A method of fluid flow measurement includes a emitting a light beam into a pipe through which a fluid flows, the light beam illuminating the fluid flowing in the pipe, using a light detector array to detect light caused by scattering of the beam with particles found in the fluid, the light beam being outside a field of view of the light detector array, dividing the field of view of the light detector array into layers, and determining an instantaneous flow velocity in each of the layers as a function of signals transmitted from the light detector array in each of the layers.

The present invention provides an online measuring method of particle (such as bubbles, droplets and solid particles) velocity in multiphase reactor. The method based on an online multiphase measuring instrument includes the following steps: (1) the online multiphase measuring instrument is placed into the multiphase reactor, and then a particle image produced by two or more exposures are obtained; (2) the actual size of individual pixel in the particle image is determined; (3) valid particles are determined in the depth of field; (4) then the centroid coordinates are conversed to the actual length of the coordinates (x.sub.t,i, y.sub.t,i) and (x.sub.t+Δt,i, y.sub.t+Δt,i) using the actual size of individual pixel. Thus, the instantaneous velocity of particles can be calculated by

[00001]$V_i=\sqrt{\frac{{\left(x_{t+\Delta .Math..Math.t,i}-x_{t,i}\right)}^2+{\left(y_{t+\Delta .Math..Math.t,i}-y_{t,i}\right)}^2}{\Delta .Math..Math.t}}.$

The method can realize real-time measurement of the velocity distribution of bubbles, droplets or solid particles in a multiphase reactor, and the measurement accuracy is high.

A method and device for determining a velocity of a flowing medium that allows an as high as possible measuring accuracy without requiring a complicated measuring construction is achieved in that a vortex is generated in the medium and an electromagnetic signal is emitted into the medium. Then, the permittivity of the medium is determined and the velocity of the medium is determined using the permittivity measurement.

A method and device for determining a velocity of a flowing medium that allows an as high as possible measuring accuracy without requiring a complicated measuring construction is achieved in that a vortex is generated in the medium and an electromagnetic signal is emitted into the medium. Then, the permittivity of the medium is determined and the velocity of the medium is determined using the permittivity measurement.

The invention relates to a method for measuring a flow velocity (v) of a gas stream (14) featuring the steps: (a) time-resolved measurement of an IR radiation parameter (E) of IR radiation of the gas stream (14) at a first measurement point (P1) outside of the gas stream (14), thereby obtaining a first IR radiation parameter curve (E.sub.g1,1(t)), (b)time-resolved measurement of an IR radiation parameter (E) at a second measurement point (P2) outside of the gas stream (14), thereby obtaining a second IR radiation parameter curve (E.sub.g1,2(t)), (c) calculation of a transit time (τ1) from the first IR radiation parameter curve (E.sub.g1,1(t)) and the second IR radiation parameter curve (E.sub.g1,2(t)), in particular by means of cross-correlation, and (d) calculation of the flow velocity (vG) from the transit time (τ1), (e) wherein the IR radiation parameter (E.sub.g1) is measured photoelectrically at a wavelength (g1) of at least 780 nm, and (f) a measurement frequency (f) is at least 1 kilohertz.

While a light sheet is generated at a designated region, images of fluid flowing through the designated region are formed at different times. For an inspection region of the plurality of inspection regions defined in the images that has a degree of difference exceeding a threshold between the local flow velocity vector v(a, b, T) at a certain time T and a reference flow velocity vector v(a, b, T.sub.±) at times T.sub.± that are different from the certain time T, the flow velocity vector v(a, b, T) at the reference time T is corrected with the reference flow velocity vector v(a, b, T.sub.±).

While a light sheet is generated at a designated region, images of fluid flowing through the designated region are formed at different times. For an inspection region of the plurality of inspection regions defined in the images that has a degree of difference exceeding a threshold between the local flow velocity vector v(a, b, T) at a certain time T and a reference flow velocity vector v(a, b, T.sub.±) at times T.sub.± that are different from the certain time T, the flow velocity vector v(a, b, T) at the reference time T is corrected with the reference flow velocity vector v(a, b, T.sub.±).

A method includes: receiving, from a plurality of sensors, detection signals indicative of fluid flow, the fluid flow having a direction and a speed, the plurality of sensors having respective mutual positions and distances between pairs of sensors in the plurality of sensors; determining, as a function of the detection signals, a first detection sensor in the plurality of sensors detecting the fluid flow prior to other sensors in the plurality of sensors; determining time delays between detection of the fluid flow by a first sensor and by a second sensor in each pair of sensors in the plurality of sensors; and determining a fluid flow velocity vector indicative of the direction and the speed of the fluid flow as a function of the mutual positions and distances between the pairs of sensors in the plurality of sensors and the time delays.

A method includes: receiving, from a plurality of sensors, detection signals indicative of fluid flow, the fluid flow having a direction and a speed, the plurality of sensors having respective mutual positions and distances between pairs of sensors in the plurality of sensors; determining, as a function of the detection signals, a first detection sensor in the plurality of sensors detecting the fluid flow prior to other sensors in the plurality of sensors; determining time delays between detection of the fluid flow by a first sensor and by a second sensor in each pair of sensors in the plurality of sensors; and determining a fluid flow velocity vector indicative of the direction and the speed of the fluid flow as a function of the mutual positions and distances between the pairs of sensors in the plurality of sensors and the time delays.

A wind turbine for generating electric energy including a tower equipped with rotatable nacelle with rotor which is rotatable about a horizontal rotational axis and which comprises an electric generator. The wind turbine additionally comprises a device for determining flow direction and speed of the wind and a device for or regulating the alignment of the rotor against the wind. The device for determining speed and flow direction comprises pair of receiving antennas, for obtaining electric signals using electrically influenced particles, molecules carried by the wind and are supplied to a correlation measurement device. Here, the time needed by the electrically influenced particles/molecules to traverse the distance between the receiving antennas of a pair of receiving antennas is determined. Subsequently, speed and flow direction of the wind are calculated in a computing device and are supplied to the device for controlling or regulating the alignment of the rotor.