Method for determining a mass flow of a fluid flowing in a pipe

A method for determining a mass flow rate of a fluid flowing in a pipe, comprising the steps of:

• producing vortices, especially Karman vortices, in the flowing fluid by means of a bluff body around which the fluid flows, the bluff body having at least two separation edges, and determining a repetition frequency with which the vortices are produced;
• producing, on the basis of the determined repetition frequency, a flow rate measurement value, which represents a volume flow rate or a flow velocity;
• local registering of a first pressure, p1, acting in the flowing fluid at a first measurement point, which is located, with reference to the flow direction, by the two separation edges of the bluff body or downstream from at least one of the separation edges;
• local registering of a second pressure, p2, acting in the flowing fluid at a second measurement point separated from the first measurement point in the flow direction:
• wherein, by the action of the generated vortices, at least one of the registered pressures, p1, p2, changes periodically at least with the repetition frequency;
• and
• producing, using the registered first pressure, p1, and the registered second pressure, p2, a pressure measurement value that represents an average dynamic pressure acting, averaged over time, at least partly in the flow direction, as well as
• producing, using the pressure measurement value and the flow rate measurement value, a mass flow rate measurement value a mass flow rate measurement value representing the mass flow.