Abstract: The invention concerns a combustion chamber (10) comprising a neck (15) downstream of the injection (11) of gases, and downstream of this neck a divergent section (20) whereof the outer face of the wall (30), when in operation, is cooled by a cooling system using a cryogenic product and surrounding this outer face. This divergent section (20), on the inner face (32) of its wall (30), comprises a coating (40) acting as temperature compensator so that the temperature of the inner face (42) of the coating (40) is higher than the condensation temperature of the combustion gases on this inner face (42) under operating conditions, such that no condensation is formed on this inner face (42).

Abstract: An apparatus for carrying out high cycle fatigue tests of a specimen under high pressure, including: a pressure vessel; a load train including a first horn and a second horn between which a specimen is to be arranged, wherein the load train is arranged within an internal chamber of the pressure vessel; and a converter configured to apply ultrasonic waves into the load train by exciting the first horn to apply a dynamic stress to the specimen. A base part of the second horn is movably seated in the pressure vessel such that two separated chambers are formed within the pressure vessel with the first chamber for the specimen, wherein both chambers can be fed with gas and charged with different gas pressures in order to apply a static stress to the specimen.

Abstract: A system for cooling and holding a testpiece in an effective manner while the testpiece is subjected locally to high heat flux. The testpiece includes an inside face extended by parallel strips that leave between them channels for passing a cooling fluid, and parallel fins of an intermediate part are inserted between the strips.

Abstract: An apparatus for carrying out high cycle fatigue tests of a specimen under high pressure, including: a pressure vessel; a load train including a first horn and a second horn between which a specimen is to be arranged, wherein the load train is arranged within an internal chamber of the pressure vessel; and a converter configured to apply ultrasonic waves into the load train by exciting the first horn to apply a dynamic stress to the specimen. A base part of the second horn is movably seated in the pressure vessel such that two separated chambers are formed within the pressure vessel with the first chamber for the specimen, wherein both chambers can be fed with gas and charged with different gas pressures in order to apply a static stress to the specimen.

Abstract: A system for cooling and holding a testpiece in an effective manner while the testpiece is subjected locally to high heat flux. The testpiece includes an inside face extended by parallel strips that leave between them channels for passing a cooling fluid, and parallel fins of an intermediate part are inserted between the strips.

Abstract: The invention concerns a combustion chamber (10) comprising a neck (15) downstream of the injection (11) of gases, and downstream of this neck a divergent section (20) whereof the outer face of the wall (30), when in operation, is cooled by a cooling system using a cryogenic product and surrounding this outer face. This divergent section (20), on the inner face (32) of its wall (30), comprises a coating (40) acting as temperature compensator so that the temperature of the inner face (42) of the coating (40) is higher than the condensation temperature of the combustion gases on this inner face (42) under operating conditions, such that no condensation is formed on this inner face (42).

Abstract: A regenerative circuit structure is built up by implementing the following steps in particular: an intermediate layer is made on a support core representing the inner profile of the structure; a series of channels regularly distributed around the core is made with the channels opening to face the intermediate layer, each of the channels being provided with a soluble insert; the support core is preheated and the body of the structure is made by thermal spraying under a vacuum; channels are machined in the body from the outside, and said channels are filled by means of soluble inserts; a closure layer is formed to close the channels in the body, and an outer envelope is formed by thermal spraying under a vacuum, after preheating; and all of the soluble inserts and the intermediate layer are eliminated.

Abstract: A regenerative circuit structure is built up by implementing the following steps in particular: an intermediate layer is made on a support core representing the inner profile of the structure; a series of channels regularly distributed around the core is made with the channels opening to face the intermediate layer, each of the channels being provided with a soluble insert; the support core is preheated and the body of the structure is made by thermal spraying under a vacuum; channels are machined in the body from the outside, and said channels are filled by means of soluble inserts; a closure layer is formed to close the channels in the body, and an outer envelope is formed by thermal spraying under a vacuum, after preheating; and all of the soluble inserts and the intermediate layer are eliminated.

Abstract: A positive power ophthalmic lens has a central optically active area the diameter of which is at most equal to the diameter of its geometrical contour. It has an optional peripheral merging area around the central optically active area, between the latter and the geometrical contour. The diameter D.sub.1 in millimeters of the central optically active area is related to the power P of the lens in diopters by a general equation of the type:D.sub.1 =a-b.pwhere a is a numerical parameter taking a value between 84 and 89 and b is a numerical parameter taking a value between 4 and 4.9. This equation makes it possible to obtain well corrected positive power ophthalmic lenses with a large diameter that are relatively light in weight.