ON THE IMPROVEMENT OF THE TILTING BOTTOM CURRENT METER

The article describes the advanced design of Tilt Current Meter (TCM), developed in the Shirshov Institute of Oceanology. This type of meters is used in recent years mainly in Western countries due to low cost, ease of manufacture and the possibility of replication. In most designs the device is a physical pendulum in the form of a long floating cylinder attached to a stationary platform and deviating from the vertical in the action of hydrodynamic force. The tilt is recalculated to the flow rate by the accelerometer signals. The main drawback of the existing samples is the presence of contaminating signals in measurements due to transverse auto – oscillations of the cylinder in a stable flow in the formation of vortices wake. In the advanced design the watertight container with the electronics block and the additional element of buoyancy are placed in an external rigid shroud. The shroud is made of cylindrical plastic pipe with a wall perforation area of 55%, this measure effectively prevents the appearance of transverse oscillations in a wide range of Reynolds numbers. For the developed design the simple calculation ratios allowing to carry out estimation of a measuring range and sensitivity of the meter on the basis of its geometrical and mass parameters are given. The improved design of the ISTT is primarily intended for the measurement of weak bottom currents, although it is possible to regulate the sensitivity for measurements in the surf zone. The range of measured bottom current velocities is 3–56 cm/s with a maximum relative error of 25% for small velocities and 3–5% for maximum velocities.