A wind measurement apparatus comprises: a frame assembly; four transducers mounted to the frame assembly such that their locations serve as vertices of a regular tetrahedron; and a reflector assembly mounted to the frame assembly, positioned substantially at a center of said regular tetrahedron to allow for airflow between the reflector assembly and the transducers. The reflector assembly comprises a reflector element provided as a solid that has eight vertices and six substantially identical concave faces that serve as reflector surfaces and that is oriented such that each transducer is facing a respective vertex of the reflector element. Each transducer is arranged to: transmit a TX beam towards the reflector assembly such that the TX beam meets the three reflector surfaces that meet at the vertex of the reflector element faced by the transducer, and receive, via said three reflector surfaces, partial reflections of TX beams originating from other transducers.

A wind measurement apparatus includes: base and cover portions; N transducers disposed on the base portion in positions that serve as vertices of a convex regular polygon of order N (N?3); and a reflector assembly arranged on the cover portion. The reflector assembly is divided into N substantially identical concave reflector portions. The reflector assembly and the base portion are disposed such that center points of the reflector assembly and the polygon are spatially aligned and each of the N transducers is spatially aligned with a respective boundary between two adjacent reflector portions. Each transducer is arranged to: transmit a TX beam towards the reflector assembly such that the TX beam meets the adjacent reflector portions on opposite sides of the respective boundary, and receive, via said adjacent reflector portions, partial reflections of the TX beams originating from those of the N transducers that are adjacent to the transducer.

A wind measurement apparatus comprises: cover and base portions arranged to allow for airflow therebetween; N receivers on the cover portion; a transmitter on the cover portion at a substantially equal distance from each of the N receivers; and a reflector assembly on the base portion. The reflector assembly is divided into N concave reflector portions. Each receiver is associated with one of the reflector portions. The reflector assembly and the base portion are disposed such that the transmitter is spatially aligned with a center point of the reflector assembly and each receiver is spatially aligned with the associated reflector portion. The transmitter is arranged to transmit a TX beam towards the reflector assembly such that the TX beam meets each of the reflector portions. Each of the receivers is arranged to receive, via the associated reflector portion, a reflection of a TX beam portion that meets the reflector portion.

A system and method of non-intrusive anemometry. The system comprises an acoustic transmitter disposed at a boundary of fluid flow and first and second acoustic receivers adapted to receive transmissions from the acoustic transmitter. A processor is coupled to the acoustic receivers to determine the time of arrival of the transmission at the acoustic receivers. The acoustic transmitter and acoustic receivers are arranged such that the acoustic transmitter is upstream from the first acoustic receiver which is in turn upstream from the second acoustic transmitter.

A method of measuring a flow rate of a fluid flowing along a path, the method comprising: transmitting successive pairs of periodic signals through the fluid, the respective signals of each pair being transmitted in opposite directions along, and from opposite ends of, the path; determining a difference in propagation times of each signal of each pair along the path; and determining a flow rate of fluid along the path based on the difference in propagation times of the signals of each pair along the path; wherein a phase of each signal is altered with respect to a phase of at least one other signal transmitted along the path.

A method of determining a measure of wave speed or wave intensity in a fluid conduit comprises uses ultrasound measurements to determine the conduit diameter, as a function of time, at a longitudinal position of the conduit, and uses ultrasound measurements to determine fluid velocity, as a function of time, in a volume element at said longitudinal position of the conduit. The ultrasound measurement to determine fluid velocity is effected by tracking objects within the fluid flow in successive frames sampling the volume element, and obtaining displacement vectors for the objects. A wave speed may be determined from a ratio of the change in fluid velocity at the longitudinal position as a function of time and the change in a logarithmic function of the conduit diameter as a function of time. A measure of wave intensity may be determined as a function of change in determined conduit diameter and corresponding change in fluid velocity.

An ultrasonic time measurement device measures a propagation time of a measurement wave transmitted from a first sensor to a second sensor. The device includes a transmission circuit that causes the first sensor to repeatedly transmit measurement waves one at a time and a reception circuit that detects reception at the second sensor, of the respective measurement wave transmitted from the first sensor. The device further measures elapsed times for the measurement waves, each of the elapsed times being an elapsed time from a reference time to a reception time of the respective measurement wave received by the second sensor and calculate the propagation time of the measurement wave from the first sensor to the second sensor based on the elapsed times measured by the time measurer.

A gases humidification system includes a measuring chamber and a mixing chamber. The mixing chamber has one or more mixing elements that improve a mixing of gases before reaching the measuring chamber. Ultrasonic sensing is used to measure gases properties or characteristics within the measuring chamber. A baffle or a vane may be used to control and direct the gases flow through the mixing chamber as the gases flow moves into the measuring chamber.

A method and corresponding device are provided for determining a flow speed in a fluid conduit. The fluid conduit is provided with first, second and third ultrasonic transducers, wherein respective connection lines between transducers extend outside of a symmetry axis of the fluid conduit. First and second measuring signals are applied to the first ultrasonic transducer and received at the second and the third ultrasonic transducer, respectively. The measuring signals comprise a respective reversed signal portion with respect to time of a response signal. Respective first and second response signals are measured and the flow speed is derived from at least one of the first and second response signals.

Methods, systems, and devices for acoustic structural reflection interference mitigation are provided in accordance with various embodiments. For example, some embodiments may provide for structural reflection interference mitigation for compact three-dimensional ultrasonic anemometers. Some embodiments include a method that may include transmitting a first acoustic signal from a first acoustic transmitter. At least a first portion of the first acoustic signal from the first acoustic transmitter may be hindered from being received at a first acoustic receiver. At least a second portion of the first acoustic signal from the first acoustic transmitter may be received at the first acoustic receiver along an acoustic propagation path. In some embodiments, the first acoustic transmitter may include a wide-beam transmitter. Some embodiments may utilize four wide-beam transducers positioned at apices of a tetrahedron.