Experimental Validation of an Analytical Prediction Model for Fan Buzz-Saw Noise

2020 ◽  
Author(s):  
Antoine Moreau ◽  
Sébastien Guérin
Keyword(s):  
Mach Number ◽  
Prediction Model ◽  
Analytical Model ◽  
Experimental Validation ◽  
Test Cases ◽  
Sound Power ◽  
Analytical Prediction ◽  
Mean Flow ◽  
Reasonable Prediction ◽  
Inflow Conditions

Abstract This paper is focused on the application of an analytical model, which was previously developed and published for the prediction of buzz-saw noise emitted by supersonic fan rotors. The application test cases are six different fan stages equipped with hardwall inlet ducts and clean inflow conditions. The model is validated through a comparison with experimental sound power levels measured along the working line of each fan in high subsonic, transonic and supersonic regimes. In terms of overall evolution and maximum levels, the model provides a reasonable prediction; the sensitivity to parameters such as the intake axial Mach number or the intake duct length is well reproduced. However the significant discrepancies observed locally show that the prediction of buzz-saw noise is still a difficult task. The model is then extended to the case of distorted mean flow impinging on the rotor. Following this extension, the maximum levels of buzz-saw noise are expected to occur over a wider range of Mach number compared to the case with clean inflow.

scholarly journals Analytical model for the depth progress of percussion drilling with ultrashort laser pulses

2021 ◽  
Vol 127 (5) ◽  
Author(s):  
Daniel Holder ◽  
Rudolf Weber ◽  
Thomas Graf ◽  
Volkher Onuseit ◽  
David Brinkmeier ◽  
...  
Keyword(s):  
Analytical Model ◽  
Experimental Validation ◽  
Laser Pulses ◽  
Ultrashort Laser Pulses ◽  
Picosecond Pulses ◽  
Hole Depth ◽  
Laser Percussion Drilling ◽  
Pulse Energies ◽  
Ultrashort Laser ◽  
Percussion Drilling

AbstractA simplified analytical model is presented that predicts the depth progress during and the final hole depth obtained by laser percussion drilling in metals with ultrashort laser pulses. The model is based on the assumption that drilled microholes exhibit a conical shape and that the absorbed fluence linearly increases with the depth of the hole. The depth progress is calculated recursively based on the depth changes induced by the successive pulses. The experimental validation confirms the model and its assumptions for percussion drilling in stainless steel with picosecond pulses and different pulse energies.

scholarly journals Influence of the Atmospheric Surface Layer on a Turbulent Flow Downstream of a Ship Superstructure

2013 ◽  
Vol 30 (8) ◽  
pp. 1803-1819 ◽  
Author(s):  
Luksa Luznik ◽  
Cody J. Brownell ◽  
Murray R. Snyder ◽  
Hyung Suk Kang
Keyword(s):  
Surface Layer ◽  
Atmospheric Surface Layer ◽  
The United States ◽  
Naval Academy ◽  
Mean Flow ◽  
Flow Distortion ◽  
Turbulent Statistics ◽  
Sonic Anemometers ◽  
Flight Deck ◽  
Inflow Conditions

Abstract This paper describes a set of turbulence measurements at sea in the area of high flow distortion in the near-wake and recirculation zone behind a ship's superstructure that is similar in geometry to a helicopter hangar/flight deck arrangement found on many modern U.S. Navy ships. The instrumented ship is a 32-m-long training vessel operated by the United States Naval Academy that has been modified by adding a representative flight deck and hangar structure. The flight deck is instrumented with up to seven sonic anemometers/thermometers that are used to obtain simultaneous velocity measurements at various spatial locations on the flight deck, and one sonic anemometer at bow mast is used to characterize inflow atmospheric boundary conditions. Data characterizing wind over the deck at an incoming angle of 0° (head winds) and wind speeds from 2 to 10 m s−1 obtained in the Chesapeake Bay are presented and discussed. Turbulent statistics of inflow conditions are analyzed using the Kaimal universal turbulence spectral model for the atmospheric surface layer and show that for the present dataset this approach eliminates the need to account for platform motion in computing variances and covariances. Conditional sampling of mean flow and turbulence statistics at the flight deck indicate no statistically significant variations between unstable, stable, and neutral atmospheric inflow conditions, and the results agree with the published data for flows over the backward-facing step geometries.

