Harmonic Coefficients of Engine Torque Curves

1943 ◽  
Vol 10 (1) ◽  
pp. A33-A48
Author(s):  
Frederic P. Porter
Keyword(s):  
Diesel Engines ◽  
Combined Effects ◽  
Connecting Rod ◽  
Engine Torque ◽  
Wide Range ◽  
Inertia Forces ◽  
Gas Pressures

Abstract Engine torque curves depend upon the combined effects of gas pressures, inertia forces, and weights. Tables for the harmonic coefficients of the torque due to inertia and weight effects are given for a wide range of crank-to-connecting-rod ratios. Families of indicator diagrams, representative of various types of engines, are shown and tables of the harmonic coefficients of the resulting torques are given. The types of engines considered are two-cycle gas, semi-Diesel, single-acting Diesel, double-acting Diesel, two-shaft opposed-piston Diesel, and four-cycle gasoline and Diesel engines.

A Numerical Study of an Electrically Assisted Boosting System for Turbocharged Diesel Engines

2019 ◽  
Author(s):  
Yifan Men ◽  
Jason B. Martz ◽  
Eric Curtis ◽  
Guoming G. Zhu
Keyword(s):  
Fuel Economy ◽  
Diesel Engines ◽  
Numerical Study ◽  
Peak Torque ◽  
Engine Fuel ◽  
Engine Torque ◽  
Low Speed ◽  
Electrically Assisted ◽  
Torque Response ◽  
Variable Geometry Turbine

Abstract Modern diesel engines are normally turbocharged in order to achieve desired fuel economy and meet emission requirements. The well-known “turbo-lag”, delayed engine torque response to driver’s demand, is the main disadvantage for turbocharged engines operated under transient conditions. In addition, at low engine speed, the peak engine output torque is heavily limited by the available turbine energy. As a result, turbocharged engines have degraded peak torque at low speed and slow transient responses in general. Various technologies (variable geometry turbine, electrically assisted turbocharger, hydraulically assisted turbocharger, etc.) have been developed to improve transient response and low-speed torque performance. This paper presents a numerical study of an electrically assisted boosting (eBoost) system for a turbocharged diesel engine through 1-D simulations. This study focuses on two main areas: the electrical compensation at steady-state and turbo-lag reduction under transient operation. It is shown that the eBoost system is capable of increasing engine fuel economy at mid-speed and greatly improving low-speed peak torque. In addition, the eBoost system improves engine transient performance by reducing response time up to 60%.

A Fundamental Thermodynamic Study on the Effects of Engine Scale in Diesel Engines

2019 ◽  
Author(s):  
Kevin J. Burnett ◽  
Ashwani K. Gupta ◽  
Jim S. Cowart
Keyword(s):  
Heat Transfer ◽  
Surface Area ◽  
Wall Temperature ◽  
Diesel Engines ◽  
Cold Start ◽  
Cylinder Wall ◽  
Piston Speed ◽  
Heat Effects ◽  
Wide Range ◽  
Significant Difference

Abstract The Navy has a wide range of diesel engines with bore sizes varying by a factor of four. In general, diesel engines can have bore scaling over a full order of magnitude. As an engine cylinder gets larger its surface area to volume ratio reduces significantly, which in turn affects in-cylinder heat transfer. In this study, a fundamental generalized thermodynamic model of diesel engines was developed. The various key model effects were systematically analyzed along with engine bore size. Further, cylinder wall temperature was varied across a range of cold start to stabilized operating temperatures. The results of this study show that smaller bore diesel engines are always more sensitive to cold start conditions. The effect is reduced with increasing wall temperature yet smaller diesel engines have cooler end-of-compression temperatures as comparted to larger engines. The effects of engine speed, in which mean piston speed is held constant, tend to modestly reduce the differences between various size diesel engines due to non-linear heat transfer effects. When variable specific heat effects are correctly considered, end-of-compression air charge temperatures are only modestly different as a function of engine bore size. The most significant difference is the overall reduced heat transfer in larger engines due to the surface area to volume effect. A difference of a factor of three for in cylinder heat transfer relative to in-cylinder inducted air mass is predicted being much greater for the smaller engines. Higher exhaust temperatures are also characteristic of the larger bore engines. This allows more combustion work to be delivered to the piston with a correspondingly higher thermal efficiency for larger diesel engines. Future work will evaluate fuel effects on varying bore size.

