Mathematical Modeling of Pneumatic Pipes in a Simulation of Heterogeneous Engineering Systems

2011 ◽  
Vol 133 (12) ◽  
Author(s):  
Zbigniew Kamiński
Keyword(s):  
Stokes Equations ◽  
Navier Stokes ◽  
Engineering Systems ◽  
Test Results ◽  
Navier Stokes Equations ◽  
Kolmogorov Smirnov ◽  
Complex Fluid ◽  
Control Circuits ◽  
Drive And Control ◽  
And Control

Pipes are widely used in hydraulic and pneumatic subsystems for transferring energy or signals. Accurate prediction of pressure transients is very important in the drive and control circuits of complex fluid-line systems. Based on the approximation of Navier-Stokes equations for one-dimensional flow, a mathematical model of the pneumatic pipe with lumped parameters was developed using ordinary differential equations, which can be easily implemented in most computer programs for the simulation of complex heterogeneous engineering systems. Implemented in Matlab-Simulink software, the computer model of the pipe makes it possible to determine the influence of capacitance, inertance, resistance and heat exchange on the dynamic characteristics of the control and power circuits of pneumatic systems. An advantage of the model is that various functions can be selected to describe linear resistances and local resistances are taken into account, particularly at the inlet and outlet. Such resistances largely affect flow resistances in short tubes (up to 10 m) that can be found, e.g., in pneumatic brake systems of road vehicles. Confirmed by Kolmogorov-Smirnov test results, the consistency of the pressure curves obtained in experimental and simulation tests proves the implemented tube model to be useful for the calculations of pneumatic system dynamics.

A Particle-Based Model for Prediction of Cement Diffusion During Osteoporotic Hip Augmentation Surgery: Theory and Validation

2010 ◽  
Author(s):  
E. Basafa ◽  
Y. Otake ◽  
M. D. Kutzer ◽  
R. S. Armiger ◽  
M. Armand
Keyword(s):  
Bone Cement ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Patient Specific ◽  
Osteoporotic Bone ◽  
Navier Stokes Equations ◽  
Injection Process ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
And Control

Elderly patients with preexisting osteoporotic hip fracture are at high risk of a subsequent fracture in their contralateral hip. Current preventive approaches commonly have a long delay in restoring bone strength leaving patients at continued risk despite preventive efforts. Femoroplasty — injection of bone cement into the proximal femur — has been proposed as a potential preventive approach. However, it can cause complications because of extravasation of the cement into unwanted regions of the bone and an increased pressure within the bone, if not controlled and planned carefully. Therefore, precise modeling of the diffusion of the bone cement in osteoporotic bone and control over the injection process is of substantial importance. This paper presents a patient-specific fluid dynamics model to simulate the diffusion of the bone cement inside femur. The model is based on the smoothed particle hydrodynamics (SPH) method for particle-based modeling of fluids. The Navier-Stokes equations were built into the SPH formulations and viscosity effects were added to model the flow of cement inside porous media. To validate the model, a new prototype automatic injection device was used to inject acrylic silicone into a porous foam block. Results of simulation of the injection show close matching with experimental data. The model is therefore promising for further development of optimized and fully controlled femoroplasty procedures.

scholarly journals Numerical Analysis for Determination of Hydrodynamic Characteristics of a Gimbaled Thrust Vectoring Nozzle

2017 ◽  
Vol 41 (1) ◽  
pp. 69-84
Author(s):  
Saad Islam ◽  
Md Shafiqul Islam
Keyword(s):  
Stokes Equations ◽  
Rocket Motor ◽  
Navier Stokes ◽  
Hydrodynamic Characteristics ◽  
Navier Stokes Equations ◽  
Thrust Vectoring ◽  
Rocket Motors ◽  
Mach Number Distribution ◽  
Solid Rocket ◽  
And Control

