scholarly journals Validating propulsion system optimization procedure for a carrier vessel

2021 ◽  
Vol 4 (398) ◽  
pp. 68-80
Author(s):  
Lobachev Mikhail ◽  
◽  
Novoselov Vladimir ◽  
Polyakov Yury ◽  
Rudnichenko Alexey ◽  
...  
Keyword(s):  
Software Package ◽  
Control Volume ◽  
Three Dimensional ◽  
Optimization Procedure ◽  
System Optimization ◽  
Parametric Model ◽  
Propulsion System ◽  
Hydrodynamic Parameters ◽  
Propulsion Performance ◽  
Flow Parameters

Object and purpose of research. This research was intended to validate supercomputer-based optimization procedure for propulsion systems of carrier ships, with a case study of hull shape and propeller optimization for a Project 1594 vessel. Materials and methods. The optimization proceeds in Russian software package pSeven. The computation core is Siemens Star CCM+ software. Three-dimensional parametric model of the propeller is generated in KSRC-developed BladePlus software, whereas three-dimensional parametric model of the hull is generated in Siemens NX software package. Hydrodynamic parameters of the propulsion system are obtained as per CFD methods. Viscous flow parameters are obtained through control volume-based solution of unsteady Reynolds equations (URANS) closed by biparametric semi-empirical turbulence model. Main results. The study yielded a new bow shape offering lower wave-making resistance for the same overall dimensions. It also yielded a new shape of propeller offering higher efficiency than the initial one taking into account the limitations for available shaft torque. Design hydrodynamic parameters have been confirmed by the model test data obtained at KSRC Deepwater Test Tank. Propulsion performance calculation has shown a growth in the achievable speed of the optimized propulsion system in different running conditions. Conclusion. The optimization studies intended to improve propulsion efficiency of Project 1594 ships yielded new shapes for hull and propeller. The solution thus obtained features high propeller efficiency and low wave-making resistance of the hull. Numerical simulation results have been confirmed with experimental data.

scholarly journals A Practical Approach to the Assessment of Waterjet Propulsion Performance: The Case of a Waterjet-Propelled Trimaran

2019 ◽  
Vol 26 (4) ◽  
pp. 27-38 ◽  
Author(s):  
Lei Zhang ◽  
Jia-ning Zhang ◽  
Yu-chen Shang ◽  
Guo-xiang Dong ◽  
Wei-min Chen
Keyword(s):  
Partial Information ◽  
Control Volume ◽  
Three Dimensional ◽  
Empirical Method ◽  
Force Balance ◽  
Design Stage ◽  
Local Pressure ◽  
Local Loss ◽  
Propulsion Performance ◽  
Cfd Method

Abstract To obtain a reasonable evaluation of the performance of waterjet propulsion at the design stage, a semi-theoretical and semi-empirical method is used to calculate the fundamental parameters of waterjet propulsion performance using an iterative approach. To calculate the ship’s resistance, a boundary element method based on three-dimensional potential flow theory is used to solve the wave-making resistance, and an empirical approach is used to evaluate the viscous resistance. Finally, the velocity and pressure of the capture area of the waterjet propulsion control volume are solved based on turbulent boundary layer theory. The iteration equation is established based on the waterjet-hull force-balance equation, and the change in the ship’s attitude and the local loss of the intake duct are considered. The performance parameters of waterjet propulsion, such as resistance, waterjet thrust, thrust deduction, and the physical quantity of the control volume, are solved by iteration. In addition, a PID-controlled free-running ship model is simulated using the RANS CFD method as a comparison. We apply the proposed approach and the RANS CFD method to a waterjet-propelled trimaran model, and the simulation process and the results are presented and discussed. Although there are some differences between the two methods in terms of the local pressure distribution and thrust deduction, the relative error in the evaluation results for the waterjet propulsion performance is generally reasonable and acceptable. This indicates that the present method can be used at the early stages of ship design without partial information about the waterjet propulsion system, and especially in the absence of a physical model of the pump.

