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.

Vortex mixers for reducing the noise emitted by jet engines

Abstract: Apparatus for internally mixing fan exhaust with primary exhaust forward of the nozzle exit plane of a turbofan engine having an outer engine cowling, a splitter wall structure and a tail plug disposed in mid engine upstream of the nozzle exit plane is provided by a plurality of struts disposed radially between the engine tail plug and the outer engine cowling upstream of the nozzle exit plane and a plurality of vortex generating means disposed on the struts for generating vorticies across the entire engine exhaust area.

Fault Tolerant Model Predictive Control of a Turbofan Engine using C-MAPSS40k

Abstract: Aircraft engine control is a crucial component for the safe and stable operation of gas turbine engines which are complex nonlinear systems. As engines have evolved to higher capabilities it is crucial to update the control strategy to ensure maximum functionality of the engine. Current industrial baseline controllers are based in the Proportional-Integral-Derivative (PID) control scheme along with individual limit controllers having critically damped responses housed in the min-max architecture. In light of the distributed engine control architecture that exploits digital electronics and hence higher on-board computational capabilities, the baseline controller is replaced by a Model Predictive Control (MPC) law with on-line optimization. MPC is a model based control technique that can handle complex constrained dynamics thus allowing the incorporation of component faults in the design process of the controller. Component faults occur during an engine’s operation mainly due to fan blade-shroud rubbing, structural wear and tear and foreign object ingestion thus affecting the engine performance. Simulations on the Linear Time Invariant (LTI) as well as the nonlinear turbofan engine of the Commercial Modular Aero-Propulsion System Simulation (CMAPSS40k) tool are carried out. In the presence of a component fault, active fault tolerant control using the multi-model MPC approach is applied by switching between the MPC blocks, each using its respective LTI reference model.The control of both

Closed-loop control of a shape memory alloy actuation system for variable area fan nozzle

Abstract: Shape Memory Alloys have been used in a wide variety of actuation applications. A bundled shape memory alloy cable actuator, capable of providing large force and displacement has been developed by United Technologies Corporation (patents pending) for actuating a Variable Area fan Nozzle (VAN). The ability to control fan nozzle exit area is an enabling technology for the next generation turbofan engines. Performance benefits for VAN engines are estimated to be up to 9% in Thrust Specific Fuel Consumption (TSFC) compared to traditional fixed geometry designs. The advantage of SMA actuated VAN design is light weight and low complexity compared to conventionally actuated designs. To achieve the maximum efficiency from a VAN engine, the nozzle exit area has to be continuously varied for a certain period of time during climb, since the optimum nozzle exit area is a function of several flight variables (flight Mach number, altitude etc). Hence, the actuator had to be controlled to provide the time varying desired nozzle area. A new control algorithm was developed for this purpose, which produced the desired flap area by metering the resistive heating of the SMA actuator. Since no active cooling was used, reducing overshoot was a significant challenge of the controller. A full scale, 2 flap model of the VAN system was built, which was capable of simulating a 20% nozzle area variation, and tested under full scale aerodynamic load in NASA Langley Jet Exit Test facility. The controller met all the requirements of the actuation system and was able to drive the flap position to the desired position with less than 2% overshoot in step input tests. The controller is based on a adaptive algorithm formulation with logical switches that reduces its overshoot error. Although the effectiveness of the controller was demonstrated in full scale model tests, no theoretical results as to its stability and robustness has been derived. Stability of the controller will have to be investigated for the next stage of technology readiness.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

ROSAS Wind Tunnel Test Campaign Dedicated to Unconventional Aircraft Concepts Study

Abstract: An extensive acoustic wind tunnel test campaign was conducted between March and September 2003 in the frame of the European research project ROSAS to assess experimentally the noise shielding effectiveness of classic airframe components for unconventional aircraft configurations for the first time ever in Europe. A complete aircraft model (1/11th-scale) was installed in the ONERA CEPrA19 anechoic wind tunnel, successively with a fan and a jet noise simulator representing the noise sources of an advanced, high bypass ratio turbofan. Various positions of the engine with respect to the airframe were tested with noise measurements being performed in the far field. The ROSAS test campaign has allowed gathering a comprehensive database on noise installation effects for novel aircraft concepts, yet with the shortcomings of the first of its kind. Hence the effects of the noise source characteristics, of a number of geometrical parameters and of the external flow were analyzed to some extent. Significant noise attenuation was evidenced as expected, and other secondary installation effects were also studied. This paper presents the ROSAS experiment, results and preliminary analyses of the acoustic shielding phenomena.