Revised for errors.
The tops of solar towers, also known as solar chimneys, should be
ringed with vertical layers of inverted airfoils. In windy
conditions, nearly always present at high altitudes in many
locations, these inverted airfoils about the periphery, with trailing
edges to the inside, have the effect of reducing air pressure at the
top of the chimney. They direct horizontal airflow upwards, thus
reducing air pressure in the chimney. This enhances the Bernoulli
effect already present for such chimneys. This pressure drop
increases airflow and thus turbine output at the base of the
chimney. Use of variable pitch airfoils permits controlled
feathering and continual operation in high winds. The airfoils
increase load on the structure and cost of the structure, but airfoil
pitch control may be of use in preventing resonant vibration buildup
in high wind conditions. The use of such airfoils increases the
optimal chimney aspect ratio to less than that which is optimal
without the airfoils. A typical (height to diameter) aspect ratio
for solar towers is currently 6.
Horace Heffner
- re: Solar chimney design enhancement Horace Heffner
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