Full-Scale Measurements of Wave Impact Loading on a Flat Plate

2012 ◽  
Author(s):  
David Drazen ◽  
Eric Terrill ◽  
Don Walker ◽  
Joel Hazard ◽  
Tom Cook ◽  
...  
Keyword(s):  
Flat Plate ◽  
Impact Loading ◽  
Extended Period ◽  
Full Scale ◽  
Wave Forces ◽  
Flat Plates ◽  
Wave Impact ◽  
Incoming Wave ◽  
Engineering Design Problems ◽  
Wide Range

Full scale measurements of wave impact loads and their statistics in real sea states are desirable for validation of numerical simulations and for application to marine engineering design problems. Measuring and/or estimating wave forces on flat plates are especially problematic due to statistics of large waves in a given sea state, the intermittent statistics of wave breaking, the sensitivity of the loading relative to the phase of the incoming wave and scaling issues when translating from model scale data to full-scale. To increase our understanding of wave hydrodynamic pressures on a flat plate, an instrumented plate was deployed from the Scripps Institution of Oceanography’s research pier. The instrumented plate is exposed to a wide range of wave conditions with Hs ranging from 3–4 m in the winter and with Hs in the 1–2 m range in the summer. The instrumented flat plate is composed of three discrete modules containing 6 pressure gages. Data are being collected over a extended period, nominally 12 months, to characterize extreme value distributions due to wave impact loading.

The Influence of Boundary Layer State on Vortex Shedding From Flat Plates and Turbine Cascades

1989 ◽  
Author(s):  
C. H. Sieverding ◽  
H. Heinemann
Keyword(s):  
Boundary Layer ◽  
Flat Plate ◽  
Vortex Shedding ◽  
Turbine Blades ◽  
Suction Side ◽  
Frequency Change ◽  
Flat Plates ◽  
Turbulent Separation ◽  
Wide Range ◽  
Number Variation

The paper aims at a better understanding of the reasons for the wide range of Strouhal numbers observed on turbine blades. The investigation is restricted to the subsonic domain. Firstly, flat plate model tests are carried out to investigate the effect of both the boundary layer state and trailing edge geometry on the vortex shedding frequency. A particular objective of the tests is to obtain data for the very common case of a mixed laminar-turbulent separation from turbine blades. These basic tests are followed by three cascade tests with blades of very different suction side velocity distributions. Based on the experience gained from the flat plate test program, an attempt is made to interprete the Strouhal number variation with Mach number and Reynolds number, and to relate the vortex frequency change to the boundary layer state on the blade surfaces.

Full Scale Measurements of Wave Impact on a Flat Plate

2013 ◽  
Author(s):  
Anne M. Fullerton ◽  
David Drazen ◽  
Don Walker ◽  
Eric Terrill
Keyword(s):  
Flat Plate ◽  
Full Scale ◽  
Wave Impact

The Influence of Boundary Layer State on Vortex Shedding From Flat Plates and Turbine Cascades

1990 ◽  
Vol 112 (2) ◽  
pp. 181-187 ◽  
Author(s):  
C. H. Sieverding ◽  
H. Heinemann
Keyword(s):  
Boundary Layer ◽  
Flat Plate ◽  
Vortex Shedding ◽  
Turbine Blades ◽  
Suction Side ◽  
Frequency Change ◽  
Flat Plates ◽  
Turbulent Separation ◽  
Wide Range ◽  
Number Variation

The paper aims at a better understanding of the reasons for the wide range of Strouhal numbers observed on turbine blades. The investigation is restricted to the subsonic domain. First, flat plate model tests are carried out to investigate the effect of both the boundary layer state and trailing edge geometry on the vortex shedding frequency. A particular objective of the tests is to obtain data for the very common case of a mixed laminar-turbulent separation from turbine blades. These basic tests are followed by three cascade tests with blades of very different suction side velocity distributions. Based on the experience gained from the flat plate test program, an attempt is made to interpret the Strouhal number variation with Mach number and Reynolds number, and to relate the vortex frequency change to the boundary layer state on the blade surfaces.

