Experimental Study on the Effects of Cavitator Geometries on Supercavitation

ABSTRACT

Supercavitation is an interesting phenomenon known for its drag reducing benefits of objects travelling in liquids by reducing the skin friction drag. This makes it attractive in a variety of applications as it allows for high speeds to be achieved by objects travelling underwater. The cavitator, which is the object used to facilitate the formation of supercavitation, affects the formation and characteristics of the cavity bubble as well as the drag force experienced by the body. Despite its proclaimed drag reducing effects, the conditions and requirements needed for supercavitation to occur means that achieving it can be difficult, let alone sustaining it. As such, is there a certain cavitator geometry that’s best for supercavitation and drag reduction? Preliminary findings from an experimental study on 3 different cavitator shapes, namely the cone, disk, and streamline(ogive), and their effects of on supercavitation will be shared.

Mr. Zhuang Tao obtained his BEng (Hons) degree in Mechanical Engineering from NUS in 2023. Thereafter he joined Temasek Laboratories @ NUS as an associate scientist.

Numerical Validation and Sensitivity Tests of a Model Aircraft in Free Fall

ABSTRACT

The trajectory of a model aircraft in a free fall experiment is validated using a custom OpenFOAM subroutine 6DOF solver. Sensitivity tests involving small changes in the center of gravity position, elevator angle and moment of inertia difference are also performed numerically to assess the effects of these aerodynamic properties on the trajectory of the aircraft. Results show that the custom OpenFOAM subroutine 6DOF solver can reasonably predict the aircraft’s trajectory using the kOmegaSSTLM transitional turbulence model. On the other hand, both the laminar and kOmegaSST turbulence models are not able to predict the trajectory correctly. Moreover, sensitivity tests also show that minor aerodynamic properties changes can have far reaching effect on the aircraft’s trajectory. Hence, it is more reasonable to provide a range of possible trajectories when performing similar 6DOF simulations. These results, together with the detailed pressure and flow fields, will be useful in mission planning and control.

Dr. Tay Wee Beng obtained his Bachelor of Engineering, Master of Engineering and PhD from the National University of Singapore in 2001, 2004 and 2009 respectively. Subsequently, he went to the Taiwan’s National Taiwan University and the Netherlands’s Delft University of Technology to do his postdoctorate. He joined Temasek Laboratories in November 2013. His research interest includes flapping wing aerodynamics, immersed boundary method, machine learning and unsteady micro aerial vehicles manoeuvres.