scholarly journals Experimental Testing of a Small-Scale Truss Beam That Adapts to Loads Through Large Shape Changes

2019 ◽  
Vol 5 ◽  
Author(s):  
Arka P. Reksowardojo ◽  
Gennaro Senatore ◽  
Ian F. C. Smith
Keyword(s):  
Experimental Testing ◽  
Small Scale ◽  
Shape Changes ◽  
Large Shape

scholarly journals Design and control of a prototype structure that adapts to loading through large shape changes

2020 ◽  
Vol 53 (2) ◽  
pp. 8377-8382
Author(s):  
Arka P. Reksowardojo ◽  
Gennaro Senatore ◽  
Apoorv Srivastava ◽  
Ian F.C. Smith ◽  
Henry Unterreiner ◽  
...  
Keyword(s):  
Prototype Structure ◽  
And Control ◽  
Shape Changes ◽  
Large Shape

Experimental Testing and Numerical Modeling of Small-Scale Boat With Drag-Reducing Air-Cavity System

2021 ◽  
Author(s):  
Jeffrey M. Collins ◽  
Phillip R. Whitworth ◽  
Konstantin I. Matveev
Keyword(s):  
Adaptive Mesh Refinement ◽  
Experimental Testing ◽  
Hydrodynamic Performance ◽  
Small Scale ◽  
Video Monitor ◽  
Data Logger ◽  
Time Step ◽  
Experimental Conditions ◽  
Air Cavity ◽  
Air Supply

Abstract Hydrodynamic performance of ships can be greatly improved by the formation of air cavities under ship bottom with the purpose to decrease water friction on the hull surface. The air-cavity ships using this type of drag reduction are usually designed for and typically effective only in a relatively narrow range of speeds and hull attitudes and sufficient rates of air supply to the cavity. To investigate the behavior of a small-scale air-cavity boat operating under both favorable and detrimental loading and speed conditions, a remotely controlled model hull was equipped with a data acquisition system, video camera and onboard sensors to measure air-cavity characteristics, air supply rate and the boat speed, thrust and trim in operations on open-water reservoirs. These measurements were captured by a data logger and also wirelessly transmitted to a ground station and video monitor. The experimental air-cavity boat was tested in a range of speeds corresponding to length Froude numbers between 0.17 and 0.5 under three loading conditions, resulting in near zero trim and significant bow-up and bow-down trim angles at rest. Reduced cavity size and significantly increased drag occurred when operating at higher speeds, especially in the bow-up trim condition. The other objective of this study was to determine whether computational fluid dynamics simulations can adequately capture the recorded behavior of the boat and air cavity. A computational software Star-CCM+ was utilized with the VOF method employed for multi-phase flow, RANS approach for turbulence modeling, and economical mesh settings with refinements in the cavity region and near free surface. Upon conducting the mesh verification study, several experimental conditions were simulated, and approximate agreement with measured test data was found. Adaptive mesh refinement and time step controls were also applied to compare results with those obtained on the user-generated mesh. Adaptive controls improved resolution of complex shedding patterns from the air cavity but had little impact on overall results. The presented here experimental approach and obtained results indicate that both outdoor experimentation and computationally inexpensive modeling can be used in the process of developing air-cavity systems for ship hulls.

A Dynamic Service-Oriented Distributed Computing Framework for Evaluation of Computationally Expensive Black-Box Analyses

2014 ◽  
Author(s):  
George H. Cheng ◽  
Chao Qi ◽  
G. Gary Wang
Keyword(s):  
Distributed Computing ◽  
Service Oriented Architecture ◽  
Experimental Testing ◽  
Black Box ◽  
Small Scale ◽  
Distributed Computing Networks ◽  
Service Oriented ◽  
Computationally Expensive ◽  
Computing Framework ◽  
Load Balancing Algorithm

A practical, flexible, versatile, and heterogeneous distributed computing framework is presented that simplifies the creation of small-scale local distributed computing networks for the execution of computationally expensive black-box analyses. The framework is called the Dynamic Service-oriented Optimization Computing Framework (DSOCF), and is designed to parallelize black-box computation to speed up optimization runs. It is developed in Java and leverages the Apache River project, which is a dynamic Service-Oriented Architecture (SOA). A roulette-based real-time load balancing algorithm is implemented that supports multiple users and balances against task priorities, which is superior to the rigid pre-set wall clock limits commonly seen in grid computing. The framework accounts for constraints on resources and incorporates a credit-based system to ensure fair usage and access to computing resources. Experimental testing results are shown to demonstrate the effectiveness of the framework.

