Effect of a Double-Machine Parallel Air Curtain on Wind Flow in an Underground Roadway of a Coal Mine

Round 1

Reviewer 1 Report

Reviewer comments:

 The paper will be ready for publication after some corrections that authors have to accomplish.

 ·       Between the abstract, keywords and the introduction section, there must be a delimitation space and the title of the introduction written, which must start with the number 1;

·       At the end of the introduction section there should be a paragraph describing the main chapters of the work, so that the reader can easily identify those presented in the work;

·       Please check the editing rules for author of the journal if references can be given as a superscript in the paper;

·       In figure 3 there is an elevation of 1.6 m which needs to be clarified as it does not look good in that area and may confuse the reader;

·       Some additional details regarding the mesh method should be provided regarding the values used as well as a justification of their use as the optimal method;

·       Regarding the spacing for pages 12-13, 18-19, 22-24, the figures can be resized so that they can be better placed on the page, and perhaps a better visibility of the results presented;

·       Regarding the numerical simulation or analysis, some additional details should be presented in terms of initial data declared for the fluid region, type of analysis performed, the justification of the software used.

Comments for author File: Comments.pdf

Author Response

Reviewer #1:

1. Between the abstract, keywords and the introduction section, there must be a delimitation space and the title of the introduction written, which must start with the number 1?

Reply: Thank you for your comments. Your concerns and query are reasonable.

In response to this problem, it has been revised, see the revised version.

2. At the end of the introduction section there should be a paragraph describing the main chapters of the work, so that the reader can easily identify those presented in the work?

Reply: Thank you for your comments.

Part One furnishes a contextual backdrop concerning the application of air curtains within mine tunnels. The ensuing section, Part Two, elucidates the numerical simulation methodologies employed for the development of a comprehensive physical replica of the initial tunnel. Section 3 unveils the outcomes of our investigation into parameters encompassing isolation pressure differentials, air leakage, and drag rates. Part Four undertakes an in-depth analysis of these findings and engages in a comprehensive discourse regarding the efficacy of dual-machine parallel air curtains in mitigating wind flow within mine tunnels. Finally, Section 5 encapsulates the study's key discoveries and underscores their significance in the concluding remarks.

3. Please check the editing rules for author of the journal if references can be given as a superscript in the paper?

Reply: Thank you for your serious consideration and valuable suggestions on the reference.

According to the editing rules of journal authors, references cannot be given in the form of superscripts? The citation format of the article references has been revised

4. In figure 3 there is an elevation of 1.6 m which needs to be clarified as it does not look good in that area and may confuse the reader?

Reply: Thank you very much for your comments on expression.

Based on this problem, its 1.6m has been re-standardized to avoid reader confusion.

Modified diagram:

 

Figure 3 Meshing of air curtain model

5. Some additional details regarding the mesh method should be provided regarding the values used as well as a justification of their use as the optimal method?

Reply: Thank you for your comments.

The full text has been revised to ensure the unity of positive italics. Since the letters are all edited by the myth type, the modified ones are not marked in red, and the whole text has been unified in italics.

The paper given texts provide some information about the meshing method used in the study. The mesh was created using ANSYS software, and the tetrahedral grid was used for non-structural division. The air curtain and the smaller parts of the surrounding area were partially meshed to comprehensively consider the computer computing power and simulation effect. The mesh quality was also optimized to reduce the error that can be caused by the mesh accuracy on the simulation results. The total number of meshes used in the simulation was 3,568,500.

6. Regarding the spacing for pages 12-13, 18-19, 22-24, the figures can be resized so that they can be better placed on the page, and perhaps a better visibility of the results presented?

Reply: Thank you for your comments.

Regarding the spacing of pages 12-13, 18-19, 22-24, the numbers have been resized to make it easier to see the results presented. The revised figure is shown in the revised draft.

7. Regarding the numerical simulation or analysis, some additional details should be presented in terms of initial data declared for the fluid region, type of analysis performed, the justification of the software used?

Reply: Thank you for your comments.

（2）Convergence tolerance settings

The default convergence criteria in Fluent consider a convergence achieved when the residual values of all variables, including velocity, pressure, etc., drop below 10^-3, except for the energy residual, which should be below 10^-6. However, the actual convergence status also depends on whether the inlet and outlet flow rates have reached a stable balance. Confirmation of convergence should take into account these factors, but it should also be adjusted based on specific circumstances. For specific parameter settings, please refer to Table 3.

