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POSSIBILITIES TO IMPROVE TRANSIENT GEAR SHIFT NOISE (SHIFT CLONK) IN A PASSENGER CAR
BIERMANN J. W.,REITZ A. The Korean Society of Automotive Engineers 2005 International journal of automotive technology Vol.6 No.1
The presented investigation of shift clonk in a vehicle with front-wheel drive shows how a detailed analysis of the complete acoustic system with respect to excitation, transfer and radiation foremost enables possibilities of noise reduction to be worked out. One of the most important basics for the shift clonk analysis was a synchronous measurement of both, torsional vibrations in the drive train on the excitation side as well as airborne and structure-borne noise signals on the transfer and radiation side. Thus, root causes could be identified and improvement measures of the internal shift system could be worked out. An analysis of the transfer paths by means of airborne and structure borne noise measurements made evident that the side shafts were responsible for the disturbing frequencies in the transfer paths. With the help of the FE-simulation it was possible to develop measures of structure optimisation for the side shaft system. The realisation of these measures clearly reduced the shift-noises in the vehicle interior.
The effect of oxygenated fuel properties on diesel spray combustion and soot formation
Park, Wonah,Park, Seunghyun,Reitz, Rolf D.,Kurtz, Eric Elsevier 2017 Combustion and Flame Vol.180 No.-
<P><B>Abstract</B></P> <P>Diesel engines have advantages due to their potential for high fuel conversion efficiency. However, it is necessary to reduce pollutant emissions, particularly NOx and soot to meet emission mandates. Many studies have shown that oxygenated fuel additives can effectively reduce soot emissions. In this research, to investigate the effect of oxygenated fuel properties on combustion and soot emission, CFD simulations were carried out using newly developed chemical mechanisms for various oxygenated fuels such as tri-propylene glycol methyl ether, methyl decanoate, and dimethyl ether. The results show that the formation of soot precursors decreases with increased oxygen content and decreased number of C–C bonds in the fuel. The fuel molecular structure strongly affects soot formation in addition to fuel-air mixing. Comparisons of fuel blends (oxygenated fuels with n-hexadecane) including methyl decanoate, which have the same fuel oxygen ratio, show that the effects of the ignition delay and lift-off length control soot formation for fuels with similar fuel oxygen ratio and number of C–C bonds.</P>
THE CLONK PHENOMENON -A LOAD CHANGE REACT10N TO BE BALANCED H TERMS OF COMPORT AND ENGINE RESPONSE
Biermann, J.W.,Reitz, A.,Schumacher,T. The Korean Society of Automotive Engineers 2000 International journal of automotive technology Vol.1 No.1
The customers demand of a good vehicle agility consists of a quick reaction of the vehicle with the actuation of the throttle pedal on one hand and a high comfort level of vibration and noise within the vehicle on the other hand, which means the reduction of disturbing side effects. In order to achieve a satisfactory compromise it is necessary to gain a deeper understanding of the complex, high dynamic vibrations system "vehicle / drive train". For several years the ika has been carrying out such detailed vehicle investigations and test bench measurements in addition to comprehensive CAE analysis for various research projects in partnership with different vehicle manufacturers.
THE CLONK PHENOMENON-A LOAD CHANGE REACTION TO BE BALANCED IN TERMS OF COMFORT AND ENGINE RESPONSE
J. -W. BIERMANN,A. REITZ,T. SCHUMACHER 한국자동차공학회 2000 International journal of automotive technology Vol.1 No.1
The customers demand of a good vehicle agility consists of a quick reaction of the vehicle with the actuation of the throttle pedal on one hand and a high comfort level of vibration and noise within the vehicle on the other hand. which means the reduction of disturbing side effects. In order to achieve a satisfactory compromise it is necessary to gain a deeper understanding of the complex. high dynamic vibrations system "vehicle / drive train". For several years the ika has been carrying out such detailed vehicle investigations and test bench measurements in addition to comprehensive CAE analysis for various research projects in partnership with different vehicle manufacturers.<br/>
POSSIBILITIES TO IMPROVE TRANSIENT GEAR SHIFT NOISE (SHIFT CLONK) IN A PASSENGER CAR
J.W. BIERMANN,A. REITZ 한국자동차공학회 2005 International journal of automotive technology Vol.6 No.1
The presented investigation of shift clonk in a vehicle with front-wheel drive shows how a detailed analysis of the complete acoustic system with respect to excitation, transfer and radiation foremost enables possibilities of noise reduction to be worked out. One of the most important basics for the shift clonk analysis was a synchronous measurement of both, torsional vibrations in the drive train on the excitation side as well as airborne and structure-borne noise signals on the transfer and radiation side. Thus, root causes could be identified and improvement measures of the internal shift system could be worked out. An analysis of the transfer paths by means of airborne and structure borne noise measurements made evident that the side shafts were responsible for the disturbing frequencies in the transfer paths. With the help of the FE-simulation it was possible to develop measures of structure optimisation for the side shaft system. The realisation of these measures clearly reduced the shift-noises in the vehicle interior.
C.H.Lee,Rolf D.Reitz 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.11_1
An experimental and numerical study has been conducted of drop trajectory and breakup mechanisms for liquid drops injected into high velocity gas flows with various chamber gas pressures at room temperature. In the experimental study, air-assisted liquid drop atomization processes were investigated using photographic techniques under well-controlled experimental conditions. A monodisperse stream of drops from a vibrating-orifice drop generator