SU873218A1 - Device for regulating temperature of gas in flow-through chamber - Google Patents

Description

The invention relates to an experimental; aerogasdynamics and can be used in experimental installations for the automatic regulation and stabilization of the temperature of gas streams of variable plumes.

A device for temperature control is known, comprising a heater, a temperature-sensitive sensor and a setting device, connected in a bridge comparison circuit, an electrical amplifier and control circuit with positive feedback acting on the source of power consumption 1.

The disadvantage of this device is the limited application area for control objects whose transmission coefficient is a variable value.

A known system for automatically controlling the temperature of a gas in a flow chamber comprising a cylinder of compressed gas connected through a control valve, a restriction device and a heater to the flow chamber, a flow regulator whose output is connected to the control input of the control valve, and an input to the output of the pressure sensor.

installed between the control valve and the narrowing device, the temperature controller in the flow chamber and the power source connected to the control input of the preheater, and the shunt installed in the power supply circuit 2.

This (the system allows you to somewhat lessen the influence of the inertia of the temperature {w by means of a change in the size of the working signal, but its shortcomings are

10 the need for the operator to set the value of the constant time of the control object on the setter, which in many cases is variable and unknown; no consideration of change in transmission coefficient

15, an object of the regulator shr-a1Sh (flow-through chamber) when changing the mode and taking into account the component of the “simple delay in temperature”.

The purpose of the invention is to improve the aerodynamic characteristics of the system.

20

This goal is achieved by the fact that the system in order to control the temperature of the gas in a flow chamber containing & compressed gas, connected through the regulator:

a rusher valve, a restriction device and a heater to the flow chamber, a flow regulator whose output is connected to the control input of a control valve, and an input to the output of a pressure sensor installed between the control valve and a restriction device, a temperature regulator in the flow chamber, a source power supply connected to the control input of the heater, and the shunt installed in the power supply circuit, installed 6Hok division and quad, the input of which is connected to the power supply shunt, and the output to the first input of the block audio, a second input coupled to an output of the temperature controller of the torus, and dividing the output connected to an input power source.

The division unit consists of a series-connected first pulse-width modulator, a first key, a low-pass filter and a differential amplifier, the output of which is connected to the output of the block and the first input of the pulse-width modulator, as well as a decisive amplifier with a temperature setting in the feedback circuit. the second input of the first switch is connected to the first input of the division unit, and the input of the decision amplifier is connected to the second input of the division unit.

In addition, the quad consists of a second pulse-width modulator, a second key and a demodulator, the output of which is connected to the output of the quad, whose input is connected to the input of the second pulse-width modulator and the second input of the second key.

Indeed, taking into account that the flow rate of gas through the flow chamber with a critical nozzle is expressed as - O.4-RKR

-

where V is the gas temperature;

R. - gas pressure in the chamber;

f - area of critical section

nozzles.

Gas temperature can be represented by dependence. g. PK.f i, -)

Provided that F const and G const, V P

Thus, the gas temperature in this case can be measured by pressure sensors more sensitive and less inertial than the temperature sensor.

The control law of the transmission coefficient compensation device of the flow chamber with the heater is expressed in this

case of dependence i, Y

 32

where 3 load current is preheater.

The drawing shows the proposed scheme shstemy.

Baled compressed gas 1 through control valve 2, critical flow meter 3 (narrowing device) and ohmic. Preheater 4 is connected to the control object - flow chamber 5. Control circuit of control valve 2 is connected to gas flow controller 6, which is connected to pressure sensor 7, installed between the valve and the flow meter. Heater 4 is connected to a power source 8, the control circuit of which is connected to the output of block 9 for dividing the set temperature value by. square load current preheater. One of the inputs of the block 9 is connected via a quad 10 to the shunt 11 in the power supply circuit, the other input is connected to a temperature regulator 12, consisting of a gas pressure sensor 13 in the flow chamber 5, a temperature setpoint 14, a setting unit 15 for the flow rate and the critical area nozzle section, as well as control unit 16.

The division block 9 consists of a differential amplifier 17, one input of which is connected to temperature controller 12 through a decisive amplifier 18 with a temperature setter 19 in the feedback circuit and a resistor 20 in the direct circuit, and the other input through a low-pass filter 21 and a switch 22 - with an output of -quadrator 10, where the key is controlled by a pulse-width modulator 23, which converts the signal from the output of the differential amplifier 17. Quad 10 consists of a switch 24, a demodulator 25 and a pulse-width modulator 26 controlled by a shunt signal one 1. The temperature regulator setting device 14 is connected to the flow setting device and the nozzle throat area and to the temperature setting device 19 in the feedback loop of the decisive amplifier 18.

The system works as follows.

The gas flow regulator 6, using the regulating valve 2, directly before the critical flow meter 3, maintains the set pressure of the gas coming from the balloon, 1. At constant critical section of the flow meter, the gas flow through the heater 4 and therefore through the flow chamber 5 is constant and is proportional to the pressure of the gas measured by the sensor 7. At this, the temperature of the gas in the flow chamber 5V is Rc When the temperature of the gas changes, V detects the pressure sensor 13. this change in the form of the electrical signal that is fed to the input of the control unit 16 of the temperature regulator 12, the setting device 14 and .15 in accordance

G-VY

produce

With the expression p 0, 4-P

Claims (2)

a signal proportional to the gas pressure in the flow chamber 5, corresponding to the given flow rates G, the nozzle throat area F and temperature This signal is also fed to the input of the control unit 16, where it is compared with the signal received from the gas pressure sensor 13. The error signal The output of the regulator 12 through the division unit 9 is supplied to the control circuit of the power supply 8, changing its output voltage and, consequently, the current through the heater. In order to automatically exclude the effect of a change in the transmission coefficient of the object to be regulated, the current signal from the shunt AND included in the preheater circuit is fed to the square 10 where. using key 24, pulse-width modulator 23 and demodulator 25, squared and fed to the single input of dividing unit 9, which changes its transmission coefficient in proportion to the ratio KV / 3, compensated for the change in the transmission coefficient of the control object and expanded it dynamic control system capabilities. 1. System for controlling the temperature of gas in a flow chamber, containing a cylinder of compressed gas, connected through a control valve, a restriction device and a heater to the flow chamber, a flow regulator whose output is connected to a control input of a control valve, and an input to the sensor output the pressure set between the regulating valve and the narrowing device, the temperature regulator in the flow chamber and the power source connected to the control input of the preheater, and the shunt. installed in the power supply circuit, in order to improve the aerodynamic characteristics of the system, it has a dividing unit and a quad, the input of which is connected to the shunt of the power supply and the output to the first input of the dividing unit, the second input of which is connected to the output a temperature controller, the output of the dividing unit being connected to the input of the power source. 2. The system according to claim 1, characterized in that the division unit consists of a series-connected first isochroton-pulse modulator, a first key, a low-pass filter and a differential amplifier, the output of which is connected to the output of the block and the input of the first pulse-width modulator and also a decisive amplifier with a temperature controller in the feedback circuit, the second input of the first switch is connected to the first input of the division unit, and the input of the decision amplifier is connected to the second input of the division unit. 3. The system according to claim 1, wherein the quadrant consists of a series-connected second pulse-width modulator, a second key and a demodulator, the output of which is connected to the output of the quad, whose input is connected to the input of the second pulse-width modulator and the second input of the second key. Sources of information taken into account in the examination 1. US patent number 3236451, cl. 236-68, publ. 1966. 2. USSR author's certificate according to the application N 2600732, cl. G 05 D 23/19, 1978 (prototype).