Experimental Determination Of The Onset Of
Turbulence On Inclined Plates Using Hot Wire
Velocity Measurements
Author(s)
A. A. Rodríguez-Sevillano, I. Pérez-Grande & J. Meseguer
Abstract
The problem of determination of the turbulence onset in natural convection on
heated inclined plates in an air environment has been experimentally revisited.
The transition has been detected by using hot wire velocity measurements. The
onset of turbulence has been considered to take place where velocity fluctuations
(measured through turbulence intensity) start to grow. Experiments have shown
that the distance to the plate edge where the onset begins depends both on the
plate inclination angle and the plate temperature, and thus on the Grashof
number defined in terms of the temperature difference between the heated plate
and the surrounding air. An experimental setup to measure the above mentioned
distance has been developed. In this paper, such an apparatus is presented, as
well as the experimental procedure and some experimental results.
Keywords: mirror seeing, turbulence onset, natural convection.
1 Introduction
One of the problems arising on Earth-based solar telescopes is concerned with
image degradation due to the boundary layer, which is formed close to the Sunheated
mirror surfaces. Since these surfaces are warmer than the surrounding air,
when the surface is inclined the fluid flows over the surface due to convection,
and thus a thermal boundary layer is formed. At initial stages the boundary layer
flow regime is laminar, but after some distance turbulent eddies are formed and
Keywords
mirror seeing, turbulence onset, natural convection
Related Book
Other papers in this volume
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