The Concomitant Model Testing Approach for the Development of the Pendulous Installation Method of Heavy Devices In Deep Water

2007 ◽  
Author(s):  
Antonio Carlos Fernandes ◽  
Cassiano Rodrigues Neves ◽  
Joel Sena Sales Junior
Keyword(s):  
Model Test ◽  
Scaling Laws ◽  
Turning Point ◽  
Computer Code ◽  
Model Testing ◽  
Compensation Systems ◽  
Slender Bodies ◽  
Model Computer ◽  
Hydrodynamic Situation ◽  
Two Bodies

This paper synthesizes a method for model testing of non-conventional devices and operations. The basic idea is to perform numerical analysis in advance (or concomitantly) of the model test itself. This has been very effective over the years and its application to the development Pendulous Installation Method (PIM) of deepwater heavy devices has been effective as shown in the paper. Specifically, the PIM does not require boats with compensation systems for the usual vertical launching. The device to be installed is released from the free surface. It is hold by an auxiliary cable from a boat and connected by the installation cable to another boat some distance away. The auxiliary cable is then released and after an almost vertical trajectory of the manifold, the installation cable traction increases and the device rotates (pendulous motion) about the turning point on the other support boat. During the development of novel systems or operations, the industry is learning the importance of model testing. During the model tests, it has been understood that a two-scale problem had to be faced by the model test design. There are large bodies (the device) together with slender bodies (cables) in the same hydrodynamic situation. These two bodies have different scaling laws. How cope with it depends on the several aspects (inertia, damping, etc). However, with the help of a modern numerical model computer code, these problems may be anticipated by creating a framework of results that help in the interpretation of the model testing result itself.

Model Testing for Vortex Induced Motions of Spar Platforms

2004 ◽  
Author(s):  
Mehernosh Irani ◽  
Lyle Finn
Keyword(s):  
Gulf Of Mexico ◽  
Model Test ◽  
State Of The Art ◽  
Model Testing ◽  
Model Tests ◽  
The State ◽  
Test Results ◽  
Test Set ◽  
Vortex Induced Vibrations ◽  
Set Up

The state-of-the art in model testing for Vortex Induced Vibrations (VIV) of Spars is presented. Important issues related to Spar VIV model testing are highlighted. The parameters that need to be modeled including hull geometry, strake configuration, mass and mooring properties and, considerations of test set-up and instrumentation are discussed. Results are presented from model tests of an as-built Spar deployed in the Gulf of Mexico. It is shown that the model test results compare well with the VIV responses measured in the field.

An analytical solution for two slender bodies of revolution translating in very close proximity

2007 ◽  
Vol 582 ◽  
pp. 223-251 ◽  
Author(s):  
Q. X. WANG
Keyword(s):  
Body Length ◽  
Present Model ◽  
The Body ◽  
Attraction Force ◽  
Bodies Of Revolution ◽  
Plane Flow ◽  
Lateral Forces ◽  
Close Proximity ◽  
Slender Bodies ◽  
Two Bodies

The irrotational flow past two slender bodies of revolution at angles of yaw, translating in parallel paths in very close proximity, is analysed by extending the classical slender body theory. The flow far away from the two bodies is shown to be a direct problem, which is represented in terms of two line sources along their longitudinal axes, at the strengths of the variation rates of their cross-section areas. The inner flow near the two bodies is reduced to the plane flow problem of the expanding (contracting) and lateral translations of two parallel circular cylinders with different radii, which is then solved analytically using conformal mapping. Consequently, an analytical flow solution has been obtained for two arbitrary slender bodies of revolution at angles of yaw translating in close proximity. The lateral forces and yaw moments acting on the two bodies are obtained in terms of integrals along the body lengths. A comparison is made among the present model for two slender bodies in close proximity, Tuck & Newman's (1974) model for two slender bodies far apart, and VSAERO (AMI)–commercial software based on potential flow theory and the boundary element method (BEM). The attraction force of the present model agrees well with the BEM result, when the clearance, h0, is within 20% of the body length, whereas the attraction force of Tuck & Newman is much smaller than the BEM result when h0 is within 30% of the body length, but approaches the latter when h0 is about half the body length. Numerical simulations are performed for the three typical manoeuvres of two bodies: (i) a body passing a stationary body, (ii) two bodies in a meeting manoeuvre (translating in opposite directions), and (iii) two bodies in a passing manoeuvre (translating in the same direction). The analysis reveals the orders of the lateral forces and yaw moments, as well as their variation trends in terms of the manoeuvre type, velocities, sizes, angles of yaw of the two bodies, and their proximity, etc. These irrotational dynamic features are expected to provide a basic understanding of this problem and will be beneficial to further numerical and experimental studies involving additional physical effects.

