RU2493570C1 - Air signal system - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: air signal system includes receivers and sensors for full and static pressure and braking temperature, as well as eighteen parameter converters. At the outputs of the second, third, fourth, fifth, sixth, seventh and eighth converters, temperature of the free stream, indicated speed, true air speed, pressure altitude, density and impact pressure are generated according to a number M, and at the outputs of the thirteenth, fourteenth, fifteenth, sixteenth, seventeenth, eighteenth and twelfth converters, pressure altitude, density, true air speed, indicated speed, impact pressure and temperature of the free stream are generated according to the number M. The first and fourth converters are connected to the full and static pressure sensor, the third converter is connected to the braking temperature sensor, the ninth and seventh converters are connected to the full pressure sensor and the eleventh converter is connected to the braking temperature sensor.

EFFECT: high accuracy of measurement, wider range of measured altitude and flight speed.

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Description

The invention relates to the improvement of air signal systems in terms of measurement accuracy in the field of high altitudes and flight speeds of aircraft.

Known systems for measuring air parameters, described, for example, in [1] (p. 341-356) and [2] (p. 355-374), which are based on the perception of full braking pressure and static pressure of the unperturbed flow, as well as temperature braking. Such systems are currently installed on all classes of aircraft.

For currently designed high-altitude supersonic and hypersonic aircraft, traditional airborne signal systems may be unsuitable due to insufficient measurement accuracy.

The reason for this is the inaccuracy in the perception and measurement of static pressure, since with an increase in altitude, the error in perception and measurement approaches the measured value. This imposes corresponding limitations on the applicability of known altitude air signal systems.

The invention consists in the following.

The problem to which the invention is directed, is to expand the ability to accurately measure airborne signal systems in a wider range of altitudes and flight speeds.

The technical result consists in the fact that the proposed system uses a statistical relationship between static pressure and the temperature of the undisturbed flow, which is established by the standard atmospheres of BCA-60 [4], GOST 4401-64 [5] or GOST 4401-73 [6]. On the basis of this connection and the known relations linking the parameters of braking temperatures and non-perturbing flow, braking pressures and unperturbed flow and number M, the same set of air signals is determined as with known systems. The difference is that the direct perception of the static pressure of the unperturbed flow with a known combination of height and number M is excluded, but at the same time, like the known systems, data on pressure and braking temperature are used.

The invention is illustrated by the following drawings.

Figure 1 presents the structural diagram of known systems of air signals, where

1 - receiver full pressure R _P ,

2 - full pressure sensor R _P ,

3 - receiver braking temperature T _P ,

4 - brake temperature sensor T _P ,

5 - receiver static pressure P _N

6 - static pressure sensor P _N

7 - the first Converter

8 - the second Converter

9 - the third Converter

10 - the fourth Converter

11 - fifth converter

12 - sixth converter

13 - seventh Converter

14 - eighth Converter

q - velocity head,

M is the Mach number,

V is the true airspeed,

T _N - the temperature of the unperturbed stream,

ρ _N is the density of air,

N - barometric height

V _ol - instrument speed.

The receiver 1 and the sensor 2 of the total pressure R _P , the receiver 3 and the sensor 4 of the braking temperature T _P , the receiver 5 and the sensor 6 of the static pressure R _{N are} functionally connected with the transducers. The first transducer 7 is connected to the sensors 2 full and static 6 pressure, the second transducer 8 is connected to the first transducer 7, the third transducer 9 is connected to the brake temperature sensor 4 and the second transducer 8, the fourth transducer 10 is connected to the sensors 2 full and static 6 pressure, fifth a transducer 11 is connected to a second 8 and a third 9 transducers, a sixth transducer 12 is connected to a static pressure sensor 6, a seventh transducer 13 is connected to a static pressure sensor I 6 and a third inverter 9, the eighth inverter 14 is connected to a static pressure sensor 6 and the second transducer 8.

Figure 2 presents the structural diagram of the proposed system of air signals.