scholarly journals An Analytical Prediction Model of Time Diversity Performance for Earth-Space Fade Mitigation

2008 ◽  
Vol 2008 ◽  
pp. 1-5 ◽  
Author(s):  
Pantelis-Daniel M. Arapoglou ◽  
Athanasios D. Panagopoulos ◽  
Panayotis G. Cottis
Keyword(s):  
Prediction Model ◽  
High Frequency ◽  
Rain Attenuation ◽  
Analytical Prediction ◽  
Time Dynamics ◽  
Time Diversity ◽  
Satellite Applications ◽  
Basic Parameters ◽  
Cost Efficient ◽  
General Prediction

Time diversity (TD) has recently attracted attention as a promising and cost-efficient solution for high-frequency broadcast satellite applications. The present work proposes a general prediction model for the application of TD by approximating the time dynamics of rain attenuation through the use of the joint lognormal distribution. The proposed method is tested against experimental data and its performance is investigated with respect to the basic parameters of a satellite link.

On the Combined Effect of Mean Flow and Acoustic Excitation on Structural Response and Radiation

1997 ◽  
Vol 119 (3) ◽  
pp. 448-456 ◽  
Author(s):  
A. Frendi ◽  
L. Maestrello
Keyword(s):  
Mach Number ◽  
Response Spectrum ◽  
Structural Response ◽  
Harmonic Excitation ◽  
Two Dimensions ◽  
Physical Problem ◽  
Acoustic Excitation ◽  
Mean Flow ◽  
Power Spectral ◽  
The Mean

Numerical experiments in two dimensions are carried out in order to investigate the response of a typical aircraft structure to a mean flow and an acoustic excitation. Two physical problems are considered; one in which the acoustic excitation is applied on one side of the flexible structure and the mean flow is on the other side while in the second problem both the mean flow and acoustic excitation are on the same side. Subsonic and supersonic mean flows are considered together with a random and harmonic acoustic excitation. In the first physical problem and using a random acoustic excitation, the results show that at low excitation levels the response is unaffected by the mean flow Mach number. However, at high excitation levels the structural response is significantly reduced by increasing the Mach number. In particular, both the shift in the frequency response spectrum and the broadening of the peaks are reduced. In the second physical problem, the results show that the response spectrum is dominated by the lower modes (1 and 3) for the subsonic mean flow case and by the higher modes (5 and 7) in the supersonic case. When a harmonic excitation is used, it is found that in the subsonic case the power spectral density of the structural response shows a subharmonic (f/4) while in the supersonic case no subharmonic is obtained.

scholarly journals Approximate Analytical Models of Shock-Wave Structure at Steady Mach Reflection

Fluids ◽  
2021 ◽  
Vol 6 (9) ◽  
pp. 305
Author(s):  
Mikhail V. Chernyshov ◽  
Karina E. Savelova ◽  
Anna S. Kapralova
Keyword(s):  
Experimental Data ◽  
Shock Wave ◽  
Comparative Analysis ◽  
Analytical Model ◽  
Mach Reflection ◽  
Supersonic Jet ◽  
Wave Structure ◽  
Analytical Models ◽  
Analytical Prediction ◽  
Shock Wave Structure

In this study, we obtain the comparative analysis of methods of quick approximate analytical prediction of Mach shock height in planar steady supersonic flows (for example, in supersonic jet flow and in narrowing channel between two wedges), that are developed since the 1980s and being actively modernized now. A new analytical model based on flow averaging downstream curved Mach shock is proposed, which seems more accurate than preceding models, comparing with numerical and experimental data.

Sign in / Sign up

Export Citation Format

Share Document