1. Field of the Invention
The present invention relates to probes for measuring the velocity vector of a fluid flow, which may be a gas flow or a liquid flow, and particularly to a flow meter probe with force sensors that uses aerodynamic or hydrodynamic force sensors instead of pressure sensors.
2. Description of the Related Art
The measurement of velocity vectors in fluid flow fields is of critical importance for several applications, including the operation and monitoring of petrochemical plants, weather monitoring and forecast, air-transportation traffic control, electronic cooling, and several biomedical engineering applications. A number of flow measurement techniques have been used by researchers, including Laser-Doppler Velocimetry, Particle Image Velocimetry, multi-hole pressure probes, thermal anemometry using hot wires and hot films, etc.
Of these devices, multi-hole pressure probes are the more practical, relatively easy to use, and cost effective tools. Despite their advantages, the multi-hole probes suffer a few disadvantages, including: (i) a requirement of relatively clean fluid to avoid clogging the holes; (ii) most probes have been adopted for air-flows, while some have been modified for water with limited capabilities; (iii) limitations on fluid temperature operation; and (iv) as the pressure hole size is decreased for miniaturization purposes, the probes have a limited frequency response.
Multi-hole pressure probes are generally of the pitot tube variety, with multiple tubes extending between pressure sensing ports in the tip and sides of the probe to a pressure transducer in the body of the probe for measuring the total pressure and stagnation pressure. By Bernouli's equation, the total pressure pt is equal to the static pressure ps plus the dynamic pressure:
                                          p            s                    +                                    1              2                        ⁢            ρ            ⁢                                                  ⁢                          V              2                                      =                  p          t                                    (        1        )            where ρ is the density and V is the velocity. Equation (1) can then be solved for the velocity as follows:
                              V          2                =                              2            ⁢                          (                                                p                  t                                -                                  p                  s                                            )                                ρ                                    (        2        )            
However, because of the length of the tubing, conventional multi-hole probes do not have a rapid response time, which limits their use where the velocity of fluid flow is changing rapidly. In addition, the magnitude of the response is attenuated.
Thus, a flow meter probe with force sensors solving the aforementioned problems is desired.