Uncertainty Analysis in Experimental Investigation of Drag Reduction by Heating the Surface under a Turbulent Boundary Layer

A new technique to reduce the drag of either a new or existing aircraft configuration is investigated. Heating the surface under a turbulent boundary layer reduces the turbulent skin friction. Friction drag reduction in axisymmetric bodies is investigated experimentally، applying heat to the surface in the turbulent boundary layer. For wind tunnel test، an axisymmetric model، like an airplane body، with a length of 0. 5 m and taper ratio of 10 is manufactured for which، quarter length of its tip and end has elliptical form and the rest is flat. By wind tunnel testing، and heating various segments of a model to some specified temperatures; it will be possible to define an optimized area for drag reduction due to some specific heat supply. Therefore optimization of the heating area is performed by dividing the flat section of the model to five equal segments. The effects of temperature variation in the three first segments and changing the number of heated segments are investigated. for analyse the experimental results uncertainty analysis is performed. Experimental results show that heating 11% of the body surface in first segment to at Reynolds number of 0. 84E+6 and 1. 01E+6، causes 24 and 13 percent reduction in drag force، respectively.