Gimbaled thrust vectoring nozzles are employed in Solid Rocket Motors (SRM) to account for the aspects of maneuverability of the flight vehicle. The flow field of such a solid pulsed rocket motor is explored numerically (from dome-closeout onward) by solving Reynolds-averaged Navier-Stokes equations with Menter’s Shear Stress Transport (SST) k - ? turbulence model using a Computational Fluid Dynamics (CFD) tool. Parametric studies are carried out to find out the thermochemical and hydrodynamic characteristics of the hot gas in the rocket motor nozzle. The performances of different supersonic and subsonic sections were studied in terms of the hydrodynamic aspects such as static pressure and Mach number distribution. It is observed that the tradeoff of implementing thrust vectoring mechanism amounts to an additional pressure loss of 10.06% in the rocket motor. Such analyses are specific to certain types of Short Range Ballistic Missiles (SRBM) having solid state propellant (primary stage) in radial boost, end burning pulsed configuration with exacting demands on maneuverability and control implied upon payload and mission criterion.Journal of Bangladesh Academy of Sciences, Vol. 41, No. 1, 69-84, 2017

Three Dimensional Simulation of Bore Flow Using SPH

2010 ◽  
Author(s):  
Huaxing Liu ◽  
Soon Keat Tan ◽  
Jing Li ◽  
Xikun Wang
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Smooth Particle Hydrodynamic ◽  
Navier Stokes ◽  
Initial Water ◽  
Navier Stokes Equations ◽  
Sph Model ◽  
Complex Fluid ◽  
Dimensional Simulation

Tidal bore is a fascinating and powerful hydraulic phenomenon. In this paper, the tidal bore’s process is studied using 3D Smooth Particle Hydrodynamic (SPH) model. The Lagrangian nature of SPH suits well to the modeling of the complex fluid flow phenomenon. In the SPH method, the Navier-Stokes equations are discretized with fluid particles in the Lagrangine sense. Boundary conditions, including both no slip wall and bottom wall, are implemented using dynamic boundary particles. Using SPH, the bore’s generation together with its traverse along the channel are presented, including the description of flow field and bore’s configuration. Different types of bores’ behavior are investigated. It is observed that there is a splash of water surge up the wall and the front of the bore becomes a breaker wave when the initial water column travels at high speed. The velocity field and bore heights at different locations are visualized and discussed as well.

Development of a Second Generation In-Flight Icing Simulation Code (Keynote)

2003 ◽  
Author(s):  
Wagdi G. Habashi ◽  
He´loi¨se Beaugendre ◽  
Franc¸ois Morency
Keyword(s):  
Second Generation ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Simulation Code ◽  
Navier Stokes Equations ◽  
Stability And Control ◽  
And Performance ◽  
Light Material ◽  
And Control ◽  
Ice Shapes

Two-dimensional and quasi-3D in-flight ice accretion simulation codes have been widely used by the aerospace industry for the last two decades as an aid to the certification process. Such codes predict 2-D sectional ice shapes, which are then manufactured from a light material and attached as disposable profiles on a test aircraft to investigate it for stability and control under icing encounters. Although efficient for calculating ice shapes on simple geometries, current codes encounter major difficulties or simply cannot simulate ice shapes on truly 3D geometries such as nacelles, high-lift wings, engines and systems that combine external and internal flows. Modern Computational Fluid Dynamics (CFD) technologies can overcome many of these difficulties and FENSAP-ICE is such a second generation CFD-based in-flight icing simulation system, bringing to the icing field simulation methods already by the aircraft and turbomachinery industries. It is built in a modular and interlinked fashion to successively solve each of flow, impingement, accretion, heat loads and performance degradation via field models based on the Euler/Navier-Stokes equations for the clean and degraded flow, and new partial differential equations for the other three icing processes. This paper presents the FENSAP-ICE system and shows examples of its use.

