The flow field and surface adiabatic coolant-film effectiveness (ACE) distribution of a combustor representative effusion cooling array with cylindrical cooling holes has been studied both experimentally
and numerically. Both studies focus on the influence of inflow turbulence, especially the high inflow
turbulence which is always present in the combustor environment but rarely studied in the literature.
A fluctuating inflow at roughly 20% intensity level is generated in the wind tunnel, and distributions of
ACE measured for blowing ratios (BR) between 1.8 and 4.1. For comparison, ACE distributions are also
measured at a low inflow turbulence intensity of 5%. For further investigation on the mechanism of inflow turbulence effects, hybrid large eddy simulations (LES) are carried out at a BR of around 1.8 under
both low and high inflow turbulence intensities. The fluctuating inflow is generated using the Synthetic
Eddy Method (SEM) with similar turbulence intensity. The predicted surface ACE distributions of the
2 cases are compared with the measurements. More detailed studies of the flow field are carried out
based on the numerical results. The effects of inflow fluctuation levels are studied by comparing various
flow statistics between the low and high fluctuation cases. The formation of the coolant film is also
studied based on the development of the coolant film thickness. The interaction between the upstream
and downstream coolant jets is investigated by visualising the coolant jet centre trajectory, as well as
analyzing the turbulence structures, spectra and coherence at selected positions. These analysis clearly
show that the highly fluctuating inflow results in an enhanced mixing of the coolant and mainstream. In
the high turbulence intensity case, this leads to wider span-wise and shorter stream-wise film coverage
over the first few rows of the array. These effects diminish as soon as a thick coolant film is formed in
the downstream, especially at high BR conditions
