Experimental and Numerical Investigations of Turbocharger Rotors on Full-Floating Ring Bearings With Circumferential Oil-Groove

2017 ◽  
Author(s):  
Ioannis Chatzisavvas ◽  
Gerrit Nowald ◽  
Bernhard Schweizer ◽  
Panagiotis Koutsovasilis
Keyword(s):  
Pressure Distribution ◽  
Thermal Energy ◽  
Reynolds Equation ◽  
Load Capacity ◽  
Nonlinear Differential Equations ◽  
Equations Of Motion ◽  
Oil Viscosity ◽  
Hydrodynamic Bearing ◽  
Numerical Investigations ◽  
Run Up

This work presents experimental and numerical investigations into the vibrations of turbocharger rotors on full-floating ring bearings with a circumferential oil-groove. The pressure distribution in the fluid-film bearings is calculated through the Reynolds equation using a highly efficient global Galerkin approach with suitable trial and test functions. The numerical efficiency of the method is markedly increased as the resultant linear system is solved symbolically, establishing a semi-analytical solution. The temperature in the oil-film may increase due to the mechanical power dissipation, affecting the pressure distribution and the load capacity of the bearing. Therefore, a reduced thermal energy model is implemented together with the Reynolds equation to account for the variable oil-viscosity and for the thermal expansion of the surrounding solids. The thermal energy balance equations are implemented in a transient form, i.e. including the time dependent temperature term. The corresponding system of nonlinear differential equations is efficiently solved, leading to a further significant reduction in simulation times. The hydrodynamic bearing model including the thermal effects is finally coupled with the equations of motion of a turbocharger rotor and numerical run-up simulations are compared with experimental results. The comparisons show that the numerical model captures adequately the dynamics of the system, giving precise information about the frequencies and the amplitudes of the synchronous and the self-excited subsynchronous rotor vibrations.

On the Influence of Thrust Bearings on the Nonlinear Rotor Vibrations of Turbochargers

2016 ◽  
Author(s):  
Ioannis Chatzisavvas ◽  
Aydin Boyaci ◽  
Andreas Lehn ◽  
Marcel Mahner ◽  
Bernhard Schweizer ◽  
...  
Keyword(s):  
Hydrodynamic Model ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Oil Viscosity ◽  
Oil Film ◽  
Thrust Bearings ◽  
Run Up ◽  
Generalized Reynolds Equation

This work investigates the influence of hydrodynamic thrust bearings on the lateral rotor oscillations. Four thrust bearing models are compared in terms of their predictions of the oil-film pressure (Reynolds equation), the oil-film temperature (energy equation) and the load capacity. A detailed thrust bearing model using the generalized Reynolds equation and the 3D energy equation, a model using the standard Reynolds equation with a 2D energy equation, a model where the standard Reynolds equation and the 2D energy equation are decoupled and finally an isothermal thrust bearing model are presented. It is shown that in lower rotational speeds, the four models produce almost the same results. However, as the rotational speed is increased, the necessity for a thermo-hydrodynamic model is demonstrated. Run-up simulations of a turbocharger rotor/bearing system are performed, using an isothermal thrust bearing model with different inlet oil-temperatures. The influence of the oil-temperature of the thrust bearing on the subsynchronous rotor oscillations is investigated. Finally, a thermo-hydrodynamic model is compared with an isothermal in run-up simulations, where the influence of the variable oil-viscosity is discussed.

Squeeze-Film Behavior in Porous Circular Disks

1974 ◽  
Vol 96 (2) ◽  
pp. 206-209 ◽  
Author(s):  
P. R. K. Murti
Keyword(s):  
Adverse Effect ◽  
Film Thickness ◽  
Pressure Distribution ◽  
Finite Time ◽  
Reynolds Equation ◽  
Load Capacity ◽  
The Other ◽  
Squeeze Film ◽  
Permeability Parameter ◽  
Circular Disks

