Effect of Nozzle Port Shape of Fuel Injector of Micro Gas Turbine Engine Combustor on Mixture Gas Formation for Combustion
Round 1
Reviewer 1 Report
In this paper, CFD simulations were performed to study the injection nozzle hole of the fuel injector of a model MGT engine. Three parameters, the penetration length, diffusivity angle and injected fuel amount, were analyzed in four nozzle hole geometries (Model 1 to 4). It was concluded that Model 3 has the best performance as it has 5% more fuel injected into the combustion chamber than the base Model 1. The paper is clearly written and easy to read. Although the scientific arguments are not well made, the overall findings are good to the community. The reviewer, therefore, believes that the manuscript can be accepted for publication. However, the authors need to address the following reviewer comments:
- In Table 1, the dimension of the max thrust is “lb” instead of “N”, please check the original reference [9]!
- Line 117 on page 4, the author mentioned that the Mach number of the injection speed is less than 0.1. However, according to Table 2, the injection velocity is set to 300 m/s, which is close to the sound speed under atmospheric conditions. Could you explain further?
- The continuity equation, i.e, Eq. 1, is wrong. It is either \partial U_i/\partial x_i = 0, or \partial U_x/\partial x + U_y/\partial y+ U_z/\partial z=0. If i denotes direction, then x_i represent x, y, and z when i = 1, 2, and 3. x_i does not make sense. Also, please explain the definition of each variable before or after the equations.
- Line 156 on page 5, the author states that “The optimum grid size in the control volume was finally determined to be (84x145x84) through a grid test.” Actually, the high-speed gas injection is not easy to be resolved in a coarse mesh. It would be the best if the author can provide a figure to show results of the grid test, e.g., providing a mesh sensitivity analysis to prove that the mesh you used is sufficient to capture the flow.
- Line 188 on page 7, “more fuel is injected at the 5th row of the ports due to the higher accumulated injection pressure”. Could you please show the pressure distribution to support it?
- On page 10, I could not see the difference between conclusions 1 and 2. I suggest the author combining them to make it clear.
- I found some typos. For example,
- Line 14 on page 1, “four different shapes of the nozzle hole of the fuel injector were designed and numerically analyzed the mixed gas formation characteristics in the chamber” should be “... and the mixed gas formation characteristics in the chamber were numerically analyze.
- On page 3, Figures 1 and 2 have the same caption, you should double check.
- Line 187 on page 7 and line 209 on page 8, you use 5th and 6th. Please be consistent.
- Line 244 on page 10, “com-pared” should be “compared”.
Author Response
Thank you for your kind effort in reviewing my paper.
I followed your comments to update my writing.
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Page 1, Line 18. Please explain CFD abbreviation. Computational fluid dynamics?
Page 2, Line 55. Please explain DOE. Department of Energy?
Page 3, Line 11. Why did the authors change the pressure unit [bar], when the calculation used [kPa] (Page 4, Line 116)?
Page 5, Line 147. No space in front of the parenthesis.
Page 9, Line 233. No space for "Model 3".
Author Response
Thank you for your kind effort in reviewing my paper.
I followed your comments to update my writing.
Please see the attachment.
Author Response File: Author Response.pdf
