Demand Analysis of Lubricating Oil in Spur Gear Pairs
Round 1
Reviewer 1 Report
The article presents a new calculation and analysis models of the lubricating oil demand of spur gears. The paper is generally well written. The language is smooth with very few flaws. I think that the idea and the application of the analysis is of high interest in the appropriate design of gear lubrication systems. The article might be considered for publication if the authors demonstrate the potential of the method by comparing their results with previous published experimental data.
Line 28: It is true that the most of studies are split to the solving analytical formulation using a numerical method or pure CFD simulation. But it is not limited into these two. You can find different analysis strategies and solution for example: Solution to EHL using fluid structure interaction: “Model of fluid–structure interaction and its application to elastohydrodynamic lubrication” by Yiping et al. Computer Methods in Applied Mechanics and Engineering, 2002.
Please avoid the general terms such as “a variety of effects” in line 20 and “numerical methods” in line 31 and specify which effects and what methods.
Line 98: Please remove the sentence “ A gear is … a gear drive” as it doesn’t add new information and it is redundant.
Line 112: Please provide a reference for Equation 1.
Please improve the quality of figure 1.
Line 164: This sentence is repetitive.
Line 196: Please provide a reference for the statement.
Please replace chapter with section (Lines 285, 383, 427, 429, 453). Section is an appropriate word in this context.
While the effects of modulus, number of teeth, and transmission ratio is discussed, it is also important to investigate the sensitivity of the formulation to these parameters and how the uncertainty of these parameters can affect the uncertainty of the mathematical model output. In other word, the paper will benefit from the sensitivity and uncertainty analysis of the mathematical model.
I understand the algorithm can be useful, but the paper needs some validation or comparison with other methodologies or experimental results to demonstrate the feasibility of the technique.
Author Response
Response to Comments of Reviewer #1 on Demand analysis of lubricating oil in spur gear pairs（applsci-882766）
Firstly, we would like to express our sincere thanks to your constructive comments and suggestions concerning our manuscript (ID: applsci-882766). We have carefully considered your comments and suggestions, and substantially revised our manuscript accordingly. Words, sentences and equations which used “Track Changes” are the changes we have made in the revised manuscript. A detailed description is given in the following.
Reviewer #1:
Comment: It is true that the most of studies are split to the solving analytical formulation using a numerical method or pure CFD simulation. But it is not limited into these two. You can find different analysis strategies and solution for example: Solution to EHL using fluid structure interaction: “Model of fluid–structure interaction and its application to elastohydrodynamic lubrication” by Yiping et al. Computer Methods in Applied Mechanics and Engineering, 2002.
Response: Thanks for your constructive suggestions, we are very sorry for our negligence that the first major research focus is not explain clearly. The first research focus study the contact state and oil film on meshing tooth surfaces, it includes the model analyses of EHL, numerical method for solving the EHL and measurement and experiment of contact area. The paper “Model of fluid–structure interaction and its application to elastohydrodynamic lubrication” by Yiping et al belong to the model analyses. We have added “The first group focuses on the state of lubricating oil film on meshing tooth surfaces, include the model analyses of EHL according to establish the nonlinear relationship amongst oil film thickness, pressure and density, numerical method for solving the EHL and Measurement and experiment of contact area”, and added the references “
5.Wu, B.; Wu, T.; An, B.Y. Numerical investigation on the high‐speed wheel/rail adhesion under the starved interfacial contaminations with surface roughness. LUBR SCI. 2020, 32(3): 93-107.
6.Kang, Y.S.; Hager, C.H.; Evans, R.D. Effects of Skewed Surface Textures on Lubricant Film Thickness and Traction. TRIBOL T. 2015, 58(3): 397-406.”
Comment: Please avoid the general terms such as “a variety of effects” in line 20 and “numerical methods” in line 31 and specify which effects and what methods.
Response: Thanks for your constructive suggestions. We have replaced “a variety of effects” with “the oil volume for lubrication increases and oil volume for cooling decreases as the modulus, tooth number and transmission ratio of the gear increase, the oil volume for lubrication and oil volume for cooling increases as the input speed and input torque increase.”, and replaced “numerical methods” with the “The traditional Integral Approach, the Single Domain Full-System Approach and the Double Domain Full-System Approach”.
