All-Speed Time-Accurate Underwater Projectile Calculations Using a Preconditioning Algorithm

2005 ◽  
Vol 128 (2) ◽  
pp. 284-296 ◽  
Author(s):  
Michael Dean Neaves ◽  
Jack R. Edwards
Keyword(s):  
High Speed ◽  
Compressible Flows ◽  
Time Derivative ◽  
Water Entry ◽  
Ideal Gas ◽  
Projectile Motion ◽  
Imaging Results ◽  
Underwater Projectile ◽  
Phase Water ◽  
Compressibility Effects

An algorithm based on the combination of time-derivative preconditioning strategies with low-diffusion upwinding methods is developed and applied to multiphase, compressible flows characteristic of underwater projectile motion. Multiphase compressible flows are assumed to be in kinematic and thermodynamic equilibrium and are modeled using a homogeneous mixture formulation. Compressibility effects in liquid-phase water are modeled using a temperature-adjusted Tait equation, and gaseous phases (water vapor and air) are treated as an ideal gas. The algorithm is applied to subsonic and supersonic projectiles in water, general multiphase shock tubes, and a high-speed water entry problem. Low-speed solutions are presented and compared to experimental results for validation. Solutions for high-subsonic and transonic projectile flows are compared to experimental imaging results and theoretical results. Results are also presented for several multiphase shock tube calculations. Finally, calculations are presented for a high-speed axisymmetric supercavitating projectile during the important water entry phase of flight.

scholarly journals On the compressibility effects in mixing layers

2016 ◽  
Vol 20 (5) ◽  
pp. 1473-1484
Author(s):  
Hechmi Khlifi ◽  
Taieb Lili
Keyword(s):  
High Speed ◽  
Compressible Flows ◽  
Mixing Layers ◽  
The Other ◽  
Compressible Turbulence ◽  
The Past ◽  
Main Indicator ◽  
Proposed Model ◽  
Precise Prediction ◽  
Compressibility Effects

Previous studies of compressible flows carried out in the past few years have shown that the pressure-strain is the main indicator of the structural compressibility effects. Undoubtedly, this terms plays a key role toward strongly changing magnitude of the turbulent Reynolds stress anisotropy. On the other hand, the incompressible models of the pressure-strain correlation have not correctly predicted compressible turbulence at high speed shear flow. Consequently, a correction of these models is needed for precise prediction of compressibility effects. In the present work, a compressibility correction of the widely used incompressible Launder Reece and Rodi model making their standard coefficients dependent on the turbulent and convective Mach numbers is proposed. The ability of the model to predict the developed mixing layers in different cases from experiments of Goebel and Dutton is examined. The predicted results with the proposed model are compared with DNS and experimental data and those obtained by the compressible model of Adumitroiae et al. and the original LRR model. The results show that the essential compressibility effects on mixing layers are well captured by the proposed model.

Research on Hydro-Dynamic of Column Body Water-Entry with Six-DOF at High-Speed

2014 ◽  
Vol 533 ◽  
pp. 40-43
Author(s):  
Shan Qi Wu ◽  
Xing Wu Kang
Keyword(s):  
Numerical Calculation ◽  
Flow Field ◽  
High Speed ◽  
Water Entry ◽  
Attitude Angle ◽  
Three Phase ◽  
Natural Cavitation ◽  
Six Dof ◽  
Phase Water ◽  
And Control

By using the commercial CFD software Fluent6.3, the three-phase (water, air, vapour) flow field with natural cavitation was established. The UDF(User Defined Function) was used to resolve and control the missiles movement. It realized the numerical calculation of unsteady high-speed water-entry flow field, which consider natural cavitation as well as the missiles multiple degree of free movement. In this paper, the missile high-speed water-entry flow field with different attitude angle were simulated and analyzed, and the influence of the attitude angle on the flow field were gained.

scholarly journals Large Eddy Simulations of Strongly Non-Ideal Compressible Flows through a Transonic Cascade

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 772
Author(s):  
Jean-Christophe Hoarau ◽  
Paola Cinnella ◽  
Xavier Gloerfelt
Keyword(s):  
Compressible Flows ◽  
Flow Behavior ◽  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Ideal Gas ◽  
Operating Conditions ◽  
Large Eddy Simulations ◽  
Working Fluid ◽  
Viscous Effects ◽  
Large Eddy

Transonic flows of a molecularly complex organic fluid through a stator cascade were investigated by means of large eddy simulations (LESs). The selected configuration was considered as representative of the high-pressure stages of high-temperature Organic Rankine Cycle (ORC) axial turbines, which may exhibit significant non-ideal gas effects. A heavy fluorocarbon, perhydrophenanthrene (PP11), was selected as the working fluid to exacerbate deviations from the ideal flow behavior. The LESs were carried out at various operating conditions (pressure ratio and total conditions at inlet), and their influence on compressibility and viscous effects is discussed. The complex thermodynamic behavior of the fluid generates highly non-ideal shock systems at the blade trailing edge. These are shown to undergo complex interactions with the transitional viscous boundary layers and wakes, with an impact on the loss mechanisms and predicted loss coefficients compared to lower-fidelity models relying on the Reynolds-averaged Navier–Stokes (RANS) equations.

scholarly journals A feature-based mesh adaptation for the unsteady high speed compressible flows in complex three-dimensional domains

2016 ◽  
Vol 40 (3) ◽  
pp. 1728-1740
Author(s):  
Hoang-Huy Nguyen ◽  
Vinh-Tan Nguyen ◽  
Matthew A. Price ◽  
Oubay Hassan
Keyword(s):  
High Speed ◽  
Compressible Flows ◽  
Three Dimensional ◽  
Mesh Adaptation ◽  
Feature Based

On the Planning and Construction of Railway Curved Track

2021 ◽  
Vol 13 (2) ◽  
Author(s):  
Sono Bhardawaj ◽  
Rakesh Chandmal Sharma ◽  
Sunil Kumar Sharma ◽  
Neeraj Sharma
Keyword(s):  
High Speed ◽  
Time Derivative ◽  
Railway Track ◽  
Lateral Acceleration ◽  
Transition Curve ◽  
Railway Vehicle ◽  
Geometric Conditions ◽  
Curve Track ◽  
Curved Track ◽  
Transition Curves

Increasing demand for railway vehicle speed has pushed the railway track designers to develop high-quality track. An important measure of track quality is the character of the transition curve track connecting different intersecting straight tracks. A good transition curve track must be able to negotiate the intermittent stresses and dynamic effects caused by changes in lateral acceleration at high speed. This paper presents the constructional methods for planning transition curves considering the dynamics of movement. These methods consider the non-compensated lateral acceleration, deviation in lateral acceleration and its higher time derivatives. This paper discusses the laying methods of circular, vertical and transition curves. Key aspects in laying a curved track e.g. widening of gauge on curves are discussed in this paper. This paper also suggests a transition curve which is effective not only from a dynamic point of view considering lateral acceleration and its higher time derivative but also consider the geometric conditions along with the required deflection angle.

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