Abstract: Embodiments of the present invention include unique gas turbine engines. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for gas turbine engines. Further embodiments, forms, features, aspects, benefits, and advantages of the present application will become apparent from the description and figures provided herewith.

Abstract: An aircraft having a moveable ejector member for assisting in alleviating a boundary layer flowing along an aircraft surface is disclosed. The moveable ejector member is capable of being placed at a variety of positions between a fully open position and a nested position to entrain the boundary layer with another fluid flow. The ejector member can take the form of an ejector shroud used with a nacelle. In some forms, a gas turbine engine is used to provide an ejector flow to entrain the boundary layer through the flow path.

Abstract: An apparatus comprising is provided including an auxiliary power unit positioned within an aircraft. A reverse thrust assembly is driven by the auxiliary power unit to provide reverse thrust during landing of the aircraft. An air flow surface having a first boundary layer of moving fluid when external air is flowed along the airflow surface which could be a nacelle, pylon or any other aircraft surface. A movable member is configured to move between a first position to direct the boundary layer to the auxiliary power unit during climb and cruise of the aircraft, and to a second position to direct a free stream air feed to the auxiliary power unit during landing of the aircraft. Further, the movable member may switch to a third conduit to extract the boundary layer from the interior surface of an engine air intake to reduce the main engine inlet losses and distortion.

Abstract: An aircraft having a moveable ejector member for assisting in alleviating a boundary layer flowing along an aircraft surface is disclosed. The moveable ejector member is capable of being placed at a variety of positions between a fully open position and a nested position to entrain the boundary layer with another fluid flow. The ejector member can take the form of an ejector shroud used with a nacelle. In some forms, a gas turbine engine is used to provide an ejector flow to entrain the boundary layer through the flow path.

Abstract: Embodiments of the present invention include unique gas turbine engines. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for gas turbine engines. Further embodiments, forms, features, aspects, benefits, and advantages of the present application will become apparent from the description and figures provided herewith.

Abstract: A method and an apparatus for determining the clearance between the rotor blades of a rotor assembly and a shroud disposed radially outside of the rotor assembly is provided that calculates steady-state operating conditions for a given power engine setting and utilizes those steady-state conditions to determine a steady-state clearance at the given power setting. The method and apparatus further calculate instantaneous thermal conditions for the rotor disk, rotor blades, and shroud. The instantaneous thermal conditions are subsequently used to determine the amount of instantaneous thermal expansion of the rotor disk, rotor blades, and shroud. A clearance transient overshoot is determined using the calculated instantaneous thermal expansions. The actual clearance is determined using the steady-state clearance and the clearance transient overshoot.

Abstract: A method and an apparatus for determining the clearance between the rotor blades of a rotor assembly and a shroud disposed radially outside of the rotor assembly is provided that calculates steady-state operating conditions for a given power engine setting and utilizes those steady-state conditions to determine a steady-state clearance at the given power setting. The method and apparatus further calculate instantaneous thermal conditions for the rotor disk, rotor blades, and shroud. The instantaneous thermal conditions are subsequently used to determine the amount of instantaneous thermal expansion of the rotor disk, rotor blades, and shroud. A clearance transient overshoot is determined using the calculated instantaneous thermal expansions. The actual clearance is determined using the steady-state clearance and the clearance transient overshoot.

Abstract: A control system for preventing a compressor stall in a gas turbine engine includes means for sensing an aerodynamic signal indicative of an impending stall condition. The weak stages of the compressor amplify an upstream disturbance originating in the low pressure compressor or fan, resulting in a discrete frequency disturbance, which is an effective stall precursor. The control system also includes means, responsive to the sensed signal, for processing the signal by isolating the relevant frequencies of the sensed signal, calculating the magnitude of the relevant portions of the sensed signal, comparing the sensed signal to a predetermined threshold indicative of a healthy compressor, and for providing a processed signal indicative of an impending stall condition. The control system further includes means, responsive to the processed signal, for providing an output to initiate corrective action to prevent the impending stall condition.

Abstract: A control system for controlling the compressor stall margin during acceleration in a gas turbine engine includes means for sensing signals indicative of the gas flow temperature and gas pressure. The control system further includes signal processing means, responsive to the sensed signals, for synthesizing and providing a processed signal indicative of a measure of compressor destabilization due to heat transfer effects. The control system also includes means, responsive to the processed signal, for providing an output to initiate corrective action to increase compressor stall margin if needed. The engine control means, which is a part of the control system, increases the compressor stall margin by either adjusting the compressor variable vanes, reducing fuel flow or modulating the compressor bleed.

Abstract: A method and an apparatus for use with a gas turbine engine receive a signal indicative of an engine operating condition, generate signals representative of thermal conditions of a rotor, blades, and a case, and in response to each of the signals above, determine a signal indicative of a difference between a instantaneous clearance for the thermal conditions and a steady state clearance for the engine operating condition. The determination includes effects related to a temporary difference that results from a difference between the steady state clearance for the engine operating condition and a steady state clearance for a preceding engine operating condition, but does not require computation of the actual temperatures or the steady state temperatures of the rotor, the blades, and the case. A signal indicative of the difference between a instantaneous clearance for the thermal conditions and a steady state clearance for the engine operating condition may be provided to various augmentation schedules.

Abstract: A variable cycle gas turbine engine (10) includes a core unit (30) having a guide vane array (36), and a hybrid stage (38) with a rotor blade array (40) and a stator vane array (42). The engine is operable in at least two modes which channel different quantities of working medium air to the core unit, and each mode corresponds to a distinct thermodynamic cycle. The vanes (54) of the hybrid stage stator vane array are bivariable so that the leading segment (140) and trailing segment (146) of each vane are separately adjustable over a range of pitch angles. The bivariable character of the vanes ensures aerodynamic stability of the engine in each of its modes of operation.

Abstract: The compressor section of an insert gas turbine engine contains a insert installed around the compressor blades that includes cells in a honeycomb configuration. Each cell is inclined at a compound angle to the blade tip to energize the tip air flow as the tip passes over the cell as the blade rotates, improving stall margin with minimum efficiency loss. Each cell is oriented in the direction of the blade chord and faces the advancing blades. As the blade rotates, it sweeps by each cell and high pressure airflow is first captured in the cell from the high pressure side of the blade and released to the low pressure side as the blade passes the cell in the form of a transient energizing jet of high velocity flow in the direction of the airflow across the blade thereby providing effective mixing of the endwall flows and enhancing the tip flow streamwise momentum.

Abstract: In an aircraft gas turbine engine, stator vane deflection and compressor bleed are controlled to alter the compressor airflow vs. compressor pressure relationship map when stall conditions are detected based on compressor speed and compressor temperature, a change that means that less change in pressure required to nudge the compressor from of a stall, accelerating stall recovery. Once the stall has ceased, the stator deflection and bleed are restored to pre-recovery values.

Abstract: In a gas turbine engine a method for thrust variation with reduced compressor RPM excursion is provided in two modes which includes adjusting pivotable compressor vanes mounted upstream of compressor rotor blades, ahead of the conventional vane schedule therefor in a closed loop fashion, responsive to compressor corrected RPM, so as to adjust the fuel demand and engine thrust thereof while maintaining relatively high scheduled compressor corrected RPM scheduled as a function of fan corrected RPM while retaining the conventional method of fuel flow scheduling. Thus mode 1 of the invention adjusts the compressor vanes in advance of the conventional schedule therefor, e.g. pre-closes them on the deceleration side of the Bodie transient and appropriately opens them on the acceleration side of such transient subject to closed loop monitoring of the corrected compressor RPM and being guided thereby so as to result in reduced excursion in such RPM, during both legs of such transient.

Abstract: In an aircraft gas turbine engine having a variable area exhaust, gas turbine compressor operating conditions are sensed to determine a sub-idle condition or a rotating stall. The exhaust area is increased to a maximum when a sub-idle condition is present. If a condition associated with a rotation stall is sensed, fuel flow is decremented but not below a minimum flow. When the rotating stall ends, fuel flow is restored to the normal level and then the engine reaches stabilized operating conditions, the nozzle area is restored at a scheduled rate.

Abstract: The deflection angle of a gas turbine stator is adjusted in proportion to the difference between two parameters computed from N.sub.2 and TT2 using the same function generator. One parameter is a reference adjustment under standard conditions for measured N.sub.2 adjusted to sea level and standard temperature. The second parameter is an adjustment for actual altitude conditions. The parameters manifest the clearance between the engine case and the turbine blade tips.

Abstract: Stall margin in a gas turbine compressor is controlled during acceleration by synthesizing the thermal enlargement of critical compressor stages to synthesize the temporary increase in blade-case clearance during acceleration. The change in clearance is used to produce an augmenting stator vane deflection signal which is summed with a steady state vane deflection signal to increase deflection during acceleration until the clearance returns to a nominal level when the expansion of the compressor parts stabilize.

Abstract: Rectangular bleed ports (24) are circumferentially arranged. Each port has an average radius (r) greater than 30 percent of the port width (W) throughout the reactant surface of the upstream facing edge (30), thereby avoiding flow separation from the surface. A tangent point (36) at the junction of the reactant surface (36) and the inside surface of casing (12) is located a distance (x) upstream to blades (18) greater than 40 percent of the spacing between the blades. This reduces flow losses in the ports caused by blade upwash.

Abstract: An active control system for use in gas turbine engines synchronizes exhaust nozzle area and burner fuel flow together with pas path variable engine parameters, such as fan variable vane and high compressor variable vane positions. As a result, extremely fast thrust transients are possible with optimized compression system stability, since fan and compressor rotor speeds are held high, allowing total engine power to be controlled by air flow and fuel flows directly.

Abstract: A pair of pressure sensing probe tubes are placed in the fan discharge of a turbofan engine, aft of the outlet guide vanes (OGVs) the tubes being circumferentially spaced by a fraction of the OGV pitch. A comparing means receives both pressures sensed by the double-barrelled probes and aerodynamically actuates to automatically select the higher of the two pressures. An accurate pressure indication representative of the mainstream pressure is therefore obtained despite the localized lower pressure turbulence area that may be caused by the presence of the upstream outlet guide vane(s).