VIV Predictions for an SCR in Sheared Ocean Currents

2002 ◽  
Author(s):  
Christopher J. Wajnikonis
Keyword(s):  
Experimental Data ◽  
Design Parameters ◽  
Finite Element Analyses ◽  
Steel Catenary Riser ◽  
Specialized Software ◽  
Design Engineers ◽  
Sensitivity Studies ◽  
Deepwater Riser ◽  
Extended Program ◽  
Areas Of Interest

Vortex Induced Vibration (VIV) prediction is one of the key areas of interest in Deepwater Riser Engineering. Several Joint Industry Projects (JIPs) are currently in progress in this field, which results in an increase of experimental data available to design engineers, in revisions of specialized software and in development of new engineering tools. This paper presents VIV predictions for a hypothetical Steel Catenary Riser (SCR) using the latest versions of the SHEAR7 and the VIVA/VIVARRAY Programs. Both built-in and extended program capabilities are utilized and detailed plots of computation results are presented. Sensitivity studies on the influence of variations of selected design parameters are also included in the paper. Finite Element Analyses (FEAs) results and simple engineering tools were utilized in parallel to built-in program features. The calculations demonstrated, that for the riser investigated and presumably also for a wide variety of similar SCRs, that the built in program features are sufficient to predict VIVs conservatively. Notes on VIV predictions in a real ocean and on selected areas that require investigation are also included.

Sensitivity Study of Critical Parameters Influencing the Uncertainty of Fatigue Damage in Steel Catenary Risers

2010 ◽  
Author(s):  
Feng Zi Li ◽  
Ying Min Low
Keyword(s):  
Fatigue Damage ◽  
Cost Effective ◽  
Sensitivity Study ◽  
Structural Safety ◽  
Critical Parameters ◽  
Design Parameters ◽  
Steel Catenary Riser ◽  
Bending Stresses ◽  
Steel Catenary Risers ◽  
Touchdown Point

The most challenging aspect of a deepwater development is the riser system, and a cost-effective choice is the Steel Catenary Riser (SCR). Fatigue is often a governing design consideration, and it is usually most critical at the touchdown point (TDP) where static and dynamic bending stresses are highest. Unfortunately, it is also at this region that uncertainty is the maximum. The increased uncertainty casts doubt on the applicability of generic safety factors recommended by design codes, and the most consistent way of ensuring the structural safety of the SCR is to employ a reliability-based approach, which has so far not received attention in SCR design. As the number of basic random variables affects the complexity of a reliability analysis, these variables should be selected with caution. To this end, the aim of this paper is to draw up a comprehensive list of design parameters that may contribute meaningfully to the uncertainty of the fatigue damage. From this list, several parameters are selected for sensitivity studies using the commercial package Orcaflex. It is found that variations in seabed parameters such as soil stiffness, soil suction and seabed trench can have a pronounced influence on the uncertainty of the fatigue damage at the touchdown point.

Model of the Performance of a Roadway Safety Fence and Its Use for Design

1998 ◽  
Vol 1647 (1) ◽  
pp. 122-129 ◽  
Author(s):  
Mark B. Bateman ◽  
Ian C. Howard ◽  
Andrew R. Johnson ◽  
John M. Walton
Keyword(s):  
Design Parameters ◽  
Vehicle Speed ◽  
Engineering Systems ◽  
Collapse Mechanisms ◽  
Development Costs ◽  
Roadway Safety ◽  
Sensitivity Studies ◽  
Complex Engineering ◽  
Alternative Designs ◽  
The Impact