Infrared Assessment of an Optimized Vane Pressure Side Film Cooling Array

2012 ◽  
Author(s):  
J. J. Johnson ◽  
P. I. King ◽  
J. P. Clark ◽  
A. T. Lethander ◽  
N. A. Posada
Keyword(s):  
Surface Temperature ◽  
Flat Plate ◽  
Infrared Thermography ◽  
Film Cooling ◽  
Full Scale ◽  
Plate Versus ◽  
Pressure Side ◽  
Flat Plates ◽  
Plate Models ◽  
Cooling Hole

The following experimental work described here entails the investigation by infrared thermography (IRT) of full-scale flat plates intended to model the pressure side (PS) of a modern fully-cooled turbine inlet vane called the High-Impact Technologies (HIT) Research Turbine Vane (RTV). The imaging system is used to make detailed full-coverage, two-dimensional, steady-state measurements of flat plate surface temperature. The PS has a total of 282 film cooling holes including three rows of showerhead holes near the leading edge and a handful of rows downstream depending on the design. The flat plates precisely match the material, thickness, and cooling hole sizes on the RTV, however they are not intended to match the external pressure field or the characteristics of internal cooling beneath the airfoil surface. Surface temperature relative to individual trial freestream gas temperatures is reported for an uncooled plate, a plate with the baseline RTV cooling scheme, and for four different hole types on a plate with a 3D-optimized cooling array designed for the RTV in previous work using genetic algorithms and computational fluid dynamics (CFD). The four different cooling hole shapes tested on the downstream rows of the optimized array plates include cylindrical holes, fan-shaped holes, Vehr holes, and a new cooling hole called a mini-trench shaped (MTS) hole. Experimentation on flat plate models using infrared thermography provides large amounts of valuable data, is inexpensive and highly repeatable relative to large rotating blowdown rigs. The results provide key insights into the differences between full-PS film cooling performance on the plate versus the 3D RTV and suggests to designers the best cooling hole shape for the next build of the RTV which will soon be tested in a full-scale blowdown rig instrumented with heat flux gauges. Overall, results clearly corroborate how cooling was redistributed and improved over the PS of the RTV in the original computational design effort and suggest that certain hole shapes are best suited for certain locations on the flat plate models.

Drag on flat plates of arbitrary porosity

2018 ◽  
Vol 853 ◽  
Author(s):  
K. Steiros ◽  
M. Hultmark
Keyword(s):  
Flat Plate ◽  
Drag Force ◽  
Free Stream ◽  
Two Dimensional ◽  
Flat Plates ◽  
New Model ◽  
Momentum Theory ◽  
Wide Range ◽  
Model Predictions

A new model for the drag force on a two-dimensional flat plate of arbitrary porosity, oriented normal to the free stream, is introduced. The model is an extension of that introduced by Koo & James (J. Fluid Mech., vol. 60(3), 1973, pp. 513–538), where the performance at low porosities is improved by including a base-suction term. The additional drag due to the base suction is calculated implicitly using momentum theory, which makes the model self-contained. The model predictions exhibit convincing agreement with experimental observations over a wide range of porosities, including the solid case, as long as shedding is absent or suppressed.

The Concept of the Optimum Alignment of Discharge Pipelines Due to the Minimization of the Wave Forces

1992 ◽  
Vol 25 (9) ◽  
pp. 211-216
Author(s):  
A. Akyarli ◽  
Y. Arisoy
Keyword(s):  
Wave Height ◽  
Wave Force ◽  
Wave Forces ◽  
Wave Direction ◽  
Incoming Wave ◽  
Pipeline Route ◽  
Optimum Alignment ◽  
The Cost ◽  
Resultant Wave

As the wave forces are the function of the wave height, period and the angle between the incoming wave direction and the axis of the discharge pipeline, the resultant wave force is directly related to the alignment of the pipeline. In this paper, a method is explained to determine an optimum pipeline route for which the resultant wave force becomes minimum and hence, the cost of the constructive measures may decrease. Also, the application of this method is submitted through a case study.

