NASA Aircraft Engine Noise Prediction Software for Jet, Fan and Propeller Research
Researchers at NASA’s Glenn Research Center are developing theory and software to predict aircraft engine noise. These tools help engineers design and analyze improved aircraft propulsion systems, from turbofan engines and fan stages to propellers and supersonic fans.
NASA Jet Noise Prediction Codes
Developing jet noise prediction codes involves several research areas. JeNo uses Lilley’s acoustic analogy and the mean-flow solution from a Reynolds-Averaged Navier–Stokes (RANS) code to predict jet noise. Accurate acoustic predictions therefore depend on accurate aerodynamic predictions.
Source modeling, turbulence modeling and advanced measurement systems are key areas of jet noise research at NASA Glenn. RANS-based jet noise prediction methods provide relatively quick results compared with alternative approaches such as large-eddy simulation (LES) and direct numerical simulation (DNS).
JeNo Jet Noise Prediction Code
JeNo calculates the spectral density of far-field sound produced by an axisymmetric jet at a user-specified observer location and across a specified frequency range. The code is currently validated for subsonic and low-supersonic unheated axisymmetric jets.
Request JeNo from the NASA Software Catalog.
MGBK Jet Noise Code
Development of the MGBK code preceded JeNo. NASA Glenn researchers used MGBK to predict jet noise trends in the exhaust nozzle of a complex aircraft engine. The code was also used to analyze the noise-reduction effectiveness of chevrons, the serrated teeth at the end of a turbofan nozzle used on many commercial aircraft engines.
Rotor–Stator Interaction Noise Prediction Software
V072 for Early-Stage Fan Design
V072 uses a simplified model of fan flow and geometry to study rotor–stator interaction tone noise. Its tonal noise predictions help engineers select important low-noise fan-stage design parameters, including the number of blades and vanes, rotor–stator spacing, and stator-vane sweep and slope.
V072 is designed for quickly estimating noise trends early in the design cycle. Request V072 from the NASA Software Catalog.
TFaNS Acoustic Coupling Analysis
TFaNS extends rotor–stator interaction noise prediction by calculating tonal noise levels and accounting for acoustic coupling effects in the blade array, including transmission and reflection. It also propagates tones into the far field.
Like V072, TFaNS is a fast tool for investigating noise trends early in the design process. Request TFaNS from the NASA Software Catalog.
Linflux for 3D Rotor–Stator Noise Analysis
When a simplified model is not sufficient, Linflux enables analysis using realistic three-dimensional flow and blade geometry. Compared with V072 and TFaNS, Linflux models more of the physical phenomena involved and therefore requires significantly more computational resources.
Linflux predicts rotor–stator tonal noise and, like software developed by the NASA Glenn Acoustics Division, has been rigorously validated against experimental data. Request Linflux from the NASA Software Catalog.
Broadband Fan Noise Prediction Codes
BFANS Leading-Edge Turbulence Noise Analysis
BFANS uses turbulence intensity and characteristic length-scale estimates to calculate broadband noise generated when turbulence strikes rotor-blade and stator-vane leading edges.
BFANS calculations, combined with experimental data from facilities such as NASA Glenn’s 9-foot by 15-foot Low-Speed Wind Tunnel, can help identify the noisiest components in a fan stage. Request BFANS from the NASA Software Catalog.
RSI Fan Rotor Wake Noise Code
RSI calculates the broadband-noise spectrum produced by the interaction of fan rotor-wake turbulence and fan exit guide vanes. Using information about incident turbulence characteristics, the software calculates acoustic power spectra upstream and downstream of the stator for each mode at each frequency of interest.
The target frequency is arbitrary and does not have to be a harmonic of the fan blade-passing frequency. Request RSI from the NASA Software Catalog.
Propeller and Supersonic Fan Noise Software
WOBBLE Propeller Noise Prediction Code
Propeller noise can be significantly affected by inflows that destabilize blade loading. The WOBBLE code calculates tonal noise associated with a propeller operating with varying entry angles and predicts axial and circumferential directivity.
The entry angle is specified by the aircraft’s yaw, pitch and roll angles. WOBBLE’s acoustic model accounts for unsteady sources, including blade-thickness and blade-loading effects. Request WOBBLE from the NASA Software Catalog.
MPT “Buzzsaw” Noise Prediction Code
The MPT code estimates multi-pure-tone noise, also known as “buzzsaw” noise, produced by the locked-rotor shock that occurs at supersonic fan-blade tip speeds. The code uses flow predictions from computational fluid dynamics (CFD) codes as input.
Engineers can use MPT to study the real-world effects of blade-to-blade manufacturing differences and variations that occur during hot-running operations, including blade-set angle and twist-return variations. Request MPT from the NASA Software Catalog.
ADPAC CFD Software for Aircraft Propulsion Systems
Developed by Allison Engine Company under contract with Glenn Research Center, ADPAC solves tightly coupled internal and external flow through future-concept short-duct turbofan engines. ADPAC is a flexible and validated computational fluid dynamics tool.
ADPAC can model 2D, axisymmetric, 3D and mixed problems; steady and transient flow; inviscid and viscous flow; rotating, irrotating and mixed components; bleed; leakage; and injection.
Source: www.nasa.gov