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Vortices shed from the tip of a rectangular half-span wing model (NACA 0012) have been investigated with particle image velocimetry at a chord Reynolds number between 3.4 x [10.sup.4] and 26.6 x [10.sup.4] and angles of attack [alpha] = 8 and 16 deg over 0.2 ~ 5 chord lengths downstream of the model. It has been found that the measured wing-tip vortex shows little dependence in the circumferential velocity [v.sub.[theta]] and vorticity [OMEGA], when normalized by their local maximum, on [alpha], Reynolds number, and downstream distance from the wing. Furthermore, the radial distributions of [v.sub.[theta]] and [OMEGA] coincide quite well with the exponential vortex solution, with only a slight departure outside the core region.

A stochastic model was developed for a turbulent forced flame extinction to represent the time evolution of the instantaneous scalar dissipation, conditional on the stoichiometric fuel mixture fraction, in a periodically strained mixing layer as a function of frequency and amplitude. The model was based on the idea of a mixinglet, which expresses the scalar quantities within the interface between the opposed jets in terms of an error function.

The output from a linear diode array is used in a modified laser Doppler velocimeter to measure the size and shape of irregular particles. The sizing accuracy for transparent and opaque particles between 30 and 140 [[micro]meter] is better than 10%. The inaccuracy caused by trajectories that lay at angles of less than 24 [degrees] to the axis of the array was less than +5%, and a further inaccuracy of [+ or -]5% was caused by defocusing of the particle from the center of the velocimeter measuring volume by up to [+ or -]500 [[micro]meter] . The advantages of the shadow Doppler technique over other techniques for sizing irregular particles, such as amplitude systems with pointer volumes, are that the shadow Doppler technique records shape, the optical arrangement is more robust, less precise alignment is required, and the equipment can be constructed at low cost. Key words: Irregular particle sizing, laser Doppler velocimetry, particle imaging.

Mean velocity and the corresponding Reynolds shear stresses of Newtonian and non-Newtonian fluids have been measured in a fully developed concentric flow with a diameter ratio of 0.5 and at a inner cylinder rotational speed of 300 rpm. With the Newtonian fluid in laminar flow the effects of the inner shaft rotation were a uniform increase in the drag coefficient by about 28 percent, a flatter and less strewed axial mean velocity and a swirl profile with a narrow boundary close to the inner wall with a thickness of about 22 percent of the gap between the pipes. These effects reduced gradually with bulk flow Reynolds number so that, in the turbulent flow region with a Rossby number of 10, the drag coefficient and profiles of axial mean velocity with and without rotation were similar. The intensity of the turbulence quantities was enhanced by rotation particularly close to the inner wall at a Reynolds number of 9,000 and was similar to that of the nonrotating flow at the higher Reynolds number. The effects of the rotation with the 0.2 percent CMC solution were similar to those of the Newtonian fluids but smaller in magnitude since the Rossby number with the CMC solution is considerably higher for a similar Reynolds number. Comparison between the results of the Newtonian and non-Newtonian fluids with rotation at a Reynolds number of 9000 showed similar features to those of nonrotating flows with an extension of non-turbulent flow, a drag reduction of up to 67 percent, and suppression of all fluctuation velocities compared with Newtonian values particularly the cross-flow components. The results also showed that the swirl velocity profiles of both fluids were the same at a similar Rossby number.

Measurements of velocity have been obtained in a centrifugal pump in terms of angle-resolved values in the impeller passages, the volute, the inlet and exit ducts and are presented in absolute and relative frames. The pump comprised a radial flow impeller with four backswept blades and a single volute, and the working liquid had the same refractive index as the transparent casing to facilitate the use of a laser-Doppler velocimeter. The flows in the impeller passages were found to depart from the curvature of the blade surfaces at off-design conditions with separation from the suction surface and from the shroud. Secondary flows from the suction to pressure surfaces were dominated by the influences of the relative motion between the shroud and impeller surfaces and the tip leakage. Geometric differences of 0.5 mm and one degree in spacing of the four blades caused differences in passage velocity of up to 6 percent of the impeller tip velocity close to the design flowrate and up to 16 percent at the lowest discharge. The flowrate from each impeller passage varied with volute circumferential position by up to 25 percent at an off-design flowrate. Poor matching of the impeller and volute at off-design conditions caused swirl and separation in the inlet and exit pipes.

Measurements of instantaneous velocity, instantaneous temperature, and the corresponding mean and r.m.s. values, were made in a number of diffusion flames. The velocity measurements were obtained with a laser anemometer and the temperature measurements with a thermocouple, in various flames of methane, town gas and hydrogen.
All the flames exhibited oscillations with frequencies around 11 Hz. The instantaneous velocity and temperature signals were nearly sinusoidal, except near the reaction zone where double frequencies and spiky signals were observed. A model which represents the many observed features of the oscillating flames is suggested. It appears that the oscillations stem from aerodynamic instabilities associated with points of inflection in the instantaneous velocity distributions. [ABSTRACT FROM AUTHOR]