Influence of Long Pressure and Short Suction Ventilation Parameters on Air Flow Field and Dust Migration in Driving Face

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper investigates the distribution of airflow and the evolution of dust pollution in roadways using long pressure and short suction ventilation systems. The study employs both similarity tests and numerical simulations to explore the airflow field, identifying distinct zones such as the jet zone, vortex zone, and reflux zone. Key findings include the optimal conditions for minimizing dust concentrations at the driver’s and pedestrian’s positions, with specific parameters for distance (L), wind speed (Va), and the ratio of pumped to pressured air volume (Q). Grey correlation analysis is used to rank the importance of these factors on various dust concentrations.

1.     The study addresses an important issue in roadway ventilation, particularly concerning dust pollution—a critical factor for the health and safety of drivers and pedestrians. The paper's findings have direct implications for improving air quality in enclosed or partially enclosed roadways.

2.     The combination of similarity tests and numerical simulations is a strong approach, allowing for both empirical validation and detailed computational analysis. This dual methodology enhances the reliability of the results and provides a comprehensive understanding of the airflow dynamics.

3.     The division of the airflow field into jet, vortex, and reflux zones is a useful classification that helps in understanding the complex interactions within the roadway environment. This categorization is likely to aid in designing more effective ventilation systems.

4.     The paper provides specific, actionable insights regarding the optimal conditions (L, Va, Q) for minimizing dust concentrations. These findings are valuable for practical applications, enabling engineers to fine-tune ventilation systems for better air quality management.

5.     The use of grey correlation analysis to rank the importance of various factors affecting dust concentrations adds a quantitative layer to the research. This statistical approach is beneficial for identifying the most critical variables and informing decision-making in ventilation design.

6.     The abstract does not provide sufficient background information on the significance of the study, such as the specific challenges posed by dust pollution in roadways or the existing limitations of current ventilation systems. Including this context would help readers better appreciate the study's contributions.

7.     While the abstract mentions key findings, it lacks specific numerical results or visual data (e.g., graphs or diagrams) that would illustrate the airflow distribution and dust concentration patterns. Providing such details, even briefly, would enhance the clarity and impact of the findings.

8.     The abstract does not discuss the generalizability of the results. It would be beneficial to know whether the findings apply broadly across different types of roadways or are specific to certain conditions or environments.

9.     The abstract could benefit from a more in-depth discussion of the practical implications of the findings. For instance, how might these results influence future roadway design, or what specific recommendations can be drawn for engineers working in this area?

10.  The abstract does not mention any limitations of the study or potential areas for further research. A brief acknowledgment of any constraints or challenges encountered during the research would provide a more balanced perspective.

 

Author Response

1. The study addresses an important issue in roadway ventilation, particularly concerning dust pollution—a critical factor for the health and safety of drivers and pedestrians. The paper's findings have direct implications for improving air quality in enclosed or partially enclosed roadways.

[Response]: Thanks for reviewer’s comments and suggestions. Through test and numerical simulation, we get the best ventilation parameters and put forward the specific measures to reduce dust, which are helpful to reduce the dust concentration in the roadway.

2. The combination of similarity tests and numerical simulations is a strong approach, allowing for both empirical validation and detailed computational analysis. This dual methodology enhances the reliability of the results and provides a comprehensive understanding of the airflow dynamics.

[Response]: Thanks for reviewer’s comments and suggestions. Through the combination of experiment and numerical simulation, this paper explores the influence of factors such as the wind speed at the outlet of the pressure duct, the distance from the pressure duct to the driving surface and the ratio of pumping air volume on the air flow field and dust field in the driving roadway. This study is helpful to understand the dust distribution law in roadway.

3. The division of the airflow field into jet, vortex, and reflux zones is a useful classification that helps in understanding the complex interactions within the roadway environment. This categorization is likely to aid in designing more effective ventilation systems.

[Response]: Thanks for reviewer’s comments and suggestions. In this paper, air flow field is divided into jet zone, vortex zone and reflux zone, which not only helps to understand the complex interaction of air flow field in roadway, but also helps to design a more effective ventilation system. For example, the height and position of air duct can be redesigned, and radial swirl air duct can be redesigned to reduce the generation of vortex zone, thus reducing the dust concentration in roadway.

4. The paper provides specific, actionable insights regarding the optimal conditions (L, Va, Q) for minimizing dust concentrations. These findings are valuable for practical applications, enabling engineers to fine-tune ventilation systems for better air quality management.