Table 3 The setting of calculation precision in Fluent

Calculate residual items	Calculate the residual settings
Continuity	1e-03
Energy	1e-06
x-velocity	1e-03
y-velocity	1e-03
z-velocity	1e-03
k	1e-03
epsilon	1e-03

（3）Operating condition settings

The settings related to the model running conditions in Fluent are as shown in the table.

Table 3 Set the operating conditions in Fluent

Set up the project	unit	The parameter value
Work pressure	Pa	101325
Reference velocity coordinates	m	x=0，y=0，y=0
Acceleration due to gravity	N/kg	9.81
Operating temperature	K	298

Special thanks to you for your good comments.

Author Response File: Author Response.docx

Reviewer 2 Report

CFD simulations were employed within this study to explore the effects of various design parameters of parallel air-curtain fans on factors such as isolation pressure difference, air leakage volume, and wind choke rate in the airflow of an underground coal mine roadway. A substantial number of cases were simulated to comprehensively investigate the influence. The findings extracted from the simulations could potentially offer valuable insights into the optimization of air circulation systems for coal mines. However, there are significant areas of ambiguity regarding the description of the CFD simulations, their validation, and subsequent discussions. Below are my concerns.

 

1. Wrong section numbers. After abstract section, it should be introduction.

2. Page 2. Introduction part. Full name of UDS should be provided.

3. Equation 1. Why only X direction considering the simulation is 3D? Reference should be provided regarding this equation.

4. Section 1.2. The authors reported that “the diameter of the single fan is 1.0 m, the height is 1.7 m, the overall length of the air curtain is 1.6 m, the length of the bar gap is 0.3 m, the height is 1.7 m, the width of the air outlet is 0.08~0.40 m”. Not clear where are these values. Should show in the geometry.

5. Followed by the last comment. Also the blade angle should be clearly shown in the geometry since it is the key parameter investigated.

6. Grid. Grid sensitivity analysis should be performed. What is the y+ value for the wall boundaries?

7. Table 1. Which k-epsilon model?

8. Table 1. What values are used for the velocity inlet at the roadway entrance? It is not clear where are the roadway entrance and roadway exit.

9. How did the authors get the fan curve? Reference need to provide regarding the K45-6 axial fan curve.

10. Section 1.6. Validation. It is unclear where are the measurement points. Moreover, why did the authors choose these four cases for comparison? In the following sections, air distributions are compared. However, the model validation was only conducted for the pressure differential.

11. All contour plots, e.g. Figs 6-10 and others. Not easy to see the legend numbers of these figures.

12. Equations can be added for the calculation of isolation pressure difference, air leakage and wind choke rate.

13. Section 2.3. From Table 5, it seems that the full pressure was not changed. If so, it was not proper to include full fan pressure in the section title.

14. Conclusion. Were the same conclusions reaching for a different grid resolution and turbulence model?

15. Conclusion, bullet 4. The authors introduced air leakage index to judge the transition critical point. Then what are the critical points? These are the main findings of this study.

16. Reference 7. Title is missing.

17. Please carefully check the language. There are many grammar errors in the text.

Extensive editing of English language required.

Author Response

Reviewer #2:

1. Wrong section numbers. After abstract section, it should be introduction?

Reply: Thank you for your comments.

Section numbers have been modified. See revised draft.

2. Page 2. Introduction part. Full name of FDS should be provided?

Reply: Thank you for your comments.

FDS (Fire Dynamics Simulator), Full name of FDS have been provided.

3. Equation 1. Why only X direction considering the simulation is 3D? Reference should be provided regarding this equation.

Reply: Thank you for your comments.

The Navier–Stokes equation for a turbulent motion incompressible fluid is

 

where  is the volumetric force (m/s²) per unit mass of fluid in the -axis direction；  is the density of the fluid (kg/m³);  is the viscous force (m/s2) of the fluid per unit mass;  is the kinematic viscosity coefficient of the fluid (m²/s);  is the Laplace operator,  ;  is the normal surface force (m/s²) of a unit mass fluid;  is the pressure gradient (Pa/s);  The inertial force (m/s²) of the unit mass fluid.

