain... and Function expressions between ; Various types of hollow bodies The fitting formula is as follows: Fully straight cavity: , Right-angle turn cavity: , Flat-angle confluence cavity: , Right-angle straight pipe confluence cavity: , Right-angle tube confluence cavity: , Exhaust vent cavity: , Flat-angle split cavity: , Right-angle straight pipe split cavity: , Right-angle tube splitter cavity: , Ventilation cavity: .

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program adapted to be loaded by a processor and executed by the method for assessing resistance loss of various cavities in the cavity floor ventilation system as described in claims 1-8.

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