THREE-DIMENSIONAL PLANNING OF BRACHYTHERAPY FOR LOCALLY ADVANCED CERVICAL CANCER BY CT/MRI IMAGES

2018 ◽  
Vol 64 (5) ◽  
pp. 645-650
Author(s):  
Olga Kravets ◽  
Yelena Romanova ◽  
Oleg Kozlov ◽  
Mikhail Nechushkin ◽  
A. Gavrilova ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Local Control ◽  
Control Volume ◽  
Locally Advanced ◽  
Three Dimensional ◽  
Advanced Cervical Cancer ◽  
3D Ct ◽  
Mri Imaging ◽  
Tumor Target ◽  
Locally Advanced Cervical Cancer

We present our results of 3D CT/MRI brachytherapy (BT) planning in 115 patients with locally advanced cervical cancer T2b-3bN0-1M0. The aim of this study was to assess the differences in the visualization of tumor target volumes and risk organs during the 3D CT/MRI BT. The results of the study revealed that the use of MRI imaging for dosimetric planning of dose distribution for a given volume of a cervical tumor target was the best method of visualization of the soft tissue component of the tumor process in comparison with CT images, it allowed to differentially visualize the cervix and uterine body, directly the tumor volume. Mean D90 HR-CTV for MRI was 32.9 cm3 versus 45.9 cm3 for CT at the time of first BT, p = 0.0002, which is important for local control of the tumor process. The contouring of the organs of risk (bladder and rectum) through MRI images allows for more clearly visualizing the contours, which statistically significantly reduces the dose load for individual dosimetric planning in the D2cc control volume, і.є. the minimum dose of 2 cm3 of the organ of risk: D2cc for the bladder was 24.3 Gy for MRI versus 34.8 Gy on CT (p = 0.045); D2cc for the rectum - 18.7 Gy for MRI versus 26.8 Gy for CT (p = 0.046). This is a prognostically important stage in promising local control, which allows preventing manifestation of radiation damage.

A Real-Time Mathematical Model for Three-Dimensional Tidal Flow and Water Quality

1991 ◽  
Vol 24 (6) ◽  
pp. 171-177 ◽  
Author(s):  
Zeng Fantang ◽  
Xu Zhencheng ◽  
Chen Xiancheng
Keyword(s):  
Mathematical Model ◽  
Water Quality ◽  
Real Time ◽  
Control Volume ◽  
Tidal Flow ◽  
Three Dimensional ◽  
River Estuary ◽  
Pearl River Estuary ◽  
Practical Application ◽  
The Pearl River

A real-time mathematical model for three-dimensional tidal flow and water quality is presented in this paper. A control-volume-based difference method and a “power interpolation distribution” advocated by Patankar (1984) have been employed, and a concept of “separating the top-layer water” has been developed to solve the movable boundary problem. The model is unconditionally stable and convergent. Practical application of the model is illustrated by an example for the Pearl River Estuary.

scholarly journals Two view NURBS reconstruction based on GACO model

2021 ◽  
Author(s):  
Deepika Saini ◽  
Sanoj Kumar ◽  
Manoj K. Singh ◽  
Musrrat Ali
Keyword(s):  
Optimization Algorithms ◽  
Three Dimensional ◽  
Optimization Procedure ◽  
Least Square ◽  
Ant Colony ◽  
Free Form ◽  
Reconstruction Process ◽  
Nurbs Curve ◽  
Data Points ◽  
Ant Colony Optimization Algorithms

AbstractThe key job here in the presented work is to investigate the performance of Generalized Ant Colony Optimizer (GACO) model in order to evolve the shape of three dimensional free-form Non Uniform Rational B-Spline (NURBS) curve using stereo (two) views. GACO model is a blend of two well known meta-heuristic optimization algorithms known as Simple Ant Colony and Global Ant Colony Optimization algorithms. Basically, the work talks about the solution of NURBS-fitting based reconstruction process. Therefore, GACO model is used to optimize the NURBS parameters (control points and weights) by minimizing the weighted least-square errors between the data points and the fitted NURBS curve. The algorithm is applied by first assuming some pre-fixed values of NURBS parameters. The experiments clearly show that the optimization procedure is a better option in a case where good initial locations of parameters are selected. A detailed experimental analysis is given in support of our algorithm. The implemented error analysis shows that the proposed methodology perform better as compared to the conventional methods.

