The Benefits of Variable Area Fan Nozzles on Turbofan Engines

2011 ◽  
Author(s):  
Ulf Michel
Keyword(s):  
Turbofan Engines

COMPUTATIONAL AND EXPERIMENTAL STUDIES OF AERODYNAMICS OF FANS FOR ADVANCED TURBOFAN ENGINES

2019 ◽  
Vol 50 (3) ◽  
pp. 219-237
Author(s):  
Vladimir Nikolaevich Korzhnev ◽  
Viktor Ivanovich Mileshin ◽  
Sergei Vladimirovich Pankov
Keyword(s):  
Experimental Studies ◽  
Turbofan Engines

Active fault tolerant control of turbofan engines with actuator faults under disturbances

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Yan-Hua Ma ◽  
Xian Du ◽  
Lin-Feng Gou ◽  
Si-Xin Wen
Keyword(s):  
Active Fault ◽  
Fault Tolerant ◽  
Fault Tolerant Control ◽  
Feedback Controller ◽  
Actuator Faults ◽  
Error Feedback ◽  
Turbofan Engine ◽  
Turbofan Engines ◽  
Interval Observer ◽  
State Error

AbstractIn this paper, an active fault-tolerant control (FTC) scheme for turbofan engines subject to simultaneous multiplicative and additive actuator faults under disturbances is proposed. First, a state error feedback controller is designed based on interval observer as the nominal controller in order to achieve the model reference rotary speed tracking control for the fault-free turbofan engine under disturbances. Subsequently, a virtual actuator based reconfiguration block is developed aiming at preserving the consistent performance in spite of the occurrence of the simultaneous multiplicative and additive actuator faults. Moreover, to improve the performance of the FTC system, the interval observer is slightly modified without reconstruction of the state error feedback controller. And a theoretical sufficiency criterion is provided to ensure the stability of the proposed active FTC system. Simulation results on a turbofan engine indicate that the proposed active FCT scheme is effective despite of the existence of actuator faults and disturbances.

Total Temperature Based Correction of the Turbulence Production in Hot Jets

2017 ◽  
Author(s):  
Jens Truemner ◽  
Christian Mundt
Keyword(s):  
Shear Layers ◽  
Efficiency Gain ◽  
Potential Core ◽  
Production Term ◽  
Turbofan Engines ◽  
Free Jet ◽  
Rans Models ◽  
Total Temperature ◽  
Turbulence Production ◽  
Good Agreement

Comparisons with experiments have shown that RANS models tend to underpredict the mixing process in shear layers with strong temperature gradients. In the modeling of jet engine’s exhaust systems this leads to an overpredicted potential core length and underestimated turbulence intensity in the free jet. In addition, the calculated efficiency gain is lower than indicated by measurements in mixed turbofan engines. Based on the findings from scale-resolving simulations a correction to the turbulence production term is proposed and compared with two NASA-experiments on hot jets. This correction is implemented in a Reynolds-stress and a k-ε model. The results are in very good agreement with the experimental data.

Mechanical Design of a Variable Pitch Fan for Turbofan Engines

2010 ◽  
Author(s):  
John A. Violette ◽  
Eric S. Loos
Keyword(s):  
Mechanical Design ◽  
High Strength ◽  
Variable Pitch ◽  
Fuel Savings ◽  
Turbofan Engines ◽  
Change Mechanism ◽  
Engine Efficiency ◽  
Retention System ◽  
Fan Blade ◽  
Control Forces

The mechanical design of a new variable pitch fan system for high bypass turbofan engines is presented, offering 10–14% fuel savings for next generation turbofan engines. Comparable in weight to current fans, the new design incorporates a compact pitch change mechanism that fits within a current fan’s center body. The key to compactness is the use of multiple high strength tension/torsion straps, which support blade centrifugal loads with unique structural efficiency and redundancy, while allowing ten to fifteen degrees of blade pitch rotation. The new retention system also offers significant reduction of pitch control forces by balancing blade centrifugal twisting loads with strap restoring moments, achieving a desired pitch setting. The use of a pin root fan blade facilitates on-wing blade replacement. Fan blade incidence angles are decreased at low aircraft speeds to avoid fan stall flutter problems. Therefore, advanced engines no longer need the addition of a variable area nozzle to the exit of the fan duct to prevent flutter, saving additional weight, complexity, and cost. This new fan system offers the best solution for achieving a major improvement in turbofan engine efficiency, at the lowest weight.

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