Journal of Mechanical Science and Technology

, Volume 33, Issue 11, pp 5527–5536 | Cite as

Numerical study on unsteady film cooling performance under the mainstream swing condition

  • Wei ZhangEmail author
  • Hui-ren Zhu
  • Quan-peng Yu
  • Guang-chao Li


Significant unsteady film cooling performance of a turbine shroud can be found under the periodic disturbance of rotor blades. The mainstream flow in film cooling on a turbine shroud is simplified as the periodic swing based on the alternate appearance of the cascade passage flow and the blade tip clearance flow. Three-dimensional unsteady numerical simulation was employed to analyze the film cooling effectiveness with a single cylindrical hole injection at mainstream swing frequencies of 100, 160 and 220 Hz, and at blowing ratios of 0.5, 0.8, 1.1 and 1.4, respectively. A steady simulation was also carried out as a comparison. The results show that mainstream swing provides instantaneous film spots. It is a novel phenomenon in film cooling. Spanwise coverage of film was more uniform compared with the steady case. There are considerable differences of film cooling effectiveness under the various mainstream swing frequencies. A larger swing frequency results in higher spanwise averaged time-averaged film cooling effectiveness.


Turbine shroud Film cooling effectiveness Blowing ratio Mainstream swing frequency Unsteady numerical simulation 



Diameter of the cylindrical hole, m


Mainstream velocity, m/s


Temperature, K


Time, s


Streamwise coordinate, m


Vertical coordinate, m


Spanwise coordinate, m


Density, kg/m3


Dynamic viscosity, kg/(m×s)


Pressure at local location of the cooled surface, Pa


Total pressure at inlet of the mainstream, Pa


Swing frequency of the mainstream inlet velocity, Hz


Area of a grid, m2


The number of time steps in a period


The number of spanwise grids


Blowing ratio, (ρcUc)/(ρU)


Film cooling effectiveness, (T - Taw)/(T- Tc)


Spanwise averaged film cooling effectiveness, \(\sum\limits_{i = 1}^n {A_i\eta_i} /\sum\limits_{i = 1}^n {A_i}\)


Time-averaged film cooling effectiveness, \(\sum\limits_{j = 1}^m {\eta_j}/m\)


Spanwise averaged time-averaged film cooling effectiveness, \(\sum\limits_{J = 1}^m {\sum\limits_{i = 1}^n {A_{ij}} \eta_{ij}} /\sum\limits_{i = 1}^m {\sum\limits_{i = 1}^n {A_{ij}}} \)


Enhancement factor, (ηtave_f - ηtave_0)/ηtave_0)


Nondimensional excess temperature, (TreTc) / (TTc)


Strouhal number, Df/U


Reynolds number, ρUD/μ


Viscous dissipated energy


Pressure coefficient, (p* - p)/(1 / 2 ρU2)



Adiabatic wall





Spanwise averaged


Spanwise averaged time-averaged




Spanwise time-averaged of various swing frequencies


Spanwise time-averaged without swing frequencies


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This study was supported by the National Natural Science Foundation of China (Grant No. 51406124).


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Copyright information

© KSME & Springer 2019

Authors and Affiliations

  • Wei Zhang
    • 1
    Email author
  • Hui-ren Zhu
    • 1
  • Quan-peng Yu
    • 2
  • Guang-chao Li
    • 2
  1. 1.School of Power and EnergyNorthwestern Polytechnical UniversityXianChina
  2. 2.Department of Aero EngineShenyang Aerospace UniversityShenyangChina

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