Blowin’ in the Wind: Wind Dispersal Ability of Phytopathogenic Fusarium in a Wind Tunnel Experiment

Dispersal processes play an essential role in cereal diseases caused by phytopathogenic Fusarium. However, most empirical studies of Fusarium spore dispersal have focused on vertical transport by rain splash, while wind dispersal has been mostly neglected. Our objective was to determine the ability of Fusarium conidiospores to disperse via wind under controlled conditions in a wind tunnel study. Ten Fusarium species with diverse spore varieties were studied by placing them in the wind stream at wind velocities of 5 and 8 m s−1 and collecting them after 6 m and a period of 1 h using a newly developed air sampling box. Although spore concentrations were high in the releasing Petri Dishes, the tested isolates were recaptured in only 18 of 78 runs. F. equiseti and F. cerealis were the most frequently recovered species. Changing abiotic conditions, wind speed, and spore shapes had no significant effect on Fusarium spore recapture rates. Another experiment showed that conidiospores were rarely released from the grown mycelium. Therefore, the importance of wind alone as a dispersal medium for Fusarium conidiospores may have been overestimated so far. Further studies should investigate the importance of carrier media or mobile linkers combined with the wind dispersal of spores.

A Wind Tunnel Study on the Aerodynamic Characteristics of Ice-Accreted Twin Bundled Conductors

Galloping of twin bundled overhead conductors accreted by ice is a frequent phenomenon during freezing weather, which may damage the operation of transmission lines. To analyze the galloping behavior of iced conductors, their aerodynamic characteristics must be studied. In this study, models with two different outlines were designed and tested to determine a more suitable ice-accreted conductor testing model. Subsequently, the influences of the conductor type, ice thickness, wind turbulence intensity, and wake effect of the windward conductor on the aerodynamic coefficients of the conductors with crescent-shape ice are investigated. The results show that the strand outline of overhead conductors must be considered to improve the accuracy of aerodynamic tests. With increasing ice thickness, the aerodynamic stability becomes rapidly deteriorated. Under the wind turbulence intensity of 4%, the aerodynamic stability gets the most enhancement. Moreover, different conductor types have little impact on the aerodynamic coefficients. The wake caused by the windward conductor is the leading cause for the twin bundled iced conductors to have weaker aerodynamic stability than a single conductor. The aerodynamic coefficients determined in this study are essential for predicting the galloping amplitudes of ice-accreted twin bundled overhead conductors under different weather conditions.

Comparative Study of Ram Air Turbines based on Wind Tunnel Study for Specific Air Borne Energy Extraction

Ram Air Turbines (RAT) are used for emergency on-board power generation on aircraft and associated systems. Many studies on usage of RATs have shown promising results in terms of using RATs as a source of emergency on-board power generation. Many external podded systems on aircraft utilise RATs for self-sufficient adaptation. These pods generate their own power using RATs for their power requirements instead of depending on the mother aircraft power. Commercial cargo planes use RATs for generating emergency hydraulic power. A RAT was suggested to be used for emergency power, during failure of main alternator on a prototype aircraft. A specific requirement of the RAT was also to produce high drag for aerodynamic braking when deployed and concurrently generate electrical energy. Three models with different solidity were studied in wind tunnel at different wind speeds for suitability of this drag-energy combination. This paper presents the results of the study. Based on the results, a suitable RAT was selected for further analysis and ground trials.