1 - receiver full pressure R _P ,

2 - full pressure sensor R _P ,

3 - receiver braking temperature T _P ,

4 - brake temperature sensor T _P ,

5 - receiver static pressure P _N

6 - static pressure sensor P _N

7 - the first Converter

8 - the second Converter

9 - the third Converter

10 - the fourth Converter

11 - fifth converter

12 - sixth converter

13 - seventh Converter

14 - eighth Converter

15 - ninth converter

16 - tenth converter

17 - eleventh Converter

18 - twelfth converter

19 - thirteenth converter

20 - fourteenth Converter

21 - fifteenth - Converter

22 - sixteenth Converter

23 - seventeenth Converter

24 - eighteenth Converter.

q - velocity head,

M is the Mach number,

V is the true airspeed,

T _N - the temperature of the unperturbed stream,

ρ _N is the density of air,

N - barometric height

V _ol - instrument speed.

The receiver 1 and the sensor 2 of the total pressure R _P , the receiver 3 and the sensor 4 of the braking temperature T _P , the receiver 5 and the sensor 6 of the static pressure R _{N are} functionally connected with the transducers. The first transducer 7 is connected to the sensors 2 full and static 6 pressure, the second transducer 8 is connected to the first transducer 7, the third transducer 9 is connected to the brake temperature sensor 4 and the second transducer 8, the fourth transducer 10 is connected to the sensors 2 full and static 6 pressure, fifth a transducer 11 is connected to a second 8 and a third 9 transducers, a sixth transducer 12 is connected to a static pressure sensor 6, a seventh transducer 13 is connected to a static pressure sensor 6 and the third transducer 9, the eighth transducer 14 to the static pressure transducer 6 and the second transducer 8, the ninth transducer 15 is connected to the total pressure transducer 2 and the tenth transducer 16, the eleventh transducer 17 is connected to the brake temperature sensor 4 and the twelfth transducer 18, which is connected to the ninth converter 15, the thirteenth converter 19 is connected to the tenth converter 16, the fourteenth converter 20 is connected to the ninth converter 15, the fifteenth converter The transmitter 21 is connected to the ninth 15 and twelfth 18 transducers, the sixteenth transducer 22 is connected to the twelfth 18 and thirteenth 19 transducers, the seventeenth transducer 23 is connected to the full pressure transducer 2 and the ninth transducer 15, the eighteenth transducer 24 is connected to the thirteenth 19 and ninth 15 transducers, when than at the outputs of the thirteenth 19, fourteenth 20, fifteenth 21, sixteenth 22, seventeenth 23, eighteenth 24 and twelfth 18 converters the numbers M, ba are formed, respectively ometricheskaya height H, the density ρ _H, V true airspeed, indicated airspeed V _pr, q and velocity head temperature T _H of the undisturbed flow.

Figure 3 in the coordinates of the height H and the number, M shows the limits of applicability of the proposed and known systems of air signals. It also shows the restrictions on the minimum velocity head q _min = 200 kg / m ² and the braking temperature T _P = 2000 ° K.

As it follows from figure 1 for known systems of air parameters based on the perception and measurement of parameters R _P , T _P and R _N , the specified set of output signals is obtained as follows:

а во втором преобразователе 8 формируется число М, в третьем преобразователе 9 по числу М и температуре торможения Т_П формируется температура невозмущенного потока как $${Т}_{Н}=\frac{{Т}_{П}}{1+0.2\cdot {М}^2},$$

в четвертом преобразователе 10 на основе разности давлений Р_П и Р_Н формируется значение приборной скорости V_пp, в пятом преобразователе 11 на основе числа М и температуры Т_Н формируется значение истинной воздушной скорости VIn the first transducer 7, the ratio $$\frac{P_P}{R_N}=\psi \left(M\right),$$

and in the second converter 8, the number M is formed, in the third converter 9 by the number M and the braking temperature T _P the temperature of the unperturbed flow is formed as $$T_N=\frac{T_P}{\mathrm{one}+0.2\cdot {\mathrm{<figure-callout\; id="2"\; label="M"\; filenames="00000018.png,00000019.png"\; state="\{\{state\}\}">M</figure-callout>}}^2},$$

in the fourth transducer 10, based on the pressure difference P _P and P _N , the value of the instrument speed V _{p is formed} , in the fifth transducer 11, based on the number M and temperature T _N , the value of the true air speed V is formed

С - постоянная, $$V=C\cdot M\cdot \sqrt{T_H},$$

C is a constant

a sixth inverter 12 based on the pressure P _H is formed barometric altitude H

H = f (P _N ) based on the standard atmosphere, in the seventh transducer 13 based on the temperature T _N and pressure P _N the density ρ _{N is formed}

, R - газовая постоянная $${\rho }_H=\frac{P_H}{R\cdot T_H}$$

, R is the gas constant

and finally, in the eighth transducer 14, on the basis of the number M and the static pressure P _N , the value of the pressure head q

. $$q=0.7\cdot {\mathrm{<figure-callout\; id="2"\; label="M"\; filenames="00000018.png,00000019.png"\; state="\{\{state\}\}">M</figure-callout>}}^2\cdot P_H$$

.

