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You searched for subject:(thermohydrodynamic analysis). Showing records 1 – 2 of 2 total matches.

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1. Sim, Kyu-Ho. Rotordynamic and thermal analyses of compliant flexure pivot tilting pad gas bearings.

Degree: PhD, Mechanical Engineering, 2009, Texas A&M University

Rotordynamic and thermal analyses of compliant flexure pivot tilting pad gas bearings were performed. First, compliant flexure pivot tilting pad gas bearings with pad radial compliance (CFTPBs) were introduced and designed for high-speed oil-free micro turbomachinery. The pad radial compliance was for accommodation of large rotor growth at high speeds. Parametric studies on pivot offset, preload, and tilting stiffness were performed using non-linear orbit simulations and coast-down simulations for an optimum design. Second, coast-down tests for imbalance response and stability of typical rotor-bearing system with a rigid rotor and two CFTPBs designed from the above design studies were conducted over operating speeds up to 55 krpm. Prediction of synchronous rotordynamic responses was made in terms of critical speed for various imbalance modes by using a rotordynamic analysis software (XLTRC), combined with dynamic force coefficients from the perturbation analysis. For stability analyses, a generalized orbit simulation program was developed considering both the translational and angular rotor motions with two different bearings. Linear stability analyses for the conical vibration mode were also performed by using XLTRC and the perturbation analysis based on the Lund method. Predictions of whirl speed showed good agreement to the tests, but the estimated onset speed of instability appeared lower than the measured instability. Finally, a new thermo-hydrodynamic analysis model of a typical rotor-bearing system with CFTPBs was presented, accompanying linear perturbation analyses to investigate thermal effects on the rotordynamic performance. A numerical procedure was established for solving the generalized Reynolds equation, the 3-D energy equation, and the associated boundary conditions at the pad inlet flow and solid walls (rotor and pad) simultaneously. Parametric studies were conducted on nominal clearance and external load. Nominal clearance showed significant influence on temperature fields, and external load had uneven thermal effects among pads. Case studies with heat flux and temperature boundary conditions on the rotor end surface were performed to simulate various working conditions of the bearing. Large rotor thermal growth due to the high rotor temperature showed noticeable influence on rotordynamic performance by increasing direct stiffness and damping coefficients. Advisors/Committee Members: Kim, Daejong (advisor), Hung, Wayne N.P. (committee member), Morrison, Gerald L. (committee member), Palazzolo, Alan B. (committee member).

Subjects/Keywords: gas bearings; tilting pad bearings; perturbation analysis; orbit simulation; thermohydrodynamic analysis; rotordynamic analysis; stability analysis; coast-down test

…68 THERMO-HYDRODYNAMIC ANALYSIS OF CFTPBS ................................. 70 5.1… …66 5.1 Parameters for THD analysis… …89 5.2 Description of thermal analysis cases… …5.7 Flow chart for the THD analysis… …developing numerical programs for the orbit simulation and the perturbation analysis. Experimental… 

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Sim, K. (2009). Rotordynamic and thermal analyses of compliant flexure pivot tilting pad gas bearings. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-1575

Chicago Manual of Style (16th Edition):

Sim, Kyu-Ho. “Rotordynamic and thermal analyses of compliant flexure pivot tilting pad gas bearings.” 2009. Doctoral Dissertation, Texas A&M University. Accessed October 24, 2020. http://hdl.handle.net/1969.1/ETD-TAMU-1575.

MLA Handbook (7th Edition):

Sim, Kyu-Ho. “Rotordynamic and thermal analyses of compliant flexure pivot tilting pad gas bearings.” 2009. Web. 24 Oct 2020.

Vancouver:

Sim K. Rotordynamic and thermal analyses of compliant flexure pivot tilting pad gas bearings. [Internet] [Doctoral dissertation]. Texas A&M University; 2009. [cited 2020 Oct 24]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-1575.

Council of Science Editors:

Sim K. Rotordynamic and thermal analyses of compliant flexure pivot tilting pad gas bearings. [Doctoral Dissertation]. Texas A&M University; 2009. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-1575

2. Alakhramsing, Shivam Sharwien. Towards a fundamental understanding of the tribological behaviour of cam-roller follower contacts.

Degree: 2019, University of Twente

Cam-roller followers are part of the valve train mechanisms found in internal combustion engines. Valve train friction losses may contribute up to 10% of the total engine friction losses. The lubricated cam-roller follower unit consists of two lubricated contacts, namely the cam-roller contact and roller-pin contact. While the former is a non-conformal contact, the latter is a conformal contact. The traction induced by the cam-roller contact drives the roller. It is important to study friction between the cam and roller as it influences the engine efficiency and the onset of wear – and thus ultimately lifetime – of components. Understanding lubrication conditions in the cam-roller contact is complicated due to transient variations of the geometry, force and friction in the roller-pin contact. A very important variable, affecting the cam-roller lubrication performance, is the frictional force (which resists the motion of the roller) at the roller-pin contact. The lubricated cam-roller contact studied in this thesis is highly loaded with contact forces up to 16 kN. Important lubrication performance indicators of the cam-roller contact are the pressure, film thickness and frictional force. This thesis focuses on the factors influencing the aforementioned lubrication performance indicators. Relying on the aforementioned, the factors studied in this work are: •The influence of axial shape of the roller: The axial shape of the roller and its influence on the generated film thickness, pressure and friction in the cam-roller contact. This was done by means of a smooth surface finite element method (FEM)-based finite line contact elastohydrodynamic lubrication (EHL) model. The model shows the effects of parameters describing the axial shape of the roller, velocity, load and material properties on the lubrication performance indicators. •The influence of elastic deformation in the roller-pin contact: In order to better quantify the friction, film thickness and pressure in the roller-pin contact a similar smooth surface FEM-based EHL model was developed for the roller-pin contact. The model demonstrates the importance of allowing for elastic deformation of the conformal roller-pin contact and its effect on film thickness, pressure and friction coefficient. •The influence of roller-pin contact friction in the high slide-to-roll ratio (SRR) domain of the cam-roller contact: At increasing levels of friction in the roller-pin contact the amount of sliding at the cam-roller contact increases, in turn affecting the film thickness, pressure and cam-roller contact friction coefficient. In order to analyse the effects of higher values of roller-pin friction coefficient on the cam-roller lubrication performance, an infinite line contact mixed-thermo-elastohydrodynamic (TEHL) model was developed for the cam-roller contact. The mixed-lubrication model is based on the load-sharing concept and uses real surface roughness measurement data as input. The complete model is based on a smooth surface FEM-based EHL line contact model and a boundary… Advisors/Committee Members: de Rooij, Matthias B., Schipper, Dirk J..

