Laser Interferometric Studies of the Control of Heat Transfer from Flame Gases by Electric Fields

The effects of dc electric fields on heat transfer between flame gases and solid bodies are studied under three conditions: (1) Sub-breakdown fields are used to displace hot combustion gases relative to calorimetric probes. The case of maintaining a solid body cool by deflecting flame gases away from it is shown to be the most promising practical application. (2) Additional ions generated by corona discharges are used to induct cold air flow from outside the flame. This is relevant, for example, to improving the cooling of perforated walls of combustion chambers. (3) Corona discharges are generated within the boundary layers of tubular calorimetric probes. The results are relevant to modifying heat transfer between pipes and un-ionized gases. In each case, the analysis is based on calorimetric measurements and on data produced by a large area, double-exposure, laser interferometer that was designed for this purpose on the plan of a schlieren system. Theoretical correlations developed to account for heat transfer under the influence of fields and corona discharges show good agreement with the experimental results