scholarly journals Experimental Observation of Inertial Particles through Idealized Hydroturbine Distributor Geometry

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 471 ◽  
Author(s):  
Samuel Harding ◽  
Marshall Richmond ◽  
Robert Mueller
Keyword(s):  
High Speed ◽  
Laboratory Data ◽  
Bead Geometry ◽  
Inertial Particles ◽  
Video Cameras ◽  
Through Flow ◽  
Flow Speeds ◽  
Biological Performance ◽  
Neutrally Buoyant ◽  
Collision Target

To increase and maintain existing hydropower capacity within biological performance-based regulations, predictive simulation methods are needed that can reliably estimate the risk to fish passing through flow passage routes at hydropower facilities. One of the central challenges is to validate the software capabilities for simulating the trajectories, including collisions, of inertial particles against laboratory data. In this work, neutrally buoyant spherical- and rod-shaped beads were released upstream of laboratory-scale geometries representative of the distributor of a hydroturbine. The experimental campaign involved a test matrix of 24 configurations with variations in bead geometry, collision target geometry, flow speeds, and release locations. A total of more than 10,000 beads were recorded using high-speed video cameras and analyzed using particle tracking software. Collision rates from 1–7% were observed for the cylinder geometry and rates of 1–23% were observed for the vane array over the range of test configurations.

High-speed impacts of slender bodies into non-smooth, complex fluids

2018 ◽  
Vol 861 ◽  
Author(s):  
Ishan Sharma
Keyword(s):  
Penetration Depth ◽  
High Speed ◽  
Complex Fluids ◽  
Laboratory Data ◽  
Impact Speed ◽  
High Speed Impact ◽  
Smooth Complex ◽  
Theoretical Predictions ◽  
Slender Bodies ◽  
The Impact

We present a simple hydrodynamical model for the high-speed impact of slender bodies into frictional geomaterials such as soils and clays. We model these materials as non-smooth, complex fluids. Our model predicts the evolution of the impactor’s speed and the final penetration depth given the initial impact speed, and the material and geometric parameters of the impactor and the impacted material. As an application, we investigate the impact of deep-penetrating anchors into seabeds. Our theoretical predictions are found to match field and laboratory data very well.

Flow Visualization and Forces From a Squeeze Film Damper Operating With Natural Air Entrainment

2003 ◽  
Vol 125 (2) ◽  
pp. 325-333 ◽  
Author(s):  
Luis San Andre´s ◽  
Sergio E. Diaz
Keyword(s):  
High Speed ◽  
Air Entrainment ◽  
Squeeze Film ◽  
Natural Phenomenon ◽  
Squeeze Film Damper ◽  
Feed Pressure ◽  
Video Recordings ◽  
Free Air ◽  
Through Flow ◽  
Discharge Operation

Measurements of dynamic film pressures and high-speed photographs of the flow field in an open-ended Squeeze Film Damper (SFD) operating with natural free air entrainment are presented for increasing whirl frequencies (8.33–50 Hz), and a range of feed pressures to 250 kPa (37 psig). The flow conditions range from lubricant starvation (air ingestion) to a fully flooded discharge operation. The test dynamic pressures and video recordings show that air entrainment leads to large and irregular gas fingering and striation patterns. This is a natural phenomenon in SFDs operating with low levels of external pressurization (reduced lubricant through flow rates). Air ingestion and entrapment becomes more prevalent as the whirl frequency raises, and increasing the feed pressure aids little to ameliorate the loss in dynamic forced performance. As a result of the severity of air entrainment, experimentally estimated damping forces decrease steadily as the whirl frequency (operating speed) increases.

scholarly journals Standard of the Initial Ball Velocity for a Fly Ball in Baseball Hitting

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 137
Author(s):  
Hirotaka Nakashima ◽  
Gen Horiuchi ◽  
Shinji Sakurai
Keyword(s):  
Initial Velocity ◽  
High Speed ◽  
Baseball Players ◽  
Ball Impact ◽  
Video Cameras ◽  
High Speed Video ◽  
Before And After ◽  
Ball Velocity ◽  
Opposite Field ◽  
Measuring Tape

