The unmanned underwater vehicle: An alternative for the SSK or a valuable addition?

The future of manned submarines is currently in question as a result of rapid developments in autonomy in other fields (e.g. autonomous cars). Therefore, the feasibility of an unmanned submarine, basically a large unmanned underwater vehicle (UUV), as a replacement for a conventional diesel-electric submarine (SSK), was investigated....

High amplitude vortex-induced pulsations in a gas transport system

High Reynolds number, low Mach number gas flows in pipe systems with closed side branches exhibit spectacular low frequency self-sustained pulsations driven by periodic vortex shedding at specific values of the Strouhal number. A detailed study is presented of the behaviour of the flow in a system with two opposite closed side branches of equal...

Stromingsgeïnduceerde resonantie in een holte afgedekt door een rooster / Flow excited resonance in a cavity covered by a grid: Theory and experiments

Sound generation by flow past a cavity covered by a grid with louvers with rectangular cross section at 45’ to the flow direction is analyzed. Simple models for the aero-acoustic source are presented for two cases: 1) grazing flow past the grid, and 2) grazing flow past the grid in combination with flow through the grid into the cavity. The...

A note on "sound radiation by baffled plates and related boundary integral equations"

In a 1985 paper the second author presented a solution for the radiation problem of a fluid-loaded, baffled plate driven by a time harmonic force. By using the Green's kernel for the infinite fluid-loaded plate equation (written in a form suitable for efficient and accurate computations a coupled system of two integral equations along the...

Flow induced pulsations in gas transport systems: Analysis of the influence of closed side branches

A theoretical analysis is presented of the low frequency aero-acoustic behavior of closed side branches along a gas transport pipe. The theory predicts the hydrodynamic conditions for moderate and strong pulsations. A model is proposed which predicts the order of magnitude of the power generated by the aero-acoustic source. The theoretical...

The 'whistler nozzle' and horn as aero-acoustic sound sources in pipe systems

The propagation of low-frequency sound in a two-dimensional duct system with T joints and right angle bends: Theory and experiment

The method of matched asymptotic expansion is used to determine a low-frequency approximation of the acoustic pressure in a waveguide system with a T joint. The low-frequency approximation is compared with (a) experimental data of Lippert [Acustica 4, 313-319 (1954)]; (b) new experimental data; and (c) the first approximation of the mode...