Abstract: A total temperature probe comprising a hollow elongate shroud defined by a shroud wall that envelops a first cavity. The shroud wall is comprised of an inner skin and an outer skin which enclose a second cavity therebetween. A temperature sensor mounted in the first cavity. In use, fluid flow is received into the first cavity, passes through at least one aperture in the inner skin into the second cavity and then passes out of the shroud through at least one aperture in the outer skin. Beneficially, heat conduction across the inner skin is minimal.

Abstract: A total temperature probe comprising a hollow elongate shroud defined by a shroud wall that envelops a first cavity. The shroud wall is comprised of an inner skin and an outer skin which enclose a second cavity therebetween. A temperature sensor mounted in the first cavity. In use, fluid flow is received into the first cavity, passes through at least one aperture in the inner skin into the second cavity and thence passes out of the shroud through at least one aperture in the outer skin. Beneficially, heat conduction across the inner skin is minimal.

Abstract: Fluid velocity measurement apparatus which utilizes Doppler-shift spectral analysis includes a narrow line width light source, the light from which passes through a beam expander to provide an irradiated region, for example a two-dimensional plane, in which velocity measurements may be taken. Light scattered from small particles in the irradiated region is collected in an imaging system which enables spectral analysis of the scattered light for determining the velocity of the light scattering particles in the irradiated region. A single camera is used in the imaging system to obviate the need for costly electronics to synchronize images obtained Also to improve the accuracy of measurement, selected parameters of the apparatus may be measured to allow for perturbations in the velocity measurements obtained.