The optimization of roadway safety design by experimental means is expensive and time consuming. Computer simulation of such complex engineering systems improves understanding of how and why the system behaves as it does, aids in decision making, and reduces development costs and time involved. The simulation presented is based on a computer model developed from a study of the results of full-scale experiments of impact on the Brifen wire-rope safety fence (WRSF). The code comprises a dynamic vehicle model and a quasi-static fence model interacting in time through the important collapse mechanisms of the system. The principles governing them are described and their inclusion is validated by demonstrating good correlation between the predictions of the simulation and the experimental test data. Sensitivity studies show that the performance of a WRSF is particularly sensitive to the impact conditions of vehicle speed and angle and the design parameters offence height, post spacing, post strength, and rope pre-tension. The sensitivity work is extended to show that for fences installed with a low rope pre-tension, performance may not be significantly impaired if rope pre-tension is not maintained. However, significant gains in fence performance may be made should a fence be installed and maintained with a high rope pre-tension. The use of the simulation in assessing cost-effectiveness of alternative designs in achieving a target performance is also demonstrated.

Influence of Film Cooling Hole Angles and Geometries on Aerodynamic Loss and Net Heat Flux Reduction

2011 ◽  
Author(s):  
Chia Hui Lim ◽  
Graham Pullan ◽  
Peter Ireland
Keyword(s):  
Heat Flux ◽  
Film Cooling ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Design Parameters ◽  
Aerodynamic Loss ◽  
Design Engineers ◽  
Net Heat Flux ◽  
Cooling Hole ◽  
Shaped Hole

Turbine design engineers have to ensure that film cooling can provide sufficient protection to turbine blades from the hot mainstream gas, while keeping the losses low. Film cooling hole design parameters include inclination angle (α), compound angle (β), hole inlet geometry and hole exit geometry. The influence of these parameters on aerodynamic loss and net heat flux reduction is investigated, with loss being the primary focus. Low-speed flat plate experiments have been conducted at momentum flux ratios of IR = 0.16, 0.64 and 1.44. The film cooling aerodynamic mixing loss, generated by the mixing of mainstream and coolant, can be quantified using a three-dimensional analytical model that has been previously reported by the authors. The model suggests that for the same flow conditions, the aerodynamic mixing loss is the same for holes with different α and β but with the same angle between the mainstream and coolant flow directions (angle κ). This relationship is assessed through experiments by testing two sets of cylindrical holes with different α and β: one set with κ = 35°, another set with κ = 60°. The data confirm the stated relationship between α, β, κ and the aerodynamic mixing loss. The results show that the designer should minimise κ to obtain the lowest loss, but maximise β to achieve the best heat transfer performance. A suggestion on improving the loss model is also given. Five different hole geometries (α = 35.0°, β = 0°) were also tested: cylindrical hole, trenched hole, fan-shaped hole, D-Fan and SD-Fan. The D-Fan and the SD-Fan have similar hole exits to the fan-shaped hole but their hole inlets are laterally expanded. The external mixing loss and the loss generated inside the hole are compared. It was found that the D-Fan and the SD-Fan have the lowest loss. This is attributed to their laterally expanded hole inlets, which lead to significant reduction in the loss generated inside the holes. As a result, the loss of these geometries is ≈ 50% of the loss of the fan-shaped hole at IR = 0.64 and 1.44.

Calculation of Meshing Efficiency of Helical Gear Based on Double Integral Method

2016 ◽  
Vol 693 ◽  
pp. 458-462
Author(s):  
D.G. Chang ◽  
F. Shu ◽  
X.B. Chen ◽  
Y.J. Zou
Keyword(s):  
Experimental Data ◽  
Coordinate System ◽  
Theoretical Basis ◽  
Integral Method ◽  
Helical Gear ◽  
Design Parameters ◽  
Double Integral ◽  
Rectangular Coordinate System ◽  
Helical Gears ◽  
Theoretical Results

The meshing efficiency of helical gear transmission is calculated by using the method of double integral. The external involute helical gear meshing is taken and the model of helical gears is simplified by the idea of differential. The instantaneous efficiency equation of a meshing point is derived, and further more the rectangular coordinate system of meshing zone of helical gears is established. The average meshing efficiency of helical gears is achieved by using double integral method. Then, the influence of design parameters is studied and the efficiency formula is verified by comparing the theoretical results with relevant experimental data, which can provide a theoretical basis for decide the design parameters.

