SU1239603A1 - Method of determining velocity of non-equilibrium gas flow - Google Patents

Abstract

The invention relates to the field of measurement of motion parameters and allows to increase the accuracy and expand the measurement range. From the non-equilibrium gas flow 2 flowing through channel 1 through the nozzles 3, a part of gas 4 is withdrawn, the flow rate of which is measured by special devices 5. As a result, the static pressure of the flow changes depending on its initial velocity. The static pressure is measured before and after the zone of action by an auxiliary stream at the boundaries of the section whose length is set to be less than the relaxation length of the excited molecules of the investigated nonequilibrium gas flow. The absolute value of the measured pressure drop and the flow rate of the gas withdrawn from the flow determine the rate of the nonequilibrium flow under study. 1 il. i (o you

Description

one

The invention relates to the field of measurement of motion parameters and can be used to determine the speed of non-equilibrium gas media. The aim of the invention is 51 increasing the accuracy of determining the velocity in non-equilibrium gas flows and extending the measurement range.

The drawing shows a device that implements the proposed method. The device contains a k-anal 1 through which the test gas stream flows, nozzles 2 and 3 for sampling a part of the gas from the test stream, connected to a suction system, gas taken from the stream 4, device 5 for measuring the flow rate of the gas being withdrawn from the gas flow, sensors 6 pressures set before and after the extraction zone, Example. Determination of the rate of water vapor excited in electrical discharge. From the non-equilibrium gas stream 2 flowing through channel 1, consisting of excited molecules Hj, 0 (for example, asymmetric vibrations are excited, (OOV), where V is the corresponding vibrational quantum number), part of the gas is taken off through pipes 3 connected to the suction system 4, the flow rate of which (g) is measured by special devices 5 and directed further to the suction system. When a part of the gas (go) oi is taken out of the flow under study consisting of vibrationally excited water vapor, the gasdynamic parameters of the flow change, including the static pressure. Moreover, the change in static pressure before and after the extraction zone depends on the initial velocity of the nonequilibrium flow under study. Therefore, by measuring the static pressure drop before and after the sampling zone by sensors 6, it is possible to determine the rate of non-equilibrium gas flow. In order to eliminate the influence of the relaxation of the vibrational energy of excited molecules H20 (001) on the change in the gas-dynamic parameters of the flow of the proposed method, it is only necessary to select the distance between the static pressure sensors 6 less than the relaxation length of the vibrational energy of the molecules

 (001) + (000) + M,. where M is any gas molecule.

12396031

According to the absolute value of the measured pressure drop before and after the sampling point (p. P) and the flow rate of gas withdrawn from the gas flow (gp), the speed of the nonequilibrium flow under study (U) is determined by the formula

and

A2 - 4F2 (LR)

2F KHR)

ten

where and - the speed of the studied flow; gp is the flow rate of gas taken through the pipes 3; a is the speed of sound in the stream under study; rp is the measured differential pressure before and

5 after the selection zone; F is the cross-sectional area of the channel. (The + sign corresponds to the speed, and the sign - - and a).

The presented formula for determining the division of the flow rate is valid at low relative costs of gas taken through the pipes 3

 F

where G-, - gas consumption in

25 of the test stream, namely gp "0.1 GO

The minimum value of g. equals 0.01 GO.

The proposed method of determining the flow rate allows, by comparison with the known, to determine with a high degree of accuracy (10-15% Bbmie) the rate of non-equilibrium gas flow by eliminating the influence of the mixing zone on the relaxation processes, and also significantly The measurement range is due to the expansion of the class of gas mixtures under investigation in composition.

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The sensitivity and high stability of the proposed method is ensured by the fact that the pressure change in the measurement zone is carried out during the entire measurement time, i.e. The measured pressure differential before and after the extraction zone does not vary with time.

Claims (1)

Invention Formula The method of determining the rate of a nonequilibrium gas flow, which consists in exposing it to an auxiliary flow of a given flow rate selected from the condition gpiO, 1 G, 55 50 and A2 - 4F2 (LR) 2F KHR) ten where and - the speed of the studied flow gp - the flow rate of the gas drawn through the pipes 3; a is the speed of sound in the stream under study; rp is the measured differential pressure before and 5 after the selection zone; F is the cross-sectional area of the channel. (The + sign corresponds to the speed, and the sign - - and a). The presented formula for determining the division of the flow rate is valid at low relative costs of gas taken through the pipes 3  F where G-, - gas consumption in 25 of the test stream, namely gp "0.1 GO The minimum value of g. equals 0.01 GO. The proposed method of determining the flow rate allows, by comparison with the known, to determine with a high degree of accuracy (10-15% Bbmie) the rate of non-equilibrium gas flow by eliminating the influence of the mixing zone on the relaxation processes, and also significantly The measurement range is due to the expansion of the class of gas mixtures under investigation in composition. The sensitivity and high stability of the proposed method is ensured by the fact that the pressure change in the measurement zone is carried out during the entire measurement time, i.e. The measured pressure differential before and after the extraction zone does not vary with time. Invention Formula The method of determining the rate of a nonequilibrium gas flow, which consists in affecting it with an auxiliary flow of a given flow rate selected from the condition gpiO, 1 G, where G is the maximum flow rate of the gas flow under study, measuring the static pressure before and after the zone of action by the auxiliary flow  one and determining this desired parameter from the relation  ra ± a- (1pr -4Р (лР) 2 2FuP where + is selected at M 1; - with M; f 1; a - the speed of sound in the test gas flow; RR - measured differential static pressure before and after the mixing zone} Editor L. Gratilllo Order 3390/44 Compiled by V. Nazarov Tehred O. Sopko. Proofreader M. Maksimishinets Circulation 778 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 396034 F is the cross-sectional area of the channel with the gas stream under study; M is the Mach number 5 characterized in that, in order to increase the accuracy and expand the measurement range, an auxiliary flow is formed by selecting a part of the test flow, and the measurement of the static pressure is carried out at the boundaries of the section whose length is less than the relaxation length of the excited molecules of the nonequilibrium under study. gas flow, J