Abstract: A nuclear fuel assembly has a plurality of fuel rods and a lower tie plate supporting their lower ends. Coolant apertures extending through the lower tie plate. A channel box surrounds the fuel rods and receives the lower tie plate, to confine the coolant. To restrict leakage of coolant between the tie plate and the channel box, the coolant apertures include, adjacent the periphery of the lower tie plate, a plurality of peripheral apertures which are located at least partly outside the outermost fuel rods. The peripheral apertures each provide a coolant velocity peak located further from the axial center line of the tie plate than the axial center lines of the closest neighboring fuel rods. The invention also provides venturis in the leakage path between the channel box and the tie plate, to restrict deformation of the tie plate.

Abstract: A gas turbine combustor for reducing a production of NOx. The combustor includes a head combustion chamber and a rear combustion chamber which is larger in diameter than the head combustion chamber. The head combustion chamber is provided with an axially extending hollow frustoconical tubular member to form an annular combustion space therein, air holes for axially jetting air into the annular combustion chamber, air holes formed on a peripheral wall for injecting air and a plurality of fuel nozzles projected into the annular combustion space for injecting fuel into vortex formed by the air jet and the injected air flow whereby the flame is stabilized and lean combustion can be effected. The rear combustion chamber has a fuel and air supply means on the upstream side which includes air inlets formed by whirling vanes and fuel nozzles disposed in the air inlets so that fuel and air are mixed well.

Abstract: A wheel or rotor with a plurality of blades arranged at irregular or unequal pitch angles circumferentially of a disk, a hub or the like, wherein the characteristic level e.sub.k representative of the order-of-harmonic characteristic of blade pitch is defined bye.sub.k =10 log.sub.e d.sub.k +100where ##EQU1## Z=a number of blades k=1,2, . . . and n; n.gtoreq.Z.theta..sub.j =the angular position of the tip or root of each blade defined in terms of a central angle subtended at the center of a circle, which is the axis of said wheel or rotor, by an arc extended from a reference point on said circle to said tip or root of each blade on said circle, j=1,2, . . . and Z; andthe characteristic level e.sub.k satisfies the following conditions ##EQU2## where e=-13.14 log.sub.10 Z+99.70k=2,3, . . . n.