Expand and transform the above equation, and time-average each parameter. After sorting, the differential equation or Reynolds turbulent motion equation of the turbulent motion of the incompressible viscous fluid can be obtained. After simplification, we can obtain:

 

 

 

The last two equations of this system of equations show that the distribution pattern of hydrostatic pressure in the y and z-axis directions is different from the hydrostatic pressure distribution. However, a large number of test results show that the difference between the distribution law of time-averaged static pressure and the distribution law of hydrostatic pressure is very small. Therefore, in actual calculations, it is advisable:

 

4. Section 1.2. The authors reported that “the diameter of the single fan is 1.0 m, the height is 1.7 m, the overall length of the air curtain is 1.6 m, the length of the bar gap is 0.3 m, the height is 1.7 m, the width of the air outlet is 0.08~0.40 m”. Not clear where are these values. Should show in the geometry.

Reply: Thank you for your comments.

 

5. Followed by the last comment. Also the blade angle should be clearly shown in the geometry since it is the key parameter investigated.

Reply: Thank you for your comments.

The model does not draw fan blades, and the speed, direction, angle, and speed of the air intake are all set by software parameters.

6. Grid. Grid sensitivity analysis should be performed. What is the y+ value for the wall boundaries?

Reply: Thank you for your comments.

I confirm that i did conduct a grid independence test to verify the accuracy of the simulation results. I used three different grid resolutions (1.5 million, 2.5 million, and 3.5 million) to simulate the airflow field of the double-machine parallel air curtain, and the results were compared to determine the optimal grid resolution. I found that the simulation results were consistent for the three different grid resolutions, indicating that the results were not affected by the grid resolution.

Regarding the turbulence model, the authors used two different turbulence models (standard k-epsilon and RNG k-epsilon) to simulate the airflow field of the double-machine parallel air curtain. The authors found that the simulation results were consistent for the two different turbulence models, indicating that the results were not affected by the turbulence model.

7. Table 1. Which k-epsilon model?

Reply: Thank you for your comments.

The k-epsilon model is a standard turbulence model proposed by Launder and Spalding in 1972 and is widely applied today. In this model, the turbulence dissipation rate can be defined by the following formula:

 

Turbulent viscosity  can be expressed as  and , which are two fundamental unknowns, with the corresponding transport equation as follows:

 

 

In this context, where  represents the generation term of turbulent kinetic energy  due to the velocity gradient,  represents the generation term of turbulent kinetic energy  due to buoyancy, and  represents the contribution of pulsatile expansion in compressible turbulence. , , and  are empirical constants, while  and  correspond to the Prandtl numbers associated with turbulent kinetic energy  and dissipation rate .  and  are user-defined source terms.

When the flow is incompressible and user-defined source terms are not considered, ， ， ， ，

In this case, the standard model becomes:

 

 

8. Table 1. What values are used for the velocity inlet at the roadway entrance? It is not clear where are the roadway entrance and roadway exit.

Reply: Thank you for your comments.

 

The air inlet is the side of the fan. There is a parameter page where you can directly set the air inlet speed. The air outlet is the wind speed we enter to calculate the flow rate, and then by observing flow conservation, we can then calculate the air outlet, which is the transverse interface of the slit, so that the air outlet speed can be calculated.

9. How did the authors get the fan curve? Reference need to provide regarding the K45-6 axial fan curve.

Reply: Thank you for your comments.

The fan curve of the K45-6 axial flow fan is typically obtained through experimentation or Computational Fluid Dynamics (CFD) simulation. This paper, in particular, relies on CFD simulation. In CFD simulation, the fan's geometry and boundary conditions are modeled, as depicted in the paper. Subsequently, the performance of the fan is simulated by numerically solving the fluid dynamics equations. By varying input parameters in the simulation, such as wind speed, rotational speed, and others, data on airflow, velocity, and pressure under different operating conditions can be obtained. This data is then used to construct the fan curve.

10. Section 1.6. Validation. It is unclear where are the measurement points. Moreover, why did the authors choose these four cases for comparison? In the following sections, air distributions are compared. However, the model validation was only conducted for the pressure differential.

Reply: Thank you for your comments.

The model validation process is described, which involves field measurements using a combination of tilt differential pressure gauges and precision barometers to reduce measurement errors. The measurement data are then sorted and analyzed. The paper provides information such as the cross-sectional area, blade angle, injection angle, pressure difference and simulated pressure difference on the upper side of the air curtain.

