A Telemetry System for Military Fan Vibration Detection Under Inlet Distortion Conditions
Abstract
Program Officer: Steve Martens, Ph.D.; Power, Propulsion, and Thermal ManagementOffice of Naval Research Code 351Aircraft engines op,erating in naval fighter applications have unique challenges, particularly for the fan. Inlet distortion due to aggressive flight m,aneuvers and carrier take-off constraints leads to reduced stall margin and reduced flutter margin, both limiting the operating rang,e of the engine. Navy fans have operability limitations driven by: highly loaded airfoils, inlet distortion due to the shape of the, inlet and aircraft maneuvers, and steam / hot gas ingestion. These three demands not only pose significant challenges to the perfo,rmance of the engine, but they will intensify with next generation aircraft and propulsion systems. Inlet distortion will worsen as, inlets shorten and become more embedded for low-observability aircraft. Additionally, unmanned aircraft could execute maneuvers th,at would also exacerbate the distorted inlet flow. Finally, aircraft catapulted off the deck of a carrier pass through a steam clou,d produced by the catapult creating a temperature inlet distortion during takeoff. Therefore, there is a need to de-sensitize the f,an to these harsh conditions while still maintaining good performance and durability.Therefore, a new military fan research facility, is being developed at Purdue University for this research topic in collaboration with the Office of Naval Research. Different inle,t distortion patterns will be introduced into the fan and the performance and blade vibration conditions will be measured. To incre,ase fan aerodynamic performance and fuel efficiency, modern fan blades favor wider chords with complicated geometry to increase load,ing, while being manufactured using special alloy or composite materials to reduce weight. However, good aerodynamic performance mus,t be accompanied with structural integrity. In operation, fan blades can experience two important aeromechanics problems: forced res,ponse and flutter. Wakes from the inlet guide vanes (as in most of the military turbofan engine) or inlet distortion can excite the,fan blades at their resonant frequency and cause severe vibrations at certain rotational speeds. Flutter is another common aeromecha,nics problem and is a self-excited vibration due to unstable aerodynamic-structural interactions. Accurate determination of flutter,boundaries is still a challenging problem. Stall flutter due to leading edge flow separation is a very common type of flutter, which, can greatly limit operating range of a turbofan engine.To monitor fan blade vibrations during the experiments, strain gages must be, applied to the fan blad, a telemetry system is needed. In a telemetry system, data transmission from the rotating to the stationary component is achieved u,sing a high-frequency carrier (antenna) while the electric power is commonly supplied in an inductive manner. A modern digital telem,etry system typically contains: transmitter(s), receiver(s), and a power supply. The transmitter is the rotating component of the te,lemetry system. In the transmitter, the analog signals from rotor blade strain gages get conditioned (i.e. amplified, filtered), con,verted to digital data streams, and then transmitted to the stationary reference frame via a high-frequency carrier. On the stationa,ry side, the digital data get demodulated and finally converted to analog signals. This proposal seeks $259,650 in funding to purcha,se a 30-channel telemetry system that will allow strain gage measurements to be acquired in the new military fan research facility a,t Purdue.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 05, 2022
- Source ID
- N000142212221
Entities
People
- Nicole Leanne Key
Organizations
- Office of Naval Research
- Purdue University
- United States Navy