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Theo G. Keith

Bio: Theo G. Keith is an academic researcher from University of Toledo. The author has contributed to research in topics: Bearing (mechanical) & Aerodynamics. The author has an hindex of 24, co-authored 187 publications receiving 2238 citations. Previous affiliations of Theo G. Keith include National Research Council & Glenn Research Center.


Papers
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Journal ArticleDOI
TL;DR: In this article, a numerical procedure to predict the effects of gaseous cavitation in moderately to heavily loaded bearings is developed, which is an outgrowth of the Elrod algorithm which is simple to use and automatically implements cavitation boundary conditions at film rupture and reformation.
Abstract: A numerical procedure to predict the effects of gaseous cavitation in moderately to heavily loaded bearings is developed. The method is an outgrowth of the Elrod algorithm which is simple to use and which automatically implements cavitation boundary conditions at film rupture and reformation. The current procedure makes use of type differencing in the shear induced flow formulation to automatically switch from central to upwind differences, and vice versa, at cavitation boundaries. Comparison is made with the results obtained using Elrod's algorithm for various test cases involving both slider and journal bearings. Presented at the 43rd Annual Meeting in Cleveland, Ohio May 9–12, 1988

197 citations

Journal ArticleDOI
TL;DR: In this paper, an implicit numerical scheme, based on an approximate factorization technique, is applied to a cavitation algorithm, which automatically predicts film rupture and reformation in bearings, and provides time accurate solutions with a minimum expenditure of CPU time.
Abstract: In this paper, an implicit numerical scheme, based on an approximate factorization technique, is applied to a cavitation algorithm. The algorithm is a modified version of the Elrod cavitation algorithm, which automatically predicts film rupture and reformation in bearings. At each time step, Newton iterations are performed to achieve time accurate solutions for unsteady problems. This numerical scheme is applied in both orthogonal and nonorthogonal grid arrangements. An aligned finite grooved bearing and a flared, misaligned line grooved bearing are analyzed using this new approach. The predictions are compared with the results obtained with procedures currently being used. The new scheme is robust, quickly convergent, and provides time accurate solutions with a minimum expenditure of CPU time.

109 citations

Journal ArticleDOI
15 Nov 1989-Wear
TL;DR: A modified version of the Elrod cavitation algorithm, which automatically predicts film rupture and reformation in bearings, is used to analyze a misaligned grooved journal bearing as mentioned in this paper, and the predicted performance of the misaligned bearing is compared with available experimental and theoretical results.

61 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of journal misalignment on the predicted performance of a finite-grooved journal bearing is analyzed, and the numerical procedure used incorporates a cavitation algorithm, which automatically predicts film rupture and reformation in the bearings.
Abstract: The effect of journal misalignment on the predicted performance of a finite grooved journal bearing is analyzed in this paper. The numerical procedure used incorporates a cavitation algorithm, which automatically predicts film rupture and reformation in the bearings. The misalignment considered varies in magnitude and direction with reference to the boundaries of the bearing. In addition to the misalignment, the effect of lubricant starvation at the groove is also considered and compared with flooded inlet conditions. The effects of various degrees of starvation, or higher lubricant supply pressure, bearing length to diameter ratio and groove size are also investigated

60 citations

Proceedings ArticleDOI
01 Jan 1990
TL;DR: In this paper, a time domain approach is used to determine the dynamic aeroelastic stability of a cascade of blades, and the effect of interblade phase angle is included in the analysis by allowing each blade to have an independent motion and considering a number of blade passages.
Abstract: A time domain approach is used to determine the dynamic aeroelastic stability of a cascade of blades. The structural model for each blade is a typical section with two degrees of freedom. The aerodynamic model is the unsteady, two-dimensional, full-potential flow through the cascade of airfoils. The unsteady equations of motion for the structure and the fluid are integrated simultaneously in time starting with the steady flowfield and a small initial disturbance applied to the airfoils. The motion of each blade is analyzed to determine the aeroelastic stability of the cascade. The effect of interblade phase angle is included in the analysis by allowing each blade to have an independent motion and considering a number of blade passages. Calculations are made using an airfoil section and structural parameters that are representative of a propfan. The results are compared with those from a separate frequency domain analysis. Good agreement between the results is observed. With the time domain approach, it is possible to consider nonlinear structural models and nonlinear force-displacement relations. The method allows a realistic simulation of the motion of the fluid and the cascade blades for a better physical understanding and it also has the potential for saving computational time when compared to the frequency domain approach for the flutter analysis of cascades.