Quantifying Customer Perception of Product Harmony Using Kansei Engineering Method

2002 ◽  
Vol 46 (6) ◽  
pp. 720-724 ◽  
Author(s):  
Lijian Zhang
Keyword(s):  
Interior Design ◽  
Truck Drivers ◽  
Design Parameters ◽  
Kansei Engineering ◽  
Vehicle Interior ◽  
Quantification Theory ◽  
Customer Perception ◽  
Design Elements ◽  
Design Engineers ◽  
Significant Difference

Vehicle interior harmony has drawn increasing attention from customers in recent years. Kansei Engineering is an effective approach to quantify customers' perception of harmony, and to correlate it to design parameters of the products. Herein, we investigated the customer perception of the visual aspects of commercial truck door interior design using classification methods. This article describes how these visual impressions are related to design elements using quantification theory, a commonly used method in Kansei Engineering. The results reveal that trim material, shape, color, window shape, and map pocket are design elements that strongly affect the perception of “elegance” and preferences of truck drivers. The results also showed a significant difference between the perception of the truck drivers and that of design engineers.

scholarly journals Reducing car audio button noise while maintaining tactile quality

2018 ◽  
Vol 10 (1) ◽  
pp. 168781401775259
Author(s):  
Hyo-Chan Kwon ◽  
Chang-Hee Cho ◽  
Cheong-Wu Nam ◽  
Soo-Won Chae ◽  
Seong-Yun Seo ◽  
...  
Keyword(s):  
Finite Element ◽  
Design Parameters ◽  
Model Parameters ◽  
Finite Element Analyses ◽  
Passenger Cars ◽  
Cabin Noise ◽  
Prototype Test ◽  
Subsequent Response ◽  
Car Audio ◽  
Improved Design

Recently, interior noise levels of passenger cars have been significantly reduced. The reduction of major cabin noise led to the recognition of small noises that are previously unnoticed. Specifically, the button noises of electrical devices in passenger compartments have been identified as belonging to this category of noise. The aim of this study is to improve the auditory quality of a car audio button while maintaining its tactile quality that is familiar to users. The tactile and auditory qualities can be described by the load versus stroke characteristics and the operation noise level. For buttons with rubber domes, the buckling behavior of the domes governs the tactile and auditory qualities. To preserve the tactile quality, the sensitivity of load versus stroke characteristics to each of the eight identified parameters is obtained from the finite element analyses using model parameters varied by ±10%. Four parameters to which the tactile quality was insensitive are selected. To identify the contributions of these four design parameters to auditory quality, finite element analyses were performed in conjunction with design of experiments. The improved design obtained by the subsequent response surface methodology optimization was validated by a prototype test with a 12 dBA reduction in noise.

Numerical and Experimental Studies of Ballistic Compression Process in a Soft Recovery System

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Girijesh Mathur ◽  
Nachiketa Tiwari ◽  
Neha Chaturvedi
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Experimental Studies ◽  
Pressure Rise ◽  
Sensitivity Analyses ◽  
Design Parameters ◽  
Strong Positive Correlation ◽  
Compression Process ◽  
Recovery System ◽  
Two Parameters

Abstract A ballistic compression type soft recovery system can stop a free-flying supersonic projectile in a controlled manner. The moment such a projectile enters the System, a normal shock gets created and starts hurtling down, to kick off a train of events involving shock reflections, diaphragm rupture, shock merger, creation of new shocks and contact discontinuities, and expansion wave-shock interactions. A good understanding of these phenomena and sensitivity of the System's performance to changes in design parameters is needed to design an efficient soft recovery system. Unfortunately, not much information is available about this. The present work fills this gap. We have developed a numerical model for the system and conducted sensitivity analyses using four design parameters; pressure, molecular weight, the ratio of specific heats, and temperature of gas used in the system. We show that while there is a strong, positive correlation between the first two parameters and projectile deceleration, the other two parameters are less critical. We conducted experiments to corroborate our conclusions and improve our numerical model. Post such improvements, we found the difference between simulation and experimental data to be acceptable. Experiments also confirmed the findings of our sensitivity studies. Finally, we conducted a two-dimensional finite volume analysis to understand the reasons underlying the residual difference between our numerical and experimental data. We show that such differences are due to pressure-rise at a point once a shock passes by it, and such a rise in pressure is attributable to boundary layer effects.

