Assessment of a Wind Turbine Blade Erosion Lifetime Prediction Model with Industrial Protection Materials and Testing Methods

Round 1

Reviewer 1 Report

The in-hand research study proposes an advancement over a previously published modelling approach for determining blades rain erosion. The authors have made a good research effort in their work, which included different characterizations. However, I think that their manuscript can be further improved after undertaking the following remarks.

General:

• The manuscript needs to be revised in terms of English grammar.

Abstract:

• The abstract should be a standalone text, and therefore I recommend that you remove the reference from it (i.e., Ref. 3). Instead, the authors can replace reference [3] with the date (i.e., 1976).
• The abstract needs to explain to the reader what the problem is, what is the general methodology used in the paper, and the outcome in general. Please revise.

Keywords:

• Please remove the keyword ‘Wind turbine blades’. This is because it is already available in the title, and therefore repeating it will not increase the exposure of the manuscript if accepted.
• Also, please arrange your keywords alphabetically.

Introduction:

• Please add a reference to your statement ‘Currently, there is no thoroughly validated method to relate test results to real-world erosion performance.’ (lines 40-41). I suggest that you cite one of MDPI’s articles (e.g., https://www.mdpi.com/2227-9717/8/8/984) or any other one you see fit.
• You need to include a reference to your statement ‘A combination of aluminium, polyester and epoxy were used as the substrate in the historic testing, whereas glass fibre reinforced plastic is used in current testing.’ (lines 60-62).
• Change ‘thethose’ to ‘those’ (line 68).
• In line 81, please replace ‘RET’ with ‘rain erosion test (RET)’. This is because it has only appeared in the main body of your manuscript.

Section 2:

• In line 90, please replace ‘Rain Erosion Testing’ with ‘RET’.
• I am assuming that Figure 2 was obtained from the literature. If so, then please make sure that you obtain a reuse permission from the publisher.

Section 3:

• Please provide more details on the coating method used for your sample. I recommend that you add a separate sub-section for that.

Section 3.1:

• Please mention the accuracy of the Guy-Lussac pycnometer system used.
• Also, give more details on the mass and the volume of both the add water and the solid sample.
• In general, you need to give more details on the equipment’s used and the experimental procedure that was conducted for all systems.

 

 

Author Response

Dear editor and reviewer, Thank you very much for the reviews.

 

We have resolved all of the reviewer's suggestions and comments and have included them all in a later version. Reviewer's questions and our answers are listed below in italics

 

Author's Reply to the Review Report (Reviewer 1)

 

Comments and Suggestions for Authors

The in-hand research study proposes an advancement over a previously published modelling approach for determining blades rain erosion. The authors have made a good research effort in their work, which included different characterizations. However, I think that their manuscript can be further improved after undertaking the following remarks.

 

The authors would like to thank the reviewer for acknowledging the issue of leading-edge erosion (LEE) material characterizations and modelling of wind turbine blades

 

General:

• The manuscript needs to be revised in terms of English grammar.

English revision has been done.

 

Abstract:

• The abstract should be a standalone text, and therefore I recommend that you remove the reference from it (i.e., Ref. 3). Instead, the authors can replace reference [3] with the date (i.e., 1976).
• The abstract needs to explain to the reader what the problem is, what is the general methodology used in the paper, and the outcome in general. Please revise.

This reference is now removed and the abstract rewritten.

 

Keywords:

• Please remove the keyword ‘Wind turbine blades’. This is because it is already available in the title, and therefore repeating it will not increase the exposure of the manuscript if accepted.
• Also, please arrange your keywords alphabetically.

Done

 

Introduction:

• Please add a reference to your statement ‘Currently, there is no thoroughly validated method to relate test results to real-world erosion performance.’ (lines 40-41). I suggest that you cite one of MDPI’s articles (e.g., https://www.mdpi.com/2227-9717/8/8/984) or any other one you see fit.

 

This has been changed and rewritten as: Currently, there is no thoroughly validated method to relate test results to in-field erosion performance during its complete lifetime. It is an active research topic for wind blade manufacturers and material developers.

 

• You need to include a reference to your statement ‘A combination of aluminium, polyester and epoxy were used as the substrate in the historic testing, whereas glass fibre reinforced plastic is used in current testing.’ (lines 60-62).

Done

• Change ‘thethose’ to ‘those’ (line 68).

Done

 

• In line 81, please replace ‘RET’ with ‘rain erosion test (RET)’. This is because it has only appeared in the main body of your manuscript.

Done

 

Section 2:

• In line 90, please replace ‘Rain Erosion Testing’ with ‘RET’.

