An airfoil includes a metal body that has holes, a cover panel carried on the metal body, and push fasteners that extend through the cover panel and into the holes to lock the cover panel on the metal body. Each of the push fasteners includes flexible barbs that engage sides of the holes to resist retraction of the fasteners from the holes. The heads of the push fastener are embedded in recesses in the cover panel.

A pump assembly includes multiple impeller stages, each impeller stage including at least one impeller vane. At least one impeller stage includes at least one impeller vane with at least one perforation disposed therethrough.

An apparatus comprises a gas turbine engine having a compressor for increasing a total pressure of a working fluid prior to delivery to a combustor for mixing with fuel. The compressor has a plurality of airfoil members that extend between a first flow surface and a second flow surface. The plurality of airfoil members have a first camber shape at a tip portion that provides a cumulative integral according to the relationship $0.4<\frac{{\int }_0^1\left[{\int }_0^x{\beta }^{\prime }\mathrm{dx}\right]\mathrm{dx}}{{\int }_0^1{\beta }^{\prime }\mathrm{dx}}\le 0.5$
where x is chord location, ${\beta }^{\prime }=\frac{{\beta }_i-\beta }{{\beta }_i-{\beta }_e},$
β.sub.i is inlet metal angle, β.sub.e is exit metal angle, and β is a camber angle at a given chord location.

A vane includes an airfoil that defines a leading edge, a trailing edge, a pressure side, and a suction side. The airfoil includes a truss structure that has ribs that define there between a plurality of through-cavities from the pressure side to the suction side. Honeycomb cells are disposed in the cavities. A face sheet defines at least one of the pressure side or the suction side. The face sheet has perforations that correspond in location to the honeycomb cells.

Turbines and associated components, systems, and methods are described. In some embodiments, the turbine blades and turbines are configured to convert kinetic energy present in fluid (e.g., water) to other forms of energy (e.g., in a hydrokinetic energy system in a river or ocean) relatively efficiently and/or at relatively low cut-in speeds. The turbine blades may have a shape and/or include structural features that contribute at least in part to relatively high efficiency and/or relatively low cut-in speeds. In some embodiments, the turbine blades have a geometry similar to the geometry of a maple seed.

A turbomachine rotor blade includes plural blade sections stacked along an axis between a blade root and a blade head defining between the blade root and the blade head the height of the blade, each blade section including a chord and a maximum sweep defined by the maximum length of a segment perpendicular to the chord line and connecting a point of the chord line and a point of a camber line formed of all points located equidistant from the extrados and the intrados in the section, and verifying that the ratio between the maximum sweep and the chord at mid-height of the blade and the same blade head ratio is between 25% and 40% of the ratio between a maximum sweep and a blade root chord.

A gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, a propulsor section, a geared architecture, a high spool and a low spool. The high spool includes a high pressure compressor and a high pressure turbine. The low spool includes a low pressure compressor and a low pressure turbine. At least one stage of the turbine section includes an array of rotatable blades and an array of vanes. A ratio of the number of vanes to the number blades is greater than or equal to 1.55. A mechanical tip rotational Mach number of the blades is greater than or equal to 0.5 at an approach speed.

An airfoil includes an airfoil wall that defines a leading end, a trailing end, a first side wall, and a second side wall. A rib connects the first and second side walls of the airfoil wall. The rib includes first and second unbranched arms that initiate at the second side wall and extend there from to meet at a node. A third unbranched arm initiates at the first side wall. The third unbranched arm extends perpendicularly there from and connects at either the node, the first unbranched arm, or the unbranched second arm.

A rotor assembly for a gas turbine engine includes a rotatable hub that has a main body and an array of annular flanges that extend about an outer periphery of the main body to define an array of annular channels. An array of airfoils are circumferentially distributed about the outer periphery. Each one of the airfoils includes an airfoil section extending from a root section received in the annular channels. Retention pins extend through the root section of a respective one of the airfoils and through the array of annular flanges to mechanically attach each root section to the hub.

A gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, a turbine section including a fan drive turbine, a compressor section driven by the turbine section, a geared architecture driven by the fan drive turbine, and a fan driven by the fan drive turbine via the geared architecture. At least one stage of the turbine section includes an array of rotatable blades and an array of vanes. A ratio of the number of vanes to the number blades is greater than or equal to about 1.55. A mechanical tip rotational Mach number of the blades is configured to be greater than or equal to about 0.5 at an approach speed.