A constant-temperature, internally cooled, cylindrical t!1infilm (diameter .0152 cm and length .15 cm) has been used for an experimental investigation of the structure of turbulent premixed flames.

The static and dynamic response characteristics of the cooledfilm as a tool for the measurement of heat-flux beoveen itself and a surrounding high temperature flow have been evaluated. From measurements in a D.C. archeated jet, a forced convection heat transfer correlation pertaining to cooled-film measurements in high temperature nonreacting flows of gas mixtures at low Reynolds numbers has been established. The heat transfer characteristics in flows containing radicals has been determined from measuremcnts in the products of laminar flat-flames of propane, ethane and methane of various stoichiometry. The methods of simultaneous evaluation of the average and/or the r.m.s. fluctuations of more than one flow parameter from cooled-film heat-flux measurements in high temperature flows have been analyzed.

From an investigation of the response of thp. cooled-film to open, turbulent premixed flames, it has been established that,

1. the cooled-film behaves essentially as a fast-response thermometer in the flame-brush, and
2. the cooled-film behaves essentiëi11y as a fast-response anemometer in the product flow of lean flames.

Analyses of the instantaneous temperature fluctuations measured in the flame-brush of two-dimensional (burner port dimensions - 1 cm x 4 cm) and axisymmetric bluff-body.stabilized (burner port diameter - 4.5 cm), open propane-air premixed flames with an approach velocity in the range 6.92 - 15.3 m/sec and with an approach flow of longitudinal relative intensity of turbulence less than 4.5%, indicate that the flame structure is described appropriately by the 'fluctuating laminar flame' model.

Measurements of longitudinal intensity of turbulence in the products of bluff-body stabilized axisymmetric open, enclosed and transitional, propane-air, lean premixed flumes with approach flow Reynolds number in the range 28,700 - 57,400, indicate that 'flame-generated turbulence', even if present, is certainly not of as great a magnitude as to dominantly characterize the turbulence in the product flow.