[Response]: Thanks for reviewer’s comments and suggestions. In this paper, the optimal conditions for minimizing dust concentration (L=1.6m, Va=8m/s, Q=0.8) were obtained through a large number of experiments and numerical simulations. The dust concentration in the roadway was greatly reduced through reasonable adjustment parameters in the field.

5. The use of grey correlation analysis to rank the importance of various factors affecting dust concentrations adds a quantitative layer to the research. This statistical approach is beneficial for identifying the most critical variables and informing decision-making in ventilation design.

[Response]: Thanks for reviewer’s comments and suggestions. According to the analysis of grey correlation results, it can be seen that the influencing factors on the total dust concentration at the position of drivers and pedestrians are of the same importance, and the order is: L > Va >Q, that is, the main influencing factors on the total dust concentration at the position of drivers and pedestrians are the distance from the pressure tuyere to the driving surface, followed by the wind speed at the outlet of the pressure duct, and finally the ratio of the pumping air volume. The order of importance of influencing factors on the dust concentration of the driver's position is as follows: Va > L >Q, that is, the main influencing factor on the dust concentration of the driver's position is the wind speed of the air outlet of the pressure duct, followed by the distance from the pressure outlet to the driving surface, and finally the ratio of the suction air volume. The order of importance of influencing factors on the dust concentration at the pedestrian position is as follows: Va > Q > L, that is, the main influencing factor on the dust concentration at the pedestrian position is the wind speed at the outlet of the pressure duct, followed by the ratio of pumping air volume, and finally the distance from the pressure tuyere to the driving surface.

6. The abstract does not provide sufficient background information on the significance of the study, such as the specific challenges posed by dust pollution in roadways or the existing limitations of current ventilation systems. Including this context would help readers better appreciate the study's contributions.

[Response]: Thanks for reviewer’s comments and suggestions. We provide more detailed background information on the significance of this study in article (), highlighted in red font in the article: As a kind of mixed ventilation, long-pressure short-pump ventilation has been gradually popularized in low-gas driving roadway due to its better dust control effect compared with pressurized ventilation [30, 31]. However, the dust removal effect of long pressure and short pumping ventilation is different under different parameters. It is necessary to explore the influence of different ventilation parameters on air flow field and dust field in the roadway, and to obtain the best ventilation parameters or the influence of ventilation parameters on the dust field in the roadway can help adjust the ventilation system or change the layout of the roadway.

7. While the abstract mentions key findings, it lacks specific numerical results or visual data (e.g., graphs or diagrams) that would illustrate the airflow distribution and dust concentration patterns. Providing such details, even briefly, would enhance the clarity and impact of the findings.

[Response]: Thanks for reviewer’s comments and suggestions. In this paper, we used cloud maps to characterize the influence of different ventilation parameters (L, Va, Q) on the air flow field and dust field in the roadway, and listed the specific total dust and exhued dust mass concentrations under different parameters in Table 4, Table 5 and Table 6.

8. The abstract does not discuss the generalizability of the results. It would be beneficial to know whether the findings apply broadly across different types of roadways or are specific to certain conditions or environments.

[Response]: Thanks for reviewer’s comments and suggestions. This study focuses on the study of long pressure short pumping ventilation roadway in coal mining face. Due to the different internal layout and ventilation mode of different roadway, it is difficult to apply one specific parameter to all roadway. However, the research ideas in this paper can provide references for determining the optimal ventilation parameters of different roadways, and the dust distribution law in the roadway can be studied by this method, so as to take targeted dust reduction measures.

9. The abstract could benefit from a more in-depth discussion of the practical implications of the findings. For instance, how might these results influence future roadway design, or what specific recommendations can be drawn for engineers working in this area?

[Response]: Thanks for reviewer’s comments and suggestions. We have added a discussion part in the paper and marked it in red letters: This study conducted a detailed study on ventilation and dust removal in a tunnel under long pressure and short suction. Experimental and numerical simulation results show that the air flow field in a tunnel can be divided into three regions: jet region, vortex region and reflux region, which is similar to the results of literature [54]. The dust mass concentration on the side away from the air duct was significantly higher than that on the other side, which was similar to the conclusion in the literature [55]. Therefore, it can be measured in the return air of the roadway, especially in the vicinity of the roadheader with large dust collection amount, the dust removal device can be added to reduce the dust concentration. There are many eddies at the front end of the TBM, so it is possible to implement targeted dust removal measures for the eddies area. In order to effectively capture small particles of dust, spray dust removal should be carried out at higher dust concentrations. This study helps to improve the understanding of dust distribution in driving face, and provides guidance for designing ventilation scheme and zoning dust control. In addition, this study can provide theoretical guidance for the determination of parameters such as the optimal wind speed in the roadway, the distance from the duct to the driving face and the ratio of pumping air volume.

