Galloping criteria for multi-flue coupled chimneys

Wind tunnel model tests of multi-flue chimneys coupled in groups of two, three and four stacks have been carried out in a wind tunnel with an open working section of 1.5 m diameter. All models, in the form of cylindrical bars, placed between end plates, were covered with sand particles to give them artificial roughness. Values of the den Hartog criterion have been determined on the base of the dependence of drag and lift force coefficients on wind direction. An attempt has been made to determine the functional dependence of the den Hartog criterion on the distance between cylinders.