Process for detection of rotating stall

Claim 1

A process for detecting rotating stall in a turbojet engine having at least two revolving spools including a high pressure spool and a low pressure spool, comprising: measuring the rotational speeds (N HP ,N BP ) of each of the two spools; obtaining the derivative relative to time dN HP/dt the rotation speed (N HP ) of the high pressure spool; multiplying the rotation speed (N BP ) of the low pressure spool by a first constant value A; subtracting from the rotation speed (N HP ) of the high pressure spool the product (A·N BP ); comparing the subtraction result (N HP -A·N BP ) with a second constant value B; comparing the derivative dN HP/dt with a third constant value C; and, generating a command signal serving to trigger a procedure enabling restoration of the engine's normal operating conditions as soon as the following relationships are met, ##EQU7## where constant values A and B are determined for the considered engine by the coefficients of the line which is tangent to all the normal operating curves showing the variations of the rotational speeds (N HP , N BP ) of each of the two spools in the coordinates N HP and N BP , this line being of the shape: N.sub.HP -A·N.sub.BP =B: and where constant value C is determined for the considered engine with regard to the normal deceleration conditions of the engine which meets the following relationship: ##EQU8##