Cavitation Research Projects

Viscous flow about under water bodies

The motivation for this project relates to the hydrodynamic design of remotely operated underwater vehicles (ROVs) currently used for mine disposal and being investigated for force multiplication with submarines. They are typically low aspect bluff bodies operated at a range of Reynolds numbers and incidences for which a range of flow regimes are possible. These include attached and separated flows ranging from sub to super-critical at low and high incidence. The objectives of this project are experimental investigation of the flows described as well as the gathering of experimental data sets for comparison with computational fluid dynamics (CFD). Two physical models, an ellipsoid and a spheroid, have been developed for sting mounting in the cavitation tunnel and include instrumentation for measurement of surface flow properties. The models have also been developed for sting mounting on a 6 component force balance or for force measurement with an internal 6 component force balance. Studies of off body flow phenomena are being carried out using a range of physical probes and an automated 3 component traverse system. This project is supported by the Australian Maritime College, the Maritime Platforms Division of the Defence Science and Technology Organisation and the University of Tasmania.

Project supervisors: Dr Paul Brandner (AMC) and Dr Greg Walker (UTas)

DSTO researcher/PhD Student: Mr David Clarke (MPD - DSTO)

Investigation of Spheroid Boundary Layer Transition Using Sting Mount and 3D Automatic Traverse and 1D Fast Response Probe


Flow Visualisation of Separation on a Spheroid

Ventilated super-cavitating ride control foils

Test of a Super-cavitating Ventilated Hydrofoil

This project involves research and development contributing to the realisation of a patented system for, among other applications, ride control foils for high speed craft. The patented system developed by Elms Australia, as applied to ride control, consists of a flapped symmetric hydrofoil arrangement that can be used for generation of bi-directional lift. The flap is configured to produce a forward facing step or interceptor upon upward or downward deflection. This combined with ventilation produces a simple means to generate lift in an upward or downward direction suitable for high speed operation. The problem of ride control for high speed craft involves the use of lift producing devices at low cavitation numbers and there are several advantages if these can be made to operate in the supercavitating flow regime including flow stability and improved efficiency. A range of basic experimental and numerical investigations are being made to study viscous effects with natural and ventilated cavities associated with interceptors. The results of these are being used in the design of suitable foil sections to be tested in the cavitation tunnel. Foil tests include both static and dynamic test using an oscillating 6 component force balance. It is also envisaged that as part of the project results from foil investigations will be developed in other applications such as high speed propulsors. This project is supported by the Australian Maritime College and Elms Australia.

Project supervisors: Dr Paul Brandner (AMC) and Mr Tony Elms (Elms Australia)

PhD Student: Mr Bryce Pearce (AMC)

2D Boundary Element Solution for Super-cavitating Flow Behind a Hydrofoil With Trailing Edge Fence or Inteceptor

Performance of surfboard fins

Testing of a Surfboard Fin

The development of surfboards, and fins for their control, has to date been purely based on surfer and manufacturer experience or current trends. With ever increasing competitiveness in professional and amateur surfing Surf Hardware International, (SHI), an international manufacturer of surfboard accessories including fins, decided upon a research and development program for their range of surfboard fins. The project is headed by Americas Cup yacht designer, Mr Andrew Dovell of Murray, Burns and Dovell with research and testing expertise being contributed by cavitation tunnel staff. The existing range of ISH fins have been tested in the cavitation tunnel using a 6 component force balance as well as flow visualisation studies for investigation of viscous and cavitation aspects. Tests are also being carried out on a range of new fin designs utilising modern foil sections and current knowledge on planforms to develop a series of fins optimised for various Reynolds numbers and incidences. This project is funded by International Surf Hardware and by the AusIndustry R&D Start Program.

Flow investigation about submarine counter measures

Counter measures are a critical aspect of submarine defence and to better understand their behaviour hydrodynamic manoeuvring models are being developed for trajectory prediction after ejection. The hydrodynamic forces acting on the counter measure required for the mathematical modeling are being investigated in the cavitation tunnel. A range of models with differing scales, configurations and incidence are being tested using a 6 component force balance in both cavitating and non-cavitating conditions. This project is supported by the Australian Maritime College, the Maritime Platforms Division of the Defence Science and Technology Organisation and the University of Tasmania.