Seismic Performance of Vibration Control Device That Generates Power

2009 ◽  
Author(s):  
Taichi Matsuoka ◽  
Katsuaki Sunakoda ◽  
Kazuhiko Hiramoto ◽  
Issei Yamazaki ◽  
Akira Fukukita ◽  
...  
Keyword(s):  
Vibration Control ◽  
Earthquake Engineering ◽  
Vibration Suppression ◽  
Experimental Testing ◽  
Control Device ◽  
Shaking Table ◽  
Ball Screw ◽  
Scale Model ◽  
Small Scale ◽  
Wide Range

In a previous paper the authors proposed a semi-active vibration control device (VCD) that generates power. The device utilizes a ball screw, and has inertial and damping forces. The damping coefficient is adjusted by altering resistance at the terminal of the power generator. A small-scale VCD was manufactured for experimental testing. Frequency responses of a small-scale spring mass structure were measured in order to confirm the effects of vibration suppression within a wide range of frequencies. In this paper, as the next step, vibration tests using a benchmark structure with an installed VCD that has a 30 kN capacity are carried out at the National Center for Research on Earthquake Engineering (NCREE) in Taiwan. The benchmark structure has three stories with a 3 m height and a mass of 6 tons at each floor level for a total height and weight of 9 m and 18 tons, respectively. The VCDs are installed between adjacent floors with steel chevron braces. A simple control law that is based on a minimized Lyapunov function and employs bang-bang operation is used as a variable current controller instead of the modifying the resistance level of the VCD. Scaled earthquake motions including the Imperial Valley El Centro north-south component that is normalized to be a peak level of 0.5 m/s2, are applied to the base of the steel framed structure in the horizontal direction by a shaking table. Experimental responses of each floor for the uncontrolled and controlled cases are compared with analytical responses, and effects of vibration suppression for the large-scale model are discussed quantitatively.

The Development of an Experimental Force Feedback Dynamometer to Investigate the Real Time Control of an Oscillating Wave Surge Converter

2013 ◽  
Author(s):  
Daniel Banks ◽  
Jos van ’t Hoff ◽  
Kenneth Doherty
Keyword(s):  
Force Feedback ◽  
Position Control ◽  
Experimental Testing ◽  
Control Strategies ◽  
Small Scale ◽  
Real Time Control ◽  
Time Control ◽  
Scale Models ◽  
Damping Torque ◽  
And Control

An Oscillating Wave Surge Converter (OWSC) is a Wave Energy Converter (WEC) that consists of a bottom-hinged flap which oscillates due to wave action. Extensive research has been performed on this type of WEC through small scale experimental wave tank tests. One of the key challenges of experimental testing is replicating the characteristics of the Power Take-Off (PTO) system of the equivalent full scale WEC. Many scale models rely on simplified mechanical designs to simulate a PTO system. This can often restrict the experimental research into the influence of PTO design and control strategies of WECs. In order to model PTO systems and control strategies more accurately other tools are needed. This paper describes the design and build of a PLC controlled Force Feedback Dynamometer (FFD) system that enables the testing of more sophisticated control strategies applicable to an OWSC through fast application of a variable PTO damping torque. A PLC system is shown to be a viable control for PTO strategy investigations through velocity triggered damping levels. Examples of both PTO and position control strategies are presented.