The squeeze film behavior between two circular disks is analyzed when one disk has a porous facing and approaches the other disk with uniform velocity. The modified Reynolds equation governs the pressure in the film region while the pressure in the porous facing satisfies the Laplace equation. These equations are solved in a closed form and expressions are derived for pressure distribution, load capacity, and time of approach for the plates in terms of Fourier-Bessel series. It is found that an enhanced value for the permeability parameter diminishes the pressure over the entire disk and also evens out the pressure distribution; however, there is an adverse effect on the load capacity and time of approach. Unlike in the nonporous case, the entire fluid can be squeezed out in a finite time resulting in actual contact of the disks. The porous effects are shown to predominate at very low film thickness values.

scholarly journals Thrust Porous Bearing with Rough Surfaces Lubricated by a Rotem-Shinnar Fluid

2016 ◽  
Vol 10 (1) ◽  
pp. 50-55 ◽  
Author(s):  
Anna Walicka ◽  
Edward Walicki
Keyword(s):  
Pressure Distribution ◽  
Carrying Capacity ◽  
Reynolds Equation ◽  
Hydrodynamic Lubrication ◽  
Equations Of Motion ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Porous Bearing ◽  
Load Carrying ◽  
Plastic Fluid

Abstract In the paper the influence of both bearing surfaces roughness and porosity of one bearing surface on the pressure distribution and load-carrying capacity of a thrust bearing surfaces is discussed. The equations of motion of a pseudo-plastic fluid of Rotem-Shinnar, are used to derive the Reynolds equation. After general considerations on the flow in a bearing clearance and in a porous layer using the Morgan-Cameron approximation and Christensen theory of hydrodynamic lubrication the modified Reynolds equation is obtained. The analytical solutions of this equation for the cases of squeeze film bearing and externally pressurized bearing are presented. As a result one obtains the formulae expressing pressure distribution and load-carrying capacity. Thrust radial bearing with squeezed film is considered as a numerical example.

scholarly journals Numerical Solution of the MHD Reynolds Equation for Squeeze-Film Lubrication between Porous and Rough Rectangular Plates

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Ramesh B. Kudenatti ◽  
N. Murulidhara ◽  
H. P. Patil
Keyword(s):  
Pressure Distribution ◽  
Couple Stress ◽  
Reynolds Equation ◽  
Load Capacity ◽  
Roughness Parameter ◽  
Transverse Magnetic ◽  
Couple Stress Fluid ◽  
Squeeze Film ◽  
Physical Parameters ◽  
Rectangular Plates

The present theoretical study investigates the effects of surface roughness and couple-stress fluid between two rectangular plates, of which an upper rough plate has a roughness structure and the lower plate has a porous material in the presence of transverse magnetic field. The lubricant in the gap is taken to be a viscous, incompressible, and electrically conducting couple-stress fluid. This gap is separated by a film thickness H which is made up of nominal smooth part and rough part. The modified Reynolds equation in the film region is derived for one-dimensional longitudinal roughness structure and solved numerically using multigrid method. The numerical results for various physical parameters are discussed in terms of pressure distribution, load capacity, and squeeze film time of the bearing surfaces. Our results show that, the pressure distribution, load capacity and squeeze film time are predominant for larger values of Hartman number and roughness parameter, and for smaller values of couple-stress parameters when compared to their corresponding classical cases.

On the Analytical Evaluation of the Lubricant Pressure in the Finite Journal Bearing

2012 ◽  
Author(s):  
Athanasios Chasalevris ◽  
Dimitris Sfyris
Keyword(s):  
Analytical Solution ◽  
Pressure Distribution ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Numerical Solutions ◽  
Load Capacity ◽  
Separation Of Variables ◽  
Closed Form Expression ◽  
Linear Ordinary Differential Equations ◽  
Definition Of