10. The abstract does not mention any limitations of the study or potential areas for further research. A brief acknowledgment of any constraints or challenges encountered during the research would provide a more balanced perspective.

[Response]: Thanks for reviewer’s comments and suggestions. The limitations of the study are explained in detail in the discussion section, and marked in red in the paper: The study in this paper still has certain limitations due to the obstacles of equipment and space in the actual roadway, and the numerical simulation results may be different from the actual situation in the field. Numerical simulations often require building models based on assumptions and simplifications that may not be completely consistent with the actual situation. It takes a certain time for the formation of jet zone, vortex zone and reflux zone, which can provide a theoretical basis for the installation position and opening time of the cyclone ventilation device attached to the wall of the mine air pipe or the windscreen device of the tunnel header. If different ventilation methods are used, the experimental results may be different, and future research should focus on the development of new ventilation methods, such as the development of intelligent air ducts and new risk control devices.

Special thanks to you for your good comments and excellent suggestions.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The authors' article is devoted to an important and topical issue related to determining the impact of suction ventilation parameters on the air flow field and dust migration in the roadway.

After mining operations, a huge amount of pollutants in the form of particles in a wide range of sizes can enter the environment. Their wind transfer leads to the contamination of large areas with chemically active dust. Despite the fact that dust associated with human activity has been a polluting factor for quite a long time, systematic study of this problem is still in its early stages. The reason for this situation is both the underestimation of dust as an important polluting factor, and the difficulty of determining the forces acting on particles from the air flow, and the lack of reliable data on the magnitude of molecular forces that prevent particles from being torn off the ground and from each other. The issue of the removal of heavy particles from the underlying surface and their distribution in the flow has been considered by a number of researchers. It has been shown that if the flow contains sufficiently heavy particles, its turbulent energy is significantly reduced due to the costs of separating the particles from the underlying surface and maintaining them in a suspended state. In this case, it is necessary to consider the propagation of particles in the flow and the motion of the flow itself in a interconnected manner. It is noted that if the work expended by the flow on suspending the particles is small, the flow structure remains virtually unchanged due to the presence of particles in it. In this case, the propagation of particles in the flow can be considered within the framework of the diffusion theory. Concentration and dispersion are the main characteristics, the determination of which is an indispensable condition in the design, conduct of scientific research, development, testing and adjustment of various technical means of suppression, removal and sedimentation of dust, as well as in assessing the sanitary and hygienic state of the air environment. Reliable values of the concentration and dispersed composition of dust can only be obtained using devices that meet modern requirements. The mass concentration of dust and the distribution of particles by aerodynamic diameters must be determined without introducing any distortions into the dispersed composition. The most correct method for determining the concentration and dispersion of dust is to study it directly in the flow, eliminating the destruction of aggregates and crushing of particles. Since the dispersion and concentration of dust in industrial conditions change interrelatedly in time and space, they must be determined simultaneously at a common point in the dusty space. Performing analyses taking these conditions into account is a complex problem that has not yet been fully resolved. Dust suspended in turbulent air flows, as a rule, does not consist of primary particles, but of their aggregates, the number and size of which continuously change during movement depending on various factors. It has been established that the forces of mutual adhesion of particles are inversely proportional to their size and for fine dust are so great that it is practically impossible to re-disperse pre-deposited dust to the original size. Nevertheless, most existing analysis methods are designed to study dust deposited from the air (powders). Dust in powder form is analyzed in air or liquid medium, in which case the aggregates are either destroyed or formed more intensively, and the results of the analysis differ significantly from the true dispersed composition.

The studies presented in the work are undoubtedly of interest to readers in the field under consideration.

 

However, it would be necessary to clarify a number of comments that are available to the article:

1. The introduction should expand the literature review by providing a more in-depth examination of the problems that arise in coal mines due to air dustiness, in particular by providing examples of the selection of a ventilation system, consideration of various aerological risks, etc. The following works could be analyzed: https://doi.org/10.21177/1998-4502-2022-14-1-107-116, https://doi.org/10.25018/0236_1493_2021_11_0_123. Along with this, the values of dust concentration in the air during the operation of mines in different regions of the world could be given.

