scholarly journals A hydrodynamic optimization design methodology for a ship bulbous bow under multiple operating conditions

2016 ◽  
Vol 10 (1) ◽  
pp. 330-345 ◽  
Author(s):  
Yu Lu ◽  
Xin Chang ◽  
An-kang Hu
Keyword(s):  
Design Methodology ◽  
Optimization Design ◽  
Operating Conditions ◽  
Bulbous Bow ◽  
Hydrodynamic Optimization

Numerical and experimental study on hydrodynamic bulbous bow hull-form optimization for various service conditions due to slow steaming of container vessel

2018 ◽  
Vol 233 (4) ◽  
pp. 1103-1122
Author(s):  
Xun-bin Yin ◽  
Yu Lu ◽  
Jin Zou ◽  
Lei Wan
Keyword(s):  
Optimization Design ◽  
Optimization Technique ◽  
Experimental Studies ◽  
Design Stage ◽  
Probability Density Distribution ◽  
Hull Form ◽  
Slow Steaming ◽  
Service Conditions ◽  
Bulbous Bow ◽  
Hydrodynamic Optimization

In this article, an innovative hydrodynamic optimization design of bulbous bow hull-form under various service conditions resulting from the slow steaming of container vessel is presented, improving the overall performances for the real multi-variant usage situations more practical than the single specification of design, which includes both numerical computation and experimental validation. Effects of slow steaming–based statistical analysis of the actual operative occurrence during the lifetime is conducted, obtaining a combined probability density distribution of speed and displacement ushering in the evaluation of objective function. Three main component elements of the hydrodynamic optimization procedure that comprises parametric design of bulbous bow hull-form variation part, hydrodynamic numerical solver part, and optimization technique part are established and integrated. The proposed optimization process is subsequently applied to find the optimal bulbous bow of a container carrier for the hipping demand of different speeds and displacement distributed utilization, reducing significantly total conditions resistance of the hull, on a higher level decreasing the operative cost as well as gas emissions of the ship. Finally, there is an experimental campaign carried out between the optimal and original models to validate the numerical optimization computations. The compared investigation has provided a good agreement from the perspective of both numerical and experimental studies, as a result confirming the success of the present optimization framework and the utility value of the proposed optimization consideration on various service conditions during ship design stage.

Geometric Optimization of Radiant Enclosures Containing Specular Surfaces

2003 ◽  
Vol 125 (5) ◽  
pp. 845-851 ◽  
Author(s):  
K. J. Daun ◽  
D. P. Morton ◽  
J. R. Howell
Keyword(s):  
Design Methodology ◽  
Optimization Design ◽  
Numerical Algorithms ◽  
Geometric Optimization ◽  
Trial And Error ◽  
Design Problems ◽  
Design Iteration ◽  
Optimization Methodology ◽  
Reflecting Surfaces ◽  
Specular Surfaces

This paper presents an optimization methodology for designing radiant enclosures containing specularly-reflecting surfaces. The optimization process works by making intelligent perturbations to the enclosure geometry at each design iteration using specialized numerical algorithms. This procedure requires far less time than the forward “trial-and-error” design methodology, and the final solution is near optimal. The radiant enclosure is analyzed using a Monte Carlo technique based on exchange factors, and the design is optimized using the Kiefer-Wolfowitz method. The optimization design methodology is demonstrated by solving two industrially-relevant design problems involving two-dimensional enclosures that contain specular surfaces.

Analysis of the internal flow behavior on S-shaped region of a Francis pump turbine on turbine mode

2016 ◽  
Vol 33 (2) ◽  
Author(s):  
Yexiang Xiao ◽  
Wei Zhu ◽  
Zhengwei Wang ◽  
jin zhang ◽  
Chongji Zeng ◽  
...  
Keyword(s):  
Design Methodology ◽  
Flow Characteristic ◽  
Stokes Equations ◽  
Flow Behavior ◽  
Internal Flow ◽  
Optimal Operation ◽  
Operating Conditions ◽  
Unit Discharge ◽  
Pump Turbine ◽  
Runner Blade