56 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the aerodynamic properties of wind turbine wakes are studied, focusing on the physics of power extraction by wind turbines, and the main interest is to study how the far wake decays downstream in order to estimate the effect produced in downstream turbines.

1,161 citations

Journal ArticleDOI
TL;DR: In this article, the authors focus on the recent development in the synthesis, property characterization and application of aluminum, magnesium, and transition metal-based composites reinforced with carbon nanotubes and graphene nanosheets.
Abstract: One-dimensional carbon nanotubes and two-dimensional graphene nanosheets with unique electrical, mechanical and thermal properties are attractive reinforcements for fabricating light weight, high strength and high performance metal-matrix composites. Rapid advances of nanotechnology in recent years enable the development of advanced metal matrix nanocomposites for structural engineering and functional device applications. This review focuses on the recent development in the synthesis, property characterization and application of aluminum, magnesium, and transition metal-based composites reinforced with carbon nanotubes and graphene nanosheets. These include processing strategies of carbonaceous nanomaterials and their composites, mechanical and tribological responses, corrosion, electrical and thermal properties as well as hydrogen storage and electrocatalytic behaviors. The effects of nanomaterial dispersion in the metal matrix and the formation of interfacial precipitates on these properties are also addressed. Particular attention is paid to the fundamentals and the structure–property relationships of such novel nanocomposites.

877 citations

Journal ArticleDOI
TL;DR: In this article, a comprehensive review of wind turbine aeroelasticity is given, starting with the simple aerodynamic Blade Element Momentum Method and ending with giving a review of the work done applying CFD on wind turbine rotors.

618 citations

Journal ArticleDOI
TL;DR: In this paper, the authors provide a comparative summary of different modeling techniques for fluid flow, cavitation and micro-hydrodynamic effects for surface texturing, and provide the key findings.

590 citations

Journal ArticleDOI
TL;DR: In this article, the authors defined accumulation parameter Cd drag coefficient Ci = lift coefficient Cm = moment coefficient Cp = pressure coefficient c = specific heat at constant pressure, J/(kg-K); airfoil chord, m D = propeller diameter, m; flexural stiffness, N-m D drag force, N d = droplet diameter, E = total collection efficiency / = freezing fraction g = acceleration caused from gravity, m/s Hi = ice thickness, m Hp = plate thickness.
Abstract: Nomenclature Ac = accumulation parameter Cd drag coefficient Ci = lift coefficient Cm = moment coefficient Cp = pressure coefficient c = specific heat at constant pressure, J/(kg-K); airfoil chord, m D = propeller diameter, m; flexural stiffness, N-m D drag force, N d = droplet diameter, m E = total collection efficiency / = freezing fraction g = acceleration caused from gravity, m/s Hi = ice thickness, m Hp = plate thickness, m h = airfoil projected height, m hc = convective heat transfer coefficient, W/(m-K) hfg = heat of vaporization, J/kg hsi = heat of fusion, J/kg / = airfoil drag constant K = thermal conductivity, W/(m-K); inertia parameter K0 = modified inertia parameter k = roughness diameter, m LWC = liquid water content, kg/m M = local Mach number MVD = median volume droplet diameter, m m = mass, kg ra = mass flow rate, kg/s m' = mass flow rate per unit width, kg/(m-s) m" = mass flux, kg/(m-s) n = normal direction P = pressure, Pa p spatial pressure distribution, N/m <2 = heat rate, W q = normal pressure distribution, N/m

335 citations