2. Is it permissible to vary the initial characteristics of the test platform shown in Figure 1 more widely? Is it planned to obtain a patent for the invention in order to enable other researchers to use the given setup when carrying out similar work?

3. It is necessary to conduct a more detailed comparative analysis of the data shown in Figure 2.

4. It is necessary to explain how the most significant factors (section "2.2. Model") that were used in the numerical modeling were determined. Was the method of expert assessments and cluster analysis used?

5. It is necessary to provide a more detailed technology for conducting full and fractional factorial experiments used in the work. Particular attention should be paid to calculating the regression coefficients, checking for significance and adequacy.

6. It is necessary to provide a generalized methodology for conducting experimental studies.

7. Based on the results of the modeling, the corresponding regression equations should be provided, allowing for the calculation and forecasting of the output parameter under consideration depending on the most significant input factors.

8. It is necessary to systematize the values of the degree of correlation of each influencing factor shown in Figure 16 in order to form the main conclusions of the work performed.

9. A "Discussion" section should be added.

10. The work does not provide prospects for further research on the presented topic.

Author Response

1. The introduction should expand the literature review by providing a more in-depth examination of the problems that arise in coal mines due to air dustiness, in particular by providing examples of the selection of a ventilation system, consideration of various aerological risks, etc. The following works could be analyzed: https://doi.org/10.21177/1998-4502-2022-14-1-107-116, https://doi.org/10.25018/0236_1493_2021_11_0_123. Along with this, the values of dust concentration in the air during the operation of mines in different regions of the world could be given.

[Response]: Thanks for reviewer’s comments and suggestions. We have expanded the introduction and marked it in red: BOSIKOV I.I. [25] Using statistical dynamics, correlation function of random variables, set theory, basic laws of mine aerodynamics, graph theory and discrete mathematics, the authors analyzed and estimated the aerodynamic parameters of coal mine air distribution control system. БОСИКОВ И.И [26, 27] evaluated and analyzed the aerodynamic parameters of air distribution control in coal mines, and obtained an equation system to describe the continuous flow patterns of air and gas in production and storage areas of mining areas from an aerodynamic point of view.

25. Bosikov I. I., Klyuev R. V., Azhmukhamedov I. M., Revazov V. Ch. Statistical dynamics-based estimation of ventilation control in coal mines. MIAB. Mining Inf. Anal. Bull. 2021;(11):123-135. [In Russ]. DOI: 10.25018/0236_1493_2021_11_0_123.
26. БОСИКОВ И.И., КЛЮЕВ Р.В., КЛЮЕВ Р.В., РЕВАЗОВ В.Ч. ОЦЕНКА УПРАВЛЕНИЯ ПРОВЕТРИВАНИЕМ УГОЛЬНЫХ ШАХТ С ПОМОЩЬЮ МЕТОДОВ СТАТИСТИЧЕСКОЙ ДИНАМИКИ. 2021. ;(11):123-135.
27. Босиков И.И., Клюев Р.В., Майер А.В., Стась Г.В. Разработка метода анализа и оценки оптимального состояния аэрогазодинамических процессов на угольных шахтах // Устойчивое развитие горных территорий. 2022. Т. 14, №1. С. 97–106.

 

2. Is it permissible to vary the initial characteristics of the test platform shown in Figure 1 more widely? Is it planned to obtain a patent for the invention in order to enable other researchers to use the given setup when carrying out similar work?

[Response]: Thanks for reviewer’s comments and suggestions. The device structure and functionality in Figure 1 can be extended, and the device is also pending a patent for invention.

