Measurements of Turbulence Parameters: Scalar Fields

Abstract

In turbulent flow both fluid velocity and scalar quantities, like temperature, density, or concentration, may be separated into mean and fluctuating ensemble average components. The turbulence of the scalar fields is superimposed to the turbulent velocity field. Both velocity and scalar statistics are necessary for the description of turbulent heat and mass transfer. Diagnostics of the turbulent parameters based on the velocity statistics are discussed in the previous chapter. The methods are based on the statistical analysis of the particle seeded into the flow displacement under light sheet illumination. This chapter is devoted to the scalar flowfield statistical analysis using line-of-sight flow probing. An obvious advantage of such flow probing is the absence of the necessity to introduce into the flow the seeded particles. A disadvantage of these methods is a spatial data averaging along an optical path. A way to overcome this disadvantage, multi-angular flow probing with subsequent local parameter reconstruction with the help of computerized tomography, will be discussed in the next chapter.