Assessment of Unsteady Flows in Turbines

1992 ◽  
Vol 114 (1) ◽  
pp. 79-90 ◽  
Author(s):  
O. P. Sharma ◽  
G. F. Pickett ◽  
R. H. Ni
Keyword(s):  
Unsteady Flow ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Experimental Investigations ◽  
Flow Parameters ◽  
Research Activities ◽  
Flow Features ◽  
Computational Fluid Dynamics Cfd ◽  
Turbine Design ◽  
The Impact

The impacts of unsteady flow research activities on flow simulation methods used in the turbine design process are assessed. Results from experimental investigations that identify the impact of periodic unsteadiness on the time-averaged flows in turbines and results from numerical simulations obtained by using three-dimensional unsteady Computational Fluid Dynamics (CFD) codes indicate that some of the unsteady flow features can be fairly accurately predicted. Flow parameters that can be modeled with existing steady CFD codes are distinguished from those that require unsteady codes.

Integral Modeling of a Twin-Screw Compressor

2016 ◽  
Vol 138 (7) ◽  
Author(s):  
Sarah Van Erdeweghe ◽  
Joris De Schutter ◽  
Eric Van den Bulck
Keyword(s):  
Working Conditions ◽  
Control Volume ◽  
Optimization Procedure ◽  
Future Research ◽  
Screw Compressor ◽  
Positive Displacement ◽  
Rotor Profile ◽  
Twin Screw ◽  
Large Application ◽  
Similarity Law

In this paper, an integral methodology for the modeling of a twin-screw compressor is presented. Starting from a known rotor profile, all the algorithms to calculate the second rotor profile, the size of the control volume, and the compressor's performance are presented. The proposed modeling approach can be applied in an optimization procedure to find the optimal rotor profiles for a given application, with corresponding working conditions. Furthermore, based on the modeling results and substantiated with measurements on different compressor types, a similarity law for positive displacement compressors seems to exist. The existence of a similarity law has large application potential as it could be used to predict the performance of a positive displacement compressor in other than the (lab) tested working conditions. Further investigation of the similarity law for positive displacement compressors is therefore proposed as a key topic for future research.

scholarly journals OPTIMALLY STAGGERED FINNED CIRCULAR AND ELLIPTIC TUBES IN FORCED CONVECTION

2003 ◽  
Vol 2 (2) ◽  
pp. 65 ◽  
Author(s):  
R. S. Matos ◽  
T. A. Laursen ◽  
J. V. C. Vargas ◽  
A. Bejan
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Optimization Procedure ◽  
Total Heat ◽  
Cross Sectional ◽  
Maximum Heat ◽  
Pressure Drops ◽  
Tube Cross Section ◽  
Fixed Volume ◽  
Maximum Heat Transfer

This work presents a three-dimensional (3-D) numerical and experimental geometric optimization study to maximize the total heat transfer rate between a bundle of finned tubes in a given volume and a given external flow both for circular and elliptic arrangements, for general staggered configurations. The optimization procedure started by recognizing the design limited space availability as a fixed volume constraint. The experimental results were obtained for circular and elliptic configurations with a fixed number of tubes (12), starting with an equilateral triangle configuration, which fitted uniformly into the fixed volume with a resulting maximum dimensionless tube-to-tube spacing S/2b = 1.5, where S is the actual spacing and b is the smaller ellipse semi-axis. Several experimental configurations were built by reducing the tube-to-tube spacings, identifying the optimal spacing for maximum heat transfer. Similarly, it was possible to investigate the existence of optima with respect to other two geometric degrees of freedom, i.e., tube eccentricity and fin-to-fin spacing. The results are reported for air as the external fluid in the laminar regime, for 125 and 100 Re 2b , where 2b is the ellipses smaller axis length. Circular and elliptic arrangements with the same flow obstruction cross-sectional area were compared on the basis of maximum total heat transfer. This criterion allows one to quantify the heat transfer gain in the most isolated way possible, by studying arrangements with equivalent total pressure drops independently of the tube cross section shape. This paper reports three-dimensional (3- D) numerical optimization results for finned circular and elliptic tubes arrangements, which are validated by direct comparison with experimental measurements with good agreement. Global optima with respect to tube-to-tube spacing, eccentricity and fin-tofin spacing ( 0.5 e 0.5, S/2b and 06 . 0 f for 125 and 100 Re 2b , respectively) were found and reported in general dimensionless variables. A relative heat transfer gain of up to 19% is observed in the optimal elliptic arrangement, as compared to the optimal circular one. The heat transfer gain, combined with the relative material mass reduction of up to 32% observed in the optimal elliptic arrangement in comparison to the circular one, show the elliptical arrangement has the potential for a considerably better overall performance and lower cost than the traditional circular geometry.

