scholarly journals Jet Noise Prediction Comparisons with Scale Model Tests and Learjet Flyover Data

2019 ◽  
Author(s):  
Brenda S. Henderson ◽  
Dennis L. Huff ◽  
Jeffrey J. Berton
Keyword(s):  
Jet Noise ◽  
Model Tests ◽  
Scale Model ◽  
Noise Prediction

Determination of CFD Turbulence Scales for Lobed Mixer Jet Noise Prediction

2007 ◽  
Author(s):  
Sid-Ali Meslioui ◽  
Mark Cunningham ◽  
Patrick Germain
Keyword(s):  
Jet Noise ◽  
Prediction Method ◽  
New Method ◽  
Noise Model ◽  
Excess Noise ◽  
Scale Model ◽  
Frequency Noise ◽  
Noise Prediction ◽  
Single Stream ◽  
Noise Data

Many turbofan engine exhaust designs feature internal forced mixers to rapidly mix the hot core flow with the cold bypass flow before the nozzle exit, primarily to enhance mixing and thus improve Specific Fuel Consumption (SFC). Although the design is intended for performance improvement, it may also considerably reduce low frequency noise because of the lower relative mixed jet velocity compared to a confluent nozzle. In reality, the presence of the mixer adds complexity to the jet flow fields and additional high frequency source noise commonly labeled “mixer excess noise”. There is no industry standard on predicting such jet noise contribution. As a remedy to this, a new method was recently developed by the Institute of Sound and Vibration Research (ISVR), UK, and Purdue University, USA, under the AeroAcoustics Research Consortium (AARC) contract to predict jet noise of lobed mixers. The method essentially relies on SAE ARP876D or ESDU98019 far field noise spectra predicted for single stream jets, with appropriate filtering to decompose the spectrum into an enhanced jet spectrum and a fully mixed jet spectrum. The process is similar to the four source model earlier developed for the coplanar separate flow jets. In addition to mixer flow parameters, the prediction method requires the knowledge of two parameters related to mixer excess noise: a turbulence factor Fm, defined as the ratio of the turbulence in a forced mixer to the ‘normal’ turbulence in a single-stream mixed jet at equal distances downstream of the nozzle; and LenJ that represents the axial length of the effective jet over which Fm exceeds unity. Extensive analysis of NASA scale model lobed mixers noise data showed that the method is promising. RANS CFD was also performed to numerically determine equivalent turbulence scales based on the turbulent kinetic energy in forced mixer jets relative to confluent mixer jets. The present paper extends this work, refining the prediction method and providing validation of the new method with full-scale engine noise data. In addition, the potential of CFD to enhance noise prediction for lobed mixer jets by providing the turbulence scales needed for the empirical model is further investigated. A new definition of the equivalent CFD turbulence parameters is proposed that agrees well with those derived from empirical jet noise model. Comparison of the CFD results with NASA PIV data for a confluent mixer configuration showed that the CFD methodology is not yet fully mature and additional work is required. However, the resolution of the mixer turbulence scales predicted by CFD analysis is sufficient to identify noise trends between two mixer designs. As a result, CFD is seen as a tool with the potential to identify mixer designs that result in lower jet noise.

scholarly journals EXTREME WAVE PRESSURES AND LOADS ON A PILE-SUPPORTED WHARF DECK - INFLUENCES OF AIR GAP AND WAVE DIRECTION

2018 ◽  
pp. 5
Author(s):  
Andrew Cornett
Keyword(s):  
Offshore Structures ◽  
Model Tests ◽  
Scale Model ◽  
Extreme Waves ◽  
Wave Direction ◽  
Coastal Structures ◽  
Extreme Wave ◽  
Wave Impact ◽  
The Past ◽  
Water Depths

Many deck-on-pile structures are located in shallow water depths at elevations low enough to be inundated by large waves during intense storms or tsunami. Many researchers have studied wave-in-deck loads over the past decade using a variety of theoretical, experimental, and numerical methods. Wave-in-deck loads on various pile supported coastal structures such as jetties, piers, wharves and bridges have been studied by Tirindelli et al. (2003), Cuomo et al. (2007, 2009), Murali et al. (2009), and Meng et al. (2010). All these authors analyzed data from scale model tests to investigate the pressures and loads on beam and deck elements subject to wave impact under various conditions. Wavein- deck loads on fixed offshore structures have been studied by Murray et al. (1997), Finnigan et al. (1997), Bea et al. (1999, 2001), Baarholm et al. (2004, 2009), and Raaij et al. (2007). These authors have studied both simplified and realistic deck structures using a mixture of theoretical analysis and model tests. Other researchers, including Kendon et al. (2010), Schellin et al. (2009), Lande et al. (2011) and Wemmenhove et al. (2011) have demonstrated that various CFD methods can be used to simulate the interaction of extreme waves with both simple and more realistic deck structures, and predict wave-in-deck pressures and loads.

