Experimental Hydraulic Investigation of Angled Fish Protection Systems—Comparison of Circular Bars and Cables
Round 1
Reviewer 1 Report
The manuscript submitted for review presents the problem of experimental study investigates the flexible fish fence, a physical barrier created by horizontally arranged steel cables, and an angled horizontal trash rack with circular bars. In particular the effect of bar spacing, rack angle and the influence of flow-induced cable vibrations on the head loss coefficient were examined. A new formula was defined for determining local losses based on traditional approaches (Kirschmer and Meusburger) using multiparameter regression. New additional coefficients have been determined.
I believe that the article is written well and clearly with theoretical background. Experimental research has been carried out with due diligence. The basic elements such as measurement uncertainty and its accuracy as well as scale effects were taken into account. Below are the comments to which the authors should respond.
In the introduction, the authors review the literature of the studied subject. Literature review is relatively extensive and contains many items from 1926 to the latest ones from 2018. There are a lot of current and classic items (like Kirschmer). The problem is that the authors cite many items in German (some PhD Thesis). A translation is missing in the references.
The authors present the basic formulas based on the Bernoulli’s equation and assuming that the kinetic energy correction factor is equal to 1. For turbulent flow, the value is assumed to be about 1.1. Does this matter with regard to the results of the carried out tests?
In Chapter 2, the authors present the material and methods. This chapter contains a description of the measurement stand prepared in the hydraulic laboratory. The water supply description is missing. It is probably a closed water circulation. Was the water temperature during the tests constant? In the case of small tanks, the long operation of the pumps can affect the water temperature, and thus the viscosity. The Bar-Reynolds number has been defined. Its critical value was not given. Have the tests been carried out only for turbulent flow? (the flap gate at the end of the channel allowed forcing small velocities).
The authors write that the experiments were conducted according to Froude similarity. Please expand this.
In Chapter 3, the authors present the results, measurement accuracy and data verification. The empirical formula determined on the basis of the conducted research was also quoted. The chapter is very extensive but divided into 5 logical subchapters that facilitate the reading of the manuscript. The reviewer has no comments for this part.
Chapter 4 presents a discussion of the conducted research with reference to literature and possible technical applications. The reviewer has no comments on this chapter.
In chapter 5, the authors present 5 main conclusions which summarise the findings of carried out experimental investigating. Succinctly and properly.
References – note as above regarding the translation of papers in German.
Author Response
Attached file including both responses. Thank you!
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Good paper!
Minor observations:
Lines 31, 39, 51 etc.: Use everywhere normal fonts for measurement units; ex. mm, m3/s etc.
Line 68: What represents index R of the square velocity?
Line 145-146: Bar-Reynolds Number was noted as Reb and in eq. 8 is written Rb.
Line 256-257: Use the same Greek letter for head loss coefficient in text and in figures 5, … 9.
Line 306-307: At the end of eq. 10 use dot “.”.
Author Response
Attached file including both responses. Thank you!
Author Response File: 
Author Response.docx
