Abstract: A method of predicting workpiece deformation prior to machining that causes the workpiece to deform through release of residual stresses. The method includes emitting a beam of ultrasound waves onto the workpiece surface in such a way that a longitudinal wave is propagated in a given direction under and substantially parallel to the surface, positioning at least one transducer in receive mode on the surface to receive a subsurface longitudinal wave that has been propagated, and measuring the propagation velocity of the subsurface longitudinal wave. The method further includes performing these steps in two workpiece regions, a first region sensitive to residual stresses and a second region somewhat insensitive to residual stresses, then calculating a difference in propagation velocity between the velocity measured in the first region and the velocity measured in the second region and from the difference, deducing the deformation that will result from machining the first region.

Abstract: Method of predicting the deformation of a workpiece (13) prior to machining that causes the workpiece to deform through release of residual stresses, which method consists in emitting a beam of ultrasound waves onto the surface of the workpiece (13) in such a way that a longitudinal wave (12) is propagated substantially parallel to and under the surface of the workpiece (13), then in measuring the propagation velocity of the subsurface longitudinal wave in a first region (A) sensitive to residual stresses and in a second region (B) somewhat insensitive to residual stresses, then in calculating the difference in the measured velocities and from this deducing the deformation that will result from machining the first region of the workpiece (13).

Abstract: A carbureted flameholder (30) with optial cooling is provided for a bypass turbojet-engine. The flameholder (30) comprises a body (34) which extends radially into the primary flow. The body (34) is formed by a V-dihedral having two outer plates (35, 36) which intersect at a common ridge apex (37). An air tube (38) is mounted between the two outer plates (35, 36) and at least one fuel conduit (44, 45) is disposed to the rear of the air tube (38). The overall cross-section of the air tube (38) is approximately triangular and the air tube (38) includes a transverse downstream wall that is curved to define a trough (42) in which the fuel conduit (44, 45) is located. The air tube (38) includes orifices (41, 46) directed against the dihedral plates (35, 36) and the fuel conduit (44, 45) to cool them. The fuel conduit includes a nozzle injector (46) directed downstream towards the afterburner chamber (23).

Abstract: A method of preventing instabilities due to combustion in a multi-flow turbojet engine including an afterburner into which an air-fuel mixture is injected in proportions measured in richness terms, which includes the steps of detecting experimentally, when tuning the turbojet engine, the zones of vibrations due to afterburn as a function of the operating conditions of the engine and as a function of the afterburn operating region, and selecting operating points for regulating the fuel richness of each flow to enable the detected vibration zones to be avoided.