Large scale model tests on Royal Schelde SES

1989 ◽  
Author(s):  
R. DE GAAIJ ◽  
E. VAN RIETBERGEN ◽  
M. SLEGERS
Keyword(s):  
Large Scale ◽  
Model Tests ◽  
Scale Model ◽  
Large Scale Model

scholarly journals Jet-Surface Interaction Test: Far-Field Noise Results

2013 ◽  
Vol 135 (7) ◽  
Author(s):  
Clifford A. Brown
Keyword(s):  
High Speed ◽  
Radial Distance ◽  
Jet Noise ◽  
Surface Interaction ◽  
Shielding Effect ◽  
Noise Prediction ◽  
Far Field ◽  
Wide Range ◽  
Field Noise ◽  
Surface Length

Many configurations proposed for the next generation of aircraft rely on the wing or other aircraft surfaces to shield the engine noise from the observers on the ground. However, the ability to predict the shielding effect and any new noise sources that arise from the high-speed jet flow interacting with a hard surface is currently limited. Furthermore, quality experimental data from jets with surfaces nearby suitable for developing and validating noise prediction methods are usually tied to a particular vehicle concept and, therefore, very complicated. The Jet-Surface Interaction Tests are intended to supply a high quality set of data covering a wide range of surface geometries and positions and jet flows to researchers developing aircraft noise prediction tools. The initial goal is to measure the noise of a jet near a simple planar surface while varying the surface length and location in order to: (1) validate noise prediction schemes when the surface is acting only as a jet noise shield and when the jet-surface interaction is creating additional noise, and (2) determine regions of interest for future, more detailed, tests. To meet these objectives, a flat plate was mounted on a two-axis traverse in two distinct configurations: (1) as a shield between the jet and the observer and (2) as a reflecting surface on the opposite side of the jet from the observer. The surface length was varied between 2 and 20 jet diameters downstream of the nozzle exit. Similarly, the radial distance from the jet centerline to the surface face was varied between 1 and 16 jet diameters. Far-field and phased array noise data were acquired at each combination of surface length and radial location using two nozzles operating at jet exit conditions across several flow regimes: subsonic cold, subsonic hot, underexpanded, ideally expanded, and overexpanded supersonic. The far-field noise results, discussed here, show where the jet noise is partially shielded by the surface and where jet-surface interaction noise dominates the low frequency spectrum as a surface extends downstream and approaches the jet plume.

Full scale model tests on slab track constructed on embankment

2012 ◽  
pp. 547-553 ◽  
Author(s):  
Jiang Hongguang ◽  
Bian Xuecheng ◽  
Chen Yunmin ◽  
Jiang Jianqun
Keyword(s):  
Model Tests ◽  
Full Scale ◽  
Scale Model ◽  
Slab Track

scholarly journals SCALE-MODEL TESTS OF A MOORED TANKER AT LEIXOES PORT WITH BREAKWATER'S EXTENSION

2020 ◽  
pp. 37
Author(s):  
Liliana Pinheiro ◽  
Hossam Abdelwahab ◽  
Joao A. Santos ◽  
Conceicao Fortes ◽  
Carlos Guedes Soares
Keyword(s):  
Physical Model ◽  
Model Tests ◽  
Scale Model ◽  
Experimental Setup ◽  
Detailed Model ◽  
Total Length ◽  
Oil Tanker

This paper describes the physical model, experimental setup and tests performed to study the motions and forces of a ship moored to the pier A at the Leixoes oil terminal, following the breakwater's extension at 300m, for different sea states. The Leixoes port layout was implemented at scale 1:80 with the detailed model similar to the prototype bathymetry and surrounding structures. The moored ship is a scale model of an oil tanker with a total length of 3.43 m and 0.135 m draft.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/ny5ByZtdjTs

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