Purpose Numerically analyzed the flow characteristic and explored the hydrodynamic mechanism of the S-shaped region formation of a Francis pump-turbine. Design/methodology/approach Three-dimensional steady and unsteady simulations were performed for a number of operating conditions at the optimal guide vanes opening. The steady Reynolds averaged Navier-Stokes equations with the SST turbulence model were solved to model the internal flow within the entire flow passage. The predicted discharge-speed curve agrees well with the model test at generating mode. This paper compared the hydrodynamic characteristics of for off-design cases in S-shaped region with the optimal operating case, and more analysis focuses particularly on very low positive and negative discharge cases with the same unit speed. Findings At runaway case towards smaller discharge, the relative circumferential velocity becomes stronger in the vaneless, which generates the “water ring” and blocks the flow between guide vane and runner. The runner inlet attack angle becomes larger, and the runner blade passages nearly filled with flow separation and vortexes. The deterioration of runner blade flow leads to the dramatic decrease of runner torque, which tends to reduce the runner rotation speed. In this situation, the internal flow can’t maintain the larger rotating speed at very low positive discharge cases, so the unit discharge-speed curves bend to S-shaped near runaway case. Originality/value The analysis method of four off-design cases on S-shaped region with the comparison of optimal operation case and the calculated attack angles are adopted to explore the mechanism of S characteristic. The flow characteristic and quantitative analysis all explain the bending of the unit discharge-speed curves.

Hydrodynamic Optimization of a Wedge Hull

2015 ◽  
Author(s):  
Lijue Wang ◽  
Fuxin Huang ◽  
Chi Yang ◽  
Raju Datla
Keyword(s):  
Hydrodynamic Performance ◽  
Surface Mesh ◽  
Nurbs Surface ◽  
Bottom Edge ◽  
Hull Form ◽  
Entrance Angle ◽  
Total Drag ◽  
Rounded Corner ◽  
Bulbous Bow ◽  
Hydrodynamic Optimization

A novel wedge-shaped hull form is optimized for reduced drag using a further developed practical hydrodynamic optimization tool. The hull features a sharp entrance angle, rectilinear sides, sharp bottom edges, a triangular waterplane and a linear aftward taper from a deep bow to a shallow transom. The optimization involves two modifications of the hull form, one is to smooth out the sharp bottom edge with a rounded corner and the other is to generate a bulbous bow. In order to perform the hydrodynamic optimization of the hull, a Non-Uniform Rational BSpline (NURBS)-based hull surface modification tool, a NURBS surface mesh generator, a surrogate model and an evolutionary optimization solver are developed and integrated into the practical hydrodynamic optimization tool. The hydrodynamic performances, i.e., the total drag and the flow field near the obtained hull bodies are assessed and compared with the original wedge hull using numerical simulations. Results showed that rounding the sharp edge of the wedge hull can reduce the total drag by alleviating the flow separations around the hull body. The wedge hull with rounded bottom edge and optimized bulbous bow can achieve larger drag reduction and the flow separations are almost eliminated. The total drag of the optimal hull is compared with an earlier-optimized wedge hull that has a different type of bulbous bow, whose hydrodynamic performance has been validated by model tests.

scholarly journals A Review of the Flow-Induced Noise Study for Centrifugal Pumps

2020 ◽  
Vol 10 (3) ◽  
pp. 1022 ◽  
Author(s):  
Chang Guo ◽  
Ming Gao ◽  
Suoying He
Keyword(s):  
Optimization Design ◽  
Sound Field ◽  
Operating Conditions ◽  
Response Analysis ◽  
Centrifugal Pumps ◽  
Noise Optimization ◽  
Operating Stability ◽  
Study Results ◽  
Flow Induced Noise ◽  
Negative Impacts

Flow-induced noise is a significant concern for the design and operation of centrifugal pumps. The negative impacts of flow-induced noise on operating stability, human health and the environment have been shown in many cases. This paper presents a comprehensive review of the flow-induced noise study for centrifugal pumps to synthesize the current study status. First, the generation mechanism and propagation route of flow-induced noise are discussed. Then, three kinds of study methodologies, including the theoretical study of hydrodynamic noise, numerical simulation and experimental measurement study, are summarized. Subsequently, the application of the three study methodologies to the analysis of the distribution characteristics of flow-induced noise is analyzed from aspects of the noise source identification and comparison, the frequency response analysis, the directivity characteristics of sound field and the noise changing characteristics under various operating conditions. After that, the analysis of the noise optimization design of centrifugal pumps is summarized. Finally, based on previous study results, this paper puts forward the unsolved problems and implications for future study. In conclusion, the information collected in this review paper could guide further study of the flow-induced noise of centrifugal pumps.

