A Generalized Compressor Power Model for Turbocharged Internal Combustion Engines With Reduced Complexity

2016 ◽  
Author(s):  
Tao Zeng ◽  
Devesh Upadhyay ◽  
Harold Sun ◽  
Guoming G. Zhu
Keyword(s):  
Internal Combustion Engines ◽  
Ad Hoc ◽  
Power Transmission ◽  
Internal Combustion ◽  
Mechanical Efficiency ◽  
Combustion Engines ◽  
Proposed Model ◽  
Adequate Accuracy ◽  
Compressor Power ◽  
Isentropic Efficiency

Control-oriented models of automotive turbocharger compressors typically describe the compressor power assumming an isentropic thermodynamic process with a fixed isentropic efficiency and a fixed mechanical efficiency for power transmission between the turbine and compressor. Although these simplifications make the control model tractable, they also introduce additional errors due to unmodeled dynamics, especially when the turbocharger is operated outside its normal operational region. This is also true for map-based approaches, since these supplier-provided maps tend to be sparse or incomplete at the boundary operational regions and often ad-hoc extrapolation is required, leading to large modeling error. Furthermore, these compressor maps are obtained from the steady flow bench tests, which introduce additional errors under pulsating flow conditions in the context of internal combustion engines. In this paper, a physics-based model of compressor power is developed using Euler equations for turbomachinery, where the mass flow rate and compressor rotational speed are used as model inputs. Two new coefficients, speed and power coefficients are defined. This makes it possible to directly estimate the compressor power over the entire compressor operating range based on a single analytic relationship. The proposed modeling approach is validated against test data from standard turbocharger flow bench, steady state engine dynamometer as well as transient simulation tests. The validation results show that the proposed model has adequate accuracy for model-based control design and also reduces the dimension of the parameter space typically needed to model the compressor dynamics.

A General Rezoning Technique for KIVA3V Internal Combustion Engines CFD Simulations

2010 ◽  
Author(s):  
Randy P. Hessel ◽  
Ettore Musu ◽  
Salvador M. Aceves ◽  
Daniel L. Flowers
Keyword(s):  
Combustion Chamber ◽  
Internal Combustion Engines ◽  
Ad Hoc ◽  
National Laboratory ◽  
Internal Combustion ◽  
Computational Time ◽  
Combustion Engines ◽  
Combustion Chambers ◽  
Time Step ◽  
Engine Cycle

A computational mesh is required when performing CFD-combustion modeling of internal combustion engines. For combustion chambers with moving pistons and valves, like those in typical cars and trucks, the combustion chamber shape changes continually in response to piston and valve motion. The combustion chamber mesh must then also change at each time step to reflect that change in geometry. The method of changing the mesh from one computational time step to the next is called rezoning. This paper introduces a new method of mesh rezoning for the KIVA3V CFD-combustion program. The standard KIVA3V code from Los Alamos National Laboratory comes with standard rezoners that very nicely handle mesh motion for combustion chambers whose mesh does not include valves and for those with flat heads employing vertical valves. For pent-roof and wedge-roof designs KIVA3V offers three rezoners to choose from, the choice depending on how similar a combustion chamber is to the sample combustion chambers that come with KIVA3V. Often, the rezoners must be modified for meshes of new combustion chamber geometries to allow the mesh to successfully capture change in geometry during the full engine cycle without errors. There is no formal way to approach these modifications; typically this requires a long trial and error process to get a mesh to work for a full engine cycle. The benefit of the new rezoner is that it replaces the three existing rezoners for canted valve configurations with a single rezoner and has much greater stability, so the need for ad hoc modifications of the rezoner is greatly reduced. This paper explains how the new rezoner works and gives examples of its use.

Optimal Linkage Design for Bicycle Power Transmission Using Symmetric Four-Bar

2006 ◽  
Author(s):  
Carl A. Nelson
Keyword(s):  
Internal Combustion Engines ◽  
Power Transmission ◽  
State Of The Art ◽  
Mechanical Efficiency ◽  
Substantial Improvement ◽  
Combustion Engines ◽  
Force Transmission ◽  
Linkage Design ◽  
Potential Applications ◽  
Four Bar Linkage

Use of a symmetric crank-rocker four-bar linkage is presented as an alternative to the standard bicycle crank. With the coupler being the driven link, a kinematic and force-transmission analysis is presented. Results of constrained nonlinear optimization for geometric synthesis show a substantial improvement in mechanical efficiency compared to the state of the art. Dead-center positions are also eliminated. Potential applications to other linear-to-rotary power transmission devices, such as internal-combustion engines, are also discussed.

