Journal of Mechanical Engineering 52 (2006) 1

Editorial

 

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The Influence of Biodiesel Fuel on the Injection, Combustion, Emissions and Performance of a Direct-Injected Diesel Engine

Corresponding author - Aleš Hribernik

Abstract

A study was carried out on the influence of biodiesel fuel on a diesel engine’s performance, exhaust emissions, combustion and fuel-injection processes. These tests were performed on a direct-injected diesel engine using standard D2 diesel and commercial 100% biodiesel fuels. The tests were carried out using both fuels, under the same conditions. The exhaust emissions and the engine performance were measured and compared. The in-cylinder pressure was also measured, and the heat-release-rate curves were computed by means of a zero-dimensional one-zone combustion model. Some macro-parameters of the combustion process were obtained from the heat-release-rate curves. The injection system was separated from the engine and tested on a special test bench. The quantity of injected fuel was measured, and the injection pressure and injector-needle lift-time history were measured. The injection-rate curves were then computed and some macro-parameters of the injection process were obtained and analysed.

Keywords - Diesel engines, biodiesel fuels, fuel injections, combustion

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 52(2006)1, 3-14
UDC 621.43.057:504.05

The Influence of Biodiesel Fuel on the Injection, Combustion, Emissions and Performance of a Direct-Injected Diesel Engine (pdf)

 

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A Novel Algorithm for the Simulation of an Automotive Turbocharger Turbine

Corresponding author - Tomaž Katrašnik

Abstract

A new, innovative algorithm for the simulation of a turbocharger turbine based on the method of characteristics is introduced. This algorithm makes it possible to consider the variable inlet and outlet pressures as well as the variable gas properties. The theory of the method of characteristics is derived for ideal and perfect gases – the physical properties of the gas do not change with a variation in temperature and composition. New equations for the simulation of the boundary element suitable for considering the variation in gas properties and the tracking of the gas concentration are therefore derived. The improved equations and the improved algorithm ensure a much better conservation of mass flux for only a slightly increased computational time.

Keywords - turbocharger turbine, boundary conditions, method of characteristics, gas properties, variable physical properties

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 52(2006)1, 15-25
UDC 621.43.052:004.94

A Novel Algorithm for the Simulation of an Automotive Turbocharger Turbine (pdf)

 

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Measuring a Driver’s Reaction Time

Corresponding author - Tone Magister

Authors - Rok Krulec - Milan Batista - Leon Bogdanović

Abstract

Since the real reaction time of a driver involved in an accident will always be unknown to reconstruction experts, and because the driver’s reaction-time databases published in the relevant literature have become almost obscure and hard to compare with the everyday practice of accident reconstruction, an expert decision was made at the Transport Safety Laboratory to investigate a driver’s reaction time and reaction-time measurement techniques as well as to develop a PC-based simulator for measurements of a driver’s reaction time. The driver-reaction-timer simulator’s structure and its components are described together with its measuring algorithm. The measurements of the driver’s reaction time in real and simulated driving environments were performed, and the results obtained are discussed. By comparing these results, a quality evaluation of the current stage of development of the simulator is addressed and the necessary further development of the simulator is defined.

Keywords - traffic accident, reaction times, measurements, simulations, dangerous situations

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 52(2006)1, 26-40
UDC 614.86:159.937.53+004.94

Measuring a Driver’s Reaction Time (pdf)

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The Difference Between a Front-Axle Stress Calculation Using the Finite-Element Method and the Same Calculation According to DIN743

Corresponding author - Ivan Okorn
Authors - Tomaž Bešter - Petar Orbanič - Matija Fajdiga

Abstract

The front-axle assembly is used to transmit forces from the wheels to the chassis of a vehicle. The main parts of the front-axle assembly are the I beam, the knuckle extension and the bolt. The loads on the elements depend on the road and the driving conditions (straight driving, bumpy road, cornering and panic braking). The dynamic forces were calculated with regard to the vehicle mass and the dynamic coefficients. To more accurately determine the wheel forces, measurements of the load spectrum need to be carried out. The first calculation, according to DIN743, was carried out for critical spots on the assembly. Later, a finite-element analysis was carried out, which confirmed the positions of the critical spots. A comparison of the safety coefficients obtained by both methods was also made.

Keywords - front axles, knuckle extensions, dynamic forces, finite-element methods

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 52(2006)1, 41-51
UDC 629.11.012.1:519.61/.64+006(430)

The Difference Between a Front-Axle Stress Calculation Using the Finite-Element Method and the Same Calculation According to DIN743 (pdf)

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The Effects of Different Analysis Parameters on the Calculated Temperature of a Loaded Headlamp

Corresponding author - Andrej Wagner

Authors - Tomaž Bučar - Matija Fajdiga

Abstract

Modern headlamps are made from low-cost plastic materials, which are very convenient for modern headlamp design. On the other hand, plastic materials do not withstand high temperatures. This can cause deformations that result in problems with the photometric properties and with the sealing of headlamp. In this article the stress-strain state of a fog lamp from Saturnus avtooprema d.d. caused by thermal loads was analyzed with finite-element analyses (FEA). The effects of different analysis parameters and finite-element types on the thermo-mechanical properties were analyzed.  With the results of the FEA we determined the deformations to the headlamp housing. This analysis helped us to eliminate the causes of the bad sealing between the housing and the cover of the headlamp.

Keywords - automotive headlamp, temperature loads, stress-strain state, finite-element methods

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 52(2006)1, 52-62
UDC 656.057.87:539.3+519.61/.64

The Effects of Different Analysis Parameters on the Calculated Temperature of a Loaded Headlamp (pdf)

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