Wind Tunnel Experiments with Anti-Icing Fluids

An experimental methodology for investigating the effects of anti-icing fluids is presented in this paper. A wing model was designed, fabricated, and instrumented for testing anti-icing fluids in a wind tunnel facility. In addition, a video capturing method was developed and used to document fluid behavior during simulated takeoff tests. The experiments were performed at the Wichita State University 2.13-m by 3.05-m (7-ft by 10-ft) wind tunnel facility with two pseudoplastic fluids representative of Type IV anti-icing fluids. The experimental data obtained included fluid wave propagation speeds, chordwise fluid thickness distributions as a function of time, and boundary layer velocity profiles for the clean and fluid contaminated wing model at select chordwise stations. During simulated takeoffs with initial fluid depths of either 4 mm or 2 mm, the fluids were observed to thin in the forward (upstream) regions of the wing model and accumulate in the aft regions. In some cases, as much as 5.0 mm of fluid had accumulated near the wing's trailing edge region by the start of rotation. For all of the test configurations investigated, fluid thickness forward of the 0.65c chord station was 0.5 mm or less during wing rotation. Increasing tunnel airspeed from 35 m/s to 65 m/s caused the thickness of the residual fluid layer to decrease to 0.5 mm or less over the entire wing model. Boundary layer thickness over the fluid layer was found to be greater than that of the clean wing model. Between the two fluids tested, the higher viscosity fluid produced thicker boundary layers over the wing's upper surface.