Balancing the Moments of a VR5 Engine Taking into Account a Desaxial Crank Mechanism and Cylinder Camber Angle

2020 ◽  
pp. 41-49
Author(s):  
N.D. Chainov ◽  
P.R. Vallejo Maldonado
Keyword(s):  
Relative Displacement ◽  
Working Fluid ◽  
Inertial Forces ◽  
Structural Elements ◽  
Connecting Rod ◽  
Cylinder Axis ◽  
Acoustic Characteristics ◽  
Camber Angle ◽  
Inertia Forces ◽  
Crank Mechanism

Automobile piston engines with a desaxial crank mechanism are characterized by increased vibration activity associated with a cyclic change in the pressure of the working fluid in the cylinders and inertial forces associated with the reciprocating and rotational movement of the crank mechanism moving masses. Properties reflecting the consumer properties of the engine, including acoustic characteristics, are largely determined by the level of vibration of the structural elements of the desaxial crank mechanism and, first of all, by the balance of inertial forces during operation. The article discusses balancing of five-cylinder four-stroke VR type engines with a desaxial crank mechanism and uniform flash alternation. The authors introduce formulas that can be used to determine and analyze moments of the inertia forces of the reciprocating and rotating masses arising in VR5 engines at the set values of the cylinder camber angle, the ratio of the crank radius to the connecting rod length and the relative displacement of the cylinder axis. A method of balancing the moments of inertia forces of the reciprocating and rotating masses is proposed.

Combined Effects of Surface Trips and Unsteady Wakes on the Boundary Layer Development of an Ultra-High-Lift LP Turbine Blade

2004 ◽  
Vol 127 (3) ◽  
pp. 479-488 ◽  
Author(s):  
Xue Feng Zhang ◽  
Howard Hodson
Keyword(s):  
Boundary Layer ◽  
Turbine Blade ◽  
Parametric Study ◽  
Combined Effects ◽  
Suction Surface ◽  
High Lift ◽  
Boundary Layer Development ◽  
Wide Range ◽  
Profile Losses ◽  
Layer Development

An experimental investigation of the combined effects of upstream unsteady wakes and surface trips on the boundary layer development on an ultra-high-lift low-pressure turbine blade, known as T106C, is described. Due to the large adverse pressure gradient, the incoming wakes are not strong enough to periodically suppress the large separation bubble on the smooth suction surface of the T106C blade. Therefore, the profile loss is not reduced as much as might be possible. The first part of this paper concerns the parametric study of the effect of surface trips on the profile losses to optimize the surface trip parameters. The parametric study included the effects of size, type, and location of the surface trips under unsteady flow conditions. The surface trips were straight cylindrical wires, straight rectangular steps, wavy rectangular steps, or wavy cylindrical wires. The second part studies the boundary layer development on the suction surface of the T106C linear cascade blade with and without the recommended surface trips to investigate the loss reduction mechanism. It is found that the selected surface trip does not induce transition immediately, but hastens the transition process in the separated shear layer underneath the wakes and between them. In this way, the combined effects of the surface trip and unsteady wakes further reduce the profile losses. This passive flow control method can be used over a relatively wide range of Reynolds numbers.

Hall-Petch and Multiple Linear Regression Equations for the Prediction of Mechanical Properties in Gamma-Based Titanium Aluminides

1996 ◽  
Vol 460 ◽  
Author(s):  
W. O. Soboyejo ◽  
A. B. O. Soboyejo ◽  
Y. Ni ◽  
C. Mercer
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Linear Regression ◽  
Multiple Linear Regression ◽  
Titanium Aluminides ◽  
Regression Equations ◽  
Combined Effects ◽  
Wide Range ◽  
Elongation To Failure ◽  
Prediction Of Mechanical Properties

In a recent paper, Mercer and Soboyejo [1] demonstrated the Hall-Petch dependence of basic room- and elevated-temperature (815°C) mechanical properties (0.2% offset strength), ultimate tensile strength, plastic elongation to failure and fracture toughness) on the average equiaxed/lamellar grain size. Simple Hall-Petch behavior was shown to occur in a wide range of extruded duplex α2-γ alloys (Ti-48A1, Ti-48Al-1.4Mn Ti-48Al-2Mn and Ti-48Al-1.5Cr). As in steels and other materials [2–5], simple Hall-Petch equations with were derived for the above properties [1]. However, the Hall-Petch equations did not include the effect of other variables that can affect to the basic mechanical properties of gamma alloys. Multiple linear regression equations for the prediction of the combined effects of several (alloying, microstructure and temperature) variables on basic mechanical properties temperature are presented in this paper.