This study aimed to determine the minimum required initial velocity to hit a fly ball toward the same field (left-field for right-handed batters), center field, and opposite field (right field for right-handed batters). Six baseball players hit fastballs launched by a pitching machine. The movements of the balls before and after bat-to-ball impact were recorded using two high-speed video cameras. The flight distance was determined using a measuring tape. Seventy-nine trials were analyzed, and the minimum required initial velocities of batted balls were quantified to hit balls 60, 70, 80, 90, 100, 110, and 120 m in each direction through regression analysis. As a result, to hit a ball 120 m, initial velocities of 43.0, 43.9, and 46.0 m/s were required for the same field, center field, and opposite field, respectively. The result provides a useful index for batters to hit a fly ball in each of the directions.

Design-Optimization Approach to Multistage Axial Contra-Rotating Turbines

2013 ◽  
Author(s):  
Ernesto Sozio ◽  
Tom Verstraete ◽  
Guillermo Paniagua
Keyword(s):  
High Speed ◽  
Differential Evolution Algorithm ◽  
Design Procedure ◽  
Second Step ◽  
Optimization Approach ◽  
Rocket Engines ◽  
Multi Stage ◽  
Through Flow ◽  
Evolution Algorithm ◽  
Turbine Airfoils

Air Turbo Rocket engines, suitable for high-speed propulsion, require compact turbomachinery. This paper presents the design of an innovative multi-stage turbine mounted at the hub of a counter-rotating fan. Hence, the turbine airfoils are required to deliver high torque at low peripheral speeds. The design methodology specifically developed for this fourteen-stage turbine relies on two successive optimization cycles. The first one is based on a through-flow 1D code. This optimization cycle explores a vast set of possible design solutions. In a second step, an optimization using a 3D high fidelity RANS defines the 3D airfoil geometry. In order to accelerate the entire design procedure, a special routine was developed to morph the 1D results into the required info for the 3D optimization. Both the 1D and 3D optimizations are based on differential evolution algorithm.

The ignition of a thin layer of explosive by impact

1974 ◽  
Vol 338 (1612) ◽  
pp. 77-93 ◽  
Keyword(s):  
Pressure Drop ◽  
Thin Layer ◽  
High Speed ◽  
Large Scale ◽  
Flow Speed ◽  
Thin Layers ◽  
Drop Weight ◽  
Flow Speeds ◽  
Show Evidence ◽  
Weight Impact

The behaviour of thin layers of solid materials under drop-weight impact is studied with the aid of high-speed photographic and pressure-measuring techniques. Photographic sequences taken with a high-speed framing camera show that explosive materials suffer large-scale deformation before initiation of explosion. The sample may undergo plastic flow in bulk, show evidence of partial fusion, and even (with PETN) melt completely. There is also evidence of Munroe jetting and instability of flow of material at the anvil/layer interfaces. The flow speed of the sample during these processes is considerable and may reach 300 m/s. When ignition of the layer occurs it does so at a small number of local hot spots, following which rapid combustion develops at speeds of 200-700 m/s. Strain-gauge measurements show that the pressures attained during drop-weight impact are typically 0.5-1 GPa (5–10 kbar) and the duration of impact 300–500 μs. In the course of impact of a thin layer of granular material a sharp pressure drop may occur, frequently from several hundred MPa down to zero. With an explosive layer, ignition occurs immediately following the instant of the pressure drop. The sudden fall in pressure is due to mechanical failure of the sample, and correlation of the two experiments shows that this is the cause of the very high flow speeds attained during impact. On the basis of these results a possible mechanism of ignition is suggested.

scholarly journals Eddy diffusivity of quasi-neutrally-buoyant inertial particles

2018 ◽  
Vol 3 (4) ◽  
Author(s):  
Marco Martins Afonso ◽  
Paolo Muratore-Ginanneschi ◽  
Sílvio M. A. Gama ◽  
Andrea Mazzino
Keyword(s):  
Eddy Diffusivity ◽  
Inertial Particles ◽  
Neutrally Buoyant

