Abstract The future generation of wind turbines will be characterised by longer and more flexible blades. These large are facing higher Reynolds numbers, as a consequence chord lengths increased relative speeds. Higher tip speeds, however, also result in an Mach number. Although the maximum speed steady design conditions may remain (well) below critical value, presence turbulence, gusts, blade ...

An attempt is made to describe and review the most widely used methods for flow visualization. The first part described the basis and applications of different visualization methods for subsonic and supersonic flow in wind and water tunnels. This part concentrates on optical methods (shadow, schlieren and interferometry) and their application in compressibe flow visualization. Almost all presen...

By way of axisymmetric numerical hydrodynamical simulations we study the interaction of a fast tenuous stellar wind with a thick toroidal distribution of high-density clouds embedded in a stationary intercloud medium with a power-law density fall-off of index −1.9. We find that the supersonic wind percolates through the cloud ensemble, producing finger-like structures in the contact discontinui...

Supersonic retropropulsion provides an option that can potentially enhance drag characteristics of high mass entry, descent, and landing systems. Preliminary flow field and vehicle aerodynamic characteristics have been found in wind tunnel experiments; however, these only cover specific vehicle configurations and freestream conditions. In order to generate useful aerodynamic data that can be us...

[1] Scatterometer radar backscatter depends on the relationship linking surface stress and surface roughness. SST can alter the growth rate of centimeter-scale waves through its impact on air and water density and water viscosity. This SST-dependency has not been included in the standard Geophysical Model Functions. This study uses a radar imaging model to evaluate this SST-dependence and compa...

The potential application of aggregates of nanoparticles for high-speed flow diagnostics is investigated. Aluminum nanoparticles around 10 nm in diameter are produced by spark discharge in argon gas. Through rapid coagulation and oxidation, aggregates of small effective density are formed. They are characterized by microscopy and their aerodynamics and optical properties are theoretically evalu...

Supersonic commercial aircraft noise predictions have frequently considered only exhaust noise from the jet engines. Meeting the stringent noise requirements that apply to the subsonic fleet will require reducing jet exhaust noise to the point that fan noise may also require reduction. This report discusses the prediction of fan noise for a supersonic commercial aircraft using existing empirica...

Portions of western NorthAmerica have experienced prolonged drought over the last decade. This drought has occurred at the same time as the global warming hiatus—a decadal period with little increase in global mean surface temperature. Climate models and observational analyses are used to clarify the dual role of recent tropical Pacific changes in driving both the global warming hiatus and Nort...