A steam or air cooled combined cycle gas turbine includes first and second turbine stages (12,14) and a second nozzle stage (16). During start-up, cooling air is supplied radially inwardly through the second stage nozzle for flow into the gas flow through the turbine and for combining with cooling air flowing radially outwardly from a high pressure compressor port. The combined air flow flows radially outwardly through the turbine blades. In normal operation, steam in lieu of air flows radially inwardly through the second nozzle stage and radially outwardly between the turbine wheels and spacer therebetween. Part of the steam through the nozzle stage combines with the radially outwardly flowing steam for cooling the turbine blades. The balance of the steam flows into the gas flow through the turbine. Combined steam/air cooling is effected for abnormally high turbine blade temperatures by combining cooling air from the high pressure discharge port of the compressor with the steam flowing radially outwardly through the turbine blades.

Integrated steam/air cooling system for gas turbines

A transpiration cooling system for avoiding overheating of an airfoil is provided The airfoil is provided with a plurality of apertures and a source of pressurized fluid for providing a flow of fluid through the apertures to establish an aerodynamic radius The aerodynamic radius of curvature of leading edge is sufficiently greater than the mechanical radius of curvature of the leading edge that peak heat flux is independent of the mechanical radius of curvature The mechanical radius of curvature is preferably less than 50% of the aerodynamic radius of curvature during hypersonic operation Preferably the mechanical radius of curvature is the smallest allowed by the fabrication method (ie, a knife edge), such as being less than about 002 inches, preferably less than about 001 inches The transpiration blowing rate can be adjusted so that the blowing rate and aerodynamic radius of curvature are relatively low except during periods of maximum heat flux, such as the shock-on-lip point Since the mechanical radius of curvature is effectively zero, control of the aerodynamic radius of curvature provides complete control of peak heat flux By adjusting blowing rate to the minimum necessary at any given velocity, transpiration consumption, drag and fuel injection are reduced or eliminated

Transpiration cooling for a vehicle with low radius leading edges

An apparatus and method for thermal protection is provided. A thermal protection apparatus includes a porous layer attached to an inner structural member requiring thermal protection. The porous layer serves as both a cooling air plenum and a transpiring medium. The porous layer may include a low strength ceramic foam layer. Thermal protection may be achieved by flowing cooling air the length of the porous layer. The voids in the porous layer may be sized to less than 50 μm, producing uniquely efficient thermal protection due to micro-fluidic effects in the air flowing through the layer. A semi-permeable layer may be attached to the outer surface of the porous layer. The semi-permeable layer may prevent erosion of the porous layer and may transform the porous layer into a plenum by making the majority of the cooling air flow the length of the porous layer before exiting through small holes drilled or punched through the semi-permeable layer.

Actively cooled ceramic thermal protection system

A multiple liquid flow proportioning system for use in reentry vehicles with transpiration cooled nose tips (TCNT). The basic system includes: a first reservoir containing coolant; a second reservoir containing the same type or a different coolant; a piston for forcing the coolant from the first reservoir and a piston for forcing the coolant from the second reservoir with both pistons integrated to form a unified structure movable in unison; and, a gas-operated mechanism to actuate the pistons and control the flow of coolants to the TCNT. The system provides for the simultaneous fluid cooling of the nose tip at high pressure and low flow rate and cooling of the nose-skirt area at low pressure and high flow rate with a single control device (e.g., valve).

Multiple fluid flow proportioning system

A high strength, lightweight, heat resistant control surface for a high speed aircraft such as a missile or the like, comprises a heat resistant lightweight composite such as a graphite reinforced polyimide having a leading edge portion comprising a heat resistant metal such as Inconel. The leading edge portion includes a web fixing the leading edge portion to the composite by bonded attachment thereto at a location remote from the leading edge and adjacent surfaces thereby providing delayed exposure of the bond to leading edge heat buildup during flight.

High speed aircraft control surface

A transpiration cooling system for dissipating heat loads in sharp edges of flight vehicle structures moving at hypersonic velocities and sharp leading edges of gas turbine blades operation in high temperature environments, the invention comprises a compact plenum formed by a longitudinal coolant passage having a longitudinal porous segment in its wall, the compact plenum passage fitting within the leading edge structure and extending along the leading edge in a direction transverse to the external hot gas flow. Pressurized gaseous coolant, supplied by a remote reservoir or engine compressor thus flows within the compact plenum inside the leading edge structure and also transpires in a forward direction from the compact plenum through the porous segment and into the critically heated forward stagnation line region of the sharp leading edge structure.

Allen R

Papers

Compact transpiration cooling system