Elastohydrodynamic Lubrication Model of Connecting Rod Big-End Bearings: Application to Real Engines

1997 ◽  
Vol 119 (3) ◽  
pp. 568-578 ◽  
Author(s):  
Toshihiro Ozasa ◽  
Takashi Noda ◽  
Toshiaki Konomi
Keyword(s):  
Boundary Condition ◽  
Power Loss ◽  
Body Force ◽  
Structural Model ◽  
Elastohydrodynamic Lubrication ◽  
The Body ◽  
Connecting Rod ◽  
Ehd Lubrication ◽  
Oil Flow ◽  
Oil Jet

This study presents an elastohydrodynamic (EHD) lubrication model of connecting rod big-end bearings developed taking into consideration the effects of inertia and oil holes. In this model, the effect of inertia, namely the body force, on load and deformation is practically and rationally expressed based on engine dynamics and a structural model of a connecting rod. A method of defining the deformation of bearings has been proposed to simplify numerical analysis. The effect of oil holes, namely an oil feed hole in a journal and an oil jet hole in a bearing, is considered as a boundary condition in the EHD lubrication theory. Calculations of oil flow rate and power loss are also included.

A Nonlinear Structure Based Elastohydrodynamic Analysis Method for Connecting Rod Big End Bearings of High Performance Engines

2004 ◽  
Vol 126 (4) ◽  
pp. 664-671 ◽  
Author(s):  
Fabrizio A. Stefani ◽  
Alessandro U. Rebora
Keyword(s):  
High Performance ◽  
Structural Model ◽  
Rotation Speed ◽  
Fluid Model ◽  
Elastohydrodynamic Lubrication ◽  
Element Model ◽  
The Body ◽  
Connecting Rod ◽  
Coupled Equations ◽  
High Rotation Speed

Big end bearings of connecting rods for high performance automotive engines are quite compliant and exhibit relatively large deformations at high rotation speed. Nowadays numerical simulation provides good estimate of tribological parameters for bearings operating in severe, but not extreme elastohydrodynamic lubrication conditions. At very high rotation speed regimes, reliable previsions are achieved only if an effort to increase the accuracy of structural modeling is accomplished. A finite element model able to account for the nonlinear friction controlled sliding phenomena occurring at the junction surface between the cap and the body of the rod has been developed. A new method to solve the coupled equations governing the interaction between the hydrodynamic fluid model and the nonlinear structural model of the connecting rod bearing is presented, together with a simple application example.

scholarly journals Computational Modeling of Vortex Generators for Turbomachinery

2002 ◽  
Author(s):  
R. V. Chima
Keyword(s):  
Computational Models ◽  
Body Force ◽  
Secondary Flows ◽  
The Body ◽  
Vortex Generators ◽  
Force Model ◽  
Suction Surface ◽  
Near Surface ◽  
Compressor Rotor ◽  
Surface Particle

In this work computational models were developed and used to investigate applications of vortex generators (VGs) to turbomachinery. The work was aimed at increasing the efficiency of compressor components designed for the NASA Ultra Efficient Engine Technology (UEET) program. Initial calculations were used to investigate the physical behavior of VGs. A parametric study of the effects of VG height was done using 3-D calculations of isolated VGs. A body force model was developed to simulate the effects of VGs without requiring complicated grids. The model was calibrated using 2-D calculations of the VG vanes and was validated using the 3-D results. Then three applications of VGs to a compressor rotor and stator were investigated: 1. The results of the 3-D calculations were used to simulate the use of small casing VGs used to generate rotor preswirl or counterswirl. Computed performance maps were used to evaluate the effects of VGs. 2. The body force model was used to simulate large partspan splitters on the casing ahead of the stator. Computed loss buckets showed the effects of the VGs. 3. The body force model was also used to investigate the use of tiny VGs on the stator suction surface for controlling secondary flows. Near-surface particle traces and exit loss profiles were used to evaluate the effects of the VGs.

Stresses and Displacements in a Rotating Conical Shell

1943 ◽  
Vol 10 (2) ◽  
pp. A53-A61
Author(s):  
J. L. Meriam
Keyword(s):  
Conical Shell ◽  
Body Force ◽  
Theory Of Elasticity ◽  
Common Type ◽  
The Body ◽  
Surface Loading ◽  
Thin Walled Structures ◽  
Special Cases ◽  
Engineering Problems ◽  
Rotating Conical Shell

Abstract The analysis of shells is an important subdivision of the general theory of elasticity, and its application is useful in the solution of engineering problems involving thin-walled structures. A common type of shell is one which possesses symmetry with respect to an axis of revolution. A theory for such shells has been developed by various investigators (1, 2, 3, 6) and applied to a few simple cases such as the cylindrical, spherical, and conical shapes. Boundary conditions, for the most part, have been simple static ones, and conditions of surface loading have been included in certain special cases. This paper extends the theory of axially symmetrical shells by including the body force of rotation about the axis and applies the results to the rotating conical shell. The analysis follows a pattern established by several investigators (1, 2, 3, 6) and for this reason is abbreviated to a considerable extent. Only where the inclusion of the body force makes elucidation advisable or where a slightly different method of approach is used are the steps presented in more detail.