Done

 

• I am assuming that Figure 2 was obtained from the literature. If so, then please make sure that you obtain a reuse permission from the publisher.

 

The figure is adapted from: [¡Error! No se encuentra el origen de la referencia.]. But this is a well-known statement in fatigue analysis. The unique novelty is related to the equation parameters that are referenced from the literature at [3].

 

Section 3:

• Please provide more details on the coating method used for your sample. I recommend that you add a separate sub-section for that.

 

We have included details on it. But We consider it is not valuable information for adding a sub-section.

...”the filler was applied by filler knife and sanded smooth to achieve the required thickness using 120grit sandpaper. Thickness was measured initially using a wet film comb and subsequently using an ultrasonic thickness gauge (elcometer PTG8). The LEP coating was applied by brush, again using the wet film comb for coating thickness measurement.”

 

Section 3.1:

1. Please mention the accuracy of the Guy-Lussac pycnometer system used.

 

The accuracy of the pycnometer has now been included in the sentence: "The density of the coating was determined with a 30ml Guy-Lussac pycnometer with a tolerance of ± 0.001 ml"

 

2. Also, give more details on the mass and the volume of both the add water and the solid sample.

 

The volume of the sample used has now been included in the sentence: "A piece of solid cured coating of approximate dimensions 20 x 30 x 20 mm was placed into the pycnometer and the pycnometer filled with water to find its true volume." Using the density value in Table 1, the reader can now determine the mass of the sample. The volume of water added has now been included through the inclusion of the 50 ml pycnometer and the statement 'filled' in the above sentences.

 

3. In general, you need to give more details on the equipment’s used and the experimental procedure that was conducted for all systems.

 

Thank you for pointing this out. Further information has been added to each of the measurements.

For the density measurement: see the response to the previous comment.

For the speed of sound measurement: further information about the equipment and procedure has been included in the following: “The speed of sound values in this work were found using the calibration mode of an Elcometer PTG8 ultrasonic thickness gauge and single element 20 MHz transducer. The Elcometer is widely used to non-destructively measure dry film coating thicknesses. Before determining the coating of the thickness, the device must be calibrated against a known thickness to obtain the material speed of sound. A known thickness of each material was applied to separate composite blocks and, using the transducer, a pulse generated at one end of the sample, reflected at the material-composite interface, and captured at the same end. The speed of sound of the materials were then determined by the device from the electronically calculated transit time of the pulse, and the distance travelled by the pulse, which was twice the thickness of the material.”

For the tensile tests: the dimension and failure mode has been added in the sentences: “The static and fatigue tests were completed on 30 x 8 mm rectangular thin film coatings” and “All thin films were observed to be elongated up to fracture.”, respectively.

For the fatigue tests: further information on the experimental procedure and equipment used has been added. The grips used in the study, the testing procedure and the failure mode have been included in the following: “Emery paper grips were manufactured and applied to the ends of the samples. … . All tests were completed continuously until failure. … . Grips can introduce stress concentrations into the ends of the sample and cause premature and unacceptable failure. For the failure to be acceptable, failure had to occur away from the grips, defined by a sample width in length away from the grips, and within the gauge length.”

 

 

Author Response File: Author Response.pdf

Reviewer 2 Report

See attached file.

Comments for author File: Comments.pdf

Author Response

Dear editor and reviewer, Thank you very much for the reviews.

 

We have resolved all of the reviewer's suggestions and comments and have included them all in a later version. Reviewer's questions and our answers are listed below in italics

 

Author's Reply to the Review Report (Reviewer 2)

 

 

The paper submitted by R. Herring et al., entitled "Assessment of a Wind Turbine Blade Erosion Lifetime Prediction Model with Industrial Protection Materials and Testing Methods" aims to understand the differences between the experimental data used by Springer and the current industry approach to rain erosion testing and to determine how it may introduce inaccuracies into lifetime predictions of current leading-edge protection coating systems since they are very different to those tested in the historic modelling validation. The manuscript is clearly written. I have only some comments below.

1. Introduction – The introduction is well written. Some references must be added to paragraphs (The Springer formulation..). Historic testing...references.

Done

 

2. Line 104 – I think Equation 2 into Equation 1 instead of Equation 1 into Equation 2.

Done

 

3. Line 105 – Reference is required.

In this section, the Springer model is introduced and reviewed before being applied in the subsequent sections. All the terms and equations are referenced from [3]. The reader is guided through the section as a review.

 

4. Line 113 – Reference is required.

 

In this section, the Springer model is introduced and reviewed before being applied in the subsequent sections. All the terms and equations are referenced from [3]. The reader is guided through the section as a review.

