Search Results

Numerically predicted roughness distributions obtained in in-flight icing simulations with a beading model are used in a quasi-steady manner to compute ice shapes. This approach, called "Multishot," uses a number of steady flow and droplet solutions for computing short intervals (shots) of the total ice accretion time. The iced geometry, the grid, and the surface roughness distribution are updated after each shot, producing a better match with the unsteady ice accretion phenomena. Comparisons to multishot results with uniform roughness show that the evolution of the surface roughness distribution has a strong influence on the final ice shape. The ice horns that form are longer and thinner compared to constant roughness results. The constant roughness approach usually fails to capture the formation of the pressure side horns and under-predicts the thickness of the ice in this region.

The high computational cost of 3-D viscous turbulent aero-icing simulations is one of the main limitations to address in order to more extensively use computational fluid dynamics to explore the wide variety of icing conditions to be tested before achieving aircraft airworthiness. In an attempt to overcome the computational burden of these simulations, a Reduced Order Modeling (ROM) approach, based on Proper Orthogonal Decomposition (POD) and Kriging interpolation techniques, is applied to the computation of the impingement pattern of supercooled large droplets (SLD) on aircraft. Relying on a suitable database of high fidelity full-order simulations, the ROM approach provides a lower-order approximation of the system in terms of a linear combination of appropriate functions. The accuracy of the resulting surrogate solution is successfully compared to experimental and CFD results for sample 2-D problems and then extended to a typical 3-D case.

CFD-Icing (CFD-I) is a powerful companion to CFD-Aero (CFD-A) in the design and certification of new aircraft, rotorcraft and jet engines. It can drastically reduce the number of tunnel and flight tests, and their associated costs, by simulating on computers the full Appendix C and beyond such as is proposed in new Appendices D and O. It can also predict performance and moment coefficients in roll, pitch and yaw. These predictions can then be used in original certification or supplemental certifications to the type design, allowing mitigating potential hazards of flight-testing. This work presents an example of the application of FENSAP-ICE to predict 45 minutes of ice accretion on a RC-26B aircraft fuselage retrofitted by the addition of a FLIR sensor and a SATCOM antenna. The predicted aerodynamic penalties are compared with recorded flight test data obtained with simulated ice shapes.

A fully CFD-based methodology for ice particle tracking based on a Monte Carlo statistical approach and a six-degrees-of-freedom particle-tracking module has been developed within the FENSAP-ICE in-flight icing system. A one-way aerodynamic coupling between the airflow and the ice particle has been adopted, such that the flowfield determines the forces and moments on the particle at each location on its track, but the particle, being much smaller, has no aerodynamic effect on the aircraft's flowfield. A complete envelope of force and moment coefficients has been computed for a representative ice shape, in order to generate a permanent database. At each time step during the integration of the particle track, the angles of the local flow velocity vector with the principal axes of the particle are determined and used to interpolate the corresponding force and moment coefficients from the particle's database. These 6-DOFs are then used to compute the next particle location.

The assessment of an unsteady approach for the simulation of in-flight electro-thermal de-icing using a Conjugate Heat Transfer (CHT) technique is presented for a NACA0012 wing and a swept wing. This approach is implemented in the FENSAP-ICE in-flight icing system, and provides simulation capabilities for the heat transfer and ice accretion phenomena occurring during in-flight de-icing with power cycling through several heater pads. At each time step, a thermodynamic balance is established between the water film, the ice layer and the solid domains. The ice shape is then modified according to ice accretion and melting rates. Numerical results show the complex interactions between the water film, the ice layer and the heating system. The NACA0012 validation test case compares well against one of the very few experimental de-icing test cases available in the open literature.