In the proposed system of air signals in figure 2, with a certain ratio of height and speed, simultaneously with the receiver 1 and the sensor 2 of the total pressure R _P , the receiver 3 and the sensor 4 of the braking temperature T _P begin to operate the converters from the ninth to the eighteenth 24.

So in the ninth transducer 15, based on the known function ψ (M) from the tenth transducer 16 and the braking pressure P _P from the sensor 2, a static pressure P _{N is formed} , as

, где $$R_N=\frac{P_P}{\psi \left(M\right)}$$

where

при М≥1. $$\psi \left(M\right)=\frac{166.92\cdot M^7}{{\left(7\cdot M^2-\mathrm{one}\right)}^{2.5}}$$

with M≥1.

In the twelfth transducer 18, on the basis of the accepted atmospheric model, which establishes the connection T _Н = f (Р _Н ), the temperature of the undisturbed flow Т _Н is formed at the output, in the eleventh transducer 17, based on the braking temperature from the sensor 4 and the temperature Т _Н from the twelfth transducer 18, is formed function of the number M, of the form

$$\frac{T_P}{T_N}=\mathrm{one}+0.2\cdot {\mathrm{<figure-callout\; id="2"\; label="M"\; filenames="00000018.png,00000019.png"\; state="\{\{state\}\}">M</figure-callout>}}^2,$$

which is the input to the tenth transducer 16, the output of the thirteenth transducer 19 is formed based on the value of the function ψ (M) from the output of the tenth transducer 16, the number M is formed in the fourteenth transducer 20 based on the pressure Р _Н from the ninth transducer 15 and the barometric height H = f (Р _H ), in the fifteenth transducer 21 on the basis of pressure P _N and temperature T _N the density ρ _{H is formed}

$${\rho }_H=\frac{P_H}{R\cdot T_H},$$

R is the gas constant

in the sixteenth transducer 22, based on the number M and the temperature T _N , the true air speed is formed

С - постоянная, $$V=C\cdot M\cdot \sqrt{T_H},$$

C is a constant

in the seventeenth transducer 23, based on the pressures P _P and P _N , respectively, from the sensor 2 and the ninth transducer 15, the instrument speed is formed as

, $$V_{PR}=f\left(P_P-P_H\right)$$

,

in the eighteenth transducer 24, based on the number M and pressure P _N from the thirteenth 19 and ninth 15 transducers, a pressure head q

$$q=0.7\cdot {\mathrm{<figure-callout\; id="2"\; label="M"\; filenames="00000018.png,00000019.png"\; state="\{\{state\}\}">M</figure-callout>}}^2\cdot P_H.$$

To determine the approximate limits of applicability of the known systems of air signals, the elements of which are indicated in figure 1 and figure 2 from 1 to 14, and the proposed system, the elements of which are indicated in figure 2 from 1 to 4 and from 15 to 24, it is enough to spend them comparison by measurement accuracy.

Since both the known figure 1 and the proposed structure of the system of figure 2 use information about the pressure and braking temperature, which are measured quite accurately, when analyzing their errors can be neglected.

As already indicated, the main part of the error in known systems with increasing flight altitude is introduced by the error in the perception and measurement of the static pressure of the unperturbed flow P _N.

We assume that in the known range of bevel angles, the total pressure perception error P _N , as well as the measurement error P _N by the pressure sensor, does not exceed 0.5 mm Hg. (66.5 Pa), which is calculated in terms of the height H during take-off and landing, the error is ΔН≈5.5 m.