Scaling Laws for Model Test Based BWR Steam Dryer Fluctuating Load Definitions

2006 ◽  
Author(s):  
Daniel V. Sommerville
Keyword(s):  
Model Test ◽  
Research Program ◽  
Scaling Laws ◽  
Model Tests ◽  
Boiling Water ◽  
Boiling Water Reactors ◽  
Model Data ◽  
Physical Mechanisms ◽  
Predictive Methods ◽  
Water Reactors

In recent years some Boiling Water Reactors have experienced significant steam dryer cracking. In some cases this cracking has necessitated unplanned outages to implement steam dryer repairs and has also resulted in de-rated operation of the affected units. In response to these recent steam dryer failures, GE has initiated a research program focused on identifying the nature of the fluctuating loads experienced by the steam dryer and developing predictive methods that can be used to develop load definitions for steam dryers. The physical mechanisms responsible for excitation of aero-acoustic resonances are not easily modeled using purely analytic methods; therefore, GE has decided to perform model tests to investigate the nature of the expected steam dryer loading. The objectives of the study documented in this paper are to: 1) Provide guidance regarding how to preserve, in the model, the significant fluid phenomena occurring in the plant, and 2) Derive scaling laws to convert model data to plant load predictions.

Design of scaled model for dynamic characteristics of stiffened cylindrical shells based on equivalent similar method

2019 ◽  
Vol 123 (1261) ◽  
pp. 398-415 ◽  
Author(s):  
L. L. Zhou ◽  
D. K. Li
Keyword(s):  
Cylindrical Shell ◽  
Model Test ◽  
Scaling Laws ◽  
Effective Means ◽  
Scaled Model ◽  
Numerical Examples ◽  
Stiffened Cylindrical Shell ◽  
Bending Mode ◽  
Scaled Models ◽  
Stiffened Cylindrical Shells

ABSTRACTScaled model test is an effective means to verify the design of a stiffened cylindrical shell. However, there is a problem of similarity distortion by use of the traditional dimensional analysis to design scaled models. In this present study, an equivalent similar method is proposed to solve the problem. The method is applied to an axial stiffened cylindrical shell, and the equivalent criteria and scaling laws satisfying the equivalent similarity of global bending mode are derived and verified by numerical examples. The results indicate that the similarity distortion caused by practical conditions for the stiffened cylindrical shell can be solved and the parameters of scaled model can be designed more freely with the proposed equivalent similar method.

A Program for the Development of a Benchmark Compartment Fire Model Computer Code

2009 ◽  
pp. 116-116-12 ◽  
Author(s):  
LY Cooper ◽  
JA Rockett ◽  
HE Mitler ◽  
DW Stroup
Keyword(s):  
Computer Code ◽  
Compartment Fire ◽  
Fire Model ◽  
Model Computer

Stern End Bulb for Energy Enhancement and Speed Improvement

2012 ◽  
Vol 28 (04) ◽  
pp. 172-181
Author(s):  
Gabor Karafiath
Keyword(s):  
Fluid Flow ◽  
Free Surface ◽  
Model Test ◽  
Computer Code ◽  
Inviscid Flow ◽  
Improve Performance ◽  
Maximum Resistance ◽  
Resistance Reduction ◽  
Hydrodynamic Mechanism ◽  
Lewis And Clark

Unlike the bow bulb, the stern end bulb (SEB) has been used on just a few ships to improve performance. In one of these rare, full-scale applications, a maximum resistance reduction in the 5% to 7% range is claimed. A few applications of SEBs are shown along with some model test data for a Naval Auxiliary ship. The rationale for SEB is discussed along with the hydrodynamic mechanism associated with a SEB. In addition to wave-making reduction, the SEB can reduce eddy-making and possibly improve course-keeping. The results of several fluid flow computations with initial SEB designs are shown for two ship classes: the T-AKE LEWIS and CLARK dry cargo ship and the DDG 51 ARLEIGH BURKE destroyer. The calculations use the Ship Wave Inviscid Flow Theory potential flow computer code and the FreeRans viscous flow free surface computer code. Several SEBs were designed and investigated analytically for the T-AKE class ships, and the best of these is predicted to reduce resistance by 4.5% at 20 knots. In addition, several initial SEB/Stern Flap configurations were designed for the DDG 51 Class Flight IIa destroyers and five configurations, some with just an SEB added to the hull and others with a combined SEB-Stern Flap configuration were model-tested. The examination of these initial efforts led to the design of several new-style combined SEB-Stern flap configurations, the best of which is predicted to save at least 745 Bbls of fuel per ship per year.