The Reynolds equation for the pressure distribution of the lubricant in a journal bearing with finite length is solved analytically. Using the method of the separation of variables in an additive and in a multiplicative form, a set of particular solutions of the Reynolds equation is added in the general solution of the homogenous Reynolds equation and a closed form expression for the definition of the lubricant pressure is presented. The Reynolds equation is split in four linear ordinary differential equations of second order with non constant coefficients and together with the boundary conditions they form four Sturm-Liouville problems with the three of them to have direct forms of solution and one of them to be confronted using the method of power series. The mathematical procedure is presented up to the point that the application of the boundaries for the pressure distribution yields the final definition of the solution with the calculation of the constants. The current work gives in detail the mathematical path with which the analytical solution is derived, and it ends with the pressure evaluation and a comparison with past numerical solutions and an approximate analytical solution for a finite bearing. Also the parameters of primary interest to the bearing designer, such as load capacity, attitude angle, and stiffness and damping coefficients are evaluated and compared with numerical results.

Application of an Efficient Pressure-Temperature Coupled Solver to Industrial Hydrodynamic Bearings in Conjunction With Multi-Objective Evolutionary Optimization

2011 ◽  
Author(s):  
V. Indriolo ◽  
G. Melina ◽  
G. Ottino ◽  
G. Romanelli ◽  
S. Minniti ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Reynolds Equation ◽  
Pressure Field ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Oil Viscosity ◽  
Hydrodynamic Bearings ◽  
Hydrodynamic Bearing ◽  
Vibration Absorption ◽  
Multi Objective

Hydrodynamic bearings have a key role in the functioning of heavy duty gas turbines: they join a great vibration absorption with an efficient power dissipation by means of a film oil inserted between the turbo machine axes and the bearing case. A classical approach for studying the functioning and the performance of this kind of bearings is to solve the so called Reynolds’ equation, which is obtained from the Navier-Stokes equations under simplifying assumptions. As a result the pressure field is derived, the fluid film being considered isothermal: dissipation effects have to be estimated a posteriori in a postprocessing procedure. On the other hand a fluid environment having to be taken into account, a direct approach is carried out by the time consuming CFD analysis. After defining an appropriate mesh and choosing the appropriate solver, an almost exact solution of the entire flow field is obtained, that is pressure, velocity and temperature distributions. The main drawback is that the required time is several order greater than that required for the solution of the Reynolds’ equation. In the present work an alternative strategy is proposed, which consists of an iterative procedure: at each step the Reynolds’ equation is solved in order to obtain the pressure field; a 1D energy balance is then applied along the length of the bearing for computing the temperature field. In this way the close relationship between pressure and temperature is modelled, the former depending on the oil viscosity locally changing with temperature, and the latter depending on the local oil mass flow and on dissipated power strictly correlated to the pressure distribution. The upgrading of both the entities ends when the convergence is reached. Comparisons with literature test cases reveal the efficiency of the proposed technique: treating the interaction between pressure and temperature gives a solution which is very close to industrial configurations investigated, and at the same time the computational load is as light as that needed for the solution of the only Reynolds’ equation. The performance of the above coupled solver can be greatly emphasised applying it to the bearing design. An integration with a multi-objective genetic optimization process is proposed, taking as objects to be optimized both geometrical and environmental variables. Application examples are shown about an industrial Ansaldo Energia lemon bore hydrodynamic bearing: given a currently applied configuration, possible improvements are suggested. Results are presented.

scholarly journals Thrust Bearing with Rough Surfaces Lubricated by an Ellis Fluid

2014 ◽  
Vol 19 (4) ◽  
pp. 809-822
Author(s):  
A. Walicka ◽  
E. Walicki ◽  
P. Jurczak ◽  
J. Falicki
Keyword(s):  
Pressure Distribution ◽  
Analytical Solutions ◽  
Carrying Capacity ◽  
Reynolds Equation ◽  
Thrust Bearing ◽  
Equations Of Motion ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Plastic Fluid

Abstract In the paper the influence of bearing surfaces roughness on the pressure distribution and load-carrying capacity of a thrust bearing is discussed. The equations of motion of an Ellis pseudo-plastic fluid are used to derive the Reynolds equation. After general considerations on the flow in a bearing clearance and using the Christensen theory of hydrodynamic rough lubrication the modified Reynolds equation is obtained. The analytical solutions of this equation for the cases of a squeeze film bearing and an externally pressurized bearing are presented. As a result one obtains the formulae expressing pressure distribution and load-carrying capacity. A thrust radial bearing is considered as a numerical example.

