Experimental Analysis of Rudder Contribution to Roll Damping

2008 ◽  
Author(s):  
Ali Etebari ◽  
Paisan Atsavapranee ◽  
Christopher Bassler ◽  
Jason Carneal
Keyword(s):  
Flat Plate ◽  
Plate Theory ◽  
Added Mass ◽  
Sine Wave ◽  
Plate Model ◽  
Flat Plates ◽  
Roll Damping ◽  
Clear Trend ◽  
Current Effort ◽  
Drag And Lift

Measuring and modeling the forces on the appendages of surface ships is important for understanding roll-damping and validating numerical simulations. In recent years, Atsavapranee et al (2007) showed that the bilge keel damping component can be modeled using the flat plate theory established by Keulegan and Carpenter (1958). This model treats the bilge keels as a flat plate that generates viscous damping, as well as added mass. The model comes as an improvement to models used in computational codes used for predicting roll damping, due to the fact that the added mass component is significant. In this study, uncoupled roll motion is investigated to quantify the rudder forces on a fully appended DTMB model #5415 with instrumented appendages at Froude numbers of 0 and 0.138. The objective of the current effort is to decompose the rudder force into its steady, symmetric, and antisymmetric components using Fourier analysis. In the force analysis the rudders are treated as flat plates for the Fr = 0 tests, using the model described by Keulegan and Carpenter (1958). The drag and lift forces are consistent with the flat plate model. The anti-symmetric term, however, does not show a clear trend. For a flat plate model, the anti-symmetric term should resemble a negative sine wave with respect to roll. However, the rudders represent a higher aspect ratio flat plate, and thus require a modification to the added mass formulation. Furthermore, during a normal roll period they tend to interact with the free surface, which can lead to wave damping, which should resemble a positive sine wave with respect to roll. Thus, the two components of the anti-symmetric portion of the signal are superimposed upon one another. In an attempt to decouple these two components, the added mass was artificially removed from the antisymmetric component of the force. This paper will detail the methods used to model the rudder forces for both the standstill and positive Froude number cases.

Applicability of Stress Intensity Factor Solution for Flat Plate to Nozzle Crotch Corner Flaw

2016 ◽  
Author(s):  
Fuminori Iwamatsu ◽  
Katsumasa Miyazaki ◽  
Minoru Masuda ◽  
Fumihito Hirokawa
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Fracture Mechanics ◽  
Intensity Factor ◽  
Flat Plate ◽  
Structural Integrity ◽  
Nozzle Geometry ◽  
Plate Model ◽  
Flat Plates ◽  
Nozzle Geometries

The applicability of a stress intensity factor (SIF) solution for a flat plate with a surface flaw (flat plate model) to nozzle crotch corner flaw is investigated by using a 3-D finite element method (FEM). Flaws due to stress corrosion cracking (SCC), fatigue, etc. are frequently postulated or detected at discontinuity regions. To evaluate the structural integrity of flawed components, it is important to calculate fracture mechanics parameters rationally and appropriately. SIF is one of the key fracture mechanics parameters for linear elastic fracture mechanics evaluation. Therefore, almost all fitness-for-service codes, e.g. ASEM BPVC Section XI, JSME FFS Code and R6 provide SIF solutions. However, they essentially provide SIF solutions only for flat plates or cylinders with flaws. Since nozzle crotch corner suffers from stress concentration and there are a lot of nozzle geometry parameters, there is no direct SIF solution for arbitrary nozzle geometries. To estimate SIFs for nozzle crotch corner flaws rationally and appropriately, the applicability of the SIF solution for the flat plate model needs to be verified. SIFs were calculated by using 3-D FEM for a flawed nozzle, and the results were compared with those calculated by equations and coefficients in the code solution. Our comparison showed that the flat plate model is applicable to nozzle crotch corner flaws rationally and conservatively.

Elastic Buckling of Infinitely Long Trapezoidally Corrugated Plates in Shear

1978 ◽  
Vol 45 (3) ◽  
pp. 579-582 ◽  
Author(s):  
D. Perel ◽  
C. Libove
Keyword(s):  
Flat Plate ◽  
Energy Method ◽  
Orthotropic Plate ◽  
Plate Theory ◽  
Elastic Buckling ◽  
Flat Plates ◽  
Buckling Loads ◽  
Plate Elements ◽  
Corrugated Plates

Buckling loads are calculated for a class of infinitely long trapezoidally corrugated plates under uniform in-plane edge shear. This class consists of corrugated plates in which all interior plate elements are of equal width, with the end elements clamped. The energy method is used as the basis of analysis, which considers the corrugated plate as a nonplanar assemblage of flat plates. Buckling loads calculated using this method are compared to those obtained by using orthotropic plate theory, which represents the corrugated plate by an orthotropic flat plate. The comparison shows significant differences in predicted buckling loads.

Towards the Understanding of Manifold Fluttering During Pendulous Installation: Flow Induced Rotation of Flat Plates in Uniform Flow

2010 ◽  
Author(s):  
Antonio Carlos Fernandes ◽  
Sina Mirzaei Sefat ◽  
Fabio Moreira Coelho ◽  
Mario Ribeiro
Keyword(s):  
Flat Plate ◽  
Rio De Janeiro ◽  
Center Of Pressure ◽  
Numerical Models ◽  
Free Fall ◽  
Reynolds Numbers ◽  
Uniform Flow ◽  
Experimental Results ◽  
Flat Plates ◽  
Drag And Lift

The pendulous installation method of a manifold has a first phase that can be considered as a free fall in water. Of course, this is not free due to the fluid action. The consequence is that the manifold may oscillate rotationally which characterizes a fluttering behavior. However, the manifold is a complex body with non-uniform shape, several modules, porosity etc. Hence, in order to improve the understanding of the fluttering, this work presents advances in the observation of flow induced rotation on a flat plate in uniform flow. This has been started experimentally and subsequently numerical models yielded a confirmation of quasi-steady observations. The experimental results were obtained at the Laborato´rio de Ondas e Correntes (LOC) [Laboratory of Waves and Current] in COPPE/Federal University of Rio de Janeiro. The drag and lift forces coefficients and the center of pressure have been obtained for angles of attack θ = 0°–90° and for different Reynolds numbers.

