Aerodynamic characteristics of an aerostat under unsteady wind gust conditions

Abstract

An analysis of the effect of wind gusts on the aerodynamic characteristics of an aerostat is presented in this study. A three dimensional computational fluid dynamics based flow analysis of an aerostat using the realizable k−ϵ model is presented. The performance of the aerostat is analyzed by varying the angle of attack, gust amplitude, gust duration, gust velocity profile and the aerostat shape. Actual wind data is used to formulate the gust parameters used for the study. It is found that the aerostat drag is unaffected by the angle of attack because of the streamlined structure. A trade-off between the drag and lift values suggests the use of a slight positive angle of attack for the stable operation of the aerostat. A gust with a short rising or falling time with small amplitude is severe than the symmetric gust with larger amplitude and a slower rising or falling profile. A scaling methodology for the aerodynamic characteristics of the aerostat for different angles of attack, gust amplitudes, gust duration and aerostat shapes is presented. The scaling obtained for different angles of attack and gust amplitudes is linear, whereas for different gust duration the scaling is not linear.