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Peer-Review Record

Model Analysis and System Parameters Investigation for Transient Wave in a Pump–Pipe–Valve System

Water 2020, 12(4), 1014;
by Zubin Liu 1, Dingyi Pan 2, Fengzhong Qu 3 and Jianxin Hu 4,*
Reviewer 1: Anonymous
Reviewer 2: Anonymous
Water 2020, 12(4), 1014;
Submission received: 14 March 2020 / Revised: 29 March 2020 / Accepted: 31 March 2020 / Published: 2 April 2020
(This article belongs to the Section Hydraulics and Hydrodynamics)

Round 1

Reviewer 1 Report

This paper studies the transient frequency response for a pump-pipeline-valve (PPV) system. The system transfer matrix analysis (STMA) is adopted in the paper for the method development and systematic analysis. The response of transient flow behavoirs in a simple PPV system is obtained, which is then used for analyzing the results under various valve operation and system conditions (i.e., system parameters). In particular, an index of the Valve signal intensity (VSI) is proposed to quantify the impact of system parameters and operations on the transient response in the PPV system.

Overall this paper is well presented for its objective and content as well as results and discussion. Meanwhile, the topic and findings of this paper may be useful to the community of this research. I just have several minor concerns or suggestions to this paper before its acceptance and publishing on this journal:

  1. Firstly I am sorry that I did not check all the mathematical derivations, and assumed these derivations are correct during my review process. So I urge the authors could check them again and make sure they are fine;
  2. As it is know that the STMA is a linearized method and analysis method for deriving the transient frequency response of pipe flows, including the PPV system case in this study. That is, the linearization assumption or operation has been automatically made during the derivations, such as the results of Eq. (3) or (4) in this paper. Since all the results and analysis of this study are based on this assumption, it is appreciated (and also useful to the paper) if the authors could discuss this assumptions in the paper, for example, mentioned this or discuss their results based on this assumption in the relevant part ("discussion" section). For this purpose, the following paper can be reviewed: (i) for quantifying the linearization of turbulent steady friction: Duan, H.F. et al. (2018). "Influence of nonlinear turbulent friction on the system frequency response in transient piape flow modelling and analysis." Journal of Hydraulic Research – IAHR, 56(4), 451-463, DOI: 10.1080/00221686.2017.1399936; (ii)for quantifying the linearization of valve formula: Lee PJ. and Vitkovsky JP. (2010) Quantifying Linearisation Error When Modeling Fluid Pipeline Transients Using the Frequency Response Method. Journal of Hydraulic Engineering 136(10): 831-836. DOI: 10.1061/(ASCE)HY.1943-7900.0000246.
  3. Further to comment 2 above, could  the authors list all the initial conditions of the test cases in this paper (e.g., Re0)?  I just noticed one value for the case in Fig. 5 (or I missed out some others?).
  4. I suggest the authors could add more recent reference relating to this paper topic. In current paper, the latest ones were published in 2015 (which was already 5 years ago). In this regard, I may provide some suggestions: (i) about the transient modeling and analysis for pipelines, with doi: 10.1061/(ASCE)HY.1943-7900.0001700;10.1016/j.ymssp.2019.05.065; 10.1007/s11269-015-1126-4; (ii) about the transient-based application in water pipes (e.g., pipe defects detection): 10.2166/hydro.2016.008; 10.1061/(ASCE)HY.1943-7900.0001383; (iii) transient wave mechanics in pipe flows: 10.1115/1.4037504; 10.1115/1.4039711; 10.1016/j.jher.2017.08.002; etc....Note that these references are only some of typical ones published recently in this field. The authors may determine to find out more by themselves.
  5. Finally, this paper may provide useful information to this relevant research topic, and thus is worthy of publishing. A minor revision is requested to address above comments. Congratulations to the authors.

Author Response

Please find our response in the attached file.

Author Response File: Author Response.pdf

Reviewer 2 Report

I think that the paper is scientifically sound and well written. I only have minor comments about the paper.

1 - There are some errors in the English. Proofreading is recommended.

2 - In equations 19-22, the symbol "=" has dropped.

3 - the Authors use the unsteady friction model. How does it relate to the typical model that is used in water distribution network modelling(e.g., see paper "Unsteady flow modeling of pressure real-time control in water distribution networks" or "On the choice of the demand and hydraulic modeling approach to WDN real-time simulation"), in which the steady flow resistance is increased with a term proportional to velocity spatial and temporal variations? Please, also explain in the manuscript.


Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The comments and concerns have been fully addressed in this revised version. Now it is recommended to accept as it is. 
Congratulations to the authors.

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