Heat and Mass Transfer

, Volume 55, Issue 12, pp 3575–3587 | Cite as

Numerical investigation on the flow character and film cooling performance of novel merged holes structure

  • Junfei Zhou
  • Xinjun WangEmail author
  • Jun LiEmail author
  • Weitao Hou


In order to investigate the flow characteristics and film cooling performance of novel merged holes cooling method, merged cylindrical holes structures have been applied on a flat plate with three merging ratios under three blowing ratios. Single cylindrical hole film cooling structure is also established as a benchmark structure. The numerical results of the single cylindrical hole are validated with the experimental results available in open literatures. The discharge coefficient, aerodynamic loss, tangential velocity vectors and total vorticity distributions are studied and compared. The spanwise averaged film cooling effectiveness and adiabatic temperature contours are studied and compared. Results show that the development of the kidney vortex is impeded and the film cooling performance is promoted in merged holes cooling cases. The blowing ratio and merging ratio both affect the cooling performance of merged holes cooling cases. In this paper, the best film cooling performance is obtained at the biggest merging ratio.


Flat plate film cooling Merged holes cooling Gas turbine Numerical simulation 



cross section area of one film cooling hole (m2)


discharge coefficient of film cooling hole


diameter of cylindrical jet hole (m)


diameter of each circle of the merged holes structure (m)


blowing ratio

mass flow rate (kg·s−1)


cooling air mass flow rate through one film cooling hole (kg·s−1)


static pressure (Pa)


static pressure at the film cooling hole exit (Pa)


total pressure at the film cooling hole outlet (Pa)


total pressure at the mainstream inlet (Pa)


total pressure at the film cooling hole inlet (Pa)


distance between two merged cylindrical holes (m)


temperature (K)


total temperature at the film cooling hole inlet (K)


turbulent intensity


total vorticity


velocity (m·s−1)


velocity along x direction (m·s−1)


velocity along y direction (m·s−1)


velocity along z direction (m·s−1)


coordinate along the chamber axial direction (m)


coordinate along the jet hole axial direction (m)


non-dimensional wall distance


coordinate along the direction normal to both the x and y directions (m)

Greek letter


merging ratio of the merged holes structure


film cooling hole inclination angle (°)


film cooling effectiveness

\( \overline{\eta} \)

span averaged film cooling effectiveness


span averaged film cooling effectiveness enhancement in merged holes cooling cases


dynamic viscosity (Pa·s−1)


density (kg·m−3)



adiabatic wall




one film cooling hole




mainstream air


mainstream channel outlet


overall averaged parameter of the flat plate surface


parameter with total value


Compliance with ethical standards

Conflict of interest

On behalf of all authors, the corresponding author states that there is no conflict of interest.


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Institute of Turbomachinery, Shaanxi Engineering Laboratory of Turbomachinery and Power EquipmentXi’an Jiaotong UniversityXi’anChina

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