Cooling Characteristic of a Wall Jet for Suppressing Crossflow Effect under Conjugate Heat Transfer Condition

Round 1

Reviewer 1 Report

This paper provides numerical results of the novel jet scheme study applied to the blade leading edge area. The calculation were carried at the boundary conditions relevant to the actual operational conditions, they were compared with impingement and swirl flow cooling. As found, the SST turbulence model describes can be used in calculations The presented data are useful for designers who deals with advanced cooling systems. The paper can be recommended to publication however minor improvements are required.

1. The novel means the patent existence. Do the authors have it? If so, some corrections should be made in the paper title.
2. Another novel blade views additional to Fig.1 is necessary to see the coolant in-pass movement in more details.
3. The swirl tube with two tangential inlets and a single outlet was firstly proposed and investigated by Ligrani et. al (97 -GT-530). This paper data did not mention both in Fig. 9, as well as in the introduction section.
4.  The Fig. 13 is too small and difficult for analysis. The same is Fig.17.
5. The pressure losses are not discussed in the paper. However it can reduce heat transfer advantages of double wall technique. The thermal performance analysis might be very much useful in the paper. 
6. The jetting Reynolds number 20 000 should be justified.
7. In the "key words" section the word "cooling" is repeated two times (it is better to join  as impingement and swirl cooling), "pressure loss" should be excluded here as no remarkable information was given on this.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Summary: The manuscript presents a novel wall jet cooling technique for turbine blade leading edge. The flow and heat transfer characteristics are analyzed in detail numerically for the wall jet method along with two conventional methods i.e., impinging cooling and swirl cooling. These cooling methods are evaluated for three different coolant inlet boundary conditions. The total heat flux, mass flow rate, cooling effectiveness, pressure ratio and Nusselt number are evaluated and compared in detail. The authors provide sufficient details of the model for readers to reproduce the study. The numerical setup and the details of the computational grid as well as the grid independence study are provided. Authors mention that there are limited number of experimental studies about wall jet cooling, thus they argue that the flow structure of wall jet is a combination of impingement jet and swirl jet and rather validate these two instead and use it as a justification for the use of k-omega SST for the wall jet cooling case.  

Overall, the work presented in this manuscript is novel and of great value to the readers of this journal. However, there are a few minor things that need to be addressed to improve the quality of this manuscript.  

1. Abstract – 19-54% is a very wide range, is it for different locations? This must be clearly stated.
2. Lines 30-32 and 32-34 – Please provide references. 
3. Line 99 – Some quantifiable data should be provided to show what the authors mean by 'dramatically'. 
4. Line 174 – Do the authors mean Workbench meshing when they say Ansys Mesh? 
5. Line 176 – How many inflation layers are considered? 
6. Line 182 – How many elements across the tip clearance? 
7. Lines 187 – 190 should be moved to the end of the subsection, ie, after 204 as the authors provide definition of Nusselt number and explain the plot in Fig 6 after having already described the results from the solid domain's grid convergence study. 
8. Line 208 - The names of the models tested are incorrect. The first two model should be k-epsilon and RNG k-epsilon
9. Line 261 – Please use a more precise statement than 'discussed in detail below'
10. Line 342 – Legend and axes font size is too small. 
11. Line 345 – Incorrect equation number
12. Line 380 – Figure 15, for the all the middle streamline plots there are two long black arrows which need to be annotated.  

Author Response

Please see the attachement.

Author Response File: Author Response.docx