A CFD Study of Focused Extreme Wave Impact on Decks of Offshore Structures

2014 ◽  
Author(s):  
Xin Lu ◽  
Pankaj Kumar ◽  
Anand Bahuguni ◽  
Yanling Wu
Keyword(s):  
Real World ◽  
Offshore Structures ◽  
Air Gap ◽  
Irregular Waves ◽  
Linear Wave ◽  
Extreme Wave ◽  
Wave Impact ◽  
Loading Test ◽  
Wide Range ◽  
Wave Maker

The design of offshore structures for extreme/abnormal waves assumes that there is sufficient air gap such that waves will not hit the platform deck. Due to inaccuracies in the predictions of extreme wave crests in addition to settlement or sea-level increases, the required air gap between the crest of the extreme wave and the deck is often inadequate in existing platforms and therefore wave-in-deck loads need to be considered when assessing the integrity of such platforms. The problem of wave-in-deck loading involves very complex physics and demands intensive study. In the Computational Fluid Mechanics (CFD) approach, two critical issues must be addressed, namely the efficient, realistic numerical wave maker and the accurate free surface capturing methodology. Most reported CFD research on wave-in-deck loads consider regular waves only, for instance the Stokes fifth-order waves. They are, however, recognized by designers as approximate approaches since “real world” sea states consist of random irregular waves. In our work, we report a recently developed focused extreme wave maker based on the NewWave theory. This model can better approximate the “real world” conditions, and is more efficient than conventional random wave makers. It is able to efficiently generate targeted waves at a prescribed time and location. The work is implemented and integrated with OpenFOAM, an open source platform that receives more and more attention in a wide range of industrial applications. We will describe the developed numerical method of predicting highly non-linear wave-in-deck loads in the time domain. The model’s capability is firstly demonstrated against 3D model testing experiments on a fixed block with various deck orientations under random waves. A detailed loading analysis is conducted and compared with available numerical and measurement data. It is then applied to an extreme wave loading test on a selected bridge with multiple under-deck girders. The waves are focused extreme irregular waves derived from NewWave theory and JONSWAP spectra.

scholarly journals A Generalized Method for Flat Plates Impact Detection and Location

2013 ◽  
Vol 543 ◽  
pp. 171-175
Author(s):  
Jose Andrés Somolinos ◽  
Rafael Morales ◽  
Carlos Morón ◽  
Alfonso Garcia
Keyword(s):  
Signal Processing ◽  
Flat Plate ◽  
Acoustic Signal ◽  
Experimental Results ◽  
Piezoelectric Sensors ◽  
Experimental Setup ◽  
Flat Plates ◽  
Impact Detection ◽  
Timing Difference

In the last years, many analyses from acoustic signal processing have been used for different applications. In most cases, these sensor systems are based on the determination of times of flight for signals from every transducer. This paper presents a flat plate generalization method for impact detection and location over linear links or bars-based structures. The use of three piezoelectric sensors allow to achieve the position and impact time while the use of additional sensors lets cover a larger area of detection and avoid wrong timing difference measurements. An experimental setup and some experimental results are briefly presented.

Coupled Thermo-Hydro-Geochemical Models of Engineered Barrier Systems: The Febex Project

2000 ◽  
Vol 663 ◽  
Author(s):  
J. Samper ◽  
R. Juncosa ◽  
V. Navarro ◽  
J. Delgado ◽  
L. Montenegro ◽  
...  
Keyword(s):  
Large Scale ◽  
Reference Model ◽  
Numerical Models ◽  
Full Scale ◽  
Small Scale ◽  
Model Parameters ◽  
In Situ Test ◽  
Wide Range ◽  
Engineered Barrier