Observation of Wall Slip in Elastohydrodynamic Lubrication

1990 ◽  
Vol 112 (3) ◽  
pp. 447-452 ◽  
Author(s):  
M. Kaneta ◽  
H. Nishikawa ◽  
K. Kameishi
Keyword(s):  
Experimental Technique ◽  
Elastohydrodynamic Lubrication ◽  
Wall Slip ◽  
Optical Interferometry ◽  
Stepping Motor ◽  
Ehd Lubrication ◽  
Pure Rolling ◽  
Direct Indication ◽  
Contact Surfaces ◽  
Oil Films

A new experimental technique using optical interferometry has been developed to obtain a direct indication of non-Newtonian response of an oil film under conditions of elastohydrodynamic (EHD) lubrication. A glass disk or a steel ball has been driven by a stepping motor so that crescent-shaped thick oil films with undulation in thickness along the direction of motion have been generated. The experiments have been carried out under pure rolling and pure sliding conditions. It has been found that the oil in an EHD contact behaves like a solid and slips at or near the contact surfaces.

A Review of Inlet-Fan Coupling Methodologies

2017 ◽  
Author(s):  
Benjamin Godard ◽  
Edouard De Jaeghere ◽  
Nabil Ben Nasr ◽  
Julien Marty ◽  
Raphael Barrier ◽  
...  
Keyword(s):  
Experimental Data ◽  
Industrial Design ◽  
Body Force ◽  
The Body ◽  
Source Terms ◽  
Force Modeling ◽  
Actuator Disc ◽  
Flow Deviation ◽  
New Challenges ◽  
Bypass Ratio

With the rise of ultra high bypass ratio turbofan and shorter and slimmer inlet geometries compared to classical architectures, designers face new challenges as nacelle and fan design cannot anymore be addressed independently. This paper reviews CFD methods developed to simulate inlet-fan interactions and suitable for industrial design cycles. In addition to the reference isolated fan and nacelle models, the methodologies evaluated in this study consist of two fan modeling approaches, an actuator disc and body-force source terms. The configuration is a modern turbofan with a high bypass ratio under cross-wind. Results are compared to experimental data. As to be predicted, the body-force modeling approach enables early inlet reattachment. In addition, it provides a representative flow deviation across the fan zone which enables performance and stability assessments.

Rack Level Modeling of Air Flow Through Perforated Tile in a Data Center

2012 ◽  
Author(s):  
Vaibhav K. Arghode ◽  
Pramod Kumar ◽  
Yogendra Joshi ◽  
Thomas S. Weiss ◽  
Gary Meyer
Keyword(s):  
Data Center ◽  
Body Force ◽  
Air Flow ◽  
The Body ◽  
Physical Models ◽  
Cfd Modeling ◽  
Computational Time ◽  
Force Model ◽  
Flow Through ◽  
Tile Surface

Effective air flow distribution through perforated tiles is required to efficiently cool servers in a raised floor data center. We present detailed computational fluid dynamics (CFD) modeling of air flow through a perforated tile and its entrance to the adjacent server rack. The realistic geometrical details of the perforated tile, as well as of the rack are included in the model. Generally models for air flow through perforated tiles specify a step pressure loss across the tile surface, or porous jump model based on the tile porosity. An improvement to this includes a momentum source specification above the tile to simulate the acceleration of the air flow through the pores, or body force model. In both of these models geometrical details of tile such as pore locations and shapes are not included. More details increase the grid size as well as the computational time. However, the grid refinement can be controlled to achieve balance between the accuracy and computational time. We compared the results from CFD using geometrical resolution with the porous jump and body force model solution as well as with the measured flow field using Particle Image Velocimetry (PIV) experiments. We observe that including tile geometrical details gives better results as compared to elimination of tile geometrical details and specifying physical models across and above the tile surface. A modification to the body force model is also suggested and improved results were achieved.

scholarly journals Pelvic Construct Prediction of Trabecular and Cortical Bone Structural Architecture

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Dan T. Zaharie ◽  
Andrew T. M. Phillips
Keyword(s):  
Cortical Bone ◽  
Structural Model ◽  
Thickness Distribution ◽  
Bone Adaptation ◽  
The Body ◽  
Lower Limbs ◽  
Fe Model ◽  
Adaptation Algorithm ◽  
Modeling Framework ◽  
Good Agreement