Tri-Axial Force Measurements on the Cylinder of a Motored SI Engine Operated on Lubricants of Differing Viscosity

2010 ◽  
Vol 132 (9) ◽  
Author(s):  
Bryan O’Rourke ◽  
Donald Radford ◽  
Rudolf Stanglmaier
Keyword(s):  
Axial Force ◽  
Internal Combustion Engines ◽  
Axial Direction ◽  
Internal Combustion ◽  
Mechanical Efficiency ◽  
Combustion Engines ◽  
Friction Characteristics ◽  
Colorado State University ◽  
And Performance ◽  
Lubricant Viscosity

Friction is a determining factor in the efficiency and performance of internal combustion engines. Losses in the form of friction work typically account for 10–20% of an engine’s output. Improvements in the friction characteristics of the power cylinder assembly are essential for reducing total engine friction and improving the mechanical efficiency of internal combustion engines. This paper describes the development and implementation of a new concept of the “floating liner” engine at Colorado State University that allows 0.5 crank angle deg resolved measurement of the forces on the cylinder along three axes—in the axial direction, the thrust direction, and along the wrist pin. Three different lubricants with differing properties were tested to observe the friction characteristics of each. The experimental results showed that the floating liner engine was able to resolve changes in friction characteristics coinciding with changes in lubricant viscosity and temperature. The axial force increases at TDC and BDC were observed as lubricant viscosity was decreased and larger amounts of mixed and boundary lubrication began to occur. For each test the axial friction force data was used to calculate total cycle friction work. The thrust and off-axis (wrist pin direction) forces are discussed under the same circumstances.

A Constant-Pressure Model for the Overlap of Chambers in Rotary Internal Combustion Engines

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
Ezequiel J. López ◽  
Carlos A. Wild Cañón ◽  
Sofía S. Sarraf
Keyword(s):  
Internal Combustion Engines ◽  
Constant Pressure ◽  
Combustion Engine ◽  
Flow Direction ◽  
Internal Combustion ◽  
Combustion Engines ◽  
One Dimensional ◽  
Rotary Engines ◽  
Proposed Model ◽  
Reliable Solution

In this work, a constant-pressure model capable to simulate the overlap of chambers in rotary internal combustion engines is proposed. It refers as a chamber overlap when two adjacent chambers are in communication through the same port, which could occur in some rotary internal combustion engines. The proposed model is thermodynamic (or zero-dimensional (0D)) in nature and is designed for application in engine simulators that combine one-dimensional (1D) gasdynamic models with thermodynamic ones. Since the equations of the proposed model depend on the flow direction and on the flow regime, a robust and reliable solution strategy is developed. The model is assessed using a two-dimensional (2D) problem and is applied in the simulation of a rotary internal combustion engine. Results for this last problem are compared with other common approaches used in the simulation of rotary engines, showing the importance of effects such as the interaction between overlapping chambers and the dynamics of the flow.

Tri-Axial Force Measurements on the Cylinder of a Motored SI Engine Operated on Lubricants of Differing Viscosity

2009 ◽  
Author(s):  
Bryan O’Rourke ◽  
Donald Radford ◽  
Rudolf Stanglmaier
Keyword(s):  
Axial Force ◽  
Internal Combustion Engines ◽  
Axial Direction ◽  
Internal Combustion ◽  
Mechanical Efficiency ◽  
Combustion Engines ◽  
Friction Characteristics ◽  
Colorado State University ◽  
And Performance ◽  
Lubricant Viscosity

Friction is a determining factor in the efficiency and performance of internal combustion engines. Losses in the form of friction work typically account for 10–20% of an engine’s output. Improvements in the friction characteristics of the power cylinder assembly are essential for reducing total engine friction and improving the mechanical efficiency of internal combustion engines. This paper describes the development and implementation of a new concept of the ‘floating liner’ engine at Colorado State University that allows 0.5 crank angle degree resolved measurement of the forces on the cylinder along 3 axes — in the axial direction, the thrust direction, and along the wrist pin. Three different lubricants with differing properties were tested to observe the friction characteristics of each. Experimental results showed that the floating liner engine was able to resolve changes in friction characteristics coinciding with changes in lubricant viscosity and temperature. Axial force increases at TDC and BDC were observed as lubricant viscosity was decreased and larger amounts of mixed and boundary lubrication began to occur. For each test the axial friction force data was used to calculate total cycle friction work. The thrust and off-axis (wrist pin direction) forces are discussed under the same circumstances.

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