 

5. Line 114 – without space before “where”.

Done

 

1. Line 119 – without space before “where”.

 

Done

 

 

1. Line 127 – put “:” after “as”.

Done

 

 

1. Line 135 – delete space after “analyse”.

 

Done

 

 

1. Line 192- I do not understand this sentence “Utilising the.... “. Please revise it.

Done

 

1. Figure 5 and Table 1 - ‘knee’ or “knee”.

 

Done

 

 

1. Figure 11 – Quality of Figure is no good.

 

Done

 

 

1. Line 348 – Write which instead of Which.

 

Done

 

 

1. Dots or commas after equations are missing in the whole manuscript. Please, revise it.

 

To clarify with editor.

 

Author Response File: Author Response.pdf

Reviewer 3 Report

In this manuscript, the performance of a leading-edge protection (LEP) system is assessed in an accelerated rain erosion test as a metric for industrial application. There is a lack of industry validation of complete modeling methods based on fundamental material properties for anti-erosion performance prediction. Springer [3] modeling is analyzed in this work to assess it as a tool for using material fundamental properties to predict the time to failure in a rain erosion test. This study aims to understand the differences between the experimental data used by Springer and the current industry approach to rain erosion testing and to determine how it may introduce inaccuracies into lifetime predictions of current LEP systems since they are very different from those tested in the historic modeling validation. This paper provided some valuable information and the content is very significant in this field. However, I recommended a major revision of the article from its present form before it can be published in coatings. Some specific comments are as follows:

1. The abstract and conclusion sections should be a specific and scientific approach.
2. In the introduction section, the authors should expound on the research significance of the present work.
3. The authors should explain the novelty of the present report?
4. How these results influence the previously reported results.
5. Authors can observe any abnormal outcomes in this procedure?
6. What are the problematic issues to commercialize this pathway?
7. The authors should provide a schematic representation of the mechanism.
8. The authors should check the units in equations and labels in the graph.
9. How this system is competing with the commercially available systems?
10. The authors should discuss the toxicity of the present system.
11. In the current state, there are more typographical errors and the language should be improved. Therefore, the authors are advised to recheck the whole manuscript for improving the language and structure carefully.

Author Response

Dear editor and reviewer, Thank you very much for the reviews.

 

We have resolved all of the reviewer's suggestions and comments and have included them all in a later version. Reviewer's questions and our answers are listed below in italics

 

 

Author's Reply to the Review Report (Reviewer 3)

 

Comments and Suggestions for Authors

In this manuscript, the performance of a leading-edge protection (LEP) system is assessed in an accelerated rain erosion test as a metric for industrial application. There is a lack of industry validation of complete modeling methods based on fundamental material properties for anti-erosion performance prediction. Springer [3] modeling is analyzed in this work to assess it as a tool for using material fundamental properties to predict the time to failure in a rain erosion test. This study aims to understand the differences between the experimental data used by Springer and the current industry approach to rain erosion testing and to determine how it may introduce inaccuracies into lifetime predictions of current LEP systems since they are very different from those tested in the historic modeling validation. This paper provided some valuable information and the content is very significant in this field. However, I recommended a major revision of the article from its present form before it can be published in coatings. Some specific comments are as follows:

1. The abstract and conclusion sections should be a specific and scientific approach.

The abstract and conclusion sections have been rewritten.

 

1. In the introduction section, the authors should expound on the research significance of the present work.

The introduction section has been rewritten.

 

1. The authors should explain the novelty of the present report?

The abstract, introduction and conclusions section have been rewritten to include these suggestions.

1. How these results influence the previously reported results.

The abstract, introduction and conclusions section have been rewritten to include these suggestions.

 

1. Authors can observe any abnormal outcomes in this procedure?

The abstract, introduction and conclusions section have been rewritten to include these suggestions.

 

1. What are the problematic issues to commercialize this pathway?

The modelling is well known from literature, the research is focused on its limits and capabilities discussion through application cases, but not with the intention of analyzing its commercialization.

 

1. The authors should provide a schematic representation of the mechanism.

Figure 2 is included with that intention

1. The authors should check the units in equations and labels in the graph.

Done

1. How this system is competing with the commercially available systems?

The modelling is well known from literature, the research is focused on its limits and capabilities discussion through application cases, but not with the intention of analyzing its commercialization. It is based on the implementation of a known modelling.

 

1. The authors should discuss the toxicity of the present system.

The abstract, introduction and conclusions section have been rewritten to include these suggestions.

 

1. In the current state, there are more typographical errors and the language should be improved. Therefore, the authors are advised to recheck the whole manuscript for improving the language and structure carefully.

 

Al the manuscript has been revised.

 

 

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

The manuscript can be acceptable in the present form.