Subjects/Keywords: Elastohydrodynamic lubrication; cam-roller; roller-pin; mixed-lubrication; roller slip; asperity contact; Friction; Stick-slip; slide-to-roll ratio; Finite Element Analysis; thermohydrodynamic; thermo-elastohydrodynamic; Finite line contacts; logarithmic rollers; coating

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Alakhramsing, S. S. (2019). Towards a fundamental understanding of the tribological behaviour of cam-roller follower contacts. (Doctoral Dissertation). University of Twente. Retrieved from https://research.utwente.nl/en/publications/towards-a-fundamental-understanding-of-the-tribological-behaviour-of-camroller-follower-contacts(3ea78a51-f232-480d-80e3-5a27294d2f45).html ; urn:nbn:nl:ui:28-3ea78a51-f232-480d-80e3-5a27294d2f45 ; 3ea78a51-f232-480d-80e3-5a27294d2f45 ; 10.3990/1.9789036546669 ; urn:isbn:978-90-365-4666-9 ; urn:nbn:nl:ui:28-3ea78a51-f232-480d-80e3-5a27294d2f45 ; https://research.utwente.nl/en/publications/towards-a-fundamental-understanding-of-the-tribological-behaviour-of-camroller-follower-contacts(3ea78a51-f232-480d-80e3-5a27294d2f45).html

Chicago Manual of Style (16th Edition):

Alakhramsing, Shivam Sharwien. “Towards a fundamental understanding of the tribological behaviour of cam-roller follower contacts.” 2019. Doctoral Dissertation, University of Twente. Accessed October 24, 2020. https://research.utwente.nl/en/publications/towards-a-fundamental-understanding-of-the-tribological-behaviour-of-camroller-follower-contacts(3ea78a51-f232-480d-80e3-5a27294d2f45).html ; urn:nbn:nl:ui:28-3ea78a51-f232-480d-80e3-5a27294d2f45 ; 3ea78a51-f232-480d-80e3-5a27294d2f45 ; 10.3990/1.9789036546669 ; urn:isbn:978-90-365-4666-9 ; urn:nbn:nl:ui:28-3ea78a51-f232-480d-80e3-5a27294d2f45 ; https://research.utwente.nl/en/publications/towards-a-fundamental-understanding-of-the-tribological-behaviour-of-camroller-follower-contacts(3ea78a51-f232-480d-80e3-5a27294d2f45).html.

MLA Handbook (7th Edition):

Alakhramsing, Shivam Sharwien. “Towards a fundamental understanding of the tribological behaviour of cam-roller follower contacts.” 2019. Web. 24 Oct 2020.

Vancouver:

Alakhramsing SS. Towards a fundamental understanding of the tribological behaviour of cam-roller follower contacts. [Internet] [Doctoral dissertation]. University of Twente; 2019. [cited 2020 Oct 24]. Available from: https://research.utwente.nl/en/publications/towards-a-fundamental-understanding-of-the-tribological-behaviour-of-camroller-follower-contacts(3ea78a51-f232-480d-80e3-5a27294d2f45).html ; urn:nbn:nl:ui:28-3ea78a51-f232-480d-80e3-5a27294d2f45 ; 3ea78a51-f232-480d-80e3-5a27294d2f45 ; 10.3990/1.9789036546669 ; urn:isbn:978-90-365-4666-9 ; urn:nbn:nl:ui:28-3ea78a51-f232-480d-80e3-5a27294d2f45 ; https://research.utwente.nl/en/publications/towards-a-fundamental-understanding-of-the-tribological-behaviour-of-camroller-follower-contacts(3ea78a51-f232-480d-80e3-5a27294d2f45).html.

Council of Science Editors:

Alakhramsing SS. Towards a fundamental understanding of the tribological behaviour of cam-roller follower contacts. [Doctoral Dissertation]. University of Twente; 2019. Available from: https://research.utwente.nl/en/publications/towards-a-fundamental-understanding-of-the-tribological-behaviour-of-camroller-follower-contacts(3ea78a51-f232-480d-80e3-5a27294d2f45).html ; urn:nbn:nl:ui:28-3ea78a51-f232-480d-80e3-5a27294d2f45 ; 3ea78a51-f232-480d-80e3-5a27294d2f45 ; 10.3990/1.9789036546669 ; urn:isbn:978-90-365-4666-9 ; urn:nbn:nl:ui:28-3ea78a51-f232-480d-80e3-5a27294d2f45 ; https://research.utwente.nl/en/publications/towards-a-fundamental-understanding-of-the-tribological-behaviour-of-camroller-follower-contacts(3ea78a51-f232-480d-80e3-5a27294d2f45).html

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