From [2] for supersonic speeds M> 1, the error in measuring the number M from the inaccuracy of measuring the pressure of the unperturbed flow can be determined by the formula

$${\delta }_{\mathrm{one}}=\frac{\Delta M}{M}=-\frac{7\cdot M^2-\mathrm{<figure-callout\; id="7"\; label="one"\; filenames="00000018.png"\; state="\{\{state\}\}">one</figure-callout>}}{7\cdot \left(2\cdot M^2-\mathrm{one}\right)}\cdot \frac{\Delta P_H}{P_H}=-\frac{7\cdot M^2-\mathrm{<figure-callout\; id="7"\; label="one"\; filenames="00000018.png"\; state="\{\{state\}\}">one</figure-callout>}}{7\cdot \left(2\cdot M^2-\mathrm{one}\right)}\cdot \frac{0.5}{P_H},$$

where P _N = f (N) in mmHg

The methodological error of measuring the number M of the proposed system with elements 1 ÷ 4 and 15 ÷ 24 in figure 2 from possible deviations of the temperature of the unperturbed flow T _N from the standard T _Nst depending on the height H can be determined from the relation

$$T_H=\frac{T_P}{\mathrm{one}+0.2\cdot {\mathrm{<figure-callout\; id="2"\; label="M"\; filenames="00000018.png,00000019.png"\; state="\{\{state\}\}">M</figure-callout>}}^2},$$

where from

$${\mathrm{<figure-callout\; id="2"\; label="\delta "\; filenames="00000018.png,00000019.png"\; state="\{\{state\}\}">\delta </figure-callout>}}_2=\frac{\Delta M}{M}=\frac{\mathrm{one}+0.2\cdot {\mathrm{<figure-callout\; id="2"\; label="M"\; filenames="00000018.png,00000019.png"\; state="\{\{state\}\}">M</figure-callout>}}^2}{0.4\cdot {\mathrm{<figure-callout\; id="2"\; label="M"\; filenames="00000018.png,00000019.png"\; state="\{\{state\}\}">M</figure-callout>}}^2}\cdot \frac{\Delta T_H}{T_{Hcc}}.$$

To determine the possible deviations of ΔТ _Н from the standard temperature Т _{Нst of the} standard atmosphere for the northern hemisphere, you can use Appendix 1 to the “Table of the temporary standard atmosphere” of 1960 (AFL-60) [3].

The deviations ± ΔТ _Н depending on the height Н will be determined according to [3] in the confidence interval of 80% of the probability of all possible temperature values for the entire northern hemisphere. For analysis, we accept the limiting values of temperature deviations from the standard.

From the relations δ ₁ and δ ₂ it is clear that they are a function of the number M and the height N.

Obviously, the ratio is equal to unity

$$\left|\frac{{\mathrm{<figure-callout\; id="2"\; label="\delta "\; filenames="00000018.png,00000019.png"\; state="\{\{state\}\}">\delta </figure-callout>}}_2}{{\delta }_{\mathrm{one}}}\right|=\frac{\mathrm{one}+0.2\cdot {\mathrm{<figure-callout\; id="2"\; label="M"\; filenames="00000018.png,00000019.png"\; state="\{\{state\}\}">M</figure-callout>}}^2}{0.4\cdot {\mathrm{<figure-callout\; id="2"\; label="M"\; filenames="00000018.png,00000019.png"\; state="\{\{state\}\}">M</figure-callout>}}^2}\cdot \frac{7\cdot \left(2\cdot M^2-\mathrm{one}\right)}{7\cdot M^2-\mathrm{one}}\cdot \left|\frac{\frac{\Delta T_H}{T_{Hcc}}}{\frac{0.5}{P_H}}\right|=\mathrm{one}$$

will determine the equivalence in terms of the accuracy of measuring the number M of the known system of air signals and the proposed system, shown in figure 2 by the elements designated 1-4 and 15-24. The indicated ratio in the coordinates M and H establishes the approximate boundaries of the use of existing air signal systems.

Figure 3 shows the coordinates of M and H in the range of numbers M = 2 ÷ 6 and heights H = 20 ÷ 50 km of the boundary of equal measurement accuracy of the known systems of air signals and the proposed system with elements 1 ÷ 4 and 15 ÷ 24 in figure 2 .

In the same coordinates, the restrictions on the minimum velocity head q = 200 kg / m ² and the braking temperature T _P = 2000 ° K are shown.

The shaded region in Fig. 3 between dependence 1 and dependence 2, which correspond to positive and negative maximum deviations of temperature Т _Н from the standard Т _{Нst of the} accepted atmospheric model, corresponds to the equal measurement accuracy of known air signal systems and proposed with the structure of elements 1 ÷ 4 and 15 ÷ 24 figure 2.

