Study on Compact Pre-Swirl Duct for Slender Aft-Body Crude Oil Carrier

Round 1

Reviewer 1 Report

Comments

A compact type of pre-swirl duct for a crude oil carrier was studied in this paper. The numeric study was carried out to show the performance of the the developed ring stator. I have the following comments.

 

1. The pre-swirl duct in this paper is an ESD and therefore an overview of the newest technology of ESD should be given in the introduction. The current status of existing ESD developments should be described, followed by a description of the technology in this paper. A review of the latest literature on ESDs in the introduction is not sufficient.
2. While the introduction to this paper describes the problem and the background, it does not provide a description of the methodology and conclusions. It is incomplete in its description of the methods. A complete introduction should contain the background, the topic, the methodology of the paper, the conclusions and significance of the paper. It is also desirable to conclude the introduction with a description of the content arrangement of the paper so that the reader has a general idea of the structure and content of the full paper through the introduction.
3. In the section of conclusion. Part of the conclusion in the third paragraph does not appear to be supported in this paper.
4. The structure of this article can be improved. Section 3 looks belong to section 2.
5. A comparison of advantages with existing technology is desirable.
6. Figure 1 is not clear and the text in the figure is not clear.

 

Author Response

Thank you for your kind comments on the paper.

Please see the attachment and the revised paper.

 

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper deals with the design of ESD for slender aft-body crude oil carrier, by combining numerical and experimental approach (for validation). As such, it deals with some of the most important topics in marine business now, since it contributes both to fuel savings and consequently reduction of GHG emissions. Some minor improvements are needed before I can recommend its publication, as explained below.

For the clarity of the paper, I encourage authors to include a figure with the flowchart of the procedure for designing ESDs. It is obvious that they combine potential theory, CFD and experiments, but it would be worthy to describe better the procedure on how to design ESD for general ship from scratch (as far as I understand it is trial and error based approach).

Nowadays, ESDs are of high interest and there is a number of papers confirming this, while they are not included in the reference list, neither reviewed in the paper. Similar can be noticed for EEDI. The reference list must be strengthened with recent works, as for instance:

• A. Bakica, N. Vladimir, H. Jasak, E.S. Kim: Numerical Simulations of Hydrodynamic Loads and Structural Responses of a Pre-Swirl Stator. International Journal of Naval Architecture and Ocean Engineering, Vol. 13, 2021. pp. 804–816.

• N. Vladimir, A. Bakica, Š. Malenica, H.I., I. Senjanović, D.S. Cho: Numerical Method for the Vibration Analysis of Pre-Swirl Stator. Ships and Offshore Structures, Vol. 16, Supp 1, 2021. pp. S256-S265.

• A. Bakica, N. Vladimir, I. Gatin, H. Jasak: CFD Simulation of Loadings on Circular Duct in Calm Water and Waves. Ships and Offshore Structures, Vol. 15, Supp 1, 2020. pp. S110-S122.

• N. Sakamoto et al.: Evaluation of Hydrodynamic Performance of Pre-Swirl and Post-Swirl ESDs for Merchant Ships by Numerical Towing Tank Procedure. Ocean Engineering, Vol. 178, 2019. pp. 104-133.

• Y.M. Su, J.F. Lin, D.G. Zhao, C.Y. Guo, H. Guo: Influence of a Pre-Swirl Stator and Rudder Bulb System on the Propulsion Performance of a Large-Scale Ship Model. Ocean Engineering, Vol. 218, 2020. 108189.
• I. Ancic, N. Vladimir, D.S. Cho: Determining Environmental Pollution from Ships using Index of Energy Efficiency and Environmental Eligibility (I4E). Marine Policy, Vol. 95, 2018. pp. 1–7.

• I. Ancic, G. Theotokatos, N. Vladimir: Towards Improving Energy Efficiency Regulations of Bulk Carriers. Ocean Engineering, Vol. 148, 2018. pp. 193-201.

Please, also check recent work of Koushan, published in JMSE (https://www.mdpi.com/2077-1312/8/1/47).

The authors mentioned EEDI, but the paper is completely silent on EEXI. However, ESDs seem to be beneficial for EEXI also - please, comment!

 

Additional minor comments:

• Figure 2 - include reference in the title,
• Image quality is not appropriate. For example, Fig 7, Fig 12, Fig 13.
• English should be checked for error, e.g. sentence in line 186 ".. the drag of the ESDs reaches high and ..."
• More details on the CFD simulation should be given. Mesh at the vicinity of the ESD, flow field at converged solution...
• P.3, L.62 - change "Sumitomo Integrated Lamaren Duct (SILD)" into "Sumitomo Integrated Lammeren Duct (SILD)"
• Please, explain EFD and CFD first time when you use them. I know what it means, but should be directly mentioned in the paper.

Author Response

Thank you for your kind comments on the paper.

Please see the attachment and the revised paper.

Author Response File: Author Response.pdf

Reviewer 3 Report

The present manuscript treats about a study on compact pre-swirl duct for slender aft-body crude oil carrier. The work is interesting and well written. I recommend to publish it subjected to the following modifications:

- Improve the introduction. More references and a critical analysis is needed.

- Line 25, delete the word “Background”.

- Line 39, change “Carlton (1994) [1]” to “Carlton [1]”

- Line 56, change “Kim et al., 2004 [2]” to “Kim et al. [2]”

- Line 137, change “Reynolds-averaged Navier-Stokes (Reynolds Averaged Navier-Stokes)” to “Reynolds-averaged Navier-Stokes (RANS)”

- Line 147, why have you chosen the realizable k-epsilon model?

- Line 148, delete the word “consistent”.

- Which software have you employed for meshing?

- Have you checked the mesh size independence?

- Provide the computational time needed to realize the simulations (how many time have the computer needed to realize the simulations) and characteristics of the computer employed.

- Figure 11, reduce the size letter of “Looking Upstream”.

Author Response

Thank you for your kind comments on the paper.

Please see the attachment and the revised paper.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

All the comments in the first round of review have been addressed.