scholarly journals Enhancement of thrust reverser cascade performance using aerodynamic and structural integration

2004 ◽  
Vol 108 (1090) ◽  
pp. 621-628 ◽  
Author(s):  
J. Butterfield ◽  
H. Yao ◽  
M. Price ◽  
C. Armstrong ◽  
S. Raghunathan ◽  
...  
Keyword(s):  
Structural Model ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Product Development Process ◽  
Structural Performance ◽  
Two Dimensional ◽  
Operational Conditions ◽  
Structural Integration ◽  
Thrust Reverser ◽  
Reverse Thrust

AbstractThis paper focuses on the design of a cascade within a cold stream thrust reverser during the early, conceptual stage of the product development process. A reliable procedure is developed for the exchange of geometric and load data between a two dimensional aerodynamic model and a three dimensional structural model. Aerodynamic and structural simulations are carried out using realistic operating conditions, for three different design configurations with a view to minimising weight for equivalent or improved aerodynamic and structural performance. For normal operational conditions the simulations show that total reverse thrust is unaffected when the performance of the deformed vanes is compared to the un-deformed case. This shows that for the conditions tested, the minimal deformation of the cascade vanes has no significant affect on aerodynamic efficiency and that there is scope for reducing the weight of the cascade. The pressure distribution through a two dimensional thrust reverser section is determined for two additional cascade vane configurations and it is shown that with a small decrease in total reverse thrust, it is possible to reduce weight and eliminate supersonic flow regimes through the nacelle section. By increasing vane sections in high pressure areas and decreasing sections in low pressure areas the structural performance of the cascade vanes in the weight reduced designs, is improved with significantly reduced levels of vane displacement and stress.

scholarly journals Metric for attractor overlap

2019 ◽  
Vol 874 ◽  
pp. 720-755 ◽  
Author(s):  
Rishabh Ishar ◽  
Eurika Kaiser ◽  
Marek Morzyński ◽  
Daniel Fernex ◽  
Richard Semaan ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Three Dimensional ◽  
Particle Image Velocimetry Data ◽  
Open Loop ◽  
Operating Conditions ◽  
Wall Turbulence ◽  
Circular Cylinders ◽  
Two Dimensional ◽  
Starting Point

We present the first general metric for attractor overlap (MAO) facilitating an unsupervised comparison of flow data sets. The starting point is two or more attractors, i.e. ensembles of states representing different operating conditions. The proposed metric generalizes the standard Hilbert-space distance between two snapshot-to-snapshot ensembles of two attractors. A reduced-order analysis for big data and many attractors is enabled by coarse graining the snapshots into representative clusters with corresponding centroids and population probabilities. For a large number of attractors, MAO is augmented by proximity maps for the snapshots, the centroids and the attractors, giving scientifically interpretable visual access to the closeness of the states. The coherent structures belonging to the overlap and disjoint states between these attractors are distilled by a few representative centroids. We employ MAO for two quite different actuated flow configurations: a two-dimensional wake with vortices in a narrow frequency range and three-dimensional wall turbulence with a broadband spectrum. In the first application, seven control laws are applied to the fluidic pinball, i.e. the two-dimensional flow around three circular cylinders whose centres form an equilateral triangle pointing in the upstream direction. These seven operating conditions comprise unforced shedding, boat tailing, base bleed, high- and low-frequency forcing as well as two opposing Magnus effects. In the second example, MAO is applied to three-dimensional simulation data from an open-loop drag reduction study of a turbulent boundary layer. The actuation mechanisms of 38 spanwise travelling transversal surface waves are investigated. MAO compares and classifies these actuated flows in agreement with physical intuition. For instance, the first feature coordinate of the attractor proximity map correlates with drag for the fluidic pinball and for the turbulent boundary layer. MAO has a large spectrum of potential applications ranging from a quantitative comparison between numerical simulations and experimental particle-image velocimetry data to the analysis of simulations representing a myriad of different operating conditions.