Optimization of Trenched Film Cooling Using RSM Coupled CFD

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
V.G. Krishna Anand ◽  
K.M. Parammasivam
Keyword(s):  
Film Cooling ◽  
Three Dimensional ◽  
Response Surfaces ◽  
Test Surface ◽  
Response Factor ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Flow Parameters ◽  
Considerable Impact ◽  
The Impact

AbstractThe trench film cooling employs film holes embedded in a slot created on the surface that requires protection from the impact of hot mainstream flow. The present investigation employs Response Surface Methodology (RSM) approach coupled with CFD analysis to develop a regression predictive model and to optimize the trench geometric and flow parameters viz., trench width (w), trench depth (d), film hole compound angle (β) and blowing ratio (M). The Area-averaged film cooling effectiveness (ȠAA) were chosen as a response factor for RSM and with trench design and flow parameters used as input factors for regression analysis. Analysis of variance (ANOVA) analysis was carried out on the regression model to identify the influence of individual parameters. Three dimensional response surfaces that relate the effect of input parameters on the response factor were analyzed. Experimental results of a case identified from the RSM matrix was found to correlate well with computational investigations. Results from the study indicate that the parameters d, β and M have considerable impact on film cooling performance of test surface with trenches.

Prediction of Permeability Tensor for Plain Woven Fabric by Using Control Volume Finite Element Method

2003 ◽  
Vol 11 (6) ◽  
pp. 465-476 ◽  
Author(s):  
Y. S. Song ◽  
K. Chung ◽  
T. J. Kang ◽  
J. R. Youn
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Control Volume ◽  
Three Dimensional ◽  
Woven Fabrics ◽  
Permeability Tensor ◽  
Woven Fabric ◽  
Stacking Order ◽  
Control Volume Finite Element ◽  
Element Method

The complete prediction of the second order permeability tensor for a three dimensional multi-axial preform is critical if we are to model and design the manufacturing process for composites by considering resin flow through a multi-axial fiber structure. In this study, the in-plane and transverse permeabilities for a woven fabric were predicted numerically by the coupled flow model, which combines microscopic and macroscopic flows. The microscopic and macroscopic flows were calculated by using 3-D CVFEM(control volume finite element method) for micro and macro unit cells. To avoid a checkerboard pressure field and improve the efficiency of numerical computation, a new interpolation function for velocity is proposed on the basis of analytical solutions. The permeability of a plain woven fabric was measured by means of an unidirectional flow experiment and compared with the permeability calculated numerically. Reverse and simple stacking of plain woven fabrics were taken into account and the relationship between the permeability and the structures of the preform such as the fiber volume fraction and stacking order is identified. Unlike other studies, the current study was based on a more realistic three dimensional unit cell. It was observed that in-plane flow is more dominant than transverse flow within the woven perform, and the effect of the stacking order of a multi-layered preform was negligible.

Effect of Periodic Imposed Heat Flux on Three-Dimensional Natural Convection in a Partially Heated Cubical Enclosure

2016 ◽  
Vol 831 ◽  
pp. 83-91
Author(s):  
Lahoucine Belarche ◽  
Btissam Abourida
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Numerical Study ◽  
Control Volume ◽  
Vertical Wall ◽  
Three Dimensional ◽  
Maximum Temperature ◽  
Cubical Enclosure ◽  
Simplec Algorithm ◽  
Volume Method

The three-dimensional numerical study of natural convection in a cubical enclosure, discretely heated, was carried out in this study. Two heating square sections, similar to the integrated electronic components, are placed on the vertical wall of the enclosure. The imposed heating fluxes vary sinusoidally with time, in phase and in opposition of phase. The temperature of the opposite vertical wall is maintained at a cold uniform temperature and the other walls are adiabatic. The governing equations are solved using Control volume method by SIMPLEC algorithm. The sections dimension ε = D / H and the Rayleigh number Ra were fixed respectively at 0,35 and 106. The average heat transfer and the maximum temperature on the active portions will be examined for a given set of the governing parameters, namely the amplitude of the variable temperatures a and their period τp. The obtained results show significant changes in terms of heat transfer, by proper choice of the heating mode and the governing parameters.

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