Researchers: Dr Paul Brandner (AMC), Mr David Clarke (MPD - DSTO), Mr Brendon Anderson (MPD - DSTO) and Dr Greg Walker (UTas).

Flow friction due to bio-fouling

AMC researchers are working in collaboration as part of a larger UTAS project involving the biological and hydrodynamic investigation of bio-fouling in hydroelectric power schemes. The presence of biological growth increases the cost of maintenance and reduces operating efficiency of hydroelectric infrastructure. UTas researchers are investigating the biological, topographical and hydrodynamic aspects of the fouling. Cavitation tunnel researchers are involved with the development of instrumentation and investigation of skin friction associated with the bio-fouling. The drag of plates with equivalent roughness and the actual bio-fouling are being measured in UTas and AMC facilities as well as investigation of boundary layers associated with the fouling. A new 1 dimensional balance is being developed for use in the AMC towing tank and cavitation tunnel as well as instrumentation for a new flume at UTas which will contain the organisms cultured from field samples. This project is funded by a UTas Australian Research Council Linkage Grant.

Unsteady and hydro-elastic performance of propellers

Propeller Cavitation

Propeller performance in high speed and naval applications is an area of ongoing investigation. Within this project new experimental and numerical methods for the study of a range of performance aspects are being developed. A new `silent' propeller dynamometer is being designed for acoustic measurements associated with submarine propulsion studies. New methods for simulation of wakes using vortex generators and injection of waterjets are being investigated. To better investigate simulated wakes for propulsion studies a 3D fast response probe and 3D automatic traverse have been recently completed. Using this system the intention is to not only investigate the effects of the mean velocity distribution but also the turbulence distribution on cavitation inception and unsteady non-cavitating and cavitating propeller performance. Experimental investigations also contribute to the development of Reynolds Averaged Navier Stokes Solvers for propeller performance prediction. This project is supported by the Australian Maritime College, the Maritime Platforms Division of the Defence Science and Technology Organisation and the University of Tasmania

Flow investigation about submarine control surfaces and other appendages

The performance of a submarine depends fundamentally on flow quality about the hull, appendages and control surfaces and a range of basic studies are being made to investigate means of improvement. These include experimental and numerical investigations of turbulent flow, boundary layer instabilities, skin friction, corner flows and fluid structure interactions. This project is supported by the Australian Maritime College, the Maritime Platforms Division of the Defence Science and Technology Organisation, the University of Tasmania and the Defence Materiel Organisation.

Waterjet propulsor performance

Waterjet Inlet Lip Cavitation

Waterjets have become the standard propulsion system for large high speed craft and whilst these have shown to be successful there remains considerable scope for design improvement through greater understanding of waterjet flows and optimisation. Flow problems, with flush type inlet ducts, relate to ingestion of the hull boundary layer and the complex viscous flow within the inlet streamtube and duct. These problems are manifested in the occurrence of cavitation, flow separation, unsteady flow, flow non-uniformity at the pump face and possible vibration. Investigations to date have focused on the inlet flow since flow problems associated with the pump relate largely to those created by the inlet. A range of instrumentation and experimental equipment has been developed for inlet duct flow investigation as well as for data set collection for comparison with computational predictions. These include methods for simulation of the hull boundary layer upstream of the inlet, probes for flow field surveys within the duct and at the notional pump face and techniques for flow visualisation including cavitation. The use of flow manipulation devices within the duct for elimination of separation and improvement of pump face uniformity have also been successfully investigated experimentally and using computational models. Computational models for prediction of tunnel blockage, optimisation and to aid in diagnosing flow problems are being developed in parallel with the experimental program. This project follows on from earlier extensive wind tunnel investigation of waterjet inlet duct flows by UTas. This project is supported by the Australian Maritime College and the University of Tasmania/Tasmanian Partnership for advanced Computing.

Researchers: Dr Paul Brandner (AMC), Dr Greg Walker and Dr Jason Roberts (UTas/TPAC).

Schematic of a Waterjet Propulsor


Flow Issues Associated with Waterjet Propulsors