ABSTRACTFEBEX (Full-scale Engineered Barrier EXperiment) is a demonstration and research project dealing with the bentonite engineered barrier designed for sealing and containment of waste in a high level radioactive waste repository (HLWR). It includes two main experiments: an situ full-scale test performed at Grimsel (GTS) and a mock-up test operating since February 1997 at CIEMAT facilities in Madrid (Spain) [1,2,3]. One of the objectives of FEBEX is the development and testing of conceptual and numerical models for the thermal, hydrodynamic, and geochemical (THG) processes expected to take place in engineered clay barriers. A significant improvement in coupled THG modeling of the clay barrier has been achieved both in terms of a better understanding of THG processes and more sophisticated THG computer codes. The ability of these models to reproduce the observed THG patterns in a wide range of THG conditions enhances the confidence in their prediction capabilities. Numerical THG models of heating and hydration experiments performed on small-scale lab cells provide excellent results for temperatures, water inflow and final water content in the cells [3]. Calculated concentrations at the end of the experiments reproduce most of the patterns of measured data. In general, the fit of concentrations of dissolved species is better than that of exchanged cations. These models were later used to simulate the evolution of the large-scale experiments (in situ and mock-up). Some thermo-hydrodynamic hypotheses and bentonite parameters were slightly revised during TH calibration of the mock-up test. The results of the reference model reproduce simultaneously the observed water inflows and bentonite temperatures and relative humidities. Although the model is highly sensitive to one-at-a-time variations in model parameters, the possibility of parameter combinations leading to similar fits cannot be precluded. The TH model of the “in situ” test is based on the same bentonite TH parameters and assumptions as for the “mock-up” test. Granite parameters were slightly modified during the calibration process in order to reproduce the observed thermal and hydrodynamic evolution. The reference model captures properly relative humidities and temperatures in the bentonite [3]. It also reproduces the observed spatial distribution of water pressures and temperatures in the granite. Once calibrated the TH aspects of the model, predictions of the THG evolution of both tests were performed. Data from the dismantling of the in situ test, which is planned for the summer of 2001, will provide a unique opportunity to test and validate current THG models of the EBS.

Experimental Study of Multiple Air Jets Impinging a Moving Flat Plate

2020 ◽  
Author(s):  
Flavia Barbosa ◽  
Senhorinha Teixeira ◽  
Carlos Costa ◽  
Filipe Marques ◽  
José Carlos Teixeira
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Jet Impingement ◽  
Plate Motion ◽  
Test Facility ◽  
Flat Plates ◽  
Target Plate ◽  
Wall Jets ◽  
Air Jets ◽  
Flow Interactions

Abstract The motion of the target plate is important in some industrial applications which apply multiple jet impingement, such as reflow soldering, drying and food processing. Multiple jet impingement is widely used due to its ability to generate high heat transfer rates over large and complex areas. This convective process is characterized by several flow interactions essentially due to adjacent jets mixing prior the impingement, wall jets collision after the impingement, as well as crossflow interactions induced by the motion of the wall jets that flow through the exits of the domain. These interactions lead to strong flow recirculation, pressure gradients and boundary layer development. However, the complexity of the flow interactions is increased with the surface motion in confined space, due to the generation of strong shear regions. These interactions can induce problems and product defects due to complicated thermal behavior and non-uniform heating or cooling, being important to fully understand the process in order to reduce time and costs. This work addresses the experimental analysis of multiple air jets impinging on a moving flat plate. The experiments are conducted on a purpose-built test facility which has been commissioned, using a 2D-PIV system. Through this technique, the flow structure and velocity profiles will be analyzed in detail. The effects of the impinging plate motion on the resulting global and local velocity profile is compared with a static flat plate. The multiple jet configuration consists on air flowing through 14 circular nozzles, at a Reynolds number of 690 and 1,380. The experiments are conducted for a nozzle-to-plate distance of 8 and a jet-to-jet spacing of 2. The target plate motion remains constant throughout the experiments and equal to 0.03 m/s. The results are compared for both stationary and moving flat plates cases and express the increased complexity of the flow due to strong interaction between jets and the target surface, which affects the heat transfer performance. The results obtained experimentally are important to clearly define this complex flow and these data can be used in future works for numerical model validation.

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