3. It is necessary to conduct a more detailed comparative analysis of the data shown in Figure 2.

[Response]: Thanks for reviewer’s comments and suggestions. In order to ensure the consistency of the numerical simulation results on different grids, the dependence of the numerical simulation results on the grid is evaluated. ICEM software was used to create three different numbers of coarse (2496490), medium (4321668) and fine (8701201) grids in the model fluid domain, and the mesh mass was all greater than 0.3. The numerical calculation of continuous and discrete phases was carried out under the condition that the air speed of the tuyere was 8m/s, the ratio of pumping air volume was 0.6, and the distance from the blower to the driving surface was 1.6m. The pressure side (X:1-7m, Y:0.75m, Z:0.35m) and the central region (X:1-7m, Y:0.75m, Z:1m) were extracted at the moment of air flow stability. The size of the air flow at the height of the breathing zone on the extraction side (X:1-7m, Y:0.75m, Z:1.65m) is shown in Figure 2. The wind speed of the three grids increases first, then fluctuates, and finally decreases slowly. The calculated results of the medium grid and the fine grid are similar, only the coarse grid has a relatively large difference in wind speed. This indicates that although the number and quality of grids divided by the three schemes are different, grid independence has been achieved. Considering the accuracy of the calculation results and the finiteness of the computing resources, the author chooses the medium number of meshes to divide the following meshes. At this time, the mesh shape is tetrahedron, the maximum mesh mass is 0.99, the minimum mesh mass is 0.28, and the average mass is 0.875.

4. It is necessary to explain how the most significant factors (section "2.2. Model") that were used in the numerical modeling were determined. Was the method of expert assessments and cluster analysis used?

[Response]: Thanks for reviewer’s comments and suggestions. The method of expert evaluation and cluster analysis is not used in this study, but the method of grey correlation analysis is used. The whole paper adopts the method of combining laboratory experiment and numerical simulation to carry out the research, taking Hongliulin Mine 25212 driving face as the research object, according to 1: A test platform for ventilation and dust removal with long pressure and short suction of excavating surface was built, and the Eulerian-Lagrange method in Fluent software was used for numerical simulation to calculate and solve the process, and the effectiveness of the platform was verified by this method. Then, the experimental platform was modeled to explore the influence of factors such as the wind speed at the outlet of the pressure duct, the distance from the pressure duct to the driving surface and the ratio of pumping air volume on the air flow field and dust field in the driving roadway. Grey correlation analysis was used to analyze the influence degree of each ventilation parameter on the total dust and exhume dust mass concentration at the height of the breathing belt of drivers and pedestrians.

5. It is necessary to provide a more detailed technology for conducting full and fractional factorial experiments used in the work. Particular attention should be paid to calculating the regression coefficients, checking for significance and adequacy.

[Response]: Thanks for reviewer’s comments and suggestions. This paper does not use the expert evaluation and cluster analysis method, but adopts the grey correlation analysis method, and gives the concrete six steps and detailed conclusions in the paper.

6. It is necessary to provide a generalized methodology for conducting experimental studies.

[Response]: Thanks for reviewer’s comments and suggestions. This paper focuses on the study of long pressure short pumping ventilation roadway in coal mining face. Due to the different internal layout and ventilation mode of different roadway, it is difficult to apply one specific parameter to all roadway. However, the research ideas in this paper can provide references for determining the optimal ventilation parameters of different roadways, and the dust distribution law in the roadway can be studied by this method, so as to take targeted dust reduction measures. The influence of ventilation parameters on the concentration of total dust and exhale dust at the height of drivers' and pedestrians' breathing zones was analyzed by using grey correlation analysis method.

7. Based on the results of the modeling, the corresponding regression equations should be provided, allowing for the calculation and forecasting of the output parameter under consideration depending on the most significant input factors.

[Response]: Thanks for reviewer’s comments and suggestions. Taking the total dust concentration at the driver's position as an example, the analysis steps are as follows:

(1) Initial calculation of sequence: establish matrix

 

(2) Dimensionless sequence: each dimension represents a different meaning, so it needs to be dimensionless processing. Using the range method to process each sequence, a dimensionless matrix is obtained , k=1,2,... 19.

(3) Sequence difference calculation: calculate the absolute difference of the corresponding elements of each comparison sequence and reference sequence one by one, that is , obtain the sequence difference matrix , k=1,2,... 19.

(4) Calculation of sequence two-stage difference: the maximum value of sequence difference is , and the minimum value of sequence difference is .

(5) Calculation of correlation degree coefficient: the grey correlation coefficient matrix is obtained from , where  is the resolution coefficient, 0.5 is taken.

(6) Grey correlation calculation: grey correlation calculation formula: , i=1,2,3; k=1, 2,... 19. By substituting the data, the correlation degree of total dust concentration at the driver's position is .

Similarly, the correlation degree of dust concentration at the driver's position is (0.6519, 0.6526, 0.6455), the correlation degree of total dust concentration at the pedestrian's position is (0.6725, 0.6683, 0.6503), and the correlation degree of dust concentration at the pedestrian's position is (0.6534, 0.6770, 0.6631).

