Validation of Three-Dimensional Simulation of Flow through Hypersonic Air-breathing Engine

The flow path of a conceptual hypersonic air-breathing scramjet engine integrated with the vehicle (without combustion) has been simulated numerically using ANSYS CFX software with the SST turbulence model. The computations were performed for the free stream Mach number of 6 and angle-of-attack of 5°. A strong separation bubble was observed on the bodyside wall in the internal compression region where the reflected cowl shock impinges on body which in turn increases the static pressure substantially. The external-internal flow field of the hypersonic mixed compression intake, shock-boundary layer interactions, and the shock-shock interactions present in the internal compression region have qualitatively been obtained and analysed. The variation of centreline pressure along the bodyside wall close to the symmetry plane obtained from numerical simulation centreline has been compared with the experimentally measured data. It has been observed that the computed wall pressure matches fairly well with the measured values in the external ramp compression region, internal compression region and in the combustion chamber. The flow patterns and the pressure variations near the middle wall and the fuel injecting strut locations have also been analysed.Defence Science Journal, Vol. 65, No. 4, July 2015, pp. 272-278, DOI: http://dx.doi.org/10.14429/dsj.65.6979

Download Full-text

Inline Pump Internal Flow Characterization for Optimized Diesel Injection

ASME 2008 Internal Combustion Engine Division Spring Technical Conference ◽

10.1115/ices2008-1663 ◽

2008 ◽

Cited By ~ 2

Author(s):

G. Chiatti ◽

O. Chiavola ◽

F. Palmieri

Keyword(s):

Formation Control ◽

Fuel Injection ◽

Three Dimensional ◽

Internal Flow ◽

Injection Rate ◽

Local Pressure ◽

Injection Process ◽

Flow Characterization ◽

Dimensional Simulation ◽

And Performance

The injection process optimization plays a key role in diesel engine development activities, both for pollutant formation control and performance improvement. The present paper focuses on relatively small diesel units, equipped with fully mechanical injection systems; in detail, the considered system layout is based on the use of spring injectors; the amount of delivered fuel is controlled by the positioning of the pump plunger groove. The paper highlights the role of the inline pump and the influence of fuel characteristics on the system operation. By means of a three-dimensional numerical flow study, the behavior of pump fuel passages and delivery valve is simulated. Then, on the basis of the system features, a complete lumped/one-dimensional numerical model is realized, in which the discharge coefficients evaluated through the three-dimensional simulation are employed. Fuel injection rate and local pressure time histories are investigated, paying specific attention to the occurrence of the relevant phenomena in the system components. Obtained results are compared with experimental data.

Download Full-text

Numerical Study on the Flow Characteristics of the Francis Turbine With Various Blade Profiles

Volume 1B, Symposia: Fluid Machinery; Fluid Power; Fluid-Structure Interaction and Flow-Induced Noise in Industrial Applications; Flow Applications in Aerospace; Flow Manipulation and Active Control: Theory, Experiments and Implementation; Fundamental Issues and Perspectives in Fluid Mechanics ◽

10.1115/fedsm2013-16451 ◽

2013 ◽

Author(s):

J.-H. Jeon ◽

S.-S. Byeon ◽

Y.-J. Kim

Keyword(s):

Stokes Equations ◽

Numerical Study ◽

Three Dimensional ◽

Flow Characteristics ◽

Francis Turbine ◽

Navier Stokes ◽

Navier Stokes Equations ◽

Ansys Cfx ◽

Commercial Code ◽

Sst Turbulence Model

The Francis turbine is a kind of reaction turbines, which means that the potential energy of water converted to rotational kinetic energy. In this study, the flow characteristics have been investigated numerically in a Francis turbine on the 15 MW hydropower generation with various blade profiles (NACA 65 and NACA 16 series) and discharge angles (14°, 15°, 17°, and 18°), using the commercial code, ANSYS CFX. The k-ω SST turbulence model is employed in the Reynolds averaged Navier-Stokes equations. The computing domain includes the spiral casing, guide vanes, and draft tube, which are discretized with a full three-dimensional mesh system of unstructured tetrahedral shapes. The results showed that the change of blade profiles and discharge angles significantly influenced the performance of the Francis turbine.

