Influence on Stern Flaps in Resistance Performance of a Caterpillar Track Amphibious Vehicle

In order to reduce the resistance and increasing speed for a caterpillar track amphibious vehicle (CTAV), the stern flaps were applied and the influence was researched. Numerical simulations performed by STAR-CCM+ and model towing test reveal that stern flaps have greatly reduced the resistance, trim, and sinkage of the CTAV when the length Froude number is between 0.63 and 1.05. The length and flap angle were optimized by numerical simulation. In addition, the residual resistance plays a dominant role in resistance reduction, which contributes to more than 90% of the total resistance reduction. Installing stern flaps increase the vehicle waterline by 7% and enhance the virtual-length effect. Furthermore, the running attitude becomes steadier, thereby decreasing the trim and sinkage. Therefore the resistance performance of the CTAV can be enhanced by installing stern flaps with a proper length at an optimal flap angle.