GROWTH OF VELOCITY FLUCTUATIONS LEADING TO TUR BULENCE IN FREE SHEAR FLOW,
Abstract
A special case of transition from laminar to tur bulent flow is discussed: namely, a laminar free boundary layer, as it occurs at free jets near the nozzle, passes through the stages of meander ing, vortex formation, and decay of laminar vor tex flow. Hydrodynamic stability theory has been applied to the boundary layers of axisymmetric and two-dimensional jets. For experimental data the hot-wire technique has been applied. In many details experiment and theory are in good agreement, e.g. the frequencies of amplified velocity fluctuations. The characteristic data of vortex flow have been experimentally investi gated using a Karman vortex street as model flow. The existence of a critical vortex number could be verified for one special case. The influence of the jet velocity profile at the origin of the jet on the axial and radial distribution of the mean velocity and the turbulent fluctuations has been studied experimentally. An experimental ar rangement for producing free Couette flow is described and a first experimental analysis of the highly instable Couette jet is given. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 30, 1963
- Accession Number
- AD0418294
Entities
People
- Rudolf Wille
Organizations
- Technische Universität Berlin