Simulation Study on Aircraft Fire Extinguishing Pipeline with Different Filling Conditions and Pipeline Characteristics
, Heping Zhang 1 and Jun Gong 2
Round 1
Reviewer 1 Report
The manuscript used Amesim software to investigate the filling condition and pipeline characteristics of aircraft fire extinguishing systems. The research methodology is simple, and the research results needs further experimental validation in terms of applicable manner. It is not easily to comprehend the work due to the language and grammar issues. English usage needs improvement before publication.
Detailed remarks:
1. Line 13-14, 5.55kg appears twice.
2. Line 38-40, please explain why the traditional formula-based method does not meet the application in your research.
3. Line 96 and line 144, why do you choose this type of aircraft fire exchanging system? Is it a standard system used in the aircraft safety design?
4. Page 3, Equation (5), what is z? Page 4, Equation 7, what is ?
5. Line 68-170, what is the difference between the Pressure of fire extinguisher outlet and the fire cylinder outlet pressure?
6. What causes the second sharp drop in Figure 3?
7. Could you give the definition of the emptying time? It seems that the gas agent is not completely discharged at the end of the emptying time.
8. Line 186, one of the two values (0.826, 2.816) is not correct according to Figure 3.
Line 351, is 0.962s correct?
9. Page 8, what is the Fire pressure?
10. Noticeable grammar issues are found in Section 3. It seems that the authors are confused with the usage of comma and a full stop.
Overall, the manuscript needs improvements to get it published.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
This paper systematically studies the effects of essential parameters on jet characteristics of aircraft fire extinguishing systems through simulation. The structure of the article is clear. The findings can guide the optimization of fire extinguishing systems. The main review comments are as follows:
(1) Section 3.1, " The mass of agent ejected is 3.87kg, 3.98kg, 4.08kg, 4.16kg and 4.21kg respectively under 2MPA-6mpa filling pressure 2s after discharge.". Please change the format of the "2MPA-6mpa".
(2) The filling pressure P in the fire extinguishing bottle in the steady state can be expressed as the sum of Halon1301 saturated vapor pressure P1301 and nitrogen partial pressure PN2, Eq. (11). Please add the corresponding references and explain what the specific "steady state" refers to in this case.
(3) Section 3.2, "1. Solution of state parameters of fire extinguisher". Please change the format of the subheading.
(4) Section 3.2. Please explain why "the mass flow rate at the long branch nozzle is more sensitive to changes in temperature" in the context of a specific aircraft engine compartment. Is this sensitivity due to the length of the line? Or what is the reason?
(5) Should the order of sections 3.4 and 3.5 be adjusted so that the main pipe diameter analysis is done first and then the branch pipe diameter analysis?
(6) This paper focuses on the fire extinguishing bottle outlet pressure, discharge mass and flow distribution, but section 2.1 does not mention the calculation method of the flow at the nozzle, please add the relevant calculation model.
(7) Please change the word "research" in the title to "study".
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The text of the manuscript includes a lot of minor flaws on the design, for example, there are no spaces at the dimensions throughout the whole text (lines 13-18, 97-98 ... etc.). The same applies to the figure captions design, please pay attention to this.
Figure 4, 9 is displayed incorrectly – the legend is placed in a black rectangle, which makes the graph unreadable. In Figure 5, it is worth moving the description of the mass flow into the caption under the figure. This will have a positive effect on the information presented, in the figure. In general, it seems to me that it is necessary to look at the text of the article carefully and eliminate a number of inaccuracies that significantly spoil the impression of the presented work.
The authors used the Amesim software of Siemens to simulate the flow of Halon1301 in a certain type of aircraft fire extinguishing system. It is worth referring to the work describing how this software product is organized, or to give a more detailed description.
The initial value of the pipeline temperature, which is 20°C, is given. From what considerations the choice of initial parameters is made? It is worth paying more attention to these input parameters, initial and boundary conditions and the assumptions made, to ensure the validity of the computational experiment.
The analysis of the results obtained is quite extensive, the authors operate with calculated data, but there is no comparison of the results with similar calculations or experimental results. In particular, there is discussion of the emptying time as an important characteristic of the process under consideration. But at the same time there is a question - what to consider as a standard, what estimates exist in the scientific literature, there is a lack of confirmation of the validity of the obtained result. This, on the one hand, is a consequence of insufficient literary review, on the other hand - the existing gaps in the description of the basic concepts and the formulation of the problem. It is necessary to work well here and try to conduct verification of the obtained data, to pay attention to the analysis of related scientific articles on this topic.
I recommend the authors to add a Limitations section, since any theoretical formulation has a number of assumptions and limitations that are worth mentioning.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Authors did a really nice work on updating and improving the quality of the paper.
I vote for publication.
Author Response
We are very grateful for your sincere and professional advice and are pleased to receive your approval.
