Numerical Assessment of the Noise Signature Sidewall Contamination of a Linear Cascade With Moving Bars

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Manuel A. Burgos ◽  
Roque Corral
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Numerical Data ◽  
Periodic Case ◽  
Linear Cascade ◽  
Low Pressure Turbine ◽  
Pressure Distributions ◽  
Mode Decomposition ◽  
Numerical Assessment ◽  
Noise Signature

The effect of the finite extent of a linear cascade on the acoustic and vortical modes generated at the cascade exit by a set of moving bars located at the inlet is assessed by means of a numerical study. The sidewall interference is studied for an airfoil, which is representative of the midsection of a low pressure turbine airfoil. The deviations from the purely periodic steady state have been also investigated. It is concluded that both the unsteady pressure distributions on the airfoil and the mode-decomposition at the cascade exit show a reasonable matching with the purely periodic case, provided that the nominal interblade phase angle is taken into account to postprocess the numerical data. This conclusion is a key element to the investigation of the scattering and propagation of pure tones in turbomachinery in high speed linear cascades.

Numerical Assessment of the Noise Signature Sidewall Contamination of a Linear Cascade With Moving Bars

2008 ◽  
Author(s):  
Manuel A. Burgos ◽  
Roque Corral
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Numerical Data ◽  
Periodic Case ◽  
Linear Cascade ◽  
Low Pressure Turbine ◽  
Post Process ◽  
Pressure Distributions ◽  
Mode Decomposition ◽  
Noise Signature

The effect of the finite extent of a linear cascade on the acoustic and vortical modes generated at the cascade exit by a set of moving bars located at the inlet is assessed by means of a numerical study. The sidewall interference is studied for an airfoil which is representative of the mid-section of a low pressure turbine airfoil. The deviations from the purely periodic steady state have been also investigated. It is concluded that both, the unsteady pressure distributions on the airfoil, and the mode decomposition at the cascade exit show a reasonable matching with the purely periodic case, provided that the nominal inter-blade phase angle is taking into account to post-process the numerical data. This conclusion is a key element to the investigation of the scattering and propagation of pure tones in turbomachinery in high speed linear cascades.

Effect of Sidewall Contamination on Linear Cascades With Moving Bars

2005 ◽  
Author(s):  
Roque Corral ◽  
David del Campo
Keyword(s):  
Pressure Distribution ◽  
Numerical Study ◽  
Low Pressure ◽  
Periodic Case ◽  
Unsteady Pressure ◽  
Low Pressure Turbine ◽  
Mode Decomposition ◽  
Lateral Walls

The effect of the nite extent of linear cascades on the unsteady pressure distribution due to the presence of moving bars is assessed by means of a numerical study. The height of a reference cascade made up of at plates has been changed to quantify its in uence. It is concluded that seven blades are enough to get rid of the contamination associated to the lateral walls of the cascade on the modulus of the unsteady pressure and that the resonant conditions of the cascade shall be avoided to improve its periodicity. The sidewall interference has been also studied for a representative low pressure turbine airfoil without signicantly modifying the conclusions obtained using at plates. The mode decomposition at the cascade exit shows also a reasonable matching with the periodic case.

scholarly journals Effects of a Single Blade Incidence Angle Offset on Adjacent Blades in a Linear Cascade

Processes ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1974
Author(s):  
Jiří Fürst ◽  
Martin Lasota ◽  
Jan Lepicovsky ◽  
Josef Musil ◽  
Jan Pech ◽  
...  
Keyword(s):  
High Speed ◽  
Static Pressure ◽  
Incidence Angle ◽  
Blade Loading ◽  
Linear Cascade ◽  
Pressure Distributions ◽  
Blade Cascade ◽  
Loading Function ◽  
Stationary Approach ◽  
Dimensional Section

The paper presents a numerical and experimental investigation of the effect of incindence angle offset in a two-dimensional section of a flat blade cascade in a high-speed wind tunnel. The aim of the current work is tp determine the aerodynamic excitation forces and approximation of the unsteady blade-loading function using a quasi-stationary approach. The numerical simulations were performed with an in-house finite-volume code built on the top of the OpenFOAM framework. The experimental data were acquired for regimes corresponding to the numerical setup. The comparison of the computational and experimental results is shown for the static pressure distributions on three blades and upstream and downstream of the cascade. The plot of the aerodynamic moments acting on all five blades shows that the adjacent blades are significantly influenced by the angular offset of the middle blade.

scholarly journals 3D Printed Biomodels for Flow Visualization in Stenotic Vessels: An Experimental and Numerical Study

Micromachines ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 549
Author(s):  
Violeta Carvalho ◽  
Nelson Rodrigues ◽  
Ricardo Ribeiro ◽  
Pedro F. Costa ◽  
Rui A. Lima ◽  
...  
Keyword(s):  
High Speed ◽  
Complex Disease ◽  
Numerical Study ◽  
Numerical Data ◽  
In Vivo Studies ◽  
Physiological Variables ◽  
Microscopy Technique ◽  
Dynamics Simulations

