Effects of Pressure and Nozzle Size on the Spray Characteristics of Low-Pressure Rotating Sprinklers
Round 1
Reviewer 1 Report
In this study, the authors calculated the kinetic energy and droplet trajectory angles for a low-pressure sprinkler with three nozzles and multiple working pressures. Results showed that there is a strong relationship between droplet size, velocity, trajectory angle and sprinkler uniformity. This study presents a sprinkler calibration exercise that should be done by the manufacturing companies in all sprinklers and nozzles to provide designers with information for a proper layout of irrigation systems. Based on the overall goal and results of the manuscript, I consider this manuscript needs to be improved significantly before being accepted for publication. There are multiple major methodological flaws that need to be addressed:
- It is well known that nozzle size is the major driver of droplet size, and pressure on velocity and spray characteristics. All sprinkler irrigation systems should make an initial selection of sprinkler nozzle based on pressure when designing an irrigation system. The article is showing a calibration exercise that is usually provided by manufacturing companies
- The manuscript in it present form lacks originality. There are articles from 2011 evaluating pressure and R33LP nelson sprinkler characteristics p.e Zhang,Kasem, and Pinthong, 2011- 10.1007/s00271-011-0294-0
- There was only one sprinkler evaluated with three nozzles. Nelson irrigation provide calibration tables for the selection of nozzles based on pressure. The company make these drop size analysis and data is publicly available.
- Authors discussed in one sentence (lines 429-431). The applicability of this study for the irrigation design community
Minor comments:
Line 8: edit “release stress”
Line 29: “used”
Lines 28- 30: Edit. Authors cite R Lal, 2004 wich to the statement “23 % of the farm energy is use for on-farm pumping” is referencing Sloggett, 1979, Sloggett, 1992. I suggest deleting this sentence as is not providing context to the manuscript.
Line 40: “center” pivot
Line 203-204: Clarify or describe in the methods section the two sprinklers. Line 84 mention the authors tested only one Nelson sprinkler with multiple nozzles
Lines 203-205: describe R33LP and RSPS. This sentence seems to be citing Liu et al, but is not clear the context for the discussion
Author Response
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Author Response File: 
Author Response.docx
Reviewer 2 Report
In this manuscript authors are conveying a message that low pressure sprinklers can be more effective and efficient when compared with high pressure sprinklers. However, I have few suggestions/recommendations for the authors.
Authors may not need to quantify, but should surely include the concept of physiology or different water requirement for different crop vs. suitability of low pressure to sprinklers, adoption and cost benefit ratio. Before recommendation of any design or proposing anything thing related to use of already designed component, multi dimensional data makes more sense.
In table 2: The R2 is too high,did you consider outliers?
For Figure 9: It is very confusing. It is reflected that increase in droplet size increases or decreases droplet velocity.Think about the other way Imay be box and whisker charts)to convey the message
Be consistent with the abstract. Explain the reason for line 198 -199 L-11 & 12 and L-198-199 convey the same message but in a different way, that will confuse the readers. If possible ,rewrite it.
L-84-89: Even though the recommended pressure by a manufacturer is between 175 and 350, My question here is why only the specific manufacturer was chosen and why only one manufacturer was selected. What's the rationale behind using the pressure values between 100 & 300?
Good Luck with the revisions!
Author Response
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Author Response File: Author Response.docx
Reviewer 3 Report
The document is very interesting, well written, clear, and concise. The graphics are generally explanatory and contain information necessary to understand the scientific content of the text. A little more in-depth discussion would add quality to the document, commenting on the possible origin of the results obtained in each point.
Below are some comments on the document:
L 125-127: In the measurement process, do you take into account the deformation of the falling droplets?
Figure 8: The comparison between the results of the graphics would be easier if they were ordered in two columns.
Figure 9: In these graphs, it is difficult to see clearly the information because in the drops of diameter < 1mm there is a lot of density of points. The resulting color shown does not depend so much on the number of points in each series as on the order of the series determined when making the graph.
Figure 9: In the figure caption, the series definition (distance to the sprinkler) is not commented on.
Figure 9: Do significant differences appear between the velocity of drops of the same diameter at different distances?
Conclusions: One conclusion from the text could be that the manufacturers' recommendations regarding the operating pressure of the emitters are correct since using the emitter below the recommended pressure decreases the quality of the water application. It is necessary to select the nozzles adapted to the working pressure of our system.
Author Response
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Author Response File: Author Response.docx
Reviewer 4 Report
Line 268: is the method section.
Line 265:” indicating a good agreement”, how did you find this value is good? 0.351?
Please re-write the conclusion section, write the main conclusion point by point.
Please also re-write the abstract. Add more details of the results.
Line 74: what is the novelty of the work? It is true that the research will provide guidelines, but the novelty of research should be highlighted. If there is any guideline from the company? Nelson R33LP; Nelson Irrigation Co., Walla Walla, WA, USA?
Please show the catch cans on the figure.
How is the catch cans configurations?
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
Good Work with revisions!