A two-dimensional/three-dimensional hybrid structural model of the vocal folds

2011 ◽  
Vol 130 (4) ◽  
pp. 2550-2550
Author(s):  
Douglas Cook ◽  
Pradeep George ◽  
Margaret Julias
Keyword(s):  
Structural Model ◽  
Three Dimensional ◽  
Vocal Folds ◽  
Two Dimensional

A Study of Spike and Modal Stall Phenomena in a Low-Speed Axial Compressor

1997 ◽  
Author(s):  
T. R. Camp ◽  
I. J. Day
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Operating Conditions ◽  
Two Dimensional ◽  
Stability Criteria ◽  
Stall Inception ◽  
Low Speed ◽  
The Stability ◽  
Dimensional Instability

This paper presents a study of stall inception mechanisms a in low-speed axial compressor. Previous work has identified two common flow breakdown sequences, the first associated with a short lengthscale disturbance known as a ‘spike’, and the second with a longer lengthscale disturbance known as a ‘modal oscillation’. In this paper the physical differences between these two mechanisms are illustrated with detailed measurements. Experimental results are also presented which relate the occurrence of the two stalling mechanisms to the operating conditions of the compressor. It is shown that the stability criteria for the two disturbances are different: long lengthscale disturbances are related to a two-dimensional instability of the whole compression system, while short lengthscale disturbances indicate a three-dimensional breakdown of the flow-field associated with high rotor incidence angles. Based on the experimental measurements, a simple model is proposed which explains the type of stall inception pattern observed in a particular compressor. Measurements from a single stage low-speed compressor and from a multistage high-speed compressor are presented in support of the model.

scholarly journals Effects of Operating Conditions on the Flow in the Moving Blade Passage of a Single Stage Axial-Flow Fan

1997 ◽  
Vol 3 (4) ◽  
pp. 269-276 ◽  
Author(s):  
Tsutomu Adachi ◽  
Yutaka Yamashita ◽  
Kennichiro Yasuhara ◽  
Tatsuo Kawai
Keyword(s):  
Three Dimensional ◽  
Axial Flow ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Hot Wire ◽  
Axial Flow Fan ◽  
Blade Passage ◽  
Operational Conditions ◽  
Flow Phenomena ◽  
Steady Velocity

Three dimensional steady and unsteady velocity distributions in the axial flow fan were measured using a hot wire probe for various operational conditions, various rotational speeds and various measuring positions. For measuring the velocity distributions in the blade passage, a specially designed and manufactured hot wire traversing apparatus was used. Steady velocity distributions, turning angles, effects of incident to the cascade, flow leakage through the tip clearance and effects of the flow separation show the flow phenomena through the blade passages. Unsteady velocity distributions show time dependent procedures of the wake flowing through the moving blade passage. Considering these results of measurements, the effects of the upstream stationary blade and the effects of Reynolds number on the flow were considered.

Simulation of Nonlinear Sloshing Behaviors under Dynamic Actions

2015 ◽  
Vol 772 ◽  
pp. 183-187
Author(s):  
Xiao Ye Yu ◽  
Alex To ◽  
Goman Ho
Keyword(s):  
Seismic Design ◽  
Reasonable Agreement ◽  
Three Dimensional ◽  
Structural Performance ◽  
Two Dimensional ◽  
Seismic Excitations ◽  
Structure Interaction ◽  
Ale Formulation ◽  
Steel Tank

This paper simulated the non-linear sloshing effects under typical dynamic actions. The sloshing simulation is realized with the Arbitrary Lagrangian Euleria (ALE) formulation plus bi-phase hydrodynamic biomaterial liquid gas materials. The study first investigated two dimensional (2D) sloshing problems under harmonic excitations. Through calibration studies in standard rectangular tanks, the case study demonstrated reasonable agreement with numerical results published by other researchers. The study was then extended to more complicated three dimensional (3D) sloshing problems, with the fluid-structure interaction (FSI) considered. The simulation well reflected the sloshing behaviours in a steel tank subject to given seismic excitations and provided available prediction for structural performance. The obtained results show that the used method is helpful for seismic design of liquid tanks.

