Abstract: To increase in the accuracy of vortex flow sensors measuring the flow velocity and/or the volumetric flow rate of a fluid flowing through a measuring tube, the vortex flow sensor comprises a cylindrical bluff body of circular section mounted in the measuring tube. The bluff body has a surface which is roughened. A single vortex-sensing element is responsive to pressure fluctuations caused by the vortices. The roughness can be realized by shallow depressions being identical in shape and either evenly or unevenly, particularly stochastically, distributed over the surface of the bluff body. The depressions can be only provided in a sector of the surface whose central angle is less than 180.degree..

Abstract: This device (1) produces a steep-fronted liquid pressure wave which strikes a body (12) to be tested with an adjustable table pressure. The device has a measuring tube (10) within or to which the body (12) is fixed, and which has a pressure-proof observation window (13, 14) and a pressure-relief valve (15). A pressure tube (20) with a compression system (25) which compresses a gas is closed on one side by a first diaphragm (29) which forms part of a chamber (27) that is provided with a valve (25). The chamber is closed by a second diaphragm (19) located opposite the diaphragm (29). In tube (10), a piston (18) is movable on guides (17) up to a braking device. To carry out the method, an amount of liquid which only partially fills the tube (10) is applied to the pistons In the chamber (27), a pressure equal to half the bursting strength of the diaphragms (29, 19) is set. The pressure in the tube (20) is increased until the bursting strength is exceeded.