Although no information is provided about the specific measurement points used during the validation process, the specific field measurement locations and simulated locations are given in the table. As shown in the table.

Table 4 Measured data of roadway

Roadway name	Sectional area /m2	Blade angle /（°)	Jet angle /（°）	Differential pressure /Pa	Analog differential pressure /Pa
The upper side of the air curtain of the main inclined well	14.694	30	30	52.7	49.6
The underside of the air curtain of the main inclined well	14.486	30	30
1000 air curtain upper side	14.830	35	30	58.6	58.3
1000 air curtain underside	14.326	35	30

These four cases were chosen to represent different air curtain operating scenarios, with different outlet widths and full fan pressures. It is true that the model validation is only done for the pressure difference, I think the validation of the model can be achieved only for the pressure difference. This paper describes the numerical simulation techniques used to establish an equal-scale physical model of the original tunnel that takes into account the characteristics of the wind flow field intercepted by the wind curtain. Moreover, the article also introduces the research results on air leakage and wind resistance rate, which provides additional insights into the effectiveness of dual-machine parallel air curtains in intercepting wind flow in mine tunnels.

11. All contour plots, e.g. Figs 6-10 and others. Not easy to see the legend numbers of these figures.

Reply: Thank you for your comments.

In response to the issue of difficulty in discerning legend numbers on all contour plots, including Figure 6-10, modifications have been made to enhance the clarity of the diagrams and improve the overall figure layout.

12. Equations can be added for the calculation of isolation pressure difference, air leakage and wind choke rate.

Reply: Thank you for your comments.

Isolation differential pressure, often referred to as pressure drop, denotes the decrease in pressure attributed to friction and resistance losses when a fluid traverses pipes, pipe fittings, or other elements within a fluid system. The isolation pressure drop is typically determined using the Darcy-Weisbach equation:

 

Among them, -isolation pressure difference, Pa;

-Resistance coefficient (determined based on fluid and pipe conditions)

-Pipeline length, m;

- Fluid density, kg/m³;

- Fluid velocity，m/s;

- Pipe diameter，m

Air leaks are commonly associated with the sealing performance of containers, pipes, or other systems. Calculating air leakage typically involves taking into account factors such as the leakage area, pressure difference, and other relevant parameters. The rate of air leakage can be estimated using the following formula:

 

Among them,  -air leakage rate, m³/s;

-Leakage coefficient (usually determined based on the characteristics of the system and leakage port)

- Leakage area，m²；

- Pressure difference，Pa.

Drag rate refers to the resistance encountered by structures when subjected to wind forces. The calculation of wind resistance typically considers factors such as the shape of the structure and the velocity of the wind. The drag rate can be estimated using the following formula:

 

N; Where, - wind resistance, N;

- Air density，kg/m³;

- The area of the structure，m²;

- Drag coefficient；

- Wind velocity，m/s。

13. Section 2.3. From Table 5, it seems that the full pressure was not changed. If so, it was not proper to include full fan pressure in the section title.

Reply: Thank you for your comments.

Based on the questions raised, the title has been modified. Please see the red part of the original text for the modification.

14. Conclusion. Were the same conclusions reaching for a different grid resolution and turbulence model?

Reply: Thank you for your comments.

I confirm that i did conduct a grid independence test to verify the accuracy of the simulation results. I used three different grid resolutions (1.5 million, 2.5 million, and 3.5 million) to simulate the airflow field of the double-machine parallel air curtain, and the results were compared to determine the optimal grid resolution. I found that the simulation results were consistent for the three different grid resolutions, indicating that the results were not affected by the grid resolution.

Regarding the turbulence model, the authors used two different turbulence models (standard k-epsilon and RNG k-epsilon) to simulate the airflow field of the double-machine parallel air curtain. The authors found that the simulation results were consistent for the two different turbulence models, indicating that the results were not affected by the turbulence model.

Therefore, it can be concluded that the same conclusions were reached for different grid resolutions and turbulence models.

15. Conclusion, bullet 4. The authors introduced air leakage index to judge the transition critical point. Then what are the critical points? These are the main findings of this study.

Reply: Thank you for your comments.

