Effect of geometry on the downstream flow topology of a micro ramp in a supersonic turbulent boundary layer: An experimental study

The physical relation between the geometry and the flow topology of the wake of a micro ramp is investigated by means of a parametric study. Various micro ramp geometries are placed in a supersonic turbulent boundary layer at a free-stream Mach number of 2. The flow field is measured with schlieren and Particle Image Velocimetry (PIV). The...

Coherent vortex structures over a rotating spinner under non-axial inflows at low Reynolds number

Boundary layer instabilities and the formation of coherent spiral vortices over a rotating cone and ellipsoid are studied experimentally. It is found that under a non-axial inflow, the breaking of symmetry in the flow field significantly disturbs the coherence and delays the formation of spiral vortices to higher local Reynolds numbers (Re_l)...

An experimental method to investigate coherent spiral vortices in the boundary layer over rotating bodies of revolution

Abstract: Infrared thermography is applied to measure the spiral vortices in the boundary layer over a rotating cone under axial inflow. The data sets are analysed using proper orthogonal decomposition (POD). A criterion based on the signal-to-noise ratio is defined for the selection of relevant POD modes, such that a low-order reconstruction...

Relation Between Geometry and Wake Characteristics of a Supersonic Microramp

Microramp vortex generators are robust, reliable, and simple devices for passively controlling the boundary layer in several aerospace applications. Various past studies have investigated the effectiveness of microramps in controlling the flow separation induced by shock-wave/boundary-layer interactions. Building upon the past knowledge, this...

Boundary layer instability over a rotating slender cone under non-axial inflow

Centrifugal instability of the boundary layer is known to induce spiral vortices over a rotating slender cone that is facing an axial inflow. This paper shows how a deviation from the symmetry of such axial inflow affects the boundary layer instability over a rotating slender cone with half-angle. The spiral vortices are experimentally...

Spiral instability-modes on rotating cones in high-Reynolds number axial flow

This work shows the behaviour of an unstable boundary-layer on rotating cones in high-speed flow conditions: high Reynolds number Rel > 106, low rotational speed ratio S < 1–1.5, and inflow Mach number M = 0.5. These conditions are most-commonly encountered on rotating aero-engine-nose-cones of transonic cruise aircraft. Although it has...

Boundary-layer instability on rotating cones: An experiment-based exploration

Boundary-layer instability induces spiral vortices on rotating cones. As they grow along the cone, the vortices enhance mixing of high- and low-momentum fluid, and subsequently, cause the boundary-layer to transition into a turbulent state. This transition process is scientifically enticing as it is one of the classical problems in fluid...

Instability of Rotating-Cone Boundary Layer in Axial Inflow: Effect of Cone Angle

Boundary-layer instability on a rotating cone induces coherent spiral vortices that are linked to the onset of laminar–turbulent transition. This type of transition is relevant to several aerospace systems with rotating components, e.g., aeroengine nose cones. Because a variety of options exist for the nose-cone shapes, it is important to...