Atherosclerosis is one of the most serious and common forms of cardiovascular disease and a major cause of death and disability worldwide. It is a multifactorial and complex disease that promoted several hemodynamic studies. Although in vivo studies more accurately represent the physiological conditions, in vitro experiments more reliably control several physiological variables and most adequately validate numerical flow studies. Here, a hemodynamic study in idealized stenotic and healthy coronary arteries is presented by applying both numerical and in vitro approaches through computational fluid dynamics simulations and a high-speed video microscopy technique, respectively. By means of stereolithography 3D printing technology, biomodels with three different resolutions were used to perform experimental flow studies. The results showed that the biomodel printed with a resolution of 50 μm was able to most accurately visualize flow due to its lowest roughness values (Ra = 1.8 μm). The flow experimental results showed a qualitatively good agreement with the blood flow numerical data, providing a clear observation of recirculation regions when the diameter reduction reached 60%.

A numerical study of aerodynamic characteristics of a high-speed train with different rail models under crosswind

2020 ◽  
pp. 095440972096925
Author(s):  
Zhiwei Jiang ◽  
Tanghong Liu ◽  
Houyu Gu ◽  
Zijian Guo
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Simulation Method ◽  
Aerodynamic Characteristics ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Pressure Distributions ◽  
Significant Difference ◽  
Aerodynamic Performances ◽  
Yaw Angle

The CFD (Computational Fluid Dynamics) numerical simulation method with the DES (detached eddy simulation) approach was adopted in this paper to investigate and compare the aerodynamic performance, pressure distributions of the train surface, and flow fields near the train model placed above the subgrade with non-rail, realistic rail, and simplified rail models under crosswind. The numerical methods were verified with the wind tunnel tests. Significant differences in aerodynamic performances of the train body and bogie were found in the cases with and without a rail model as the presence of the rail model had significant impacts on the flow field underneath the vehicle. A larger yaw angle can result in a more significant difference in aerodynamic coefficients. The deviations of the train aerodynamic forces and the pressure distribution on the train body with the realistic and simplified rail models were not significant. It was concluded that a rail model is necessary to get more realistic results, especially for large yaw angle conditions. Moreover, a simplified rectangular rail model is suggested to be employed instead of the realistic rail and is capable to get accurate results.

scholarly journals Numerical Study of Hydrodynamics of Heavily Loaded Hard-Chine Hulls in Calm Water

2021 ◽  
Vol 9 (2) ◽  
pp. 184
Author(s):  
Miles P. Wheeler ◽  
Konstantin I. Matveev ◽  
Tao Xing
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
The Other ◽  
Hydrodynamic Performance ◽  
Pressure Distributions ◽  
Wave Patterns ◽  
Speed Range ◽  
Calm Water ◽  
Program Star ◽  
Displacement Regime

Hard-chine boats are usually intended for high-speed regimes where they operate in the planing mode. These boats are often designed to be relatively light, but there are special applications that may occasionally require fast boats to be heavily loaded. In this study, steady-state hydrodynamic performance of nominal-weight and overloaded hard-chine hulls in calm water is investigated with computational fluid dynamics solver program STAR-CCM+. The resistance and attitude values of a constant-deadrise reference hull and its modifications with more pronounced bows of concave and convex shapes are obtained from numerical simulations. On average, 40% heavier hulls showed about 30% larger drag over the speed range from the displacement to planing modes. Among the studied configurations, the hull with a concave bow is found to have 5–12% lower resistance than the other hulls in the semi-displacement regime and heavy loadings and 2–10% lower drag in the displacement regime and nominal loading, while this hull is also capable of achieving fast planing speeds at the nominal weight with typical available thrust. The near-hull wave patterns and hull pressure distributions for selected conditions are presented and discussed as well.

Numerical study of high speed jets in crossflow

2015 ◽  
Vol 785 ◽  
pp. 152-188 ◽  
Author(s):  
Xiaochuan Chai ◽  
Prahladh S. Iyer ◽  
Krishnan Mahesh
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Near Field ◽  
Supersonic Jet ◽  
Jet Flow ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode ◽  
Good Prediction ◽  
Mode Decomposition ◽  
Sonic Jet

Large-eddy simulation (LES) and dynamic mode decomposition (DMD) are used to study an underexpanded sonic jet injected into a supersonic crossflow and an overexpanded supersonic jet injected into a subsonic crossflow, where the flow conditions are based on the experiments of Santiago & Dutton (J. Propul. Power, vol. 13 (2), 1997, pp. 264–273) and Beresh et al. (AIAA J., vol. 43, 2005a, pp. 379–389), respectively. The simulations successfully reproduce experimentally observed shock systems and vortical structures. The time averaged flow fields are compared to the experimental results, and good agreement is observed. The behaviour of the flow is discussed, and the similarities and differences between the two regimes are studied. The trajectory of the transverse jet is investigated. A modification to Schetz et al.’s theory is proposed (Schetz & Billig, J. Spacecr. Rockets, vol. 3, 1996, pp. 1658–1665), which yields good prediction of the jet trajectories in the current simulations in the near field. Point spectra taken at various locations in the flowfield indicate a global oscillation for the sonic jet flow, wherein different regions in the flow oscillate with a frequency of $St=fD/u_{\infty }=0.3$. For supersonic jet flow, no such global frequency is observed. Dynamic mode decomposition of the three-dimensional pressure field obtained from LES is performed and shows the same behaviour. The DMD results indicate that the $St=0.3$ mode is dominant between the upstream barrel shock and the bow shock for the sonic jet, while the roll up of the upstream shear layer is dominant for the supersonic jet.