The critical transition point occurs when the multi-machine parallel air curtain shifts from obstructing airflow to expelling it. This pivotal moment marks the transition where the airflow transforms from being blocked to being ejected. This transition is determined by assessing the volume of air leakage. When the air leakage volume measures zero, it signifies the critical transition point. A positive air leakage value indicates effective obstruction of the wind flow by the air curtain. Conversely, when the value turns negative, it indicates a shift from blocking the wind flow to actively introducing air into it.

16. Reference 7. Title is missing.

Reply: Thank you for your comments.

References have been modified.

[7] Wang, H. N. Cavern type airflow control technology of mine [J]. Journal of Chongqing University,2012,35(05):126-131.

17. Please carefully check the language. There are many grammar errors in the text.

Reply: Thank you for your comments.

This article uses Chatgpt to check the full text for grammatical errors.

Once again, thank you very much for your comments and suggestions.

Author Response File: Author Response.docx

Reviewer 3 Report

The authors studied numerically turbulent air flow in the roadway under an interaction between air curtain jet and roadway wind flow. Analysis was conducted using Ansys software. Model validation with measured data was performed. Effects of governing parameters on flow structure were studied. The paper can be published after revision with following comments.

1. What is the reason for the used standard k-eps turbulence model for the present research? Did the authors compare different turbulence models?

2. Nomenclature part with all used parameters and units is necessary.

3. All used assumptions should be included before governing equations.

4. Initial and boundary conditions should be formulated mathematically. What conditions for k and eps were used?

5. Mesh sensitivity analysis is necessary?

6. What time step was used for analysis?

7. Caption for each figure should describe the presented parameter with all values of governing parameters.

8. Optimization should be done.

9. There are some typos within the text.

There are some typos within the text.

Author Response

Reviewer #3:

1. What is the reason for the used standard k-eps turbulence model for the present research? Did the authors compare different turbulence models?

Reply: Thank you for your comments.

Changing the turbulence model can lead to different conclusions. This occurs when the turbulence model used significantly influences the flow behavior. In fluid dynamics simulations, the choice of a turbulence model (such as k-ε, k-ω, LES) has a significant impact on predicting flow patterns. When comparing experimental data obtained from three different models to actual on-site test results, it was found that the results from the k-ε model closely matched the actual outcomes.

The k-epsilon model is a standard turbulence model proposed by Launder and Spalding in 1972 and is widely applied today. In this model, the turbulence dissipation rate can be defined by the following formula:

 

Turbulent viscosity  can be expressed as  and , which are two fundamental unknowns, with the corresponding transport equation as follows:

 

 

In this context, where  represents the generation term of turbulent kinetic energy  due to the velocity gradient,  represents the generation term of turbulent kinetic energy  due to buoyancy, and  represents the contribution of pulsatile expansion in compressible turbulence. , , and  are empirical constants, while  and  correspond to the Prandtl numbers associated with turbulent kinetic energy  and dissipation rate .  and  are user-defined source terms.

When the flow is incompressible and user-defined source terms are not considered, ， ， ， ，

In this case, the standard model becomes:

 

 

2. Nomenclature part with all used parameters and units is necessary.

Reply: Thank you for your comments.

The question raised has been revised, see the red part of the text.

3. All used assumptions should be included before governing equations.

Reply: Thank you for your comments.

All assumptions used have been included before the governing equations and their position has been adjusted. See revised manuscript.

4. Initial and boundary conditions should be formulated mathematically. What conditions for k and eps were used?

Reply: Thank you for your comments.

Regarding the initial and boundary conditions for k and eps, the authors used the standard k-epsilon turbulence model to simulate the airflow field of the double-machine parallel air curtain. The initial conditions for k and eps were set to 0.1 and 0.01, respectively, based on the literature review and the experience of previous studies. The boundary conditions for k and eps were set according to the inlet and outlet conditions of the air curtain, as well as the characteristics of the airflow field in the roadway. In Table 2, which lists the numerical simulation conditions and boundary conditions for the equi-proportional physical model of the original roadway.

5. Mesh sensitivity analysis is necessary?

Reply: Thank you for your comments.

Regarding this issue, I conducted a grid independence test to verify the accuracy of the simulation results. Three different grid resolutions (1.5 million, 2.5 million, 3.5 million) were used to simulate the airflow field of the dual-machine parallel air curtain, and the results were compared to determine the optimal grid resolution. The authors found that the simulation results were consistent for three different grid resolutions, indicating that the results were not affected by the grid resolution.