A Theoretical and Experimental Comparison of Optimizing Angle of Twist Using BET and BEMT

2012 ◽  
Author(s):  
Timothy A. Burdett ◽  
Kenneth W. Van Treuren
Keyword(s):  
Experimental Testing ◽  
Element Model ◽  
Experimental Comparison ◽  
Speed Ratio ◽  
Small Scale ◽  
Blade Element Theory ◽  
Wind Speeds ◽  
Subsonic Wind Tunnel ◽  
Element Theory ◽  
Blade Element

Wind turbines are often designed using some form of Blade Element Model (BEM). However, different models can produce significantly different results when optimizing the angle of twist for power production. This paper compares the theoretical result of optimizing the angle of twist using Blade Element Theory (BET) and Blade Element Momentum Theory (BEMT) with a tip-loss correction for a 3-bladed, 1.15-m diameter wind turbine with a design tip speed ratio (TSR) of 5. These two theories have been chosen because they are readily available to small-scale designers. Additionally, the turbine was scaled for experimental testing in the Baylor Subsonic Wind Tunnel. Angle of twist distributions differed by as much as 15 degrees near the hub, and the coefficient of power differed as much as 0.08 for the wind speeds tested.

Foot-Terrain Interaction for a Prototype Silicon Micro-Robot

2011 ◽  
Author(s):  
Jeong Hoon Ryou ◽  
Kenn Oldham
Keyword(s):  
Analytical Model ◽  
Experimental Testing ◽  
Contact Forces ◽  
Experimental Comparison ◽  
Small Scale ◽  
Simulation Studies ◽  
Static Charge ◽  
Micro Robot ◽  
Robot Evaluation ◽  
Robot Leg

Research on dynamics of micro devices indicates that contact forces are complex in a micro-scale environment. Previous work tried to identify how small-scale forces numerically affect a walking micro system, using a similar structure to a micro-robot leg and a simple analytical model for system dynamics. This paper extends that work by focusing on further experimental testing and simulation studies on a prototype micro-robot. Evaluation of experimental data indicates that characteristics of the ground, such as material properties and static charge on the surface should be also considered in understanding foot-terrain interaction. This leads to modifications to the former foot-terrain interaction algorithm. The refined analytical model is validated through experimental comparison.

Experimental Analysis of an Ultra-Compact Combustor Powered Turbine Engine

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Brian T. Bohan ◽  
Marc D. Polanka
Keyword(s):  
Experimental Testing ◽  
Engine Performance ◽  
Combustion Products ◽  
Combustion Efficiency ◽  
Small Scale ◽  
Engine Operation ◽  
Turbine Engine ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes ◽  
Length Reduction

Abstract The innovative ultra-compact combustor (UCC) is an alternative to traditional turbine engine combustors and has been shown to reduce the combustor length and offer potential improvements in combustion efficiency. Prior UCC configurations featured a circumferential combustion cavity positioned around the outside diameter (OD) of the engine. This configuration would be difficult to implement in a vehicle with a small, fixed diameter and had difficulty migrating the hot combustion products at the OD radially inward across an axial core flow to present a uniform temperature distribution to the first turbine stage. This study draws from preliminary computational analysis which enabled experimental testing of a new UCC configuration that featured a smaller diameter circumferential cavity that exhausted axially into a dilution zone positioned just upstream of the nozzle guide vanes. The combustor was sized as a replacement burner for the JetCat P90 RXi small-scale turbine engine and fit inside the engine casing. This combustor configuration achieved a 33% length reduction compared to the stock JetCat combustor and achieved comparable engine performance across a limited operating range. Self-sustained engine operation was achieved with a rotating compressor and turbine making this study the first to achieve operation of a UCC-powered turbine engine.

scholarly journals Design of Structures That Adapt to Loads through Large Shape Changes

2020 ◽  
Vol 146 (5) ◽  
pp. 04020068 ◽  
Author(s):  
Arka P. Reksowardojo ◽  
Gennaro Senatore ◽  
Ian F. C. Smith
Keyword(s):  
Shape Changes ◽  
Large Shape
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