An Investigation of the Sources of Blowby in Single-Cylinder Supercharged Diesel Engines

1978 ◽  
Vol 192 (1) ◽  
pp. 39-48 ◽  
Author(s):  
B. Bull ◽  
M. A. Voisey
Keyword(s):  
Carbon Dioxide ◽  
Diesel Engines ◽  
Piston Ring ◽  
Carbon Dioxide Concentration ◽  
Operating Conditions ◽  
Exhaust Valve ◽  
Simple Method ◽  
Single Cylinder ◽  
Carbon Dioxide Concentrations ◽  
Wide Range

Measurements of carbon dioxide concentrations in the exhaust and in the crankcase of two different types of single-cylinder, supercharged diesel engines have been used to determine the amount of exhaust gas reaching the crankcase as piston ring blowby and as leakage through the exhaust valve stem-to-guide clearance. Over a wide range of operating conditions in both engines the carbon dioxide concentration was found to be more dependent on engine fuelling rate per hour than on fuel input per stroke. It was established that blowby through the exhaust valve guide was a major contributor to crankcase contamination. A simple method has been devised, requiring only minor modifications to the engine, that permits the blowby through the piston ring pack and the exhaust valve guides to be determined separately in turbocharged production engines.

Summary 1: The Influence of Engine Component Inertia Forces on Minimum Oil Film Thickness in Connecting Rod Big-End Bearings

1966 ◽  
Vol 181 (2) ◽  
pp. 155-155
Author(s):  
J. F. Booker ◽  
F. A. Martin
Keyword(s):  
Film Thickness ◽  
Graphical Form ◽  
Load Carrying Capacity ◽  
Eccentricity Ratio ◽  
Connecting Rod ◽  
Oil Film ◽  
First Approximation ◽  
Load Carrying ◽  
The Many ◽  
Inertia Forces

when Designing steadily loaded bearings the designer can usually predict the position of the journal centre quite easily with the aid of one of the many load carrying capacity/eccentricity relationships available. With dynamically loaded bearings, however, the journal path will vary in magnitude and direction throughout the loading cycle and one of the designer's interests is in the trends of maximum eccentricity ratio and the corresponding oil film thickness for various bearing and engine conditions. From experience with journal path predictions for big-end bearings it has been found that the eccentricity ratio in the bearing due to the peak firing load seldom exceeds that obtained by the inertia load loop (although this load is smaller) and therefore, as a first approximation, it is thought justifiable to neglect the gas forces. The results of this inertia study (numerical solution) applied to big-end bearings are presented in a general graphical form. Further work can be carried out on the same basis for main bearings, but this is more difficult to present in a general fashion as there are many more variables to consider, such as the phasing and magnitude of the crank out of balance and the firing order. This report therefore concentrates on the first step, i.e. that of big-end bearings.

scholarly journals Reduction and distribution of lateral seismic inertia forces on base isolated multistorey structures

1991 ◽  
Vol 24 (3) ◽  
pp. 225-237 ◽  
Author(s):  
Takim Andriono ◽  
Athol J. Carr
Keyword(s):  
Distribution Patterns ◽  
Seismic Behaviour ◽  
Isolation System ◽  
Wide Range ◽  
Inertia Forces

This paper presents some important results of a thorough investigation into the seismic behaviour of a wide range of Base Isolated multistorey structures. The benefits of implementing BI systems are highlighted. The reduction and distribution patterns of lateral inertia forces due to the inclusion of this isolation system are specifically discussed.

Modeling heavy-duty diesel engines using tabulated kinetics in a wide range of operating conditions

2020 ◽  
pp. 146808741989616 ◽  
Author(s):  
Qiyan Zhou ◽  
Tommaso Lucchini ◽  
Gianluca D’Errico ◽  
Gilles Hardy ◽  
Xingcai Lu
Keyword(s):  
Diesel Engines ◽  
Operating Conditions ◽  
Scalar Dissipation ◽  
Cylinder Pressure ◽  
Heavy Duty ◽  
Variable Model ◽  
Progress Variable ◽  
Wide Range ◽  
Heavy Duty Diesel ◽  
Operating Points

Fast and high-fidelity combustion models including detailed kinetics and turbulence chemistry interaction are necessary to support design and development of heavy-duty diesel engines. In this work, the authors intend to present and validate tabulated flamelet progress variable model based on tabulation of laminar diffusion flamelets for different scalar dissipation rate, whose predictability highly depends on the description of fuel–air mixing process in which engine mesh layout plays an important role. To this end, two grids were compared and assessed: in both grids, cells were aligned on the spray direction with such region being enlarged in the second one, where the near-nozzle and near-wall mesh resolution were also improved, which is expected to better account for both spray dynamics and flame–wall interaction dominating the combustion process in diesel engines. Flame structure, in-cylinder pressure, apparent heat release rate, and emissions for different relevant operating points were compared and analyzed to identify the most suitable mesh. Afterwards, simulations were carried out in a heavy-duty engine considering 20 operating points, allowing to comprehensively verify the validity of tabulated flamelet progress variable model. The results demonstrated that the proposed approach was capable to accurately predict in-cylinder pressure evolution and NO x formation across a wide engine map.

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