SU1543241A1 - Device for determining interface of two media - Google Patents

Abstract

The invention relates to a technique for determining the position of the boundary of media that differ in thermophysical properties. The device consists of a heat-conducting case 6, in which the heater 7 is placed a light-guide rod 3 with a shell 4 and a light-scattering coating 5. The light-guide rod is equipped with a splitter, the input of which is optically matched with a pulsed light source 1, and the output with a photodetector 8. placed at the interface of controlled media. The difference in the thermophysical properties of the media causes a difference in heat flux into each medium separately, which leads to the presence of a temperature gradient along the housing 6. Under the condition of the refractive index of the rod and the dependence of the refractive index of the shell 4 on the temperature at the interface of the fiber and the shell 4, the conditions for complete internal reflection for the light beam from the pulsed source 1. The light entered into the envelope 4 is reflected from the light-scattering coating 5, returns to the rod 3 and enters the photodetector 8 At the mark of the boundary of two media (temperature gradient and the gradient of the refractive index of the shell 4), the photodetector 8 registers a jump in the intensity of light. The recording of the time interval between the pulse of the light source and the jump in the output signal of the photodetector improves the accuracy of determining the position of the boundary between two media. 3 il.

Description

The invention relates to a technique for determining the position of the boundary between two media that have heploisome properties.

The aim of the invention is to improve the accuracy.

FIG. 1 is a schematic diagram of the proposed device; in fig. 2 - thermosensitive element, horizontal section; in fig. 3 form of the output signal on the recorder.

A device for determining the boundary between two media contains a pulsed light source (laser) 1, a directional optical coupler 2, a rod 3 of the light guide, a sheath C of the light guide, a light-scattering coating 5

shells, heat-conducting body 6, heater 7, and a photo collector 8 with a recorder 9.

The shell has a thermo-dependent refractive index not exceeding the refractive index of the rod 3 of the light guide. The heater 7 is connected to a stabilized power supply 10. The cavity of the housing 6 can be filled with heat-conducting medium 11.

A device for determining the boundary between two media works as follows.

The radiation source 1 emits pulses of light, which by the coupler enter the core 3 of the light guide. Since the heater provides uniform heating of the thermo-dependent sensing element - the shell A of the light guide, its refractive index is the same as the height of the vessel, which causes a uniform flow of light into the shell B. Reflected from the light-scattering coating 5, the light returns to the rod in accordance with the laws of geometric optics. The back light emission arrives at the photodetector 8. At the recorder 9, a monotonous dependence of the output signal variation with time is recorded.

When liquid enters the vessel, a portion of the heat-conducting cover is immersed in the liquid. Conditions arise for the redistribution of heat along the height of the sensing element by increasing the heat transfer from the heat-conducting body to the liquid. As a result, a temperature gradient along the height of the vessel, and, consequently, the refractive index of the shell, appears on the thermosensitive shell.

A change in the luminous flux from the rod to the shell and back becomes not monotonic, but changes abruptly.

A short pulse appears on the photodetector against the background of the exponentially decaying signal of the relay scattering, according to the position of which the liquid level is judged on the time sweep pattern of the recorder 9 (Fig. 3).

The accuracy of determining the position of the fluid boundary depends on the heat-conducting properties of the housing and the optical shell, and the correspondence between the fluid boundary marks and the optical non-uniformity front in the shell 4 is determined during calibration.

The measurement error of the change in the position of the optical inhomogeneity front does not exceed 0.3%.

Thus, the proposed device allows to determine the boundary of various media, regardless of the optical properties, the degree of contamination of the media, as well as the consistency and phase state of the two media.

Claims (1)

Invention Formula A device for determining the boundary between two media, which contains a heat-conducting case, the surface of which is associated with a heater and a temperature-sensitive element, and a recorder, characterized in that, in order to improve accuracy, the temperature-sensitive element is made in the form of a cylindrical optically transparent shell with a thermo-dependent index of refraction, outside a light-diffusing coating is applied, and a rod is installed inside with a refractive index different from that of the shell in all Range its variations (the latter), the rod is provided with a coupler having an input optically matched to the pulsed light source, and an output - a photodetector associated with the registrar. Greedy Gas Fig 1 Editor Y. Sereda Compiled by E. Podymov Tehred M. Khodanych Order 393 Circulation 535 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 1H 35, Moscow, Zh-35, Raushsk nab., A / 5 Fig 2 x / fig.Z Proofreader E. Lonchakova Subscription