Stability Analysis of Hydrodynamic Mechanical Seals in Multifrequency Excitation
Sergey Chefranov
Round 1
Reviewer 1 Report
The paper analyzes the stability of hydrodynamic mechanical seals with spiral grooves under multifrequency excitation. There are the following comments and questions:
1. Expanding the literature review regarding cavitation studies and mechanical seals' dynamics is necessary.
2. Why is there no description of the numerical model of the CFD calculation in the paper? Was it only static or also dynamic analysis? How was the gap determined in the CFD calculation from the equilibrium condition of the moving ring?
3. In Figure 2, indicate the parameters from Table 1 and inner and outer diameter pressures.
4. Graphs 5, 6, 7, 8, and 9, 10 could be placed on two different figures for comparison.
5. What is the error between the calculation results and the experiment?
6. Specify the details of the experiment or provide a reference. Was the gap measured in the experiment?
7. Check the text for minor errors. For example, on page 7, line 189, "in operation" and separate the words in table 3 - "distance between"; on page 9, in lines 244 and 246 - "average system" and "the dynamic".
It is necessary to correct some not-very-correct phrases in English and use the same terminology—for example, clearance distance, gap distance, or just gap.
Author Response
Please find the author's reply in the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Reviewer Comments
In this paper, he dynamic characteristics of the complex relationship among the sealing system, excitation, and response have a considerable impact on the operational reliability of hydrodynamic mechanical seals, which is a critical issue in the field of sealing theory and technology. Scholars at home and abroad have established dynamic models and calculated the displacement responses of dynamic and static rings in the time domain based on the force on these rings, so that the response results can be used for system stability analysis. However, the followings should be carefully addressed in the revision to be published in Coatings.
1- The authors should be followed the instruction of the journal in all parts and sections in this manuscript.
2- Complete mathematic calculation model with all nomenclature missing. Please check the number of each section, equation, and chart.
3- The abstract needs more quantitative results. The abstract section is an important and powerful representation of the research. It is better that the results should be presented with the support of specified data. Please provide your contribution and work novelty.
4- The authors should indicate this technique to enhance system performance. Also, the author should add more references that discuss the effect of using this technique. It is recommended that the authors carry out wide analysis and comparison with the state-of-the-art studies.
5- Most tables and figures are needed improve the quality of all tables and figures.
6- Add references for all equations.
7- I would also expect to validate with two more experimental works available in the literature.
8- The literature review must be improved. Please highlight in the literature review the differences between previous papers and your paper. Please clearly indicate the knowledge gap and prove that it is a really not analyzed area of the field. Please indicate new approach / new methods in a comparison to the existing investigations (literature review should be extended and add below references). Numerical Investigations of Transient Flow Characteristic in Axial Flow Pump and Pressure Fluctuation Analysis Based on the CFD Technique. Numerical investigation of flow field behaviour and pressure fluctuations within an axial flow pump under transient flow pattern based on CFD analysis method. Experimental investigation of the effect of air injection on performance and detection of cavitation in the centrifugal pump based on vibration technique. Experimental comparative investigations to evaluate cavitation conditions within a centrifugal pump based on vibration and acoustic analyses techniques.
9- Description of System leakage rate analysis should be improved.
10- You need to add error analysis of your results and add the error bars in your graphs to indicate your accuracy measurements.
11- Improve work justification. Also, add more analysis about velocity and pressure contours.
12- More quantitative conclusions should be presented. Please prepare additional comparisons, some percentage differences. There is a lack of quantitative conclusions which should contain main findings from the paper and highlight the new and high novelty and contribution of your work to the field.
13- Present the mathematical equation of the boundary conditions and initial condition.
14- I would also suggest including in the conclusion section but also in several other places in the manuscript discussion and comparison with findings from other authors with similar published research work.
15- The conclusion section on lacks in summative conclusions. The main results, novelty and academic contributions should be emphasized in this section. Moreover, are the results obtained in this paper really applicable in other similar researches?
16- In the discussion development, it is very important to emphasize points of agreement or disagreement between results in this work and others cited in references part of manuscript.
17- Authors should discuss limitations of the current study and possible improvements for future directions/research works. Authors are requested to check the reference format and correct some inconsistent formats.
18- Finally, I strongly recommend the author to read through the whole text and correct it to make it more reader-friendly.
Reviewer Comments
In this paper, he dynamic characteristics of the complex relationship among the sealing system, excitation, and response have a considerable impact on the operational reliability of hydrodynamic mechanical seals, which is a critical issue in the field of sealing theory and technology. Scholars at home and abroad have established dynamic models and calculated the displacement responses of dynamic and static rings in the time domain based on the force on these rings, so that the response results can be used for system stability analysis. However, the followings should be carefully addressed in the revision to be published in Coatings.
1- The authors should be followed the instruction of the journal in all parts and sections in this manuscript.
2- Complete mathematic calculation model with all nomenclature missing. Please check the number of each section, equation, and chart.
3- The abstract needs more quantitative results. The abstract section is an important and powerful representation of the research. It is better that the results should be presented with the support of specified data. Please provide your contribution and work novelty.
4- The authors should indicate this technique to enhance system performance. Also, the author should add more references that discuss the effect of using this technique. It is recommended that the authors carry out wide analysis and comparison with the state-of-the-art studies.
5- Most tables and figures are needed improve the quality of all tables and figures.
