Abstract: A street sweeper is provided including a vacuum pick-up head having a relatively low noise level and high sweeping efficiency resulting from the careful control of the velocity and direction of the air flow. In order to control the air flow, the internal contour of the pick-up head is optimized to accommodate the streamline flow pattern to minimize turbulence and boundary layer separation. The cross sectional area of the internal contour of the pick-up head is designed to be substantially constant or slightly converging. A support assembly for supporting a nozzle assembly is provided which minimizes damage to the pick-up head and minimizes infiltration into the pick-up head. A suction tube is also provided which minimizes the noise level and increases the efficiency of the pick-up head and the fan.

Abstract: The supersonic ejector utilized for cooling includes a cooling extension axially extending the discharge slot from the throat of the primary stream and is contoured to accelerate primary stream, to direct the primary stream to flow parallel to the secondary stream and match the static pressures of both streams and to ensure that the expansion shocks are upstream of the discharge slot. This supersonic ejector is utilized in one instance for cooling purposes in a two-dimensional vectoring nozzle of a gas turbine engine powering aircraft.

Abstract: Liner structure for a duct carrying a heated fluid is described which comprises a substantially cylindrically shaped wall member having a corrugated inner surface contour defining a first plurality of axially extending ridges defined between a corresponding plurality of axial grooves, a second plurality of axially spaced vee-shaped vanes disposed on each ridge with the legs of each vane divergent toward the downstream end of the duct, an elongated cap disposed along each ridge atop corresponding vanes and defining a corresponding plurality of slots between each cap and ridge, and a third plurality of holes through the wall member at each ridge between axially adjacent vanes for conducting fluid coolant through the wall member.

Abstract: Overlapping liner plates 12, 14, 16 are secured at the upstream end to support surface 22. Cooling air 26 supplied through compartmental plenums 24 passes between (54) the plates and over (56) the plate surface. Complementary elongated depressions 40, 46 selectively guide the airflow and provide flexibility to absorb transverse expansions.

Abstract: A film cooling passage through the wall of a hollow airfoil for a gas turbine engine has a metering section communicating with the interior of the airfoil for directing a metered amount of coolant through the passage in a first direction, followed by a mixing section to create turbulence in the flow as it leaves the metering section, followed by a diffusing section leading to the passage outlet at the outer surface of the airfoil. The mixing section comprises a sudden jog or step in the flow path of the fluid to suddenly disrupt its forward momentum in the first direction and to create turbulence therein whereby the fluid is more readily able to spread out within the following diffusing section and thereby stay attached to more widely diverging diffusion section walls. Wider diffusion angles in the coolant passage permits the same amount of coolant to be spread out over a wider area of the surface of the airfoil.

Abstract: The wall of a hollow airfoil for a gas turbine engine includes a film cooling slot therein elongated in the longitudinal direction and having a base within the wall and an outlet at the external surface of the airfoil. A plurality of metering passages extend from inlets at the internal surface of the wall and intersect the slot near its base. The metering passages are angled to direct a metered flow of coolant fluid at a sharp angle against a surface of the slot to cause turbulence and diffusion of the coolant fluid within the slot in order that the coolant fluid fill the entire slot. The coolant fluid thereupon exits the slot as a thin film over the surface of the airfoil downstream of the slot outlet along the full length of the slot.

Abstract: A film cooling passage through the external wall of a hollow airfoil for a gas turbine engine has a metering section in series flow relation with a diffusing section leading to the passage outlet at the external surface of the airfoil over which a hot gas flows during operation. The diffusing section is generally rectangular in cross section perpendicular to the axis of the passage. Upstream and downstream longitudinally extending, spaced apart, facing surfaces of the diffusing section are joined together by a pair of spaced apart side walls which face each other and diverge from each other in the longitudinal direction toward the outlet of the passage. These side walls blend, along their length, with the downstream surface as a smooth curve of large radius. The diameter of the corner curvature of the passage is on the same order of magnitude as the distance between the upstream and downstream surfaces of the diffusing section at the location in question.

Abstract: The external wall of a hollow airfoil for a gas turbine engine has a plurality of longitudinally aligned diffusing coolant passages having their outlets at the outer surface over which a hot gas is intended to flow. The airfoil external wall also includes a longitudinally extending slot formed in the inner surface thereof. Each of the coolant passages intersect such longitudinally extending slot to define metering inlets to each passage for receiving coolant fluid from the slot at a controlled rate. The coolant diffuses as it passes through each passage and exits as a thin film on the external surface of the airfoil. The slot is cast in the inner surface of the wall at the time of forming the airfoil; and the passages are machined into the wall from outside the airfoil. Very small, accurate metering areas for each passage can thereby be formed in single-piece hollow airfoils without access to the interior of the airfoil.

Abstract: In the fabrication of a hollow airfoil having a longitudinally extending slot in the airfoil wall with the slot outlet at the external surface of the airfoil, a metering passage extending from the coolant compartment within the airfoil to the slot for carrying a metered amount of coolant fluid into the slot is formed by machining a passage completely through the wall from the external surface to the internal surface and which intersects the slot. The portion of the passage between the slot and the external surface of the airfoil is blocked, such as with a plug or by welding. With this fabrication method metering passages for directing coolant fluid from inside the airfoil into the slot may be formed without access to the interior of the airfoil. Coolant fluid from the interior flows into the slot through the unblocked portion of the passage and thereupon flows out of the airfoil through the slot as a film of coolant over the surface of the airfoil.

Abstract: The wall of a hollow turbine airfoil has a longitudinally extending coolant outlet slot in its external surface which intersects, along its length, a longitudinally extending cylindrical channel within the wall. Metering passages extend from the inside surface of the airfoil wall to the cylindrical channel and direct a metered amount of coolant into the channel in a manner which results in a swirling motion being imparted to the fluid as the fluid diffuses within the channel. The coolant is thereupon ejected from the channel through the slot in the external surface as a film on the external surface of the airfoil along the length of the slot. The swirling of the fluid within the cylindrical channel helps diffuse the fluid such that the outlet slot becomes completely filled with coolant, whereby a film of coolant is created on the airfoil surface downstream of the slot over the full length of the slot.

Abstract: A sheet metal electrode for forming a shaped, diffusing film coolant passage has a straight, longitudinally extending forward section forming an acute angle with a flat middle section, which, in turn, extends from a rear section which is the base of the electrode. The middle section includes a pair of edges rearwardly diverging from the longitudinal direction and from which extend side walls substantially perpendicular to the middle section. Longitudinally extending edges of the side walls are in the same plane as a lower, flat surface of the forward section such that the surface of the passage formed by such lower surface of the forward section is in the same plane as a surface of the diffusing portion of the passage which is formed by the longitudinally extending edges of the side walls.