The X-bar control chart with restriction of the capability indices

2017 ◽  
Vol 34 (1) ◽  
pp. 38-52 ◽  
Author(s):  
Pedro Carlos Oprime ◽  
Glauco Henrique de Sousa Mendes
Keyword(s):  
Phase I ◽  
Control Chart ◽  
Design Methodology ◽  
Simulation Method ◽  
Operating Conditions ◽  
Suggested Approach ◽  
Content Type ◽  
Capability Index ◽  
Simulation Techniques ◽  
Capability Indices

Purpose The purpose of this paper is to find the configuration of the number (m) and size (n) of the sample in Phase I that would make it possible to detect the out-of-control (OOC) state of the process with the smallest number of samples and ensure a capability index (Cpk) that would meet the customer’s requirements. Design/methodology/approach The suggested approach addresses this problem using simulation techniques and design of experiments (DOE). The simulation techniques made it possible to reproduce the normal operating conditions of the process. The DOE was used to construct a predictive model for control chart performance and thus to determine combinations of m and n in Phase I that would meet the capability objectives of the process. A numerical example and a simulation study were conducted to illustrate the proposed method. Findings Using simulation techniques and DOE, the authors can find the number (m) and size (n) of the sample in Phase I that would make it possible to detect the OOC state of the process with the smallest number of samples and ensure a Cpk that would meet the customer’s requirements. Originality/value In the real situations of many companies, choosing the numbers and sizes of samples (m and n) in Phases I and II is a crucial decision in relation to implementing a control chart. The paper shows that the simulation method and use of linear regression are effective alternatives because they are better known and more easily applied in industrial settings. Therefore, the need for alternatives to the X control chart comes into play.

Design Methodology for Passive Balancing Circuit including Real Battery Operating Conditions

2020 ◽  
Author(s):  
Mauro Di Monaco ◽  
Francesco Porpora ◽  
Giuseppe Tomasso ◽  
Matilde D'Arpino ◽  
Ciro Attaianese
Keyword(s):  
Design Methodology ◽  
Operating Conditions

Analysis and Optimization Design of Pressure Compensated Flow Control Valves

2003 ◽  
Author(s):  
Duqiang Wu ◽  
Richard Burton ◽  
Greg Schoenau ◽  
Doug Bitner
Keyword(s):  
Pressure Drop ◽  
Flow Control ◽  
Flow Rate ◽  
Total Pressure ◽  
Optimization Design ◽  
Constant Pressure ◽  
Control Device ◽  
Operating Conditions ◽  
Flow Control Device ◽  
Linearized Model

A pressure compensated valve (PC valve) is a type of flow control device that is a combination of a control orifice and a compensator (often called a hydrostat). The compensator orifice modulates its opening to maintain a constant pressure drop across the control orifice. In other words, the PC valve is so designed that the flow rate through the valve is governed only by the opening of the control orifice and is independent of the total pressure drop across the valve. Because of the high non-linearities associated with this type of valve, it is impossible, in practice, to design such a valve where the flow rate is completely unaffected by the pressure drop across the valve. In this paper, the effect of the non-linerities on the performance of the PC valve is investigated. First, a generic non-liner model of a PC valve is developed. Using this model, all possible operating conditions can be determined. Then a linearized model is developed and used to analyze the dynamic behavior of the PC valve. The model can then be used to optimize the design and operation of the valve for specific applications.

Extraction Shafting Oscillation Characteristic of Hydro Turbine Generating Sets Based on Prony Algorithm

2014 ◽  
Vol 889-890 ◽  
pp. 563-568
Author(s):  
Zhe Wu ◽  
Yun Zeng ◽  
Yan Yan Zeng ◽  
Shi Ge Yu
Keyword(s):  
Optimization Design ◽  
Attenuation Factor ◽  
Vibration Signal ◽  
Simulation Method ◽  
Structure Design ◽  
Operating Conditions ◽  
Transient Model ◽  
Hydro Turbine ◽  
Generating Sets ◽  
Prony Algorithm

Hydro turbine generating sets vibration is an important factor affecting the safe operation of hydropower stations. The research on the vibration characteristics is basic for the unit structure design, control design and hydropower station powerhouse structure optimization design. Based on built transient model of the hydropower turbine generating sets shafting, this paper constructed the whole hydropower turbine generating sets operating system by combine the hydro turbine, the generator object model, the governor and the excitation controller. Using numerical simulation method to obtained the shafting vibration data under different operating conditions. And then used Prony algorithm to extract the oscillation characteristics of amplitude, frequency, attenuation factor and phase angle from the vibration signal of hydro turbine generating sets shafting parameters. The simulation results show that the proposed method is effective.

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