6- Add references for all equations.
7- I would also expect to validate with two more experimental works available in the literature.
8- The literature review must be improved. Please highlight in the literature review the differences between previous papers and your paper. Please clearly indicate the knowledge gap and prove that it is a really not analyzed area of the field. Please indicate new approach / new methods in a comparison to the existing investigations (literature review should be extended and add below references). Numerical Investigations of Transient Flow Characteristic in Axial Flow Pump and Pressure Fluctuation Analysis Based on the CFD Technique. Numerical investigation of flow field behaviour and pressure fluctuations within an axial flow pump under transient flow pattern based on CFD analysis method. Experimental investigation of the effect of air injection on performance and detection of cavitation in the centrifugal pump based on vibration technique. Experimental comparative investigations to evaluate cavitation conditions within a centrifugal pump based on vibration and acoustic analyses techniques.
9- Description of System leakage rate analysis should be improved.
10- You need to add error analysis of your results and add the error bars in your graphs to indicate your accuracy measurements.
11- Improve work justification. Also, add more analysis about velocity and pressure contours.
12- More quantitative conclusions should be presented. Please prepare additional comparisons, some percentage differences. There is a lack of quantitative conclusions which should contain main findings from the paper and highlight the new and high novelty and contribution of your work to the field.
13- Present the mathematical equation of the boundary conditions and initial condition.
14- I would also suggest including in the conclusion section but also in several other places in the manuscript discussion and comparison with findings from other authors with similar published research work.
15- The conclusion section on lacks in summative conclusions. The main results, novelty and academic contributions should be emphasized in this section. Moreover, are the results obtained in this paper really applicable in other similar researches?
16- In the discussion development, it is very important to emphasize points of agreement or disagreement between results in this work and others cited in references part of manuscript.
17- Authors should discuss limitations of the current study and possible improvements for future directions/research works. Authors are requested to check the reference format and correct some inconsistent formats.
18- Finally, I strongly recommend the author to read through the whole text and correct it to make it more reader-friendly.
Author Response
Please find the author's reply in the attachment.
Author Response File: Author Response.docx
Reviewer 3 Report
Your manuscript is very good. I believe that no corrections are needed.
-Stability synthesis of hydrodynamic seals.
-The object of the article is really original.
-Very extended analysis of the article.
-The methodology is very analytical and is needed.
-The references are very suitable and analytical.
Author Response
Thank you!
Reviewer 4 Report
The subject of the article is of interest. However, the form of representation of the mathematical model considered in it makes it difficult to understand the formulation of the problem and the results obtained in the work. For example, the derivation of equation (3) from the Navier-Stokes equations for a compressible medium and the continuity equation is not given. There are not even references to works where such a conclusion is given. In addition, there is no connection between equation (20) and considerations based on relations (3)-(19). There is also no comparative analysis of the conclusions obtained in the article with those known earlier, and therefore it is unclear what the novelty of the results is. Therefore, in this form, I consider the publication of the article inappropriate.
Author Response
Please find the author's reply in the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Even after revising the paper and making corrections, I still did not understand how the gap was determined from the condition of axial equilibrium in the CFD software when changing the boundary conditions of pressure and rotation speed. The mesh view was not presented, and the number of elements across the thickness of the gap and groove was not indicated. In Figure 2, I did not see the outer and inner radii designation. Also, the text should have the same terminology, such as the outer radius, but in Table 1, the outside radius is written. The CFD model is still insufficiently described. In addition, there is a rather large discrepancy between the calculation and the experimental results.
Author Response
Please find the reply in the attachment
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Reviewer Comments
The followings should be carefully addressed in the revision to be published in Coatings.
1- Complete mathematic calculation model with all nomenclature missing. Please check the number of each section, equation, and chart.
2- The abstract still needs more quantitative results. The abstract section is an important and powerful representation of the research. Please provide your contribution and work novelty.
3- Most tables and figures are still needed improve the quality of all tables and figures.
4- Add references for all equations.
5- I would also expect to validate with two more experimental works available in the literature.
6- The literature review must be improved. Please highlight in the literature review the differences between previous papers and your paper. Please clearly indicate the knowledge gap and prove that it is a really not analyzed area of the field. Please indicate new approach / new methods in a comparison to the existing investigations (literature review should be extended and new refs. After 2021).
7- You need to add error analysis of your results and add the error bars in your graphs to indicate your accuracy measurements.
8- Improve work justification. Also, add more analysis about velocity and pressure contours.
9- The conclusion section still on lacks in summative conclusions. The main results, novelty and academic contributions should be emphasized in this section. Moreover, are the results obtained in this paper really applicable in other similar researches?
Please see the above comments
Author Response
Please find the authors‘ reply in the attachment
Author Response File: Author Response.pdf
Reviewer 4 Report
The authors did not actually take into account the comments regarding the justification of the theoretical model used and still no quantitative comparative analysis of the results obtained with the previously known ones is presented. In my opinion, the publication of this work in its present form is not appropriate.
Author Response
Please find the author's reply in the attachment.
Author Response File: Author Response.pdf
Round 3
Reviewer 2 Report
The authors addressed the comments satisfactorily. So, the manuscript can be considered for the possible publication.
The authors addressed the comments satisfactorily. So, the manuscript can be considered for the possible publication.
Reviewer 4 Report
Paper can be published. But its content may be improved base on my earlier comments.
