Study on the Influence of Airfoil and Angle of Attack on Ice Distribution and Aerodynamic Performance of Blade Surface

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

First, I must say that I find the article very interesting. It deals with a phenomenon that occurs quite often and can affect the operation of many devices. The introduction and analysis of the problem are comprehensive and demonstrate the significance of icing on wind turbine blades. The results are systematically obtained and relatively general, i.e., applicable to a wide range of devices. The behavior of ice formation, as presented, is in line with expectations, as are the other results. 
Although the results are interesting and the combination of ice measurement and subsequent simulation of "frozen" profiles is effective and relevant, the following questions and comments arise.

The article is very long, and while the authors' desire to publish and describe all the results of their research is understandable, after reading about two-thirds of the article, the reader becomes exhausted. The article is more like a research report, but for publication in a journal, it should be shortened and condensed at least a little.
Although the article is extensive, it describes little about the methodology used to measure frosting of profiles during wind tunnel testing and does not mention the version of Fluent software, turbulence model, etc. – please add this information.

Furthermore, it is unclear why measurements were performed at intervals of 1 to 5 minutes—why not, for example, at intervals of 3 to 10 minutes? Ice cannot grow indefinitely, but how relevant are measurements taken in a tunnel to the actual behavior of icing on wind turbines? The aim is not to discredit technically interesting results, but rather to explain the methodology and relate it to reality.

The graphs in the manuscript are understandable, although some could be condensed in an appropriate manner, but the interesting images showing the growth of ice are relatively unclear due to their small size. The lack of clarity of the images is even more pronounced in the simulation results, where the matrix of small images has virtually no informational value—it would be better to select representative modes and display them clearly, i.e., larger, and present the rest only in the form of graphs and values.

Comments on the Quality of English Language

I found the English text of the manuscript understandable and readable, but before revision, I would recommend checking the spelling and removing typos.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This study presents a comprehensive and generally well-structured investigation that systematically examines the icing behavior of wind turbine blades and its effects on aerodynamic performance using both experimental and numerical approaches. It provides valuable data on blade icing, which is a critical issue affecting wind energy efficiency in cold climates. The work successfully demonstrates how parameters such as blade material, airfoil profile, and angle of attack influence ice accretion and the associated aerodynamic degradation. However, several improvements are needed. Once these revisions are addressed, the manuscript will reach an acceptable level of scientific quality and contribution.

• The Liquid Water Content (LWC) and Mean Volume Diameter (MVD)—two fundamental determinants of icing—are not reported in the test schemes presented in Tables 1, 2, and 3. This omission represents a significant barrier to the reproducibility of the study. The constant LWC and MVD values used in all experiments must be clearly specified.

• The CFD simulations are not validated against basic aerodynamic measurements such as experimentally obtained lift and drag coefficients. To demonstrate the reliability of the simulations, a comparison between experimental and numerical results for the clean (uniced) airfoils should be included.

• In the Introduction, within the section describing icing types, a sentence is duplicated (“Icing on wind turbine blades typically occurs…”). This repetition should be corrected.

• Although several figures show icing durations increasing from 0 to 5 minutes, the “Materials and Methods” section does not explicitly state the total icing duration or whether this duration is kept constant across all test conditions. In addition, the relative humidity (RH) used during the icing wind tunnel tests is not reported. Both parameters are essential for experimental clarity and reproducibility.

• The experimental airfoil chord length is fixed at 100 mm. Testing at this scale results in Reynolds numbers significantly lower than those experienced by real wind turbine blades, which may affect ice accretion morphology and aerodynamic behavior. A discussion of potential scale effects should therefore be included.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for the changes to your manuscript. The revised version is better than the first one.

The scale in Fig. 24 contains Chinese characters.

Fig. 29 should be "Velocity distribution" rather than "Pressure distribution."

Can you compare your results with similar research from the articles (not cited by you, but dealing with the same issue):

Renewable Energy, Volume 133, April 2019, Pages 663-675, https://doi.org/10.1016/j.renene.2018.10.032

LES and DES of flow and ice accretion on wind turbine blades.
Johan REVSTEDT, Robert SZÁSZ, Stefan IVANELL, Conference on Modelling Fluid Flow (CMFF’25), The 19th International Conference on Fluid Flow Technologies, Budapest, Hungary, August 26-August 29, 2025

Ice Distribution Characteristics on the DU25 and NACA63-215 Airfoil Surfaces of Wind Turbines as Affected by Ambient Temperature and Angle of Attack,
 Coatings 2024, 14(8), 929; https://doi.org/10.3390/coatings14080929 

Impact of ice accretion on the aerodynamic characteristics of Wind turbine airfoil at low Reynolds numbers, Cold Regions Science and Technology, Volume 239, November 2025, 104618

In conclusion, I find that recommendations for further research and possibilities for applying the findings of the study to real 3D blades and their behavior in icing conditions are lacking. It would be interesting, for example, to verify the average power loss of turbines under various icing conditions using real data, to examine the change in blade stress with icing, to simulate a model 3D blade with icing according to tests against a blade without icing, to examine the adhesion/detachment of ice on rotating turbine blades, etc. 

 

Comments on the Quality of English Language

I found the English text of the manuscript understandable and readable but I would recommend checking the spelling and removing typos. 

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have substantially improved the manuscript and addressed the reviewer comments in a clear and constructive manner. Most of the methodological gaps highlighted in the initial review—such as the omission of LWC, MVD, icing duration, and relative humidity—have now been sufficiently clarified. The duplicated text in the Introduction has also been corrected, and the discussion regarding scale effects has been expanded with appropriate justification and literature support.

One remaining limitation concerns the validation of the CFD simulations (Comment #2). While the authors were unable to provide experimental lift and drag measurements, they offered a comparison with established reference data from the literature. Although this does not fully replace experimental validation, the explanation is reasonable given the stated experimental constraints.

Overall, the authors’ responses are adequate, and the revisions have significantly improved the scientific clarity, completeness, and readability of the manuscript. Therefore, I find the manuscript acceptable for publication, acknowledging the minor remaining limitation regarding CFD validation.

Author Response

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Author Response File: Author Response.pdf