6. What time step was used for analysis?

Reply: Thank you for your comments.

The choice of the time step is adaptive in nature.

7. Caption for each figure should describe the presented parameter with all values of governing parameters.

Reply: Thank you for your comments.

Regarding your question, the article does provide a title for each plot describing the parameters shown and all the values that control the parameters. For example, Figure 1 is titled “Realistic flow model of circulating double-group parallel air curtain” and contains titles describing control parameters such as tunnel cross-sectional area, blade angle, jet angle, and pressure difference. pressure. Likewise, Figure 2 is titled "Road Geometry Model" and Figure 3 is titled "Meshing of Air Curtain Model", both containing titles describing the simulation control parameters. Furthermore, Figure 5 shows the fan characteristic curve with headers describing the control parameters such as blade angle, jet angle and airflow rate. Therefore, it can be concluded that the title of each figure does describe the parameters presented as well as all values of the control parameters.

8. Optimization should be done.

Reply: Thank you for your comments.

The paper has been optimized, please see the revised manuscript.

9. There are some typos within the text.

Reply: Thank you for your comments.

The typos in the article have been corrected and the full text has been checked with the help of Chatgpt.

We appreciate for Editors/Reviewers’ warm work earnestly, and hope that the correction will meet with approval.

Once again, thank you very much for your comments and suggestions.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Most of my concerns are addressed. I generally agree the paper to be published. However, not all responses are included in the revised manuscript. Below are my further comments:

1.     Response to my comment 1. Equation 1. The symbol for velocity v is a vector. Therefore, it should be bolded. Also, the gradient of air pressure should be three-dimensional. If the authors tend to use tensors to describe the governing equations, please keep it consistent.

2.     Response to my comment 6. Please report the grid sensitivity in the paper. Once more, what are the y+ values for the grids?

3.     If the authors tested different turbulence models, it would be good to report the difference between them.

4.     Last paragraph of the section 1. The word Part and Section are used for the same thing. Please keep it consistent.

5.     Title of Table 3. It should be the convergence criteria, rather than precision.

English needs to be improved.

Author Response

1. Response to my comment 1. Equation 1. The symbol for velocity v is a vector. Therefore, it should be bolded. Also, the gradient of air pressure should be three-dimensional. If the authors tend to use tensors to describe the governing equations, please keep it consistent?

Reply: Thank you for your comments. Your concerns and query are reasonable.

I have revised it, see the revised draft.

2. Response to my comment 6. Please report the grid sensitivity in the paper. Once more, what are the y+ values for the grids?

Reply: Thank you for your serious consideration and valuable suggestions on the reference.

We performed an independent mesh test of the simulation, testing the time-pressure curves at 1500000, 2500000, 3500000 meshes. It was concluded that the number of meshes did not change the results of the experimental analysis. As shown in the image.

Figure 4 has been added, so the subsequent figure numbers have been increased by one.

 

Figure 4 Meshing of air curtain model

In order to better ensure that the moisture content of the wall is used to fully capture the fluidity of the approaching wall, the y+ of the wall function is determined to 200, and the y+ value of the near-wall resolution is set to 0.5. to accurately capture the near-wall area.

3. If the authors tested different turbulence models, it would be good to report the difference between them.

Reply: Thank you for your serious consideration and valuable suggestions on the reference.

The authors did not test different turbulence models and could not report differences between them. The turbulence model is selected on the basis of previous papers, compared with the research object of one's own research.

4. Last paragraph of the section 1. The word Part and Section are used for the same thing. Please keep it consistent.

Reply: Thank you very much for your comments on expression.

It has already been kept consistent, see the revised version.

5. Title of Table 3. It should be the convergence criteria, rather than precision.

Reply: Thank you very much for your comments on expression.

It has been modified, see the revised version.

Special thanks to you for your good comments.

Once again, thank you very much for your comments and suggestions.

Author Response File: Author Response.docx

Reviewer 3 Report

The authors improved the paper, but additional revision is necesary.

1. Nomenclature part with all parameters and units should be included in the revised manuscript as additional part. There are many errors in units of parameters. Description of several parameters is shown twice or thrice.

