Elongated bubble shape in inclined air-water slug flow

•Representative shapes of elongated bubbles in continuous slug flow were obtained by a wire mesh sensor.•The bubble shapes are determined by applying averaging over large ensembles of recorded bubbles.•The averaging is performed relative to axial locations of the nose and of the tail of every bubble.•A model to determine the shape of the upper film is presented, the experimentally obtained bubble shapes are compared with the model predictions.