Paper 9. Model Testing

1972 ◽  
Vol 14 (7) ◽  
pp. 62-69
Author(s):  
R. K. Burcher
Keyword(s):  
Mathematical Modelling ◽  
Model Test ◽  
Test Methods ◽  
Model Testing ◽  
Short Discussion ◽  
Ship Model ◽  
Constrained Models ◽  
Model Correlation ◽  
Standard Tests

This paper is an introduction to model test methods as a means of establishing the manoeuvring characteristics of ships. Consideration is first given to the reasons for the adoption of model techniques and the information to be obtained. The model techniques are considered under three sections: free models, constrained models and mathematical modelling. The standard tests employed are briefly described and the information that can be obtained, together with any problems. There is finally a short discussion of the problems of ship/model correlation.

Development of a Scaled-Down Floating Wind Turbine for Offshore Basin Testing

2014 ◽  
Author(s):  
Erik-Jan de Ridder ◽  
William Otto ◽  
Gert-Jan Zondervan ◽  
Fons Huijs ◽  
Guilherme Vaz
Keyword(s):  
Wind Turbine ◽  
Wind Velocity ◽  
Scaling Laws ◽  
Scale Effects ◽  
Model Testing ◽  
Model Tests ◽  
Full Scale ◽  
Pitch Control ◽  
Model Scale ◽  
Floating Wind Turbine

In the last years MARIN has been involved in an increasing number of projects for the offshore wind industry. New techniques in model testing and numerical simulations have been developed in this field. In this paper the development of a scaled-down wind turbine operating on a floating offshore platform, similar to the well-known 5MW NREL wind turbine is discussed. To simulate the response of a floating wind turbine correctly it is important that the environmental loads due to wind, waves and current are in line with full scale. For dynamic similarity on model scale, Froude scaling laws are used successfully in the Offshore industry for the underwater loads. To be consistent with the underwater loads, the winds loads have to be scaled according to Froude as well. Previous model tests described by Robertson et al [1] showed that a geometrically-scaled turbine generated a lower thrust and power coefficient with a Froude-scaled wind velocity due to the strong Reynolds scale effects on the flow. To improve future model testing, a new scaling method for the wind turbine blades was developed originally by University of Maine, and here improved and applied. In this methodology, the objective is to obtain power and thrust coefficients which are similar to the full-scale turbine in Froude-scaled wind. This is obtained by changing the geometry of the blades in order to provide thrust equality between model and full scale, and can therefore be considered as a “performance scaling”. This method was then used to design and construct a new MARIN Stock Wind Turbine (MSWT) based on the NREL 5MW wind turbine blade, including an active blade pitch control to simulate different blade pitch control systems. MARIN’s high-quality wind setup in combination with the new model scale stock wind turbine was used for testing the GustoMSC Tri-Floater semi-submersible as presented in Figure 1, including an ECN active blade pitch control algorithm. From the model tests it was concluded that the measured thrust versus wind velocity characteristics of the new MSWT were in line with the full scale prediction and with CFD (Computational Fluid Dynamics) results.

A Comparison Among Alternatives to Assess FPSO Roll Damping via Model Testing

2014 ◽  
Author(s):  
Allan C. de Oliveira ◽  
Antonio Carlos Fernandes ◽  
Anderson R. W. Soares
Keyword(s):  
Model Test ◽  
Model Testing ◽  
Lessons Learned ◽  
Irregular Waves ◽  
Roll Damping ◽  
Test Specifications ◽  
Nonlinear Rolling ◽  
Decay Tests ◽  
Standard Strategy ◽  
Statistic Approach

The prediction of the nonlinear rolling motions of a FPSO with extended bilge keels stills a challenging problem. Despite recent advantages in CFD computations, the use of model testing is considered the standard strategy for roll damping assessments. There are different ways to assess the roll damping via model testing and the three most common are the use of decay tests, tests in regular and irregular waves. The comparison among those different kinds of tests may present incoherent results, sometimes, introducing the question of which methodology is the most appropriated in those scenarios, with impact in model test specifications. Decay tests are the easiest and the most economical way for roll assessments, but they are usually considered inaccurate compared to the other test types. Recent researches, however, have shown that a statistic approach which utilizes several decay data from the same model and loading condition improves the damping predictions. This paper provides comparisons of damping predictions from different test types based in extensive model test campaigns. It also addresses the issues and the lessons learned during the campaigns to obtain the FPSO damping database.

scholarly journals A program for the development of a benchmark compartment fire model computer code

1985 ◽  
Author(s):  
Leonard Y Cooper ◽  
John A Rockett ◽  
Henry E Mitler ◽  
David W Stroup
Keyword(s):  
Computer Code ◽  
Compartment Fire ◽  
Fire Model ◽  
Model Computer
Sign in / Sign up

Export Citation Format

Share Document