Separated and vortical flow in aircraft aerodynamics: a CFD perspective

Abstract In the early era of aviation, Frederick Lanchester was both an inventor and a theoretician driven by need for theory flight that would reduce guesswork in designing new aircraft. His book Aerodynamics 1907 laid down foundations such theory. The with contributions from others, notably Ludwig Prandtl, refined to become basis sleek designs WWII aircraft brought about little guesswork. New technology changed design radically increased speed jet propulsion reaching into transonic range nonlinear aerodynamics. late 1940s 1950s substantial returned design. legacy et al., however, lived on development computational fluid dynamics (CFD) could guide designers through effects. This article presents historical sketch how CFD developed, illustrated examples explaining some difficulties overcome first-generation swept-wing fighters. study is forensic search likely explanation designer’s choice wing shape went production long time ago. capability current applied aerodynamics slender wings surveyed. cases discussed involve flow patterns coherent vortices over hybrid moderate sweep. Vortex-flow pertains understanding interaction concentrated components. Modern Reynolds-Averaged Navier-Stokes (RANS) useful predict attached flow. But vortex other breakdown lead unsteady, largely separated which has been found out scope RANS. Direct simulation equations reach foreseeable future, better physical modeling evident. Both cruise performance stalling characteristics are influenced strong interactions. Two important aspects wing-flow physics discussed: separation smooth surface creates vortex, bursting, abrupt subsequent loss lift. Vortex not-so-slender encounter particularly challenging problems, it shown early-generation operational surmounted these difficulties. Through use CFD, concludes two case studies aerodynamic design: Saab J29A maintains control authority near stall, J32 mitigates pitch-up instability at high incidence.