Below this area, known systems have advantages in measuring accuracy, and above is the proposed structure of the system with elements 1 ÷ 4 and 15 ÷ 24 in FIG. 2. In the shaded area in figure 3, the proposed system of air signals has duplicated information on the output signals of equivalent measurement accuracy, which expands its overall functionality in terms of monitoring the health of the proposed system. In general, the proposed system significantly expands the boundaries of accurate measurement of air signals to heights of the order of 50 km.

It must be emphasized here that with this comparison, the atmospheric model and the relation P _Н = f (Т _Н ) were adopted, which is implemented in Fig. 2 in the ninth transducer 15 for the entire northern hemisphere according to many-year observations and temperature deviations from the standard. However, if we take into account latitudinal and seasonal observations (winter, summer ...), it should be expected that the atmospheric models can be different and have smaller limit deviations T _N from the standard, which can increase the measurement accuracy of the proposed system with elements 1 ÷ 4 and 15 ÷ 24. In this regard, the twelfth transducer 18 in figure 2 may contain several models that take into account both seasonal and latitudinal observations.

As can be seen from figure 3, the shaded area lies between two curves 1 and 2, which can be described by the functions of the boundary values M _G1 = f ₁ (H) and M _G2 = f ₂ (H).

Having these dependencies, the functioning of the system as a whole can be carried out as follows. The known system of air signals with elements 1 ÷ 14 in figure 1 and figure 2 measures the height H and the number M, while comparing the calculated value of the number M with the boundary M _G. When M <M _{G1, the} information of known air signal systems should be considered more preferable. With M≥M _G1 and M≤M _{G2, the} known systems with elements 1-14 and the air signal system with elements 1 ÷ 4 and 15 ÷ 24 should be considered equivalent in measurement accuracy.

When M> M _{G2, the} proposed structure in figure 2 with elements 1 ÷ 4 and 15 ÷ 24 should be considered more preferable in comparison with known systems with elements 1 ÷ 14. With the position of the aircraft in the shaded area in figure 3, the proposed system of air signals has duplicated information about the output signals, equivalent in accuracy of measurement, which allows you to control its performance in these transitional modes.

Thus, the proposed structure of the system of air signals in figure 2 significantly expands the scope of its use to heights of the order of 50 km and numbers M = 2 ÷ 6.

Information sources

1. D.A. Braslavsky and others. "Aviation devices" Engineering. M., 1964

2. V.A. Bodner "Aviation Devices" Engineering. M., 1969

3. Appendix 1 to the “Table of the temporary standard atmosphere” 1960 (ICA-60)

4. “Table of the temporary standard atmosphere” 1960 (VSA-60).

5. GOST 4401-64.

6. GOST 4401-73.

Claims (1)

An air signal system comprising receivers and sensors of full and static pressure and braking temperature, as well as parameter converters, the first of which is connected to full and static pressure sensors, the second converter is connected to the first converter, the third converter is connected to the braking temperature sensor and the second converter, the fourth transducer is connected to the sensors of full and static pressure, the fifth transducer is connected to the second and third transducers, pole the first transducer is connected to a static pressure sensor, the seventh transducer is connected to a static pressure transducer and a third transducer, the eighth transducer is connected to a static pressure transducer and a second transducer, while the outputs of the second, third, fourth, fifth, sixth, seventh and eighth transducers are formed respectively M number, undisturbed flow temperature, instrument speed, true airspeed, barometric altitude, density and pressure head, featuring By adding ten transducers from the ninth to the eighteenth, the ninth transducer is connected to the full pressure sensor and the tenth transducer, the eleventh transducer is connected to the braking temperature sensor and the twelfth transducer, which is connected to the ninth transducer, the thirteenth transducer is connected to the tenth the converter, the fourteenth converter is connected to the ninth converter, the fifteenth converter is connected to the ninth and to the twelfth transducer, the sixteenth transducer is connected to the twelfth and thirteenth transducers, the seventeenth transducer is connected to the full pressure sensor and the ninth transducer, the eighteenth transducer is connected to the thirteenth and ninth transducers, and at the outputs of the thirteenth, fourteenth, fifteenth, sixteenth, seventeenth, eighteenth and twelfth transformers respectively, the number M, barometric altitude, density, true airspeed, at ornaya speed, dynamic pressure and the temperature of the undisturbed flow.

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