Download Full-text

Performance Evaluation of an Internal Flow Navier-Stokes Solver for Compressible Viscous Flow Simulations

Volume 5: Turbo Expo 2002, Parts A and B ◽

10.1115/gt2002-30681 ◽

2002 ◽

Author(s):

H. Tug˘rul Tınaztepe ◽

Ahmet S¸. U¨c¸er ◽

I˙. Sinan Akamandor

Keyword(s):

Flow Field ◽

Separation Bubble ◽

Turbulent Viscosity ◽

Three Dimensional ◽

Internal Flow ◽

Leading Edge ◽

Navier Stokes ◽

Compressor Cascade ◽

Local Scaling ◽

Characteristic Boundary

A three-dimensional compressible full Navier-Stokes solver is developed for the analysis of the flow field inside turbomachinary cascades. The solver uses an explicit second order accurate (cell-vertex) finite volume Lax-Wendroff scheme over hexahedral cells. The viscous and heat conduction terms are discretized in conservative form at the cell center. Second and fourth order numerical smoothing terms are added with local scaling factors. Eddy viscosity is calculated by the Baldwin-Lomax model and is adapted to the pointered cell based algorithm. Turbulent viscosity is blended by inverse distance square weighting functions near corners. Characteristic boundary conditions are used. A computational analysis has been carried out to present the capability of the solver in capturing secondary velocity patterns, flow angles and total pressure loss distributions inside a linear high turning turbine cascade. A controlled diffusion compressor cascade at high incidence has been analyzed. Main features of the flow field in this compressor cascade were resolved (secondary and end wall flows and leading edge laminar separation bubble) as in the experimental data. The main aim of the work is to demonstrate the performance of the code in capturing the details of the complicated flow fields using grids that can be regarded as coarse.

Download Full-text

Pumping Performance of a Valveless Micropump Using Three-Dimensional Electro-Fluid-Structural Interaction Simulation

Smart Materials, Adaptive Structures and Intelligent Systems, Volume 1 ◽

10.1115/smasis2008-474 ◽

2008 ◽

Author(s):

Van Phuoc Phan ◽

Nam Seo Goo ◽

Cheol Heui Han

Keyword(s):

Three Dimensional ◽

Flow Simulation ◽

Structural Domain ◽

Flow Rates ◽

Structural Part ◽

Valveless Micropump ◽

Ansys Cfx ◽

Interaction Simulation ◽

Dimensional Simulation ◽

Diffuser Angle

In this study, the pumping performance of a piezoelectric valveless micropump is simulated. The micropump, which was developed in the previous work, is composed of a four-layer lightweight piezocomposite actuator, a polydimethylsiloxane (PDMS) pump chamber, and two diffusers. The piezoelectric domain, the structural domain and the fluid domain are coupled in the three-dimensional simulation. For structural part, we used ANSYS. The fluid flow simulation is done with ANSYS CFX. The water flow rates are numerically predicted for geometric parameters of the micropump such as diffuser length and diffuser angle. The simulation is also verified with the experiment and the simulation results are acceptable for predicting the pumping performance.

Download Full-text

Destabilisation and modification of Tollmien–Schlichting disturbances by a three-dimensional surface indentation

Journal of Fluid Mechanics ◽

10.1017/jfm.2017.193 ◽

2017 ◽

Vol 819 ◽

pp. 592-620 ◽

Cited By ~ 18

Author(s):

Hui Xu ◽

Shahid M. Mughal ◽

Erwin R. Gowree ◽

Chris J. Atkin ◽

Spencer J. Sherwin

Keyword(s):

Boundary Layer ◽

Linear Models ◽

Flow Instability ◽

Separation Bubble ◽

Three Dimensional ◽

Symmetry Plane ◽

Nonlinear Behaviour ◽

Numerical Work ◽

Tollmien Schlichting ◽

Topological Changes

We consider the influence of a smooth three-dimensional (3-D) indentation on the instability of an incompressible boundary layer by linear and nonlinear analyses. The numerical work was complemented by an experimental study to investigate indentations of approximately $11\unicode[STIX]{x1D6FF}_{99}$ and $22\unicode[STIX]{x1D6FF}_{99}$ width at depths of 45 %, 52 % and 60 % of $\unicode[STIX]{x1D6FF}_{99}$, where $\unicode[STIX]{x1D6FF}_{99}$ indicates 99% boundary layer thickness. For these indentations a separation bubble confined within the indentation arises. Upstream of the indentation, spanwise-uniform Tollmien–Schlichting (TS) waves are assumed to exist, with the objective to investigate how the 3-D surface indentation modifies the 2-D TS disturbance. Numerical corroboration against experimental data reveals good quantitative agreement. Comparing the structure of the 3-D separation bubble to that created by a purely 2-D indentation, there are a number of topological changes particularly in the case of the widest indentation; more rapid amplification and modification of the upstream TS waves along the symmetry plane of the indentation is observed. For the shortest indentations, beyond a certain depth there are then no distinct topological changes of the separation bubbles and hence on flow instability. The destabilising mechanism is found to be due to the confined separation bubble and is attributed to the inflectional instability of the separated shear layer. Finally for the widest width indentation investigated ($22\unicode[STIX]{x1D6FF}_{99}$), results of the linear analysis are compared with direct numerical simulations. A comparison with the traditional criteria of using $N$-factors to assess instability of properly 3-D disturbances reveals that a general indication of flow destabilisation and development of strongly nonlinear behaviour is indicated as $N=6$ values are attained. However $N$-factors, based on linear models, can only be used to provide indications and severity of the destabilisation, since the process of disturbance breakdown to turbulence is inherently nonlinear and dependent on the magnitude and scope of the initial forcing.