scholarly journals CFD Analysis of Nozzle Exit Position Effect in Ejector Gas Removal System in Geothermal Power Plant

2015 ◽  
Vol 3 (1) ◽  
Author(s):  
Setyo Nugroho ◽  
Ciptananda Citrahardhani
Keyword(s):  
Reverse Flow ◽  
Position Effect ◽  
Computational Simulation ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Two Dimensional ◽  
Exit Nozzle ◽  
Gas Removal ◽  
Nozzle Position ◽  
Dimensional Simulation

The single stage ejector is used to extract the Non CondensableGas (NCG) in the condenser using the working principle of the Venturi tube. Three dimensional computational simulation of the ejector according to the operating conditions was conducted to determine the flow in the ejector. Motive steam entering through the convergent – divergent nozzle with increasing flow velocity so that the low pressure exist around the nozzle. Comparison is done also in a two dimensional simulation to know the differences occurring phenomena and flow inside ejector. Different simulation results obtained between two dimensional and three dimensional simulation. Reverse flow which occurs in the mixing chamber made the static pressure in the area has increased dramatically. Then the variation performed on Exit Nozzle Position (NXP) to determine the changes of the flow of the NCG and the vacuum level of the ejector.Keywords: Ejector, NCG, CFD, Compressible flow.

scholarly journals Study on airflow and vibraton in a cutting/collection/discharge lawn care system

2021 ◽  
Author(s):  
Evan D. Davidge
Keyword(s):  
Three Dimensional ◽  
Operating Conditions ◽  
Two Dimensional ◽  
Discharge System ◽  
Rotating Blades ◽  
Lawn Care ◽  
Optimal Shapes ◽  
Dimensional Models ◽  
Three Dimensional Models ◽  
Care System

Airflows in the cutting/collection/discharge system of a professional lawn care system were studied numerically and experimentally in this thesis. Various three-dimensional and two-dimensional computational fluid dynamics models were developed in order to investigate the complex airflow created by a pair of counter-rotating blades. The three-dimensional models were used to study the actual flows; the two-dimensional models were developed to investigate the optimal shapes of the rotating blades using the mass flow rate per unit power consumption as the objective function. Experiments were carried out mainly to validate the computer models developed in this study for airflow velocity and power usage for an actual cutting system. Vibrations of a cutting blade were studied using the finite element method and experiments. It was found that the blades will experience resonance under normal operating conditions.

Parameterization of a Multi-Directional Tidal Turbine Performance Using Computational Fluid Dynamics

2015 ◽  
Author(s):  
Richard B. Medvitz ◽  
Michael L. Jonson ◽  
James J. Dreyer ◽  
Jarlath McEntee
Keyword(s):  
Turbine Blade ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Moving Mesh ◽  
Cfd Analysis ◽  
Two Dimensional ◽  
Peak Efficiency ◽  
Trailing Edge ◽  
Blade Shape ◽  
Tidal Turbine

