Risk of Flame Acceleration Due to Accumulation of Unburnt Volatiles in Zero-Gravity Condition

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Please address the font issue mentioned on lines 65 and 66. Additionally, the quality of the figures from 20 to 23 needs enhancement to ensure clarity.

The two-step global reaction model, despite potentially lacking precise accuracy, remains valuable given the constraints of current simulations. It would be beneficial for the author to discuss the model's accuracy and any potential shortcomings in more detail.

Author Response

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Reviewer 2 Report

Comments and Suggestions for Authors

This paper investigates the potential risk of combustion acceleration resulting from the accumulation of unburned volatiles in weightless conditions, with a specific focus on microgravity environments, such as those found in spacecraft. The paper is well written. The manuscript is appropriate for publication after the subsequent minor revisions.

 

1.       How do the numerical predictions for CO and unburnt hydrocarbon accumulation compare with existing experimental studies on microgravity combustion?

2.       What particular fire suppression strategies or ventilation modifications could effectively reduce a critical risk of flame acceleration owing to unburnt fuel exceeding the LFL within spacecraft environments?

3.       Could you please elaborate on the constraints associated with LSP and Moss soot model and propose alternative methodologies to enhance predictive accuracy?

4.       Given that soot and CO accumulation depend on oxidiser flow velocity, how might variations in spacecraft air circulation systems influence these findings?

5.       The work introduces sustainability; the relevant sections should include the latest MDPI literature to assist discussion. Authors could see the Safety, 2023, 9(4), 84; Metascience in Aerospace 1.2 (2024): 159-184.

Author Response

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Reviewer 3 Report

Comments and Suggestions for Authors

This is a good effort .

But the authors have to present the results using the same scales when comparing experiments and different soot models. ( see for example Fig. 5).

It is not clear which soot method was used for the liquid pool fires . Please explain also the model for calculating mass pyrolysis rates for the liquid pool fires.

Sections have to be made more clearly.

CONCLUSIONS must be rewritten .

 

 

 

 

Comments on the Quality of English Language

English needs refinement , for example in the conclusions section.

Author Response

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Reviewer 4 Report

Comments and Suggestions for Authors

The paper explores the influence of ventilation conditions on flame composition and risk of acceleration in reduced gravity, using models to analyze the effects on fuels like heptane and dodecane. Here are some comments and suggestions:

1. There are some typos throughout the manuscript which need careful editing.

2. The paper structure is missing, the authors can add a paragraph in Introduction to illustrate the main work of each section.

3. It is suggested to the second section to "Methods" and place model validation in the third section.

4. Why have the authors chosen the Moss model and LSP model for experimental validation in this study.

5. Please provide more details on numerical modeling, such as initial and boundary conditions, model meshing, etc., and add corresponding illustrations.

6. The comparison of calculated and measured smoke volume fractions in Figure 5 lacks clarity. To enhance understanding, it is suggested to combine Figures 5a, 5b, and 5c into one figure, allowing for a clearer observation of the difference between the LSP model, Moss model, and experimental results. The quantitative differences between different models and test results should also be provided.

7. It is recommended to enlarge all images for enhanced clarity.

8. Please explain your method limitations and future directions for related studies in Conclusions.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

the authors responded to my comments appropriately