The evaluation of one-dimensional temperature profile in a turbulent fluid flow from the amplitude distribution of measured temperature fluctuations at a fixed detector position

In a turbulent homogeneous fluid flow temperature fluctuations are generated by mixing of the fluid with a lateral temperature profile. In case of a flow with a one-dimensional temperature profile in a direction perpendicular to the flow velocity, the amplitude distribution of the temperature noise is Gaussian if this profile is linear, independently of the numerical value of the gradient. Deviations from the linear profile cause deviations from the normal distribution. Due to this fact it will be possible to calculate the underlying one-dimensional profile from the probability density function of the noise measured at a fixed position in the fluid flow. Experiments in a homogeneous turbulent water flow (Re = 27,000) confirmed the described method. The evaluation of a temperature profile by only one fixed noise detector may be of practical interest for malfunction detection in fuel elements of nuclear power reactors of the LMFBR-type. (author)