Download Full-text

Turbulent Flow Around Obstacles: Simulation and Study with Variable Roughness

International Journal of Heat and Technology ◽

10.18280/ijht.390530 ◽

2021 ◽

Vol 39 (5) ◽

pp. 1659-1666

Author(s):

Sidi Mohammed Yousfi ◽

Khaled Aliane

Keyword(s):

Three Dimensional ◽

Computer Code ◽

Numerical Approach ◽

Ansys Cfx ◽

Sst Turbulence Model ◽

Variable Roughness ◽

Recirculation Zones ◽

A New Technique ◽

Current Lines ◽

Volume Method

The present work aims to investigate the recirculation and incipient mixing zones in a channel flow supplied with obstacles. The main objective is to develop a new technique to control these recirculation zones by setting a variable roughness. For the purpose of varying that roughness, 4 small bars of heights 0.25H, 0.5H, 0.75H and H were placed downstream of the obstacle; H is the height of the obstacle. For this, a three-dimensional numerical approach was carried out using the ANSYS CFX computer code. In addition, the governing equations were solved using the finite volume method. The K-ω shear-stress transport (SST) turbulence model was utilized to model the turbulent stresses. In the end, we presented the time-averaged simulation results of the contours of the current lines (3D time-averaged streamlines, trace-lines), three components of the velocities: (velocity u contour), <v> (velocity v contour) and <w> (velocity w contour), trace-lines, stream ribbons and mean Q-criterion iso-surface.

Download Full-text

Study on Characteristics of Flow-Induced Vibration in Pre-Opening Sleeve Valve

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.562-564.1182 ◽

2012 ◽

Vol 562-564 ◽

pp. 1182-1185

Author(s):

Shan Tu ◽

Ming Hao Li ◽

Chao Wang ◽

De Dong ◽

Yue Juan Shi

Keyword(s):

Dynamic Pressure ◽

Three Dimensional ◽

Pressure Sensors ◽

Internal Flow ◽

Flow Induced Vibration ◽

Vortex Induced Vibration ◽

Vibration Data ◽

Large Pressure ◽

Valve Disc ◽

Dimensional Simulation

Flow-induced vibration widely exists in fluid power machinery, and there is a great relation between the vibration and engineering construction. In this paper, prototype valve experiment and three-dimensional simulation has been done on the pre-opening sleeve valve. High-frequency minute dynamic pressure sensors are adopted in the valve in experiment. Vibration data with dynamic pressure in different conditions are collected and measured to find out the pulsation characteristics of the valve disc during the experiment. Meanwhile, three-dimensional numerical simulation and analysis on the internal flow field of the valve has carried out, in order to discover the factors of vibration induced by fluid flow. The result shows that the main cause of flow-induced vibration varies in different conditions. At the condition of large opening and large pressure difference between valve inlet and outlet, it is mainly due to vortex-induced vibration. Several ways such as improving damping, avoiding the resonance frequency and changing the type of the valve profile can be taken to weaken the vortex-induced vibration.

Download Full-text

Experimental and Numerical Analysis of a Motorcycle Air Intake System Aerodynamics and Performance

International Journal of Automotive and Mechanical Engineering ◽

10.15282/ijame.17.1.2020.10.0565 ◽

2020 ◽

Vol 17 (1) ◽

Author(s):

M. A. Abd Halim ◽

N. A. R. Nik Mohd ◽

M. N. Mohd Nasir ◽

M. N. Dahalan

Keyword(s):

Combustion Process ◽

Three Dimensional ◽

Engine Performance ◽

Internal Flow ◽

Rapid Expansion ◽

Navier Stokes ◽

Turbulent Fluctuation ◽

Ansys Fluent ◽

Induction System ◽

Acceleration And Deceleration

Induction system or also known as the breathing system is a sub-component of the internal combustion system that supplies clean air for the combustion process. A good design of the induction system would be able to supply the air with adequate pressure, temperature and density for the combustion process to optimizing the engine performance. The induction system has an internal flow problem with a geometry that has rapid expansion or diverging and converging sections that may lead to sudden acceleration and deceleration of flow, flow separation and cause excessive turbulent fluctuation in the system. The aerodynamic performance of these induction systems influences the pressure drop effect and thus the engine performance. Therefore, in this work, the aerodynamics of motorcycle induction systems is to be investigated for a range of Cubic Feet per Minute (CFM). A three-dimensional simulation of the flow inside a generic 4-stroke motorcycle airbox were done using Reynolds-Averaged Navier Stokes (RANS) Computational Fluid Dynamics (CFD) solver in ANSYS Fluent version 11. The simulation results are validated by an experimental study performed using a flow bench. The study shows that the difference of the validation is 1.54% in average at the total pressure outlet. A potential improvement to the system have been observed and can be done to suit motorsports applications.

Download Full-text