Comment: Please remove the sentence “A gear is … a gear drive” as it doesn’t add new information and it is redundant.
Response: Thanks for your constructive suggestions. The sentence “A gear is … a gear drive” has been removed.
Comment: Please provide a reference for Equation 1.
Response: Thanks for your constructive suggestions. The reference “22. Zhang, Y.C. Study on tribology of starved oil gear transmission, PhD Thesis, Southeast university, Nanjing China, 2011.” for Equation 1 has been added.
Comment: Please improve the quality of figure 1.
Response: Thanks for your constructive suggestions. The figure 1 has been redrawn and becomes clearer.
Comment: This sentence is repetitive.
Response: Thanks for your constructive suggestions. The sentence “The thickness of the oil film is the sum of the geometric clearance and elastic deformation of the tooth surface that can be expressed as” has been replaced with “The thickness of the oil film can be expressed as”
Comment: Please provide a reference for the statement.
Response: Thanks for your constructive suggestions. The reference “24.Hobel, M.; Haffner, K. An on-line monitoring system for oil-film, pressure and temperature distributions in large-scale hydro-generator bearings. MEAS SCI TECHNOL. 1999, 10(5): 393-402.” has been added for the statement.
Comment: Please replace chapter with section (Lines 285, 383, 427, 429, 453). Section is an appropriate word in this context.
Response: Thanks for your constructive suggestions. The “chapter” (Lines 285, 383, 427, 429, 453) has been replaced with “section”.
Comment: While the effects of modulus, number of teeth, and transmission ratio is discussed, it is also important to investigate the sensitivity of the formulation to these parameters and how the uncertainty of these parameters can affect the uncertainty of the mathematical model output. In other word, the paper will benefit from the sensitivity and uncertainty analysis of the mathematical model.
Response: Thanks for your constructive suggestions. In fact, this paper focuses on the research of basic theory, the purpose the we investigate the effects of modulus, number of teeth, and transmission ratio is to obtain what are the key factors affect the lubricating demand. How these parameters affect the oil demand can obtained according to the slope of the curve. However, the sensitivity of the parameters needs quantitatively calculate, that is our following work.
Comment: I understand the algorithm can be useful, but the paper needs some validation or comparison with other methodologies or experimental results to demonstrate the feasibility of the technique.
Response: Thanks for your constructive suggestions. We consulted and read a lot of literature find that previous studies are based on the condition that the lubricating oil supply and the lubrication state of the gear are known, and the study about lubricating oil demand was not found. We will study the oil demand of gears intensively, and the investigation of parameters sensitivity and experimental verification are the key research.
Once again, thank you very much for your comments and suggestions.
Author Response File: 
Author Response.docx
Reviewer 2 Report
I have the following comments on the submitted scientific article entitled Demand analysis of lubricating oil in spur gear pairs:
- Figures 6 to 10 of the magnified area shown separately have poorly observable values on the axes.
- I propose to extend the chapter Conclusion with a more specific definition of the possibility of using the acquired knowledge in the experimental or practical sphere.
Author Response
Response to Comments of Reviewer #2 on Demand analysis of lubricating oil in spur gear pairs（applsci-882766）
Firstly, we would like to express our sincere thanks to your constructive comments and suggestions concerning our manuscript (ID: applsci-882766). We have carefully considered your comments and suggestions, and substantially revised our manuscript accordingly. Words, sentences and equations which used “Track Changes” are the changes we have made in the revised manuscript. A detailed description is given in the following.
Reviewer #2:
Comment: Figures 6 to 10 of the magnified area shown separately have poorly observable values on the axes.
Response: Figures 6 to 10 have been rearranged to give better observable values on the axes of magnified area.
Comment: I propose to extend the chapter Conclusion with a more specific definition of the possibility of using the acquired knowledge in the experimental or practical sphere.
Response: The Conclusions “(2) At the beginning and end of the meshing, gears are prone to failure” and “(3) The maximum lubricating oil demand during the meshing process should be used as the oil supply to design lubrication system design” have been added to make conclusion more specific and have possibility to use in the experimental or practical sphere.
Once again, thank you very much for your comments and suggestions.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The paper can be accepted in the present form.