scholarly journals Influence of Wall Porosity and Surfaces Roughness on the Steady Performance of an Externally Pressurized Hydrostatic Conical Bearing Lubricated by a Rabinowitsch Fluid

2017 ◽  
Vol 22 (3) ◽  
pp. 717-737 ◽  
Author(s):  
A. Walicka ◽  
E. Walicki ◽  
P. Jurczak ◽  
J. Falicki
Keyword(s):  
Pressure Distribution ◽  
Carrying Capacity ◽  
Reynolds Equation ◽  
Thrust Bearing ◽  
Hydrodynamic Lubrication ◽  
Equations Of Motion ◽  
Load Carrying Capacity ◽  
Bearing Surface ◽  
Load Carrying ◽  
Conical Bearing

AbstractIn the paper, the influence of both the bearing surfaces roughness as well as porosity of one bearing surface on the pressure distribution and load-carrying capacity of a curvilinear, externally pressurized, thrust bearing is discussed. The equations of motion of a pseudo-plastic Rabinowitsch fluid are used to derive the Reynolds equation. After general considerations on the flow in a bearing clearance and in a porous layer using the Morgan-Cameron approximation and Christensen theory of hydrodynamic lubrication with rough bearing surfaces the modified Reynolds equation is obtained. The analytical solution is presented; as a result one obtains the formulae expressing the pressure distribution and load-carrying capacity. Thrust radial and conical bearings, externally pressurized, are considered as numerical examples.

scholarly journals Porous Squeeze Film Bearing with Rough Surfaces Lubricated by a Bingham Fluid

2014 ◽  
Vol 19 (4) ◽  
pp. 795-808
Author(s):  
A. Walicka ◽  
E. Walicki ◽  
P. Jurczak ◽  
J. Falicki
Keyword(s):  
Pressure Distribution ◽  
Analytical Solutions ◽  
Carrying Capacity ◽  
Reynolds Equation ◽  
Equations Of Motion ◽  
Bingham Fluid ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Bearing Surface ◽  
Load Carrying

Abstract In the paper the effect of both bearing surfaces and the porosity of one bearing surface on the pressure distribution and load-carrying capacity of a squeeze film bearing is discussed. The equations of motion of a Bingham fluid in a bearing clearance and in a porous layer are presented. Using the Morgan-Cameron approximation and Christensen theory of rough lubrication the modified Reynolds equation is obtained. The analytical solutions of this equation for a squeeze film bearing are presented. As a result one obtains the formulae expressing pressure distribution and load-carrying capacity. A thrust radial bearing is considered as a numerical example.

scholarly journals Pressure Distribution in a Squeeze Film Spherical Bearing with Rough Surfaces Lubricated by an Ellis Fluid

2016 ◽  
Vol 21 (3) ◽  
pp. 593-610 ◽  
Author(s):  
P. Jurczak ◽  
J. Falicki
Keyword(s):  
Surface Roughness ◽  
Stochastic Model ◽  
Pressure Distribution ◽  
Analytical Solutions ◽  
Reynolds Equation ◽  
Rough Surfaces ◽  
Equations Of Motion ◽  
Squeeze Film ◽  
Plastic Fluid ◽  
Spherical Bearing

Abstract In this paper, the solution to a problem of pressure distribution in a curvilinear squeeze film spherical bearing is considered. The equations of motion of an Ellis pseudo-plastic fluid are presented. Using Christensen’s stochastic model of rough surfaces, different forms of Reynolds equation for various types of surface roughness pattern are obtained. The analytical solutions of these equations for the cases of externally pressurized bearing and squeeze film bearing are presented. Analytical solutions for the film pressure are found for the longitudinal and circumferential roughness patterns. As a result the formulae expressing pressure distribution in the clearance of bearing lubricated by an Ellis fluid was obtained. The numerical considerations for a spherical bearing are given in detail.

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