Flow velocity measuring device

A flow velocity measuring device comprising a flow passage comprising:

• an internal space having a curved wall surface,
• an introduction passage connected to the internal space at one end of the wall surface tangentially to the wall surface,
• a discharge passage connected to the internal space at the other end of the wall surface tangentially to the wall surface, and
• a branch passage connected to the internal space at substantially right angle to a direction, in which the wall surface is curved, and
• a sensor element arranged in the branch passage or a flow passage connected to the branch passage, and
• wherein a fluid is introduced into the internal space from the introduction passage to branch into the discharge passage and the branch passage, and
• the flow velocity of the fluid taken out from the branch passage is measured by the sensor element, wherein
• at least two internal spaces are provided, and the branch passage connected to one of the internal spaces and the introduction passage connected to the other of the internal space are communicated to each other.

A flow velocity measuring device comprising a first layer substrate, a second layer substrate, and an intermediate plate interposed between the first layer substrate and the second layer substrate,

• a first layer flow passage provided between the first layer substrate and the intermediate plate and including an internal space having a curved wall surface, an introduction passage connected to the internal space at one end of the wall surface tangentially to the wall surface, and a discharge passage connected to the internal space at the other end of the wall surface tangentially to the wall surface,
• a branch passage provided on the intermediate plate to extend through the intermediate plate to be connected to the internal space,
• a second layer flow passage provided between the intermediate plate and the second layer substrate to be connected to the branch passage,
• a sensor element provided on the first layer substrate or the second layer substrate to be arranged in the second layer flow passage or a flow passage connected to the second layer flow passage, and
• wherein a fluid is introduced into the internal space from the introduction passage to branch into the discharge passage and the branch passage, and
• the flow velocity of the fluid taken into the second layer flow passage from the branch passage is measured by the sensor element.