NASA is continuously pursuing innovative solutions that extend beyond space exploration to improve life on Earth. Specifically, the Glenn Research Center is developing specialized software designed to predict and mitigate noise generated by aircraft engines. This software is a crucial tool for engineers involved in the design and analysis of new, more efficient aircraft powerplants, contributing to quieter and more environmentally friendly air travel.
Software Tools for Combating Aviation Noise
Research teams at NASA’s Glenn Research Center are actively advancing the theory and software for predicting the noise levels produced by aircraft engines. This software aids engineers in designing and analyzing new and improved aircraft powerplants. Copies of the software can be accessed through the NASA Software Catalog.
Developing codes for jet-noise prediction is a multifaceted process. Because codes like JeNo utilize Lilly’s acoustic analogy and average flow calculations from Reynolds-Averaged Navier-Stokes (RANS) code, the accuracy of acoustic predictions hinges on the precision of aerodynamic calculations. Consequently, modeling noise sources, simulating turbulence, and developing advanced measurement systems are key research areas within NASA Glenn’s jet-noise prediction efforts.
Diverse Software Solutions for Specific Tasks
NASA offers a spectrum of software tools, each tailored to address specific challenges in aircraft engine acoustics:
- JeNo: Predicts jet noise using Lilly’s acoustic analogy. This code provides relatively fast results compared to alternative methods like Large-Eddy Simulations (LES) or Direct Numerical Simulation (DNS). JeNo has already demonstrated its effectiveness for subsonic and low-supersonic unheated, axisymmetric jets.
- MGBK: Used for predicting jet-noise trends for complex aircraft engine exhaust nozzles. This code has been instrumental in analyzing the noise-reduction benefits offered by chevrons—serrated elements on the edges of turbofan engine nozzles, now a common feature on many commercial aircraft engines.
- V072: Relies on simplified fan flow and geometry models, making it useful for studying rotor-stator interaction noise. It assists in making informed decisions regarding critical design parameters such as the number of blades and vanes, rotor-stator spacing, and the stagger angle and sweep of stator vanes.
- TFaNS: Elevates rotor-stator interaction noise prediction by accounting for acoustic coupling between blade rows and its propagation to the far field. Similar to V072, TFaNS operates quickly and can be employed in early design stages for trend analysis.
- Linflux: Enables the investigation of realistic, three-dimensional flows and blade geometries. Compared to V072 and TFaNS, Linflux demands significantly more computational resources as it models a wider range of physical phenomena.
- BFANS: Calculates broadband noise caused by turbulence interacting with the leading edges of rotor and stator blades.
- RSI: Computes the spectrum of broadband noise generated by the interaction of turbulence in the flow behind a fan rotor with the downstream stator vanes.
- WOBBLE: Calculates tonal noise associated with propellers exhibiting variable inflow angle and predicts both axial and circumferential directivity.
- MPT: Allows for the assessment of multiple-pure-tone (MPT) noise, also known as “buzz-saw” noise, which arises from synchronized shock waves present when fan blade tip speeds exceed the speed of sound.
- ADPAC: Developed by Allison Engine Company, it solves complex internal/external flows for future short-haul turbofan engines. ADPAC is one of NASA’s flexible and validated computational fluid dynamics (CFD) tools.
Through these developments, NASA is making a significant contribution to the creation of more environmentally friendly and quieter air transport, which will positively impact the quality of life for people worldwide.