The pelvic construct is an important part of the body as it facilitates the transfer of upper body weight to the lower limbs and protects a number of organs and vessels in the lower abdomen. In addition, the importance of the pelvis is highlighted by the high mortality rates associated with pelvic trauma. This study presents a mesoscale structural model of the pelvic construct and the joints and ligaments associated with it. Shell elements were used to model cortical bone, while truss elements were used to model trabecular bone and the ligaments and joints. The finite element (FE) model was subjected to an iterative optimization process based on a strain-driven bone adaptation algorithm. The bone model was adapted to a number of common daily living activities (walking, stair ascent, stair descent, sit-to-stand, and stand-to-sit) by applying onto it joint and muscle loads derived using a musculoskeletal modeling framework. The cortical thickness distribution and the trabecular architecture of the adapted model were compared qualitatively with computed tomography (CT) scans and models developed in previous studies, showing good agreement. The sensitivity of the model to changes in material properties of the ligaments and joint cartilage and changes in parameters related to the adaptation algorithm was assessed. Changes to the target strain had the largest effect on predicted total bone volumes. The model showed low sensitivity to changes in all other parameters. The minimum and maximum principal strains predicted by the structural model compared to a continuum CT-derived model in response to a common test loading scenario showed good agreement with correlation coefficients of 0.813 and 0.809, respectively. The developed structural model enables a number of applications such as fracture modeling, design, and additive manufacturing of frangible surrogates.

The Effect of Blade Count on Body Force Model Performance for Axial Fans

2020 ◽  
Author(s):  
Palak Saini ◽  
Jeff Defoe
Keyword(s):  
Body Force ◽  
Computational Cost ◽  
Model Performance ◽  
Aircraft Engine ◽  
The Body ◽  
Force Model ◽  
Cooling Flows ◽  
Cooling Fans ◽  
Axial Fans ◽  
Spanwise Flow

Abstract Body force models enable inexpensive numerical simulations of turbomachinery. The approach replaces the blades with sources of momentum/energy. Such models capture a “smeared out” version of the blades’ effect on the flow, reducing computational cost. The body force model used in this paper has been widely used in aircraft engine applications. Its implementation for low speed, low solidity (few blades) turbomachines, such as automotive cooling fans, enables predictions of cooling flows and component temperatures without calibrated fan curves. Automotive cooling fans tend to have less than 10 blades, which is approximately 50% of blade counts for modern jet engine fans. The effect this has on the body force model predictions is unknown and the objective of this paper is to quantify how varying blade count affects the accuracy of the predictions for both uniform and non-uniform inflow. The key findings are that reductions in blade metal blockage combined with spanwise flow redistribution drives the body force model to more accurately predict work coefficient as the blade count decreases, and that reducing the number of blades is found to have negligible impacts on upstream influence and distortion transfer in non-uniform inflow until extremely low blade counts (such as 2) are applied.

Linking responsible leadership with financial and environmental performance: determining mediation and moderation

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Zia Ur Rehman ◽  
Imran Shafique ◽  
Kausar Fiaz Khawaja ◽  
Munazza Saeed ◽  
Masood Nawaz Kalyar
Keyword(s):  
Boundary Condition ◽  
Firm Performance ◽  
Environmental Performance ◽  
Management Practices ◽  
Partial Least Square ◽  
The Body ◽  
Equation Modeling ◽  
Responsible Leadership ◽  
Institutional Pressures ◽  
Content Type

PurposeDrawing upon the institutional theory, this study examines the influence of responsible leadership on firm performance. Furthermore, this research investigates environmental management practices (EnvMP) as an underlying mechanism and institutional pressures as boundary condition between responsible leadership and firm performance.Design/methodology/approachTime-lagged data were collected using survey-questionnaire from 385 mid-level employees of construction industry in Pakistan. Partial least square-structural equation modeling (PLS-SEM) was used to analyze the data.FindingsResults demonstrate that responsible leadership impacts firm performance (financial and nonfinancial) directly and through EnvMP. Furthermore, institutional pressure moderates the link between responsible leadership and EnvMP. However, moderated mediation effect of intuitional pressures was found insignificant.Practical implicationsThis study suggest that EnvMP is a key process through which responsible leadership influences firms' financial and nonfinancial performance and shed lights as to when responsible leaders matter most in terms of firm performance through low or high institutional pressures.Originality/valueThis paper is an early attempt which contributes to the body of literature on responsible leadership by investigating mechanisms (how) and boundary condition (when) through which responsible leadership influences firms' financial and environmental performance.

Large-Amplitude Transient Motion of Two-Dimensional Floating Bodies

1979 ◽  
Vol 23 (01) ◽  
pp. 20-31
Author(s):  
R. B. Chapman
Keyword(s):  
Boundary Condition ◽  
Wave Field ◽  
Large Amplitude ◽  
The Body ◽  
Body Motion ◽  
Source Distribution ◽  
Floating Body ◽  
Two Dimensional ◽  
Body Boundary ◽  
Free Mode

A numerical method is presented for solving the transient two-dimensional flow induced by the motion of a floating body. The free-surface equations are linearized, but an exact body boundary condition permits large-amplitude motion of the body. The flow is divided into two parts: the wave field and the impulsive flow required to satisfy the instantaneous body boundary condition. The wave field is represented by a finite sum of harmonics. A nonuniform spacing of the harmonic components gives an efficient representation over specified time and space intervals. The body is represented by a source distribution over the portion of its surface under the static waterline. Two modes of body motion are discussed—a captive mode and a free mode. In the former case, the body motion is specified, and in the latter, it is calculated from the initial conditions and the inertial properties of the body. Two examples are given—water entry of a wedge in the captive mode and motion of a perturbed floating body in the free mode.

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