SU1140044A1 - Device for measuring speed of non-isothermal flows - Google Patents

Abstract

A DEVICE FOR MEASURING THE VELOCITY OF NON-ISOTHERMAL FLOWS, containing a constant-temperature hot-wire anemometer with a speed sensor included in a bridge circuit, and a resistance thermometer, so that, in order to improve the measurement accuracy, it has been entered sequentially connected by a multiplier and a controlled current source, the output of which is connected to one of the nodes of the measuring diagonal of the bridge circuit is thermo-anemos. one of the inputs of the multiplier is connected to the output of the hot-wire anemometer, and the other is connected to the output of the resistance thermometer. W 4 4;

Description

The invention relates to a measurement technique and can be used to study turbulent non-isothermal flows of gases and liquids. A device for measuring the temperature and velocity of non-isothermal fluxes is known, comprising a constant-temperature thermoelemometer with a speed sensor included in a bridge circuit and a resistance thermometer, the output of which is connected to a control input of an electrically controlled variable resistor included in an adjacent i relationship speed sensor: shoulder of the bridge circuit of the thermal anemometer 1. The disadvantage of this device is the low accuracy of the speed measurement, due to the instability of the parameters of the electric cally controlled resistance. The closest to the invention in technical essence and the achieved result is a device for simultaneous measurement of temperature and flow rate, consisting of a constant-temperature thermo-anemometer with a speed sensor connected to the measuring bridge circuit and a resistance-controlled resistance sensor additional thermoanemometer of constant temperature with a sensor connected to the measuring bridge operating in the mode of small overheating, and resistance emym voltage, and the compensation unit, wherein the output from the thermometer compensation unit is connected to the inputs of the resistances controlled by the voltage 2j. However, this device has a low measurement accuracy over a wide temperature range. The purpose of the invention is to improve the accuracy of measuring the velocity of non-isothermal flows. This goal is achieved by the fact that a device for measuring the velocity of non-isothermal currents containing a constant-temperature thermo-anemometer with a speed sensor included in a bridge circuit and a resistance thermometer is inserted sequentially connected to a multiplier and a controlled current source whose output is connected to one of the nodes the measuring diagonal of the bridge circuit of the hot-wire anemometer, with one of the inputs of the multiplier connected to the output of the hot-wire anemometer, and the other to the output of the resistance thermometer. The drawing shows the block diagram of the proposed device; The rate of non-isothermal flow is measured at the output of the flow temperature meter. The device contains a thermo-anemometer 1 of constant temperature, a resistance thermometer 2, a bridge circuit 3, one of whose arms includes a speed sensor 4. The other arm has a resistor 5, a multiplier 6, a controlled current source 7, its output is connected to one of the measuring nodes the diagonal of the bridge circuit 3 of the thermal anemometer 1, wherein one of the inputs of the multiplier 6 is connected to the output of the thermal anemometer 1, and the other of its input is connected to the output of the resistance thermometer 2. A signal proportional to the flow rate is removed from the output of the hot-wire anemometer 1, and from the output of the resistance thermometer 2 a signal proportional to the temperature of the flow is removed. The device works as follows. A flow sensor 4 of the velocity anemometer 1 and temperature (not shown) of the resistance thermometer 2 is placed in the flow. The changes in the resistance of the temperature sensor are transformed into voltage changes at the output of the thermometer 2, which are fed to one of the inputs of the multiplier 6. To the other input of the multiplier 6 a signal is received that is proportional to the output current of thermo-anemometer 1. The signal from the output of multiplier 6 is converted into current by means of a controlled current source 7 required to eliminate the effect of the low-impedance multiplier 6 ate in operation anemometer bridge circuit 1. The output current source 7 generates on the resistor 5 of the bridge circuit 3 tim voltage drop proportional to the flow and output current temperatzfe anemometer. This voltage drop compensates for the temperature portion of the drop.

31140044

voltage on the 4 speed sensor, to temperature measurements, as well as

since its resistance is the additive output of the hot-wire anemometer, it varies with speed and temperature. In the proposed device,

ry, and the current flowing through the sensor provides a setting necessary

4 speeds, accurate to constant n-5th level of temperature compensation signal

factor coincides with you, both when working in gas and in

Thermoanenometer current flow 1.Fluid flows. It is therefore necessary to change the differential so that the speed sensors and the partial difference in voltages of the uUg temperature are identical in physical properties that are invariant with respect to their properties and design.

Claims (1)

DEVICE FOR MEASURING THE SPEED OF NON-ISOTHERMIC FLOWS, containing a constant temperature hot-wire anemometer with a speed sensor j included in the bridge circuit, and a resistance thermometer, which is included in order to increase the measurement accuracy, they are introduced in series connected multiplier and controlled current source, the output of which is connected to one of the nodes of the measuring diagonal of the bridge circuit. meter, while one of the inputs of the multiplier is connected to the output of the hot-wire anemometer, and the other to the output of the resistance thermometer.