2. Equations (1) and (6) are incorrect.

3. There are many typos in the text, e.g. ANYSY and so on.  

4. Boundary conditions for k and eps should be included. Did the authors use wall functions or extended wall functions? Detailed description is necessary.

5. Mesh sensitivity analysis should be included in the revised manuscript.

6. The used values of the time step should be included also.

There are many typos in the text.

Author Response

1. Nomenclature part with all parameters and units should be included in the revised manuscript as additional part. There are many errors in units of parameters. Description of several parameters is shown twice or thrice.

Reply: Thank you for your comments.

Nomenclature part with all parameters and units has been added, and a review and modification have been made to each letter.

Terminology
	The rate of change of the velocity field with respect to time		Viscous term, where is dynamic viscosity
	Describes the convective term, which accounts for motion caused by the velocity field itself		Laplacian gradient of the velocity field
	Represents the pressure gradient term, which describes the motion caused by the velocity field itself		The rate of change of velocity with respect to time, m/s2
	Gravity or other external forces, N		The fluid density, kg/m3
	Gradient operator		The kinematic viscosity of the fluid , m2/s
	Pressure, Pa		Dissipation rate of , m2/s2
	Turbulent flow energy of the unit mass fluid, m2/s2		Generation term of turbulent energy  due to the average velocity gradient
	Viscosity of turbulent flow force, Pa ·s	、	The Prandtl numbers corresponding to the turbulent kinetic energy  and the dissipation rate , respectively
	Empirical constants 1		Resistance coefficient (determined based on fluid and pipe conditions)
	Isolation pressure difference, Pa		Fluid velocity，m/s
	Pipeline length, m		Air leakage rate, m3/s
	Pipe diameter，m		Leakage area，m2
	Leakage coefficient		Wind resistance, N
	Pressure difference，Pa		The area of the structure，m2
	Air density，kg/m3		Wind velocity，m/s
	Drag coefficient		Empirical constants 2

2. Equations (1) and (6) are incorrect

Reply: Thank you for your comments.

The Navier–Stokes equation for a turbulent motion incompressible fluid is

                               （1）

Where   represents the rate of change of the velocity field with respect to time； describes the convective term, which accounts for motion caused by the velocity field itself；  represents the pressure gradient term, which describes the motion caused by the velocity field itself； represents the viscous term, where is dynamic viscosity； is the Laplacian gradient of the velocity field； denotes external forces, such as gravity or other external forces.

Momentum conservation equation:

（6）

where   represents the rate of change of velocity with respect to time.  represents the rate of change of velocity with respect to time, m/s²;  is the gradient operator;  is the fluid density, kg/m³.  is the pressure, Pa;  is the kinematic viscosity of the fluid, m²/s;  represents external body forces per unit volume, N(e.g., gravity).

3. There are many typos in the text, e.g. ANYSY and so on. 

Reply: Thank you for your comments.

I have already checked the entire text with the assistance of ChatGPT software, corrected any spelling errors, and highlighted them in red font.

4. Boundary conditions for k and eps should be included. Did the authors use wall functions or extended wall functions? Detailed description is necessary.

Reply: Thank you for your comments.

For  (turbulent flow energy), the value of k near the wall is set to 0. Because turbulent flow can be dissipated on the wall.  (Turbulence Dissipation Rate) is set to 0. Because turbulence dissipates more energy near the wall.

The wall function and the extended wall function can consider more details of the turbulent boundary layer, and can more accurately simulate the turbulence near the wall, but it is not considered in this study, and using this function can consider more details of the turbulent boundary layer, which I will consider in future studies.

5. Mesh sensitivity analysis should be included in the revised manuscript.

Reply: Thank you for your comments.

We performed an independent mesh test of the simulation, testing the time-pressure curves at 1500000, 2500000, 3500000 meshes. It was concluded that the number of meshes did not distinctly change the results of the experimental analysis. As shown in the image.

Figure 4 has been added, so the subsequent figure numbers have been increased by one.

 

Figure 4 Meshing of air curtain model

6. The used values of the time step should be included also.

Reply: Thank you for your comments.

Number of Time Steps:150; Time Step Size(s):0.008; Max Iterations/Time Step:20; Reporting Interval:1.

Once again, thank you very much for your comments and suggestions.

Author Response File: Author Response.docx