Impingement Cooling Experiments With Flat Plate and Pin Plate Target Surfaces

1999 ◽  
Author(s):  
Rainer Hoecker ◽  
Bruce V. Johnson ◽  
Josef Hausladen ◽  
Matthias Rothbrust ◽  
Bernhard Weigand
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Copper Plate ◽  
Orifice Plate ◽  
Plate Model ◽  
Transfer Coefficients ◽  
Flat Plates ◽  
Target Plate ◽  
Average Heat ◽  
Heat Transfer Coefficients

Heat transfer experiments were conducted with three (3) different target plate configurations: a baseline copper flat smooth plate, a copper plate model with copper pins and a copper plate model with Teflon pins, to determine average heat transfer coefficients on the flat and pin surfaces for application with different plate materials. For each target plate surface configuration, the heat transfer experiments were conducted with selected impingement orifice plate configurations and with selected spacing between the orifice plate and the heat transfer target plate. The heat transfer results for the baseline copper smooth flat plate were in good agreement with a well-recognized correlation for the flow regions used in the correlation. An analytical procedure, similar to that used by Metzger et al. for pin-fins in coolant channels, was developed to separate the average heat transfer coefficients on the flat and pin surfaces. The results with the copper pins showed modest increases of approximately 35 percent in heat transfer at lower Reynolds numbers, decreasing with increased Reynolds number. Application of the experimental results to an analysis for high-pressure engine conditions with modest thermal conductivity materials showed that the overall heat transfer coefficient can decrease with pin surfaces for some conditions, compared to flat plates.

Flush probe studies of plasma flow over a flat plate: theory

1979 ◽  
Vol 12 (10) ◽  
pp. 1685-1697 ◽  
Author(s):  
C R Giles ◽  
R M Clements ◽  
P R Smy
Keyword(s):  
Flat Plate ◽  
Plasma Flow ◽  
Plate Theory

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.

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.

Effect of plasma actuator in boundary layer on flat plate model with turbulent promoter

2017 ◽  
Vol 232 (16) ◽  
pp. 3001-3010
Author(s):  
James Julian ◽  
Harinaldi ◽  
Budiarso ◽  
Chin-Cheng Wang ◽  
Ming-Jyh Chern
Keyword(s):  
Boundary Layer ◽  
Flat Plate ◽  
Aerodynamic Drag ◽  
Active Flow Control ◽  
Adverse Pressure Gradient ◽  
Plasma Actuator ◽  
Experimental Results ◽  
Plate Model ◽  
Displacement Thickness ◽  
Turbulent Promoter

This paper shows experimental results for velocity measurement in the boundary layer with the use of a flat plate model. The flat plate model is disrupted with a wire trip and the effect of the plasma actuator to alter the flow in the boundary layer is then observed. The purpose of this research is to characterize the performance of the plasma actuator in a no-flow condition and with the use of a 2 m/s flow and also to theoretically analyze the performance of actuator in the boundary layer namely, displacement thickness, momentum thickness, and energy thickness. This is all done to acquire a deeper understanding of the capabilities of plasma actuator as one of the alternative active flow control equipment and to increase the effect of aerodynamic drag reduction. One of the ways to decrease the aerodynamic drag is to manipulate the flow to have a low boundary layer thickness value in order to prevent an adverse pressure gradient from happening, which then may lead to the formation of a flow separation. From experimental results, it is known that plasma actuator could decrease the thickness of the boundary layer by 9 mm.

scholarly journals Low-frequency unsteadiness in the wake of a normal flat plate

1998 ◽  
Vol 370 ◽  
pp. 101-147 ◽  
Author(s):  
F. M. NAJJAR ◽  
S. BALACHANDAR
Keyword(s):  
Shear Layer ◽  
Flat Plate ◽  
Free Stream ◽  
Low Frequency ◽  
Separated Flow ◽  
Phase Mismatch ◽  
Streamwise Vortices ◽  
Long Time ◽  
Drag And Lift ◽  
High Degree

The separated flow past a zero-thickness flat plate held normal to a free stream at Re=250 has been investigated through numerical experiments. The long-time signatures of the drag and lift coefficients clearly capture a low-frequency unsteadiness with a period of approximately 10 times the primary shedding period. The amplitude and frequency of drag and lift variations during the shedding process are strongly modulated by the low frequency. A physical interpretation of the low-frequency behaviour is that the flow gradually varies between two different regimes: a regime H of high mean drag and a regime L of low mean drag. It is observed that in regime H the shear layer rolls up closer to the plate to form coherent spanwise vortices, while in regime L the shear layer extends farther downstream and the rolled-up Kármán vortices are less coherent. In the high-drag regime three-dimensionality is characterized by coherent Kármán vortices and reasonably well-organized streamwise vortices connecting the Kármán vortices. With a non-dimensional spanwise wavelength of about 1.2, the three-dimensionality in this regime is reminiscent of mode-B three-dimensionality. It is observed that the high degree of spanwise coherence that exists in regime H breaks down in regime L. Based on detailed numerical flow visualization we conjecture that the formation of streamwise and spanwise vortices is not in perfect synchronization and that the low-frequency unsteadiness is the result of this imbalance (or phase mismatch).

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