Experimental Measurement of In-Plane Rolling Nonpneumatic Tire Vibrations Using High-Speed Imaging

2019 ◽  
Vol 47 (3) ◽  
pp. 196-210
Author(s):  
Meghashyam Panyam ◽  
Beshah Ayalew ◽  
Timothy Rhyne ◽  
Steve Cron ◽  
John Adcox
Keyword(s):  
High Speed ◽  
Image Correlation ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode ◽  
High Speed Imaging ◽  
Correlation Algorithm ◽  
Mode Decomposition ◽  
Series Of Experiments ◽  
Plane Deformations ◽  
Dominant Frequencies

ABSTRACT This article presents a novel experimental technique for measuring in-plane deformations and vibration modes of a rotating nonpneumatic tire subjected to obstacle impacts. The tire was mounted on a modified quarter-car test rig, which was built around one of the drums of a 500-horse power chassis dynamometer at Clemson University's International Center for Automotive Research. A series of experiments were conducted using a high-speed camera to capture the event of the rotating tire coming into contact with a cleat attached to the surface of the drum. The resulting video was processed using a two-dimensional digital image correlation algorithm to obtain in-plane radial and tangential deformation fields of the tire. The dynamic mode decomposition algorithm was implemented on the deformation fields to extract the dominant frequencies that were excited in the tire upon contact with the cleat. It was observed that the deformations and the modal frequencies estimated using this method were within a reasonable range of expected values. In general, the results indicate that the method used in this study can be a useful tool in measuring in-plane deformations of rolling tires without the need for additional sensors and wiring.

Numerical Performances Study of Curved Photovoltaic Panel Integrated with Phase Change Material

2020 ◽  
Vol 22 (4) ◽  
pp. 1439-1452
Author(s):  
Mohamed L. Benlekkam ◽  
Driss Nehari ◽  
Habib Y. Madani
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Numerical Study ◽  
Numerical Data ◽  
Navier Stokes ◽  
Photovoltaic Panel ◽  
Pv Panel ◽  
Energy Equations ◽  
Solid Liquid ◽  
Change Material

AbstractThe temperature rise of photovoltaic’s cells deteriorates its conversion efficiency. The use of a phase change material (PCM) layer linked to a curved photovoltaic PV panel so-called PV-mirror to control its temperature elevation has been numerically studied. This numerical study was carried out to explore the effect of inner fins length on the thermal and electrical improvement of curved PV panel. So a numerical model of heat transfer with solid-liquid phase change has been developed to solve the Navier–Stokes and energy equations. The predicted results are validated with an available experimental and numerical data. Results shows that the use of fins improve the thermal load distribution presented on the upper front of PV/PCM system and maintained it under 42°C compared with another without fins and enhance the PV cells efficiency by more than 2%.

scholarly journals Aerodynamics of inclined cylindrical bodies free-flying in a hypersonic flowfield

2021 ◽  
Vol 62 (9) ◽  
Author(s):  
Patrick M. Seltner ◽  
Sebastian Willems ◽  
Ali Gülhan ◽  
Eric C. Stern ◽  
Joseph M. Brock ◽  
...  
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Numerical Data ◽  
Static Stability ◽  
Free Flight ◽  
Aerodynamic Coefficients ◽  
Flow Topology ◽  
Motion Data ◽  
Continuous Rotation ◽  
German Aerospace

Abstract The influence of the flight attitude on aerodynamic coefficients and static stability of cylindrical bodies in hypersonic flows is of interest in understanding the re/entry of space debris, meteoroid fragments, launch-vehicle stages and other rotating objects. Experiments were therefore carried out in the hypersonic wind tunnel H2K at the German Aerospace Center (DLR) in Cologne. A free-flight technique was employed in H2K, which enables a continuous rotation of the cylinder without any sting interferences in a broad angular range from 0$$^{\circ }$$ ∘ to 90$$^{\circ }$$ ∘ . A high-speed stereo-tracking technique measured the model motion during free-flight and high-speed schlieren provided documentation of the flow topology. Aerodynamic coefficients were determined in careful post-processing, based on the measured 6-degrees-of-freedom (6DoF) motion data. Numerical simulations by NASA’s flow solvers Cart3D and US3D were performed for comparison purposes. As a result, the experimental and numerical data show a good agreement. The inclination of the cylinder strongly effects both the flowfield and aerodynamic loads. Experiments and simulations with concave cylinders showed marked difference in aerodynamic behavior due to the presence of a shock–shock interaction (SSI) near the middle of the model. Graphic abstract

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