scholarly journals A simple model for solid oxide fuel cells

2020 ◽  
Author(s):  
Ghzzai Almutairi
Keyword(s):  
Experimental Data ◽  
Fuel Cells ◽  
Solid Oxide Fuel Cells ◽  
High Efficiency ◽  
Solid Oxide ◽  
Design Parameters ◽  
Oxide Fuel ◽  
Environment Pollution ◽  
Cell Potential ◽  
Basic Model

AbstractIt is widely accepted that solid oxide fuel cells (SOFCs) represent a promising energy conversion approach that deliver a myriad of benefits including low environment pollution, high efficiency, and system compactness. This paper describes the construction of a basic model based on ohmic considerations, mass transfer, and kinetics that can effectively evaluate the performance of small button SOFCs. The analysis of the data indicates that there is a close alignment between the cell potential calculated using the model and previous experimental data. As such, it can be concluded that the model can be employed to optimize, evaluate, or control the design parameters within a SOFC system.

Forecasting Manufacturing Quality and Optimizing Product Robustness Using Process Capability Data

Manufacturing ◽  
2003 ◽  
Author(s):  
Daniel Kern ◽  
Xiaoping Du ◽  
Agus Sudjianto
Keyword(s):  
Probabilistic Approach ◽  
Process Capability ◽  
Simulation Models ◽  
Design Parameters ◽  
Set Design ◽  
Manufacturing Quality ◽  
Design Engineers ◽  
Parameter Values ◽  
Manufacturing Variation

A company’s success is highly dependent on its ability to manufacture quality products. Designing products that can be manufactured to meet customer needs with an acceptable level of variation is challenging because design engineers are often unfamiliar with the company’s manufacturing capability or are unable to effectively use the capability data to improve a design. The authors present an approach to forecast the manufacturing quality of a product and optimize its robustness while it is being designed. The system comprises a database that stores process capability data and simulation models to simulate process capability data when actual, appropriate data are nonexistent. These data and tools are used with a new probabilistic approach through the inverse reliability strategy to optimize the robustness of a design by locating values of design parameters that enhance the performance of the design and are insensitive to manufacturing variation. Design engineers can use this approach to set design parameter values that will improve the functionality of the product while ensuring it can be produced with high capability. This approach is demonstrated with a design example of an engine valvetrain.

Design of Venturi-tube gas distributors for bubble-type reactors

1984 ◽  
Vol 49 (9) ◽  
pp. 1939-1948 ◽  
Author(s):  
Milan Rylek ◽  
Jindřich Zahradník
Keyword(s):  
Experimental Data ◽  
Gas Holdup ◽  
Venturi Tube ◽  
Design Parameters ◽  
Dispersion Characteristics ◽  
Liquid Circulation ◽  
Bed Porosity ◽  
Gas Distributor ◽  
Liquid Dispersion

The effect of individual parts of a Venturi-tube gas distributor on quality of the gas-liquid dispersion formed was studied in a bubble-type reactor with forced liquid circulation. Gas holdup (bubble-bed porosity) was used as the dispersion characteristics, type and geometry of nozzles, suction chamber arrangement, and dimensions of the mixing tube and diffuser were chosen as variable design parameters. Experimental data of gas holdup presented in dependence on the rate of energy dissipation in the place of dispersion formation characterized then the dispersion efficiency of the Venturi tube at given conditions. Recommendations for design of Venturi-tube gas distributors are presented based upon the results of the study.

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