Influence of Blade Deformations on Open-Rotor Low-Speed and High-Speed Aerodynamics and Aeroacoustics

The present activity was carried out in the framework of the Clean Sky European research project ITURB (“Optimal High-Lift Turbine Blade Aero-Mechanical Design”), aimed at designing and validating a turbine blade for a geared open rotor engine. A cold-flow, large-scale, low-speed (LS) rig was built in order to investigate and validate new design criteria, providing reliable and detailed results while containing costs. This paper presents the design of a LS stage, and describes a general procedure that allows to scale 3D blades for low-speed testing. The design of the stator row was aimed at matching the test-rig inlet conditions and at providing the proper inlet flow field to the blade row. The rotor row was redesigned in order to match the performance of the high-speed one, compensating for both the compressibility effects and different turbine flow paths. The proposed scaling procedure is based on the matching of the 3D blade loading distribution between the real engine environment and the LS facility one, which leads to a comparable behavior of the boundary layer and hence to comparable profile losses. To this end, the datum blade is parameterized, and a neural-network-based methodology is exploited to guide an optimization process based on 3D RANS computations. The LS stage performance were investigated over a range of Reynolds numbers characteristic of modern low-pressure turbines by using a multi-equation, transition-sensitive, turbulence model.

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Influence of Blade Deformations on Open-Rotor Low-Speed and High-Speed Aerodynamics and Aeroacoustics

23rd AIAA/CEAS Aeroacoustics Conference ◽

10.2514/6.2017-3869 ◽

2017 ◽

Cited By ~ 2

Author(s):

Fabrice Falissard ◽

Alain Chelius ◽

Ronan Boisard ◽

Robert Gaveriaux ◽

Sylvette Canard-Caruana ◽

...

Keyword(s):

High Speed ◽

Low Speed ◽

Open Rotor

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Do You Name Speedy Objects Faster Than Slow Objects: SPEEDED NAMING OR NAMING SPEED? THE AUTOMATIC EFFECT OF OBJECT SPEED ON PERFORMANCE

10.31234/osf.io/78b3h ◽

2018 ◽

Author(s):

Moshe Shay Ben-Haim ◽

Eran Chajut ◽

Ran Hassin ◽

Daniel Algom

Keyword(s):

High Speed ◽

Mental Representations ◽

Reading Aloud ◽

Naming Task ◽

Naming Speed ◽

Low Speed ◽

Everyday Objects ◽

Pictures And Words

we test the hypothesis that naming an object depicted in a picture, and reading aloud an object’s name, are affected by the object’s speed. We contend that the mental representations of everyday objects and situations include their speed, and that the latter influences behavior in instantaneous and systematic ways. An important corollary is that high-speed objects are named faster than low-speed objects despite the fact that object speed is irrelevant to the naming task at hand. The results of a series of 7 studies with pictures and words support these predictions.

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Splatters and Aerosols Contamination in Dental Aerosol Generating Procedures

Applied Sciences ◽

10.3390/app11041914 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1914

Author(s):

Pingping Han ◽

Honghui Li ◽

Laurence J. Walsh ◽

Sašo Ivanovski

Keyword(s):

