Nonlinear Nonlocal Transition Analysis

Abstract

The nonlinear nonlocal transition analysis code NOLOT/PSE is described in detail and its potential is exemplified. The effects of nose bluntness on first- and second-mode boundary—layer instability are discussed for the axisymmetric hypersonic flow of circular blunt cones. Furthermore, the existence of amplified entropy--layer instabilities found in experiment is numerically confirmed for the first time. Various nonlinear transition scenarios in transonic swept wing flows are analysed for the ATTAS and Fokker 100 flight experiments. Dominant nonlinear interaction scenarios are presented and the existence of threshold amplitudes for the onset of rapid nonlinear disturbance growth is pointed out. The late stages of crossflow—dominated transition are analysed further for the DLR swept flat plate experiment using high modal resolution. Thus, the formation of high--frequency secondary disturbances and their subsequent nonlinear development up to the disintegration of the secondary disturbance structures are successfully modelled by nonlinear nonlocal theory (PSE) for the first time.