Technical note | Phase I Experimental Testing of a Generic Submarine Model in the DSTO Low Speed Wind Tunnel

ABSTRACT

DSTO has conducted Phase I of planned experimental testing of a generic submarine model in its low speed wind tunnel. These wind tunnel tests aimed to gather steady-state aerodynamic force and moment data and to investigate the flow-field characteristics on and around the bare-hull. Further experimental testing is planned, extending the range of model configurations tested to include the addition of hull-casing, fin and control surfaces to the model. These experimental data will complement computational and experimental hydrodynamic analysis of the generic submarine shape.

Executive Summary

Through the DSTO Corporate Enabling Research Programme (CERP) – Future Undersea Warfare, researchers are applying computational and experimental methods to explore the flow-field characteristics on and around a modern generic submarine shape. This comprehensive research study involves the use of high-fidelity computational fluid dynamic (CFD) methods, as well as experimental hydrodynamic and experimental aerodynamic test techniques to investigate a (common) generic shape. A substantial body of data will be gathered, enhancing DSTO knowledge and understanding of these complex flows, and providing researchers with a valuable database compiled from disparate sources. This report documents Phase I testing of the generic submarine in the DSTO low speed wind tunnel.

The Phase I low speed wind tunnel experiments involved the testing of a 1.35 m long aluminium model of the generic submarine in its bare-hull configuration, that is, without the hull-casing, fin, and control surfaces attached. The submarine model was pitched and yawed through a large range of attitudes, to gather gross steady-state aerodynamic force and moment data, and to explore the characteristics of the flow-field using several different flow visualization techniques such as tufting and smoke. The experiments also included the use of a thermal imaging camera to study boundary layer transition.

The report describes the experimental equipment used during the tests, along with the test methodology. A sub-set of the data gathered is also presented and briefly discussed. Overall, the force and moment data were consistent, exhibiting expected and predictable trends. Whilst thermal imaging of boundary layer transition proved problematical, the use of conventional flow visualization techniques were more successful, allowing researchers to visualize the flow-field in regions of interest, including the tail-cone.

Further experimental testing of the model in the DSTO low speed wind tunnel is planned, and will include a detailed study of the boundary layer profile, the use of particle image velocimetry (PIV) to study the off-body flow-field, as well as additional force and moment testing with the hull-casing, fin, and the control surfaces attached.