METHOD AND DEVICE FOR DETECTING AIR TURBULENCE IN THE ENVIRONMENT OF AN AIRCRAFT

• US 20080021601A1
• Filed: 07/03/2007
• Published: 01/24/2008
• Est. Priority Date: 07/18/2006
• Status: Active Grant

• Current Assignee: Airbus Operations SAS (Airbus SE)
• Original Assignee: Airbus France
• Inventors: PUIG, Stephane
• Granted Patent: US 7,761,197 B2
• Time in Patent Office: Days
• US Class Current: 701/14
• CPC Class Codes: G01K 2203/00 Application of thermometers in cryogenics
• CPC Class Codes: G01W 1/00 Meteorology
• CPC Class Codes: G01W 1/08 Adaptations of balloons, missiles, or aircraft for meteorological purposes; Radiosondes transmission of measurements G01D; transmitting circuits H04B; balloons in general B64B; aeroplanes in general B64D; missiles in general F42B15/00
• CPC Class Codes: G01W 1/10 Devices for predicting weather conditions computers per se G06; display devices G09
• CPC Class Codes: G01W 2001/003 Clear air turbulence detection or forecasting, e.g. for aircrafts

Abstract

The device (1) comprises means (10) for determining a theoretical height corresponding to the difference between an extrapolated height of an isentropic trajectory and the current height of the aircraft, and means (16) for comparing this theoretical height with a height threshold indicating a risk of turbulence.

Claims

1. A method for detecting air turbulence in the environment of an aircraft,

wherein, in the course of a flight of the aircraft (A), the following series of successive steps is carried out in an automatic and iterative manner;

A/ at any instant ti;

a) the current values at said instant ti of the static temperature and of the static pressure, as well as the current values of auxiliary parameters tied to the flight of the aircraft are measured on board the aircraft;

b) a potential temperature θ

i is calculated on the basis of said current values of the static temperature and of the static pressure;

c) characteristics of the wind are determined;

d) on the basis of said characteristics of the wind and of said potential temperature θ

i, an extrapolated height hiE is determined, corresponding to the height attained by an isentropic trajectory of potential temperature θ

i, at a subsequent instant ti+1 such that ti+1=ti+Δ

t, Δ

t being a predetermined time interval; and

B/ at the instant ti+1;

e) the current height hi+1 of the aircraft at this instant ti+1 is determined;

f) a theoretical height δ

i+1 is calculated, corresponding to the difference between said extrapolated height hiE and said current height hi+1;

g) this theoretical height is compared with a height threshold; and

h) if said theoretical height is below said height threshold, an alert signal is emitted signaling the detection of turbulence.

2. The method as claimed in claim 1,

wherein in step A/b), the potential temperature θ

i is calculated with the aid of the following expressions;

3. The method as claimed in claim 1,

wherein in step A/c), to calculate the characteristics of the wind:

three components of the wind are calculated in a reference frame tied to the aircraft, on the basis of the current values of the following auxiliary parameters;

the ground speed, the air speed, the sideslip and the incidence of the aircraft, said three components relating respectively to the roll, pitch and yaw axes of the aircraft; and

these three components are transformed into a terrestrial reference frame in such a way as to obtain said characteristics of the wind.

4. The method as claimed in claim 1,

wherein in step A/d), the following operations are carried out:

with the aid of the current height hi of the aircraft at the instant ti, and of the local slope of the wind, obtained on the basis of said wind characteristics determined in step A/c), a theoretical profile followed by an isentropic trajectory of potential temperature θ

i is extrapolated; and

the extrapolated height hiE corresponds to the height attained by this theoretical profile at the subsequent instant ti+1.

5. The method as claimed in claim 1,

wherein in step B/g), said height threshold Zthres is calculated beforehand with the aid of the following expression:

Zthres=(Δ

.θ

.Δ

V²)/(g.Δ

θ

)

in which;

A is a predetermined constant;

θ

is the potential temperature at the instant ti+1;

Δ

V represents a vertical shear of the horizontal wind;

g is the acceleration due to gravity; and

Δ

θ

is a vertical gradient of potential temperature.

6. The method as claimed in claim 1,

wherein in step B/h), if an alert signal is emitted, the passengers of the aircraft are forewarned of the detection of turbulence.

7. The method as claimed in claim 1,

wherein in step B/h), if an alert signal is emitted, account is taken of the detection of turbulence in the piloting of the aircraft.

8. The method as claimed in claim 1,

wherein, upon detection of turbulence, the following series of successive steps is moreover carried out in an automatic manner:

the vertical component of the wind existing outside the aircraft at the current position is determined;

this vertical component is filtered with respect to predetermined frequencies;

the quadratic mean is calculated over a predetermined time window of this filtered vertical component; and

a dissipation rate providing an indication as to the level of the turbulence is deduced from this quadratic mean and from a predetermined frequency.

11. An aircraft,

which comprises a device capable of implementing the method specified under claim 1.

9. A device for detecting air turbulence in the environment of an aircraft,

which comprises:

means for measuring on board the aircraft the current values of the static temperature and of the static pressure, as well as the current values of auxiliary parameters tied to the flight of the aircraft;

means for calculating, on the basis of the current values at any instant ti of the static temperature and of the static pressure, a potential temperature θ

i relating to this instant ti;

means for determining characteristics of the wind;

means for determining, on the basis of said characteristics of the wind and of said potential temperature θ

i, an extrapolated height hiE corresponding to the height attained by an isentropic trajectory of potential temperature θ

i, at a subsequent instant ti+1 such that ti+1=ti+Δ

t, Δ

t being a predetermined time interval;

means for determining the current height of the aircraft;

means for calculating a theoretical height δ

i+1 corresponding to the difference between said extrapolated height hiE and the current height hi+1 at the instant ti+1;

means for comparing this theoretical height with a height threshold; and

means for emitting an alert signal signaling the detection of turbulence, if said theoretical height is below said height threshold.

10. The device as claimed in claim 9,

which comprises, moreover, means for determining said height threshold.

12. An aircraft,

which comprises a device such as that specified under claim 9.