Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 26 for “"vortex breakdown"”.
-
Experimental Measurements of Vortex Breakdown with non-Isothermal Inflow
Vortex breakdown occurs in many flow applications such as weather, aerodynamics, swirl combustors, and more, introducing unsteadiness that is often undesired. While vortex breakdown has been previously investigated extensively, researchers have struggled to efficiently characterize these flows due …
-
A study of the mechanisms of axisymmetric vortex breakdown
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1994.
-
On Turbulent Swirling Jets: Vortex Breakdown, Coherent Structures, and their Control
… Durch das sogenannte Aufplatzen des Wirbelkerns (vortex breakdown) entsteht eine Rückströmblase auf der Strahlachse wodurch sich eine innere und eine äußere Scherschicht manifestiert. Die Analyse und Kontrolle dieser komplexen Strömungskonfiguration stellt allgemein eine große Herausforderung für …
-
Simulation of vorticity dynamics in swirling flows, mixing and vortex breakdown
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1996.
-
Studies of Vortex Breakdown and its Stability in a Confined Cylindrical Container
A combined experimental and numerical study on vortex breakdown structure and its dynamic behavior in a confined cylindrical container driven by one rotating endwall has been performed. The experiments included flow visualization and hot-film measurements, and the numerical simulation included the …
-
Adaptive mesh Euler equation computation of vortex breakdown in delta wing flow
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1993.
-
An experimental study of the relationship between forces and moments and vortex breakdown on a pitching delta wing
… was conducted to study the development, and breakdown of the leading-edge vortices under static, dynamic, and ramp conditions. The visualization experiment was performed at a Reynolds number of 0.16 $\times$ 10$\sp6$.
-
All The King's Horses: The Delta Wing Leading-Edge Vortex System Undergoing Vortex Breakdown: A Contribution to its characterization and Control under Dynamic Conditions
… the wing. The three-dimensional streamline and vortex line distributions were visualized. Isosurfaces of vorticity, planar distributions of helicity and all three vorticity components, and the indicator of the stability of the core were studied and compared to see which indicated breakdown …
-
Loss mechanisms in turbine tip clearance flows
… takes the form of a strong embedded streamwise vortex (u=ux 1 in the vortex core), and the mainstream ow is found to be the main source of loss. Vortex line contraction, and consequent vortex core expansion, and also vortex breakdown, are identied as the two important mechanisms that determine …
-
The Role of Swirl in the Flow Structure and Response of Premixed Flames
… The recirculation zone created through vortex breakdown mechanisms is found to interact with the central recirculation zone of an upstream bluff body and this leads to a complex flow behaviour that depends on the blockage ratio and swirl number. In isothermal flows, as the swirl number …
-
Flow and heat transfer characteristics of turbulent swirling impinging jets [thesis]
… which, in free (not impinging) jets, induces vortex breakdown and other instability modes. The addition of swirl to impinging jets thus has the potential to affect the transient and steady-state convective behaviour, both of which are crucial in industrial applications. This study features …
-
Three dimensional flow analysis by the vortex-lattice method
A Vortex-Lattice Method (VLM) has been developed for the analysis of three-dimensional lifting bodies undergoing arbitrary motions. So far, the present method has been applied to thin surfaces in translational motion. Several cases were tested, such as rectangular, delta, sweptback and trapezoidal …
-
Global stability and control of swirling jets and flames
… Two types of swirling diffusion flames with vortex breakdown bubbles are considered. They show qualitatively similar behaviour to the lifted jet diffusion flames. The first type of flame is unstable to a low-frequency mode, with wavemaker located at the flame base. The second type of flame is …
-
Experimental aero-acoustic assessment of swirling flows for drag applications
… drag quietly by establishing a steady streamwise vortex. The simple concept of a so called swirl tube, a ducted set of stationary turning vanes, was implemented to experimentally assess the aerodynamic and aero-acoustic behavior of swirling flows. A modular design was chosen for the model-scale …
-
The aerodynamics of a diffuser equipped bluff body in ground effect
… flow is characterised by a counter rotating vortex pair. The present research presents a new understanding of the diffuser flow field and the mechanisms causing its behaviour in ground effect. It has been found that the behaviour of the vortices alters according to the model ride height and …
-
The lateral-directional characteristics of a 74-degree delta wing employing gothic planform vortex flaps
… employing the latest generation, gothic planform vortex flaps has been conducted. In addition, the theoretical estimates from VORSTAB were compared against experimental data to aid in documenting this new method. VORSTAB is an extension of the Quasi-Vortex-Lattice Method of Lan which empirically …
-
The Dynamic Character of the Flow Over a 3.5 Caliber Tangent-Ogive Cylinder in Steady and Maneuvering States at High Incidence
… data planes located far from the forebody tip. Vortex shedding of the type exhibited by a circular cylinder in crossflow is observed, but this shedding is skewed by the presence of the tip, the shedding process does not require equal periods of time from each side of the body, and this results …
-
Aerodynamic pitch-up of cranked arrow wings: estimation, trim, and configuration design
… 5°) during low-speed flight due to leading edge vortex influence, flow separation and vortex breakdown. The work presented here describes an investigation conducted to study past research on the longitudinal aerodynamic characteristics of highly-swept cranked wing planforms, the development of a …
-
Large -eddy simulation of a three-dimensional compressible tornado vortex
… in peak vertical velocity and the height of the vortex breakdown above the surface. The effects are much weaker for medium swirl conditions, and expected to be still weaker for high swirl corner flow where the effects are essentially limited to influencing the secondary vortices. In general, …
-
The Development and Control of Axial Vortices over Swept Wings
The natural unsteadiness in the post-breakdown flowfield of a 75° sweep delta wing at 40° angle of attack was studied with dual and single point hot-wire anemometry in the Engineering Science and Mechanics (ESM) Wind Tunnel at a Reynolds number Re = 210,000. Data were taken in five crossflow planes …
Page 1 of 2