Analysis and control of ﬂuid ﬂows, often subsidiary to industrial design issues,require measurements of the ﬂow ﬁeld. For classical transparent ﬂuids such aswater or gas a variety of well-developed techniques (laser Doppler and parti-cle image velocimetry, Schlieren optics, interferometric techniques, etc.) havebeen established. In contrast, the situation regardingopaque liquids still lacksalmost any commercial availability. Metallic and semiconductor melts oftenpose additional problems of high temperature and chemical aggressiveness,rendering any reliable determination of the ﬂow ﬁeld a challenging task. Thisreview intends to summarise diﬀerent approaches suitable for velocity mea-surements in liquid metal ﬂows and to discuss perspectives, particularly inview of some recent developments (ultrasound, magnetic tomography).Focus-ing mainly on local velocity measurements, it is subsequently distinguishedbetween invasive and non-invasive methods, leaving entirely aside the acqui-sition of temperature, pressure, and concentration, for which [1] may serve asa comprehensive reference.

Velocity Measurement Techniques for Liquid Metal Flows

Linear stability analysis and direct numerical simulations are conducted to analyse mixed convection in a liquid metal flow in a horizontal pipe with imposed transverse magnetic field. The pipe walls are electrically insulated and subject to constant flux heating in the lower half. The results reveal the nature of anomalous temperature fluctuations detected in earlier experiments. It is found that, at the magnetic field strength far exceeding the laminarization threshold, the natural convection develops in the form of coherent quasi-two-dimensional rolls aligned with the magnetic field. Transport of the rolls by the mean flow causes high-amplitude, low-frequency fluctuations of temperature.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022112013000451

Natural convection in horizontal pipe flow with a strong transverse magnetic field

Heat transfer—A review of 2004 literature

A study visualizing the collapse of vapor bubbles in a subcooled pool

Film boiling of subcooled liquids. Part I: Leidenfrost phenomenon and experimental results for subcooled water

A procedure of estimating the area of contact between cold water and a hot hemispherical surface is developed and described. Synchronous measurements of pressure pulses in liquid, the temperature of a body, and characteristics of contact between a heated body and a coolant are performed under conditions of abrupt change of boiling modes (from film to nucleate boiling). Characteristic features of the investigated processes are determined, which are largely defined by the temperature of the hemisphere, by its thermophysical properties, and by the presence of surface oxide films. It is found that the maximal value of the amplitude of pressure pulses, which may be as high as ∼1 MPa in the experiments, is observed in the region of temperatures of the hot body which are close to the temperature of limiting superheat of water. The dependences are obtained of the rate of spreading of liquid and of the time of delay of its explosive boiling from the instant of boiling on the temperature of the hemisphere.

An experimental investigation of the characteristics of explosive boiling of subcooled water on a hot surface under conditions of change of boiling modes

Results are given of an experimental investigation of the behavior of a vapor film on a highly superheated hemispherical surface immersed in water subcooled to the saturation temperature. The conditions of existence of vapor films on a hot surface and the characteristics of their collapse from the heating surface and transition to nucleate boiling are revealed, as well as the effects which accompany the vanishing of vapor film. The possibilities of internal triggering of fine fragmentation of hot melt and vapor explosion are discussed.

The behavior of a vapor film on a highly superheated surface immersed in subcooled water

The Problem of Swirling of Axisymmetric Electrovortex Flows

The present work is connected with a theoretical and experimental study of the application of two-component fibre-optic velocity sensors for diagnostics of liquid metal turbulent flow. The above sensors have high spatial resolution (10−3mm3) and exhibit insignificant sensitivity to admixtures and the magnetic field; they could also be used for liquid metals in the presence of strong currents (≈10 A). The experimental data on the velocity fields and intensity of its pulsations in strongly nonuniform liquid metal magnetohydrodynamic flows are given. Dynamical errors of velocity measurements at a frequency of 200 Hz are negligible.

Diagnostics of Liquid Metal Flows Using Fibre-Optic Velocity Sensor

A study is performed into the processes of development of instability and collapse of a vapor film on a solid hemispherical surface. Optical-fiber sensors of pressure and vapor-film thickness are used in measurements; the process is videofilmed with subsequent computer processing of images. A physical model of the phenomenon is developed, which includes superheating and explosive boiling of water in recesses of wavy vapor film. The predictions are in qualitative agreement with the experimental results.

V. G. Zhilin

Papers

An experimental investigation of the characteristics of explosive boiling of subcooled water on a hot surface under conditions of change of boiling modes

The behavior of a vapor film on a highly superheated surface immersed in subcooled water

The Problem of Swirling of Axisymmetric Electrovortex Flows

Diagnostics of Liquid Metal Flows Using Fibre-Optic Velocity Sensor

A Study into Development of Instability and Collapse of Vapor Layer on a Heated Solid Hemispherical Surface