8. It is necessary to systematize the values of the degree of correlation of each influencing factor shown in Figure 16 in order to form the main conclusions of the work performed.

[Response]: Thanks for reviewer’s comments and suggestions. According to the analysis of grey correlation results, it can be seen that the influencing factors on the total dust concentration at the position of drivers and pedestrians are of the same importance, and the order is: L > Va >Q, that is, the main influencing factors on the total dust concentration at the position of drivers and pedestrians are the distance from the pressure tuyere to the driving surface, followed by the wind speed at the outlet of the pressure duct, and finally the ratio of the pumping air volume. The order of importance of influencing factors on the dust concentration of the driver's position is as follows: Va > L >Q, that is, the main influencing factor on the dust concentration of the driver's position is the wind speed of the air outlet of the pressure duct, followed by the distance from the pressure outlet to the driving surface, and finally the ratio of the suction air volume. The order of importance of influencing factors on the dust concentration at the pedestrian position is as follows: Va > Q > L, that is, the main influencing factor on the dust concentration at the pedestrian position is the wind speed at the outlet of the pressure duct, followed by the ratio of pumping air volume, and finally the distance from the pressure tuyere to the driving surface. Because respirable dust has a greater harmful effect on the human body, in order to reduce the dust content in the roadway, we can first consider improving the wind speed at the outlet of the pressure tuyere, that is, increasing the air supply volume, and at the same time, we can appropriately shorten the distance between the outlet of the air duct and the driving face to speed up the dust discharge.

9. A "Discussion" section should be added.

[Response]: Thanks for reviewer’s comments and suggestions. We have included a discussion section in the article and highlighted it in red: This study conducted a detailed study on ventilation and dust removal in a tunnel under long pressure and short suction. Experimental and numerical simulation results show that the air flow field in a tunnel can be divided into three regions: jet region, vortex region and reflux region, which is similar to the results of literature [54]. The dust mass concentration on the side away from the air duct was significantly higher than that on the other side, which was similar to the conclusion in the literature [55]. Therefore, it can be measured in the return air of the roadway, especially in the vicinity of the roadheader with large dust collection amount, the dust removal device can be added to reduce the dust concentration. There are many eddies at the front end of the TBM, so it is possible to implement targeted dust removal measures for the eddies area. In order to effectively capture small particles of dust, spray dust removal should be carried out at higher dust concentrations. This study helps to improve the understanding of dust distribution in driving face, and provides guidance for designing ventilation scheme and zoning dust control. In addition, this study can provide theoretical guidance for the determination of parameters such as the optimal wind speed in the roadway, the distance from the duct to the driving face and the ratio of pumping air volume. The study in this paper still has certain limitations due to the obstacles of equipment and space in the actual roadway, and the numerical simulation results may be different from the actual situation in the field. Numerical simulations often require building models based on assumptions and simplifications that may not be completely consistent with the actual situation. It takes a certain time for the formation of jet zone, vortex zone and reflux zone, which can provide a theoretical basis for the installation position and opening time of the cyclone ventilation device attached to the wall of the mine air pipe or the windscreen device of the tunnel header. If different ventilation methods are used, the experimental results may be different, and future research should focus on the development of new ventilation methods, such as the development of intelligent air ducts and new risk control devices.

54. Xiu, Z., Nie, W., Yan, J., Chen, D., Cai, P., Liu, Q., Du, T., Yang, B., 2020. Numerical simulation study on dust pollution characteristics and optimal dust control air flow rates during coal mine production. Journal of Cleaner Production 248, 119197.
55. Yao, H., Wang, H., Li, Y., Jin, L., 2020. Three-dimensional spatial and temporal distributions of dust in roadway tunneling. International Journal of Coal Science & Technology 7, 88-96.
56. The work does not provide prospects for further research on the presented topic.

[Response]: Thanks for reviewer’s comments and suggestions. We have added to the discussion the limitations of the current study, that is, further work that needs to be done. The details are as follows: the formation of jet zone, vortex zone and reflux zone takes a certain time, which can provide a theoretical basis for the installation position and opening time of the cyclone ventilation device attached to the wall of the mine air pipe or the windscreen device of the tunnel header, so it needs to be further studied. If different ventilation methods are used, the experimental results may be different, and future research should focus on the development of new ventilation methods, such as the development of intelligent air ducts and new risk control devices.

Special thanks to you for your good comments and excellent suggestions.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have made the necessary changes to the article. I recommend the article for publication.