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Reed Petal Design Programme
The stiffness of the reed petals in a high performance reed valve induction two-stroke engine has a dramatic effect on the power output. The stiffness not only influences the amount that the reeds open but also the natural frequency of the reeds. Three main factors influence the stiffness.
- Reed Petal Material
- Thickness
- Free Length
The Reed Petal Design Programme calculates the natural reed frequency, reed deflection and tip ratio. These values provide a valuable indicator as to the direction that reed development should proceed for optimal performance.
Here at TorqSoft we have found that the natural frequency of the reeds should be between the values of 0.75 to 1.25 times the fundamental frequency of the engine peak power speed. Hence if an engine gives its peak power at 12000 revs/min its fundamental frequency is 200 hz. Therefore the natural frequency of the reeds should be between 150 hz and 250 hz.
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Example
Suppose you have a two-stroke reed valve induction engine that has reed petals made of glass fibre, a free length of 34 mm and a reed thickness of 0.4 mm. Click on the glass fibre button within the Material box. Now within the Dimensions box, enter 34 for the free length, hit the tab key then enter 0.4 for the reed thickness. Hit the calculate button. The answers are then calculated as 191 hz for the reed natural frequency, 7.97 mm for the reed deflection and 0.23 for the tip ratio.
