Three-dimensional implicit lambda methods

This paper derives the three dimensional lambda-formulation equations for a general orthogonal curvilinear coordinate system and provides various block-explicit and block-implicit methods for solving them, numerically. Three model problems, characterized by subsonic, supersonic and transonic flow conditions, are used to assess the reliability and compare the efficiency of the proposed methods

Rotorcraft aviation icing research requirements: Research review and recommendations

The status of rotorcraft icing evaluation techniques and ice protection technology was assessed. Recommendations are made for near and long term icing programs that describe the needs of industry. These recommended programs are based on a consensus of the major U.S. helicopter companies. Specific activities currently planned or underway by NASA, FAA and DOD are reviewed to determine relevance to the overall research requirements. New programs, taking advantage of current activities, are recommended to meet the long term needs for rotorcraft icing certification

Applications of a high resolution shock-capturing scheme to the unsteady flow computation in engine ducts

2nonenoneGiannattasio P; Dadone AGiannattasio, Pietro; Dadone, A

Quasi-Conservative Lambda Formulation

The numerical simulation of inviscid transonic flows by means of a "modified lambda formulation" takes into account the shock transition from supersonic to subsonic flow conditions, thus allowing the coupling of the supersonic region with the shocked subsonic one and, as a consequence, the upstream movement of the shock. The present methodology is applied to one- and two-dimensional transonic flows. Although the two-dimensional flow calculations involve Cartesian coordinates and are limited to the thin-airfoil approximation, the method can be generalized to arbitrary two- and three-dimensional flow cases. In all of the computed cases, the shock is found to have appropriate strength and position for steady flow conditions and to move upstream properly when a change in the downstream pressure warrants it