Visualizing Flow Partitioning in a Model of the Upper Human Lung Airways

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
K. Bauer ◽  
H. Chaves ◽  
Ch. Brücker
Keyword(s):  
High Speed ◽  
Reynolds Numbers ◽  
Tracheobronchial Tree ◽  
Convective Transport ◽  
Upper Airways ◽  
Light Pulses ◽  
Tracer Particles ◽  
Number Of Cycles ◽  
Clinical Conditions ◽  
Neutrally Buoyant

The convective transport of fluid within the human upper airways is investigated in a transparent model of the tracheobronchial tree. Oscillatory flow through the branching network with six generations was studied at varying Reynolds numbers between 400 and 2600 and Womersley numbers from 5.5 to 12.3 in the trachea representing clinical conditions during high frequency oscillatory ventilation. The flow partitioning within the model was visualized using advection of neutrally buoyant tracer particles, which were illuminated by short light pulses and recorded by a high speed camera. Integration of the particle locations for a large number of cycles provides the probability distribution of particles passing certain branches within the bifurcating network, and thus, the dispersion of particles in the airways. The results show the different characteristics of flow partitioning at varying Womersley and Reynolds numbers.

Modeling a Viscoelastic Gymnastics Landing Mat during Impact

2006 ◽  
Vol 22 (2) ◽  
pp. 103-111 ◽  
Author(s):  
Chris Mills ◽  
Matthew T.G. Pain ◽  
Maurice R. Yeadon
Keyword(s):  
High Speed ◽  
Force Plate ◽  
System Model ◽  
Video Cameras ◽  
Key Characteristics ◽  
Single Mass ◽  
Force Time ◽  
Mass Spring ◽  
The Impact ◽  
Landing Mat

Landing mats that can undergo a large amount of area deformation are now essential for the safe completion of landings in gymnastics. The objective of this study was to develop an analytical model of a landing mat that reproduces the key characteristics of the mat-ground force during impact with minimal simulation run time. A force plate and two high-speed video cameras were used to record the mat deformation during vertical drop testing of a 24-kg impactor. Four increasingly complex point mass spring-damper models, from a single mass spring-damper system, Model 1, to a 3-layer mass spring-damper system, Model 4, were constructed using Matlab to model the mat's behavior during impact. A fifth model composed of a 3-layer mass spring-damper system was developed using visual Nastran 4D. The results showed that Models 4 and 5 were able to match the loading phase of the impact with simulation times of less than 1 second for Model 4 and 28 seconds for Model 5. Both Models 4 and 5 successfully reproduced the key force-time characteristics of the mat-ground interface, such as peak forces, time of peak forces, interpeak minima and initial rates of loading, and could be incorporated into a gymnast-mat model.

scholarly journals Development and Evaluation of an Autonomous Sensor for the Observation of Sediment Motion*

2014 ◽  
Vol 31 (4) ◽  
pp. 1012-1019 ◽  
Author(s):  
Donya Frank ◽  
Diane Foster ◽  
Pai Chou ◽  
Yu-Min Kao ◽  
In Mei Sou ◽  
...  
Keyword(s):  
High Speed ◽  
Coastal Sediments ◽  
Angle Of Repose ◽  
Incipient Motion ◽  
Stress Criterion ◽  
Video Cameras ◽  
Mobile Bed ◽  
Autonomous Sensor ◽  
Lagrangian Observations ◽  
Lagrangian Measurements

Abstract Measurements within the mobile bed layer have been limited by previous Eulerian-based technologies. A microelectromechanical system device, called a smart sediment grain (SSG), that can measure and record Lagrangian observations of coastal sediments at incipient motion has been developed. These sensors have the potential to resolve fundamental hypotheses regarding the incipient motion of coastal sediments. Angle of repose experiments verified that the sensor enclosure has mobility characteristics similar to coarse gravel. Experiments conducted in a small oscillating flow tunnel verified that the sensors detect incipient motion under various hydrodynamic conditions. Evidence suggests the influence of pressure-gradient-induced sediment motion, contrary to the more commonly assumed bed shear stress criterion. Lagrangian measurements of rotation measured with the newly developed SSG agreed to within 5% of the rotation estimates made simultaneously with high-speed video cameras.

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