Abstract: For determining the ratio in which two constituents are blended in a mixture comprising an oxygen-carrying gas and a gaseous fuel to be combusted by a primary combustion system, the thermodynamic conditions (composition, pressure, temperature) of the two gases prior to and after blending being variable, a secondary combustion system reacting part of the fuel and part of the oxygen-carrying gas is used as a reference combustion chamber. A mixture reproducibly analogous with the mixture burnt by the primary combustion system is used for reaction in the reference combustion chamber. Combustion in the reference combustion chamber is measured to obtain at least one signal for measuring and controlling the ratio between the two constituents of the mixture burnt by the primary combustion system, the reference combustion chamber allowing the rapid, accurate and reliable determination of the ratio between the gaseous fuel and the oxygen-carrying gas contents of the mixture burnt by the primary combustion system.

Abstract: Method for the dynamic and density-independent determination of the mass flow of fluids. A single vortex generating bluff body is placed in the flow to generate vortices according to the principle of the Karman vortex path. The dynamic pressure (1/2.rho.v.sup.2) is determined via the effect of the drag directly at this bluff body. The velocity of flow (v) is determined via the effect of the vortex shedding at the bluff body. The mass flow is determined according to the equation:m=2.multidot.(1/2.rho.v.sup.2).multidot.1/2.multidot.Awherein A is the cross section of the flow channel.Device for implementing such method. The device consists essentially of a vortex-generating bluff body having one or two fixed ends, which itself serves as a transducer or at which one or two transducers are provided. An electronic system for processing the resultant signal is available.