Method of measuring fluid flow

Abstract

In the method for measuring the velocity of fluid or visualizing the distribution of fluid by feeding tracer particles to the fluid, irradiating the fluid with light and observing return light from the tracer particles, tracer particles containing a flourescent substance are fed at least partially to the fluid and the fluid is irradiated with exciting light to cause the tracer particles to output flourescent emissions. A filter which does not transmit the exciting light is used to substantially selectively observe the flourecent emissions of the tracer particles. This method results in a remarkable improvement in the accuracy of flow velocity measurement or visualization of fluid distribution. Moreover, in a mixed fluid system consisting of two or more different fluids, the pattern of behavior of each fluid and the intermingled state of the fluids can be observed by using a plurality of different tracer particles.

1 . A method of measuring the velocity of fluid flow or visualizing the pattern of fluid flow comprising feeding tracer particles to a fluid to be measured and observing light from said tracer particles, characterized by feeding fluorescent tracer particles to said fluid, irradiating the fluid with exciting light to cause said fluorescent tracer particles to produce fluorescent emissions and observing the fluid through a filter which does not transmit said exciting light but transmits said fluorescent emissions.  
     
     
         2 . A method of measuring fluid flows according to  claim 1  which is further characterized in that said fluorescent tracer particles are tracer particles prepared by impregnating porous silica (SiO 2 ) particles with a liquid fluorescent substance and drying the impregnated particles.  
     
     
         3 . A method of measuring fluid flows according to  claim 1  which is further characterized in that said fluorescent tracer particles are silica (SiO 2 ) particles treated with a lanthanoid or a compound thereof.  
     
     
         4 . A method of measuring fluid flows according to  claim 1  which is further characterized by feeding fluorescent tracer particles of one kind to one fluid and tracer particles of another kind which produce fluorescent emissions differing in wavelength from emissions from tracer particles of said one kind to another fluid which is to be mixed with said one fluid, allowing the two fluids to converge and irradiating the resulting mixture of fluids with exciting light for visualization of the intermingled state of said fluids.