Research on the Flow Mechanism of a High-Loading Biomimetic Low-Pressure Turbine Cascade

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The presented paper concerns  of improvement of low pressure turibne cascade model employing sawtoth-like leading edge, wich remains vortex generators thich one may found at pectoral fins  of megalopterae novaealglie. 

Micro-vortex tooth-like generatos one may find at the trailing edges of wings of many insect species . This solution increases a local maximum lift coefficient, as well as reduces drag due to stall delay. 

In this cases flow is however strongly three-dimensional.  

The study concerns a quasi two-dimensional problem, but in reality the flow around the blade is three-dimensional due to the radial variation of peripheral peripheral velocity, and infuence of Coriolis force on boundary layer flow.

Anywaly,despite these simplifications,  the work shows a potential  of proposed solution. 

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

A biomimetic cascade with a seal whisker structure was designed based on a high-loading low-pressure turbine cascade, and its flow mechanism and aerodynamic performance were studied using experimental and numerical methods under the incidences (i) of 0° to 15°.

Please neatly draw the three-dimensional perspective of the biomimetic cascade blades as a different shape so that the reader can understand the modification on the original cascade plates.

It would be better to provide a brief overview of the topic of the study and the parameters measured and predicted including Reynolds number in the abstract of the manuscript.

Titles of some figures are needed to be more informative.

Traditionally, the symbol k is used to present the pressure loss coefficient. Please use k for the pressure loss coefficient instead of capital Y.

 

A horseshoe vortex (HSV) as well as other types of vorticities developed in the junction of discs (End-plate) and blades affect the flow characteristics in the gap of blades vary significantly as presented in Figure 16. So, more information and discussions should be provided about those vortices in relation to the static pressure distributions over the cross-section of cascade blades.

Comments on the Quality of English Language

Minor editing of the English language is required

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

page 2 

line 62 - its rather a design, not modeling method (which means to recreate the real objects in a scale or simplifying the real object)

Figure 1 - error in description of (c) picture, insufficient explanation in description, the figure1 is not referenced in  main text. 

line 77 "This study designs ... blade" -> "in this study a blade ... is designed".

 

page 3

 

line 92  The overall structure of the test section is depicted in Figure 2, not 3.

line 98 Cx - at the first occurrence of the symbol in the text, it should be described: "at the 60% of Cx (axial chord) position". Further occurrences can be left as they are, but now the text is more understandable.    

line  105 - "The static pressure  ... are measured" -> "The static pressure (value? distribution?) ... is measured".

figure 2 - description is barely visible, the simplified scheme would be more useful than overlaying the real technical drawing with descriptions.

line 112 - "table 1 is" -> "table 1 contains"

table 1 "metal angle" is a jargon term, should be explained to a reader without an experimental background or at least should be shown in the test stand scheme. 

 

page 4

 

line 120 " of 3.5r" - again, at the first occurrence of symbol in the text it should be explained like "of 3.5r (leading edge radius)"

line 124 explain "SSL". Suction side length ?

line 126 what is a "pressure test scheme"? did you mean "pressure test points array"?

line 136 "combains" - "combines", " Gamma-Theta" -> "Gamma Re-Theta".

 

page 6

 

line 168 "data processing process" -> "data processing"

line 169 "full text analysis" ?

line 174 "local static pressure, and local total pressure" -> "local total pressure, and local static pressure"

line 179 reference error

line 181 "axial, circumferential ... velocity" a drawing with axial and circumferential direction in current domain and x,y,z axes would be useful. Is a circumferential direction along the airfoil contour on the suction side?

line 195 since the stall appears within a few degrees of angle of attack, a 5 deg step is rather big, especially near the stall region, and that’s the area where the difference should occur. Now you only know that the stall appears somewhere between 10 and 15 deg, but what is the stall character, is it sudden stall or smooth?

page 10 

fig 10 - y/pitch dimension not explained. Lack of coordinate system drawing in the paper is a real problem. Peak values barely visible, is the color map the same for all frames or is it local? What are the black arrows mean, why are they pointing towards its legend? What is the vector field? "secondary flow vector" is a vector of velocity or its projection on some surface? 

line 280 The examples of vortex structures from the end of the article (or simplified drawing) should be shown before this figure to understand the description. 

 

page 13

line 382 "spanwise distribution" or is it "pitchwise" as in figure description?

line 636  "And another series" -> "Another series"

 

Overall:

Lack of direct comparison of (for example) pressure distribution between CFD and experiment, only the qualitative comparison of each vortex is done.

The description of figures in the paper is overcomplicated, overdiscussed, the authors cannot extract the main causes of the phenomena, instead they discuss each vortex separately. It is, of course, great for a PhD thesis, but not for concise results presentation in the scientific paper. I know that every result is precious, but the main picture has to be withdrawn and presented in a few words. The details (if the authors want) have to be published in a few, more in-depth papers, e.g. "CFD results" and "experimental results".

 

Comments on the Quality of English Language

The text is clear and understandable, especially the CFD part.

Author Response

Please see the attachment.

Author Response File: Author Response.docx