Particle Size ◽

Disease Transmission ◽

High Speed ◽

Low Speed ◽

Dental Procedures ◽

Dental Equipment ◽

Produce Contamination ◽

Fluorescein Dye ◽

Filter Papers ◽

Airborne Disease

Dental aerosol-generating procedures produce a large amount of splatters and aerosols that create a major concern for airborne disease transmission, such as COVID-19. This study established a method to visualise splatter and aerosol contamination by common dental instrumentation, namely ultrasonic scaling, air-water spray, high-speed and low-speed handpieces. Mock dental procedures were performed on a mannequin model, containing teeth in a typodont and a phantom head, using irrigation water containing fluorescein dye as a tracer. Filter papers were placed in 10 different locations to collect splatters and aerosols, at distances ranging from 20 to 120 cm from the source. All four types of dental equipment produced contamination from splatters and aerosols. At 120 cm away from the source, the high-speed handpiece generated the greatest amount and size (656 ± 551 μm) of splatter particles, while the triplex syringe generated the largest amount of aerosols (particle size: 1.73 ± 2.23 μm). Of note, the low-speed handpiece produced the least amount and size (260 ± 142 μm) of splatter particles and the least amount of aerosols (particle size: 4.47 ± 5.92 μm) at 120 cm. All four dental AGPs produce contamination from droplets and aerosols, with different patterns of distribution. This simple model provides a method to test various preventive strategies to reduce risks from splatter and aerosols.

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Nonlinear transport of rarefied Couette flows from low speed to high speed

Physics of Fluids ◽

10.1063/5.0029680 ◽

2020 ◽

Vol 32 (11) ◽

pp. 112021

Author(s):

Jihui Ou ◽

Jie Chen

Keyword(s):

High Speed ◽

Nonlinear Transport ◽

Low Speed

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Energy Absorption Characteristics of PVC Coarse Aggregate Concrete under Impact Load

International Journal of Concrete Structures and Materials ◽

10.1186/s40069-021-00465-w ◽

2021 ◽

Vol 15 (1) ◽

Author(s):

Shi Hu ◽

Huaming Tang ◽

Shenyao Han

Keyword(s):

Compressive Strength ◽

Energy Absorption ◽

High Speed ◽

Coarse Aggregate ◽

Specific Energy Absorption ◽

Low Speed ◽

High Speed Impact ◽

Aggregate Content ◽

Dynamic Compressive Strength ◽

Absorption Characteristics

AbstractIn this paper, polyvinyl chloride (PVC) coarse aggregate with different mixing contents is used to solve the problems of plastic pollution, low energy absorption capacity and poor damage integrity, which provides an important reference for PVC plastic concrete used in the initial support structures of highway tunnels and coal mine roadway. At the same time, the energy absorption characteristics and their relationship under different impact loads are studied, which provides an important reference for predicting the energy absorption characteristics of concrete under other PVC aggregate content or higher impact speed. This study replaced natural coarse aggregate in concrete with different contents and equal volume of well-graded flaky PVC particles obtained by crushing PVC soft board. Also, slump, compression, and splitting strength tests, a free falling low-speed impact test of steel balls and a high-speed impact compression test of split Hopkinson pressure bar (SHPB) were carried out. Results demonstrate that the static and dynamic compressive strength decreases substantially, and the elastic modulus and slump decrease slowly with the increase of the mixing amount of PVC aggregate (0–30%). However, the energy absorption rate under low-speed impact and the specific energy absorption per MPa under high-speed impact increase obviously, indicating that the energy absorption capacity is significantly enhanced. Regardless of the mixing amount of PVC aggregate, greater strain rate can significantly enhance the dynamic compressive strength and the specific energy absorption per MPa. After the uniaxial compression test or the SHPB impact test, the relative integrity of the specimen is positively correlated with the mixing amount of PVC aggregate. In addition, the specimens are seriously damaged with the increase of the impact strain rate. When the PVC aggregate content is 20%, the compressive strength and splitting strength of concrete are 33.8 MPa and 3.26 MPa, respectively, the slump is 165 mm, the energy absorption rate under low-speed impact is 89.5%, the dynamic compressive strength under 0.65 Mpa impact air pressure is 58.77 mpa, and the specific energy absorption value per MPa is 13.33, which meets the requirements of shotcrete used in tunnel, roadway support and other impact loads. There is a linear relationship between the energy absorption characteristics under low-speed impact and high-speed impact. The greater the impact pressure, the larger the slope of the fitting straight line. The slope and intercept of the fitting line also show a good linear relationship with the increase of impact pressure. The conclusions can be used to predict the energy absorption characteristics under different PVC aggregate content or higher-speed impact pressure, which can provide important reference for safer, more economical, and environmental protection engineering structure design.

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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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