scholarly journals Symmetries, Dynamics, and Control for the 2D Kolmogorov Flow

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-15
Author(s):  
Nejib Smaoui
Keyword(s):  
Numerical Simulations ◽  
Stokes Equations ◽  
Order System ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Number Range ◽  
Kolmogorov Flow ◽  
Dynamics And Control ◽  
Seventh Order ◽  
And Control

The symmetries, dynamics, and control problem of the two-dimensional (2D) Kolmogorov flow are addressed. The 2D Kolmogorov flow is known as the 2D Navier-Stokes (N-S) equations with periodic boundary conditions and with a sinusoidal external force along the x-direction. First, using the Fourier Galerkin method on the original 2D Navier-Stokes equations, we obtain a seventh-order system of nonlinear ordinary differential equations (ODEs) which approximates the behavior of the Kolmogorov flow. The dynamics and symmetries of the reduced seventh-order ODE system are analyzed through computer simulations for the Reynolds number range 0<Re<26.41. Extensive numerical simulations show that the obtained system is able to display the different behaviors of the Kolmogorov flow. Then, we design Lyapunov based controllers to control the dynamics of the system of ODEs to different attractors (e.g., a fixed point, a periodic orbit, or a chaotic attractor). Finally, numerical simulations are undertaken to validate the theoretical developments.

Study of Three-Dimensional Wall Effects on Micro Nozzle’s Performance

2011 ◽  
Vol 308-310 ◽  
pp. 1497-1504
Author(s):  
Jun Jie Tong ◽  
Ji Wen Cen ◽  
Jin Liang Xu
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Numerical Results ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Test Results ◽  
Wall Effects ◽  
Navier Stokes Equations ◽  
Micro Nozzle ◽  
Test Process

According to the lever moment equilibrium, the thrust test is performed for a flat micro convergent-divergent micro nozzle with 11.72 geometry expansion ratios. During the test process, since the distances between the Piezoelectric sensors point and the bearing point are much larger than the distance between the nozzle and the bearing point, thus the thrust signal is amplified. Compared with the test results, the FLUENT6.1 software is also applied to compute steady two-dimensional and three-dimensional Navier-stokes equations for numerical results by parallel computing. The numerical results and test results show that： for the flat micro nozzle with small ratio of throat depth and width, three-dimensional wall effects are not negligible. Three-dimensional numerical results agree well with the test results while there are large differences between two-dimensional numerical results and test results. With the throat Renaults being increased, the corresponding differences between two-dimensional numerical results and test results decreased accordingly

Progress toward CFD for full flight envelope

2005 ◽  
Vol 109 (1100) ◽  
pp. 451-460 ◽  
Author(s):  
E. N. Tinoco ◽  
D. R. Bogue ◽  
T-J. Kao ◽  
N. J. Yu ◽  
P. Li ◽  
...  
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Stokes Equations ◽  
Vortex Generator ◽  
Navier Stokes ◽  
High Lift ◽  
Navier Stokes Equations ◽  
Stability And Control ◽  
Flight Envelope ◽  
And Control

Abstract The value of computational fluid dynamics, CFD, delivered to date has mainly been related to its application to high-speed cruise design. To increase its applicability CFD must apply to the full flight envelope frequently characterised by large regions of separated flows. These flows are encountered by transport aircraft at low speed with deployed high lift devices, at their structural design loads conditions, or subjected to in-flight upsets that expose them to speed and/or angle-of-attack conditions outside the envelope of normal flight conditions to name a few. Such flows can only be characterised by the Navier-Stokes equations. This paper will report the progress toward CFD for full flight envelope. The CFD methods in use at Boeing will be described. Examples presented will address high-lift, loads and stability and control concerns including Reynolds scaling from wind tunnel to flight, vortex generator simulation, spoiler and horizontal tail effectiveness. In general, results shown are in ‘good enough’ agreement with experimental data. Deficiencies and the need for further algorithm and process improvement are noted. The need for automation to enable the large scale use of CFD will also be discussed.

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