The influence of freestream turbulence on the temporal pressure distribution and lift of an airfoil

Measurements of the Effects of Freestream Turbulence on Separation-Bubble Transition

Volume 3: Turbo Expo 2002, Parts A and B ◽

10.1115/gt2002-30232 ◽

2002 ◽

Cited By ~ 13

Author(s):

M. I. Yaras

Keyword(s):

Pressure Distribution ◽

Separation Bubble ◽

Reynolds Numbers ◽

Pressure Gradients ◽

Freestream Turbulence ◽

Test Plate ◽

Laminar To Turbulent Transition ◽

Turbulent Transition ◽

Boundary Layer Development ◽

Layer Development

In this paper, measurements are presented on the effects of freestream turbulence on laminar-to-turbulent transition in separation bubbles, and correlations are proposed for the locations of transition and reattachment on the basis of this data. The boundary layer development is measured on a smooth, flat plate upon which streamwise pressure gradients are imposed by a flexible, contoured wall opposite to the test plate. Two variations in the streamwise pressure distribution are investigated, and two Reynolds numbers are considered for each pressure-gradient setting. For each combination of pressure distribution and Reynolds number, the freestream turbulence intensity and length scale are adjusted systematically by varying the open-area-ratio and cell size of the grid installed at the test-section inlet. Measured quantities consist of velocity obtained with a single-hot wire probe and surface pressures measured through pressure taps.

Download Full-text

Impact Pressure Distribution on a Monopile Structure Excited by Irregular Breaking Wave

Polish Maritime Research ◽

10.2478/pomr-2018-0019 ◽

2018 ◽

Vol 25 (s1) ◽

pp. 29-35 ◽

Cited By ~ 2

Author(s):

Duje Veic ◽

Wojciech Sulisz

Keyword(s):

Pressure Distribution ◽

Load Distribution ◽

Breaking Waves ◽

Impact Pressure ◽

Engineering Practice ◽

Breaking Wave ◽

Vertical Load ◽

Shape Distribution ◽

Significant Difference ◽

Temporal Pressure

Abstract The problem of impact pressure distribution on a monopole structure excited by irregular breaking waves is investigated. The analysis is performed by applying a numerical model that combines potential flow model with a Navier-Stokes/VOF solution. The temporal pressure distribution is analysed for two breaking wave cases characterized by the significant difference in the steepness of the wave front. The peak impact pressures are observed in the region below the overturning wave jet where the pressure increases rapidly resulting in a peak value of the slamming coefficient equal to Cs=2π. The vertical load distribution provided by the derived model is more realistic than a rectangular shape distribution applied in engineering practice. This is because the vertical load distribution strongly depends on breaking wave shape and it is difficult to uniquely approximate such a load distribution by a rectangle.

Download Full-text

Pressure Distribution Patterns under the Feet of New Walkers: The First Two Months of Independent Walking

Foot & Ankle International ◽

10.1177/107110070302400513 ◽

2003 ◽

Vol 24 (5) ◽

pp. 444-453 ◽

Cited By ~ 37

Author(s):

Ann Hallemans ◽

Kristiaan D'Août ◽

Dirk De Clercq ◽

Peter Aerts

Keyword(s):

Pressure Distribution ◽

Contact Area ◽

Center Of Pressure ◽

Distribution Patterns ◽

Load Bearing ◽

Plantar Surface ◽

Temporal Pressure ◽

Foot Function ◽

Spatio Temporal ◽

Improve Stability

In order to describe foot function during the first weeks of independent walking, spatio-temporal pressure distribution patterns were measured. These data give detailed information about roll-off of the foot, by determining the course of the center of pressure, and about load bearing, by calculating relative vertical impulses under the feet. During those first weeks of independent walking, roll-off is very unstable. Although infants can occasionally perform a mature roll-off, a consistent pattern has not yet developed and there is instability. To improve stability the entire plantar surface area contributes to load bearing – first, because a larger contact area will improve stability, and second, because a forward shifting of the load allows more muscular control to compensate for minor imbalances under the foot.

Download Full-text

Experimental and numerical study on hydrodynamic impact of a disk in pure and aerated water

Proceedings of the Institution of Mechanical Engineers Part M Journal of Engineering for the Maritime Environment ◽

10.1177/1475090220933700 ◽

2020 ◽

pp. 147509022093370

Author(s):

Yao Hong ◽

Benlong Wang ◽

Hua Liu

Keyword(s):

Pressure Distribution ◽

Void Fraction ◽

High Speed ◽

Numerical Study ◽

Pure Water ◽

Equation Model ◽

Impact Loads ◽

Temporal Pressure ◽

Drop Tests ◽

The Impact

The hydrodynamic loads of a disk impacting pure and aerated water are investigated experimentally and numerically. Experiments are performed on a rigid disk with different aeration levels and focus on the spatial and temporal pressure distribution. Drop tests are conducted by a specially designed apparatus to prevent the variation of velocity during the slamming period. A specially designed bubble generator, able to adjust the void fraction, is utilized to generate uniform and tiny bubbles. A high-speed camera is utilized to record the water spray and splash curtain. A homemade compressible multiphase solver based on the reduced five equation model is adopted to evaluate the impact loads, which assumes the water and bubbles sharing the same velocity and pressure. The results show that bubbles in the water have a significant influence on the impact loads. As the void fraction increases from zero to nearly 1%, the peak impact pressure is reduced considerably and the impact duration is becoming obviously longer. In aerated water impact, the disk has a more uniform pressure distribution on the surface. However, the pressure impulse in aerated impact tests is basically unchanged compared with that in pure water.

Download Full-text

FlowHaptics: MidairHaptic Representation of Liquid Flow

Applied Sciences ◽

10.3390/app11188447 ◽

2021 ◽

Vol 11 (18) ◽

pp. 8447

Author(s):

Photchara Ratsamee ◽

Yusuke Orita ◽

Yoshihiro Kuroda ◽

Haruo Takemura

Keyword(s):

Velocity Profile ◽

Pressure Distribution ◽

Flow Velocity ◽

Dimensional Space ◽

Subjective Evaluation ◽

Fluid Simulation ◽

Flowing Water ◽

Air Jets ◽

Distribution Change ◽

Temporal Pressure

Water is an essential substance for humans in their daily lives. There are many opportunities for us to come in contact with water, such as cooking, bathing, and swimming. However, few studies have reproduced the sensation of water touching the skin. This study aims to propose a novel midair haptic device, named FlowHaptics, that reproduces the feeling of the force of flowing water over human fingers using multiple air jets. We first estimated the temporal pressure distribution change of water in two-dimensional space using machine-learning-accelerated fluid simulation. We controlled the airflow based on the pressure distribution change obtained from the fluid simulation to reproduce the feeling of flowing water over the fingers using our proposed device, which can control multiple air jets in real time. We performed a psycho-physical evaluation of different flow velocities and a subjective evaluation of different velocity profiles. We found that FlowHaptics reliably created the illusion of the pressure distribution of flowing water on the fingers where the flow velocity could be distinguished within the range of 8.42% to 13.05%, and our estimated flow velocity profile with the configuration of three air jets felt more similar to flowing water when compared to a constant velocity profile according to the users.

Download Full-text