High resolution RANS CFD analysis is performed to support the design and development of the Ocean Renewable Power Company (ORPC) TidGen™ multi-directional tidal turbine. Two-dimensional and three-dimensional unsteady, moving-mesh CFD is utilized to parameterize the device performance and to provide guidance for device efficiency improvements. The unsteady CFD analysis was performed using a well validated, naval hydrodynamic CFD solver and implementing dynamic overset meshes to perform the relative motion between geometric components. This dynamic capability along with the turbulence model for the expected massively separated flows was validated against published data of a high angle of attack pitching airfoil. Two-dimensional analyses were performed to assess both blade shape and operating conditions. The blade shape performance was parameterized on both blade camber and trailing edge thickness. The blades shapes were found to produce nearly the same power generation at the peak efficiency tip speed ratio (TSR), however off-design conditions were found to exhibit a strong dependency on blade shape. Turbine blades with the camber pointing outward radially were found to perform best over the widest range of TSR’s. In addition, a thickened blade trailing edge was found to be superior at the highest TSR’s with little performance degradation at low TSR’s. Three-dimensional moving mesh analyses were performed on the rotating portion of the full TidGen™ geometry and on a turbine blade stack-up. Partitioning the 3D blades axially showed that no sections reached the idealized 2D performance. The 3D efficiency dropped by approximately 12 percentage points at the peak efficiency TSR. A blade stack-up analysis was performed on the complex 3D/barreled/twisted turbine blade. The analysis first assessed the infinite length blade performance, next end effects were introduced by extruding the 2D foil to the nominal 5.6m length, next barreling was added to the straight foils, and finally twist was added to the foils to reproduce the TidGen™ geometry. The study showed that making the blades a finite length had a large negative impact on the performance, whereas barreling and twisting the foils had only minor impacts. Based on the 3D simulations the largest factor impacting performance in the 3D turbine was a reduction in mass flow through the turbine due to the streamlines being forces outward in the horizontal plane due to the turbine flow resistance. Strategies to mitigate these 3D losses were investigated, including adding flow deflectors on the turbine support structure and stacking multiple turbines in-line.

Development of a Two-Dimensional Computational Fluid Dynamics Approach for Computing Three-Dimensional Honeycomb Labyrinth Leakage

2004 ◽  
Vol 126 (4) ◽  
pp. 794-802 ◽  
Author(s):  
Dong-Chun Choi ◽  
David L. Rhode
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Labyrinth Seal ◽  
Operating Conditions ◽  
Two Dimensional ◽  
Cfd Model ◽  
Resource Requirement ◽  
Three Dimensional Flow ◽  
Dimensional Flow

A new approach for employing a two-dimensional computational fluid dynamics (CFD) model to approximately compute a three-dimensional flow field such as that in a honeycomb labyrinth seal was developed. The advantage of this approach is that it greatly reduces the computer resource requirement needed to obtain a solution of the leakage for the three-dimensional flow through a honeycomb labyrinth. After the leakage through the stepped labyrinth seal was measured, it was used in numerically determining the value of one dimension (DTF1) of the simplified geometry two-dimensional approximate CFD model. Then the capability of the two-dimensional model approach was demonstrated by using it to compute the three-dimensional flow that had been measured at different operating conditions, and in some cases different distance to contact values. It was found that very close agreement with measurements was obtained in all cases, except for that of intermediate clearance and distance to contact for two sets of upstream and downstream pressure. The two-dimensional approach developed here offers interesting benefits relative to conventional algebraic-equation models, particularly for evaluating labyrinth geometries/operating conditions that are different from that of the data employed in developing the algebraic model.

CFD High L/D Riser Modeling Study

2007 ◽  
Author(s):  
Yiannis Constantinides ◽  
Owen H. Oakley ◽  
Samuel Holmes
Keyword(s):  
Fluid Flow ◽  
Computer Technology ◽  
Deep Water ◽  
Structural Model ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Flow Simulations ◽  
Dimensional Flow ◽  
Two Dimensional Flow ◽  
Good Agreement

Fully three dimensional fluid flow simulations are used with a simple structural model to simulate very long risers. This method overcomes many shortcomings of methodologies based on two dimensional flow simulations and can correctly include the effects of three dimensional structures such as strakes, buoyancy modules and catenary riser shapes. The method is benchmarked against laboratory and offshore experiments with model risers of length to diameter ratios up to 4,000. RMS values of vortex induced vibration motions are shown to be in good agreement with measurements. The resources needed to model ultra deep water drilling and production risers are estimated based on current computer technology.

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