Experimental Study of Scale Effect in Tunnel Fires at Different Sealing Ratios
Round 1
Reviewer 1 Report
The manuscript deals with scale effect of tunnel fires at different sealing ratios and the authors systemically evaluate the errors of scaling law in tunnels with varying sealing ratios. The scientific quality of the paper is very good and the topic is relevant to the Fire journal. The manuscript is in general well written and it is important to highlight the difference and new insights in the present work. In addition, the paper requires English language and style editing.
Author Response
The manuscript revised as per the comment
Reviewer 2 Report
1. Fig. 1 (b) Dimensions are not accurate and clear enough. Keywords should be started with capital letters, and the format of the figure and tables should be prepared according to the journal style.
2. Please explain why heat release rates of 15.8, 31.6 and 63.2kW are conducted. What does this data mean.
3. The explanation of low repeatability at 11.2kW heat release rate in Fig. 3 (b) is not convincing. And why is there a lack of data with a sealing ratio of 85%?
4. Tunnel-L-15.8kW-75% comparative experiment is missing in Fig.4? Please add and explain.
5. The full text uses a unified font format, and the unit symbol needs to be carefully checked.
6. Fig. 6 is not clear enough. And there are few explanations for it in the text.
7. For lines 430-433 in the conclusion, it is only based on a group of tests. Whether several groups of tests based on different full-size models should be added for verification.
Author Response
- 1 (b) Dimensions are not accurate and clear enough. Keywords should be started with capital letters, and the format of the figure and tables should be prepared according to the journal style.
Response: Fig 1(b) was revised as per the suggestion.
- Please explain why heat release rates of 15.8, 31.6 and 63.2kW are conducted. What does this data mean.
Response: the heat release rates of 15.8, 31.6 and 63.2kW in the 1:20 reduced tunnel represent the heat release rates of correspond to 5MW, 10MW and 20MW respectively in a full-scale tunnel. It is stated in revised manuscript.
- The explanation of low repeatability at 11.2kW heat release rate in Fig. 3 (b) is not convincing. And why is there a lack of data with a sealing ratio of 85%?
Response: Yes. The self-extinction behavior is quite sensitive to the ambient conditions, such as the initial temperature and wind condition (The tunnel was in a room, but there are a few openings). So the self-extinction time illustrates great difference. But the behavior prior to the self-extinction is similar.
For 11.2KW fire, a sealing ratio of 75% can lead to the occurrence of self-extinction. Therefore, a higher sealing ratio of 85% was believed to make it happen and was omitted in the experiment.
- Tunnel-L-15.8kW-75% comparative experiment is missing in Fig.4? Please add and explain.
Response: the objective of the study is to compare the behavior of self-extinction of fires at different reduced scales. As self-extinction for Tunnel-L-15.8kW-75% was not observed and the result was omitted.
- The full text uses a unified font format, and the unit symbol needs to be carefully checked.
Response: noted and revised.
- 6 is not clear enough. And there are few explanations for it in the text.
Response: Fig.6 is revised.
- For lines 430-433 in the conclusion, it is only based on a group of tests. Whether several groups of tests based on different full-size models should be added for verification.
Response: thank for the suggestion. Further study should be conducted in tunnels with different sizes.
Reviewer 3 Report
The paper presents an experimental study of scale effect in tunnel fires at different sealing ratios. The experimental work was done soundly and the paper is well written. I have just a few remarks, which are listed below:
1. Lines 91 and 93. The sentence is partially repeated, which sounds strangely.
2. Table 2. Please explain the LOI acronym. The notion ‘Limiting oxygen index’ (Table 3) should be explained as well.
3. Line 174. A typo ‘shonw’.
4. Equation 1. Please add a reference to the repeatability definition.
5. I’m wondering if it would be beneficial to transform the description of tests’ outcomes (the text portions which follow Figure3 and Figure 4) into bullet lists.
6. Figure 5. Since you show the mean of the peak temperature rises in two repeated tests, please add the temperature difference in a form of vertical error bar.
7. It is a pity you haven’t carried out tests with, for instance, 40% or 50% sealing ratio. It would confirm the overall tendency for lower values of sealing ratio.
8. Please, justify the selection of values of sealing ratio values being examined. Although it seems to be suitable in the light of fire self-extinguishing, it may appear too sparse when analyzing the maximum temperature.
9. Figure 6. The vertical error bars would be valuable again.
10. Figure 9 and 10. What is the temperature at the y-axis? Is it still the mean for two repeated experiments? If so, is it possible to mark a band of width equal to the difference? And, if this brings some new information, please discuss it (I can guess that this will bold or not the differences significance).
Author Response
The paper presents an experimental study of scale effect in tunnel fires at different sealing ratios. The experimental work was done soundly and the paper is well written. I have just a few remarks, which are listed below:
- Lines 91 and 93. The sentence is partially repeated, which sounds strangely.
Response: Revised as per the comment.
- Table 2. Please explain the LOI acronym. The notion ‘Limiting oxygen index’ (Table 3) should be explained as well.
Response: revised as per the comment.
- Line 174. A typo ‘shonw’.
Response: revised.
- Equation 1. Please add a reference to the repeatability definition.
The equation is defined by the authors and no reference is available.
- I’m wondering if it would be beneficial to transform the description of tests’ outcomes (the text portions which follow Figure3 and Figure 4) into bullet lists.
Response: the section was divided into a number of sub-sections
- Figure 5. Since you show the mean of the peak temperature rises in two repeated tests, please add the temperature difference in a form of vertical error bar.
Response: Fig. 5 was updated as per the comment.
- It is a pity you haven’t carried out tests with, for instance, 40% or 50% sealing ratio. It would confirm the overall tendency for lower values of sealing ratio.
Response: as self-extinction was not observed for 40% and 50% and the tests was omitted.
- Please, justify the selection of values of sealing ratio values being examined. Although it seems to be suitable in the light of fire self-extinguishing, it may appear too sparse when analyzing the maximum temperature.
Response: The objective of this manuscript is to systemically evaluate the differences of self-extinction behaviors in tunnels with varying sealing ratios.
- Figure 6. The vertical error bars would be valuable again.
Response: Fig.6 is updated as per the comment.
- Figure 9 and 10. What is the temperature at the y-axis? Is it still the mean for two repeated experiments? If so, is it possible to mark a band of width equal to the difference? And, if this brings some new information, please discuss it (I can guess that this will bold or not the differences significance).
Response: The Y-axis is the temperature of the 1st test.
Reviewer 4 Report
Dear Authors,
In line with the proofreading criteria of the publisher, I prepared a report, which would be as follows:
The content of the proposed paper meets the objectives set out in the special issue information letter.
Using the scientific methods applied in accordance with the author’s scientific objectives resulted useful scientific achievements.
The main strengths of the analysed experimental study is that the authors systemically evaluated the errors of scaling law in tunnels with varying sealing ratios. Examining the article, I did not reveal any weaknesses.
The references used in the main chapters are relevant and assist the reader to understand the authors proposals. The illustrations used are regular and correct.
In addition to acknowledging the high-quality work, I recommend adding a paragraph to the “Conclusions” chapter, in which the authors define the general recommendations for practitioners conducting research in the field of tunnel fire prevention. It is also recommended to consider dividing paragraphs 30-94 into several parts for better clarity.
Based on the above, I suggest publishing the reviewed article.
Author Response
Noted and thanks for the comments
Round 2
Reviewer 2 Report
None.
Reviewer 3 Report
Since the Authors have addressed all my comments I have no further remarks.
