State-of-the-art of high-speed propeller noise prediction - A multidisciplinary approach and comparison with measured data

High-speed propeller noise prediction - A multidisciplinary approach

AIAA Journal ◽

10.2514/3.11128 ◽

1992 ◽

Vol 30 (7) ◽

pp. 1716-1723 ◽

Cited By ~ 6

Author(s):

Mark H. Dunn ◽

F. Farassat

Keyword(s):

High Speed ◽

Multidisciplinary Approach ◽

Noise Prediction ◽

Propeller Noise

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Neuro-Inspired Computing with Spin-VCSELs

Applied Sciences ◽

10.3390/app11094232 ◽

2021 ◽

Vol 11 (9) ◽

pp. 4232

Author(s):

Krishan Harkhoe ◽

Guy Verschaffelt ◽

Guy Van der Sande

Keyword(s):

Processing Speed ◽

Delay Time ◽

High Speed ◽

State Of The Art ◽

Polarization Modulation ◽

Time Interval ◽

Computing Technique ◽

High Modulation ◽

Short Time ◽

Modulation Speed

Delay-based reservoir computing (RC), a neuromorphic computing technique, has gathered lots of interest, as it promises compact and high-speed RC implementations. To further boost the computing speeds, we introduce and study an RC setup based on spin-VCSELs, thereby exploiting the high polarization modulation speed inherent to these lasers. Based on numerical simulations, we benchmarked this setup against state-of-the-art delay-based RC systems and its parameter space was analyzed for optimal performance. The high modulation speed enabled us to have more virtual nodes in a shorter time interval. However, we found that at these short time scales, the delay time and feedback rate heavily influence the nonlinear dynamics. Therefore, and contrary to other laser-based RC systems, the delay time has to be optimized in order to obtain good RC performances. We achieved state-of-the-art performances on a benchmark timeseries prediction task. This spin-VCSEL-based RC system shows a ten-fold improvement in processing speed, which can further be enhanced in a straightforward way by increasing the birefringence of the VCSEL chip.

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Cavitation patterns in high-pressure homogenization nozzles with cylindrical orifices: Influence of mixing stream in Simultaneous Homogenization and Mixing

Experimental and Computational Multiphase Flow ◽

10.1007/s42757-020-0088-9 ◽

2021 ◽

Author(s):

V. Gall ◽

E. Rütten ◽

H. P. Karbstein

Keyword(s):

High Pressure ◽

Process Design ◽

High Speed ◽

State Of The Art ◽

Back Pressure ◽

High Pressure Homogenization ◽

Unit Operation ◽

Mixing Chamber ◽

Cavitation Intensity ◽

Droplet Sizes

AbstractHigh-pressure homogenization is the state of the art to produce high-quality emulsions with droplet sizes in the submicron range. In simultaneous homogenization and mixing (SHM), an additional mixing stream is inserted into a modified homogenization nozzle in order to create synergies between the unit operation homogenization and mixing. In this work, the influence of the mixing stream on cavitation patterns after a cylindrical orifice is investigated. Shadow-graphic images of the cavitation patterns were taken using a high-speed camera and an optically accessible mixing chamber. Results show that adding the mixing stream can contribute to coalescence of cavitation bubbles. Choked cavitation was observed at higher cavitation numbers σ with increasing mixing stream. The influence of the mixing stream became more significant at a higher orifice to outlet ratio, where a hydraulic flip was also observed at higher σ. The decrease of cavitation intensity with increasing back-pressure was found to be identical with conventional high-pressure homogenization. In the future, the results can be taken into account in the SHM process design to improve the efficiency of droplet break-up by preventing cavitation or at least hydraulic flip.

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Nutritional Optic Neuropathies: State of the Art and Emerging Evidences

Nutrients ◽

10.3390/nu12092653 ◽

2020 ◽

Vol 12 (9) ◽

pp. 2653

Author(s):

Matilde Roda ◽

Natalie di Geronimo ◽

Marco Pellegrini ◽

Costantino Schiavi

Keyword(s):

Bariatric Surgery ◽

Optic Neuropathy ◽

Multidisciplinary Approach ◽

State Of The Art ◽

Signs And Symptoms ◽

Therapeutic Strategies ◽

Scientific Interest ◽

Optic Nerve Atrophy ◽

Prompt Diagnosis

Nutritional optic neuropathy is a cause of bilateral, symmetrical, and progressive visual impairment with loss of central visual acuity and contrast sensitivity, dyschromatopsia, and a central or centrocecal scotoma. The clinical features are not pathognomonic, since hereditary and toxic forms share similar signs and symptoms. It is becoming increasingly common due to the widespread of bariatric surgery and strict vegetarian or vegan diets, so even the scientific interest has recently increased. In particular, recent studies have focused on possible pathogenetic mechanisms, and on novel diagnostic and therapeutic strategies in order to prevent the onset, make a prompt diagnosis and an accurate nutritional supplementation, and to avoid irreversible optic nerve atrophy. Nowadays, there is clear evidence of the role of cobalamin, folic acid, thiamine, and copper, whereas further studies are needed to define the role of niacin, riboflavin, and pyridoxine. This review aims to summarize the etiology, diagnosis, and treatment of nutritional optic neuropathy, and it is addressed not only to ophthalmologists, but to all physicians who could come in contact with a patient with a possible nutritional optic neuropathy, being a fundamental multidisciplinary approach.

