Turbofan

About: Turbofan is a research topic. Over the lifetime, 4114 publications have been published within this topic receiving 39490 citations. The topic is also known as: fanjet & turbofan engine.

A simulation study of turbofan engine deterioration estimation using Kalman filtering techniques

Abstract: Deterioration of engine components may cause off-normal engine operation. The result is an unecessary loss of performance, because the fixed schedules are designed to accommodate a wide range of engine health. These fixed control schedules may not be optimal for a deteriorated engine. This problem may be solved by including a measure of deterioration in determining the control variables. These engine deterioration parameters usually cannot be measured directly but can be estimated. A Kalman filter design is presented for estimating two performance parameters that account for engine deterioration: high and low pressure turbine delta efficiencies. The delta efficiency parameters model variations of the high and low pressure turbine efficiencies from nominal values. The filter has a design condition of Mach 0.90, 30,000 ft altitude, and 47 deg power level angle (PLA). It was evaluated using a nonlinear simulation of the F100 engine model derivative (EMD) engine, at the design Mach number and altitude over a PLA range of 43 to 55 deg. It was found that known high pressure turbine delta efficiencies of -2.5 percent and low pressure turbine delta efficiencies of -1.0 percent can be estimated with an accuracy of + or - 0.25 percent efficiency with a Kalman filter. If both the high and low pressure turbine are deteriorated, the delta efficiencies of -2.5 percent to both turbines can be estimated with the same accuracy.

Preliminary Flight Evaluation of an Engine Performance Optimization Algorithm

Abstract: A performance seeking control (PSC) algorithm has undergone initial flight test evaluation in subsonic operation of a PW 1128 engined F-15. This algorithm is designed to optimize the quasi-steady performance of an engine for three primary modes: (1) minimum fuel consumption; (2) minimum fan turbine inlet temperature (FTIT); and (3) maximum thrust. The flight test results have verified a thrust specific fuel consumption reduction of 1 pct., up to 100 R decreases in FTIT, and increases of as much as 12 pct. in maximum thrust. PSC technology promises to be of value in next generation tactical and transport aircraft.

The benefits of variable area fan nozzles on turbofan engines

Abstract: A variable area nozzle (VAN) on the bypass stream of a turbofan engine may prove to be necessary for a sufficient surge margin on an ultra-high bypass ratio fan. It is shown that such a nozzle also has benefits with respect to fuel burn and noise. The fuel burn will reduce typically about 10 % during departure and approach and likely 2 % in cruise. The noise reduction is in the order of 2 dB for sideline and flyover. Jet mixing noise in cruise is reduced by typically 1.0 dB, the reduction of broadband shock noise being larger. A VAN complements the fan rotational speed n with an additional parameter for controlling the working point on the fan performance map. The smallest nozzle area is needed only for a single flight condition, TOC, while for all other conditions, the nozzle exit area can be enlarged, yielding lower fan pressure ratios, higher mass flows and propulsive efficiencies, lower noise emissions and higher flutter margins for the fan. The benefits are studied for a UHBR fan with a pressure ratio of 1.5 at TOC. The optimal nozzle enlargement for this fan varies from small values in the range of a few percent during cruise to values larger than 15 % for take-off and approach, depending on the actual fan performance map.

Turbofan engine with means to smooth intake air

Abstract: A turbojet fan engine is disclosed having a fan or prop fan which blows air into a secondary channel and an external shroud for the turbine and the secondary channel, in which the front end of the shroud is formed with an inlet lip and the rear end of the shroud is formed in a nozzle-like, pointed manner and at least one end of the shroud is changed, with respect to its effective profile geometry, by means of air under pressure which is taken from the engine and blown out at the appropriate end of the shroud.

Gas turbine engine fan variable area nozzle with swivalable insert system

Abstract: A turbofan engine (10) includes a fan variable area nozzle (FVAN) (50) which effectively changes the physical area and geometry within a fan bypass flow path (40) to manipulate the pressure ratio of the bypass flow. The FVAN generally includes a multitude of aerodynamical Iy shaped inserts (52) circumf erentially located about the core nacelle (12). The FVAN at a fully stowed position (takeoff /landing) takes up a minimum of area within the fan bypass flow path to effectively maximize the fan nozzle exit area (44) while in the fully deployed position (cruise) takes up a maximum of area within the bypass flow path to effectively minimize the fan nozzle exit area. By separately adjusting each of the multiple of inserts relative the other inserts the FVAN provides an asymmetrical fan nozzle exit area to selectively vector the fan bypass flow.