The steady and vibrating statuses of tulip tree leaves in wind

- 73 tulip leaves were tested in suspended condition and with front as well as back surface of the lamina facing wind.
- Three types of vibrating statuses, two types of steady statuses, and five critical wind speeds were observed in the range of wind speed 0-27 m/s.
- The probabilities of existence of the statuses and criticals, the probability density distributions in the test range of wind speed, and the expected values of the criticals were shown.

The study of tree leaf aerodynamics is useful to tree protection, solar panel design and development of new power generation technology. 73 tulip leaves were tested in suspended condition and with front as well as back surface of the lamina facing wind. Three types of vibrating statuses, two types of steady statuses, and five critical wind speeds were observed. The existence probabilities of the statuses and criticals, the probability density distribution of every critical over the range of wind speed 0-27 m/s, and the expected values of the criticals were obtained by statistics. The critical Reynolds number, defined by critical wind speed and lamina length, shows an increasing trend with increasing the lamina area or length to width ratio of the lamina, but it shows no trend of increase or decrease with increasing the length ratio of petiole to lamina.