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The Influence of the Axial Rub Added in the Radial Rub on the Wear of the Seal Fins during the High Speed Rub of Labyrinth-Honeycomb Seal

Materials ◽

10.3390/ma14081997 ◽

2021 ◽

Vol 14 (8) ◽

pp. 1997

Author(s):

Bin Lu ◽

Haijun Xuan ◽

Xiaojian Ma ◽

Fangjun Han ◽

Weirong Hong ◽

...

Keyword(s):

Wear Rate ◽

High Speed ◽

State Of The Art ◽

Negative Influence ◽

Axial Thrust ◽

Cross Sectional ◽

Honeycomb Seal ◽

Aero Engine ◽

Honeycomb Seals ◽

Clearance Change

Labyrinth-honeycomb seals are a state-of-the-art sealing technology commonly used in aero-engine interstage seal. The undesirable severe rub between the seal fins and the honeycomb due to the clearance change may induce the cracking of the seal fins. A pervious study investigated the wear of the seal fins at different radial incursion rates. However, due to the axial thrust and mounting clearance, the axial rub between the seal fins and the honeycomb may occur. Hence, this paper focuses on the influence of the axial rub added in the radial rub on the wear of the seal fins. The rub tests results, including rubbing forces and temperature, wear rate, worn morphology, cross-sectional morphology and energy dispersive spectroscopy results, are presented and discussed. Overall, the participation of the axial rub leads to higher rubbing forces, temperature, and wear rate. The tribo-layer on the seal fin is thicker and the cracks are more obvious at high axial incursion rate. These phenomena indicate the axial rub has a negative influence on the wear of the seal fins and should be avoided.

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Data-Driven Structural Health Monitoring and Damage Detection through Deep Learning: State-of-the-Art Review

Sensors ◽

10.3390/s20102778 ◽

2020 ◽

Vol 20 (10) ◽

pp. 2778 ◽

Cited By ~ 12

Author(s):

Mohsen Azimi ◽

Armin Eslamlou ◽

Gokhan Pekcan

Keyword(s):

Deep Learning ◽

Structural Health Monitoring ◽

Health Monitoring ◽

High Speed ◽

Deep Neural Networks ◽

State Of The Art ◽

Data Driven ◽

Structural Health ◽

Promising Tool ◽

Significant Attention

Data-driven methods in structural health monitoring (SHM) is gaining popularity due to recent technological advancements in sensors, as well as high-speed internet and cloud-based computation. Since the introduction of deep learning (DL) in civil engineering, particularly in SHM, this emerging and promising tool has attracted significant attention among researchers. The main goal of this paper is to review the latest publications in SHM using emerging DL-based methods and provide readers with an overall understanding of various SHM applications. After a brief introduction, an overview of various DL methods (e.g., deep neural networks, transfer learning, etc.) is presented. The procedure and application of vibration-based, vision-based monitoring, along with some of the recent technologies used for SHM, such as sensors, unmanned aerial vehicles (UAVs), etc. are discussed. The review concludes with prospects and potential limitations of DL-based methods in SHM applications.

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Advanced open rotor noise prediction

The Aeronautical Journal ◽

10.1017/s0001924000009817 ◽

2014 ◽

Vol 118 (1208) ◽

pp. 1125-1135 ◽

Cited By ~ 4

Author(s):

M. J. Kingan

Keyword(s):

High Speed ◽

Broadband Noise ◽

Current Status ◽

Prediction Methods ◽

Noise Prediction ◽

Acoustic Data ◽

Rotor Noise ◽

Future Challenges ◽

Open Rotor ◽

Development And Validation

Abstract The purpose of this paper is to describe the current status of open rotor noise prediction methods and to highlight future challenges in this area. A number of analytic and numerical methods are described which can be used for predicting ‘isolated’ and ‘installed’ open rotor tonal noise. Broadband noise prediction methods are also described and it is noted that further development and validation of the current models is required. The paper concludes with a discussion of the analytical methods which are used to assess the acoustic data collected during the high-speed wind-tunnel testing of a model scale advanced open rotor rig.

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Jet-Surface Interaction Test: Far-Field Noise Results

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4023605 ◽

2013 ◽

Vol 135 (7) ◽

Cited By ~ 44

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.

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