Mathematical Modeling of the Transport of H₂O–CH₄ Steam–Gas Mixtures in Hydrodynamic Devices: The Role of Helical Screws

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

In this paper, the authors investigate the impact of the screw on the gas-liquid mixing process and cavitation effects, particularly the improvement in turbulent mixing and particle dispersion under different flow velocities. The study combines numerical simulations and particle tracking methods to analyze the relationship between flow characteristics and mixing uniformity, providing new insights into the mechanism of screw-enhanced mixing, with a certain level of innovation. However, there are some issues in the paper, and several minor comments and suggestions are provided here to help further improve the overall quality of the manuscript.

1. Figure 1 in the paper is not fully displayed, which affects the readability of the paper and the presentation of the data. Figure 1 involves the geometric characteristics of the experimental setup or model, which are crucial for understanding the research methods and results. Therefore, it is recommended that the authors recheck the figure file to ensure its completeness in the PDF format.
2. It is suggested to annotate the corresponding key structures and regions in Figure 1 and add a legend, so that readers can accurately understand the structural features of the setup or model.
3. The legends in Figure 4 (pressure distribution) and Figure 5 (velocity field) are incomplete, without showing the maximum and minimum values of pressure and velocity. This may affect the reader's intuitive understanding and comparison of the data. The authors are advised to clearly indicate the range of maximum and minimum pressure and velocity in the legends to provide more comprehensive numerical information.
4. The paper primarily relies on numerical simulations to analyze the gas-liquid mixing process and turbulence characteristics. However, the lack of experimental validation may weaken the persuasiveness of the conclusions. It is suggested to supplement experimental data or cite existing literature with experimental results to validate the accuracy of the numerical simulations. This can be achieved by comparing key parameters measured in experiments (such as pressure distribution, velocity, and particle distribution) with the simulation results, thereby increasing the credibility of the research conclusions.
5. After Figure 10, it is recommended to add transverse velocity contour plots at key positions and compare the transverse velocity distributions with and without the screw. This will more intuitively demonstrate the effect of the screw on transverse flow characteristics and mixing improvements, supporting the rationale of the research conclusions.
6. The paper includes extensive discussion on cavitation, but does not provide direct contour plots showing the cavitation regions. Only indirect analysis through pressure and velocity distributions is used to infer the formation and development of cavitation. It is suggested to add cavitation-related contour plots, such as volume fraction distribution maps of the cavitation zones or gas-phase volume fraction plots, to more intuitively show the formation and changes of cavitation areas.

Author Response

Thank you for your valuable comments and insights, which will help in improving the quality of this work. Please find in the attached word file the answers per each question.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The paper deals with an important topic - the mathematical modelling of the transport of liquid-steam-gas mixtures in the cavitation-jet chamber with and without a screw activator. The presented analysis and proposed methodology are useful for improvement of the particle mixing efficiency and particle distribution behind the cavitation-jet chamber.  

The paper is very interesting, still, there are some parts, which could be improved. 

 

1.         Minor grammar corrections will be necessary.

2.         Figure 1, Section 2: Figure 1 is incomplete and wrongly formatted in the presented PDF version. Moreover, there is no injector tube. Authors should mention that the particles are injected at the main tube inlet.  

3.         Section 3 (see please the attached file): [16] is not a relevant reference for the k-omega turbulence model. [17] is not a relevant reference for the particle tracing model used.

4.         Section 3: Eq. 1-4 are stationary, but the flow is considered to be unsteady, with the rest initial condition. In Eq. 6, is the expression on the right-hand side correct?

5.         Section 3: There is no information on the screw activator geometry and rotation speed. Also, there is no information on the particle size and properties.

6.         Section 5: There is not any coordinate system defined before referring the velocity components.

7.         Figure 10: The backflow through the domain outlet decreases the stability and correctness of the CFD analysis. Why the authors have not used an artificial extension of the computational domain?

Comments for author File: Comments.pdf

Author Response

Thank you for your valuable comments and insights, which will contribute to improving the quality of this work. Please find our responses to each question in the attached word file.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The results of numerical simulation are affected by many factors. It is difficult to judge the accuracy of the results without experimental verification. It is suggested to supplement the experimental results and verify them to ensure the credibility of the research results.

Author Response

Thank you for this valuable comment. The construction of experimental equipment is currently underway, with efforts focused on defining critical components such as sensors and other instrumentation. This study is dedicated to establishing the fundamental geometric characteristics required for the experimental setup. In future work, we plan to conduct comprehensive experimental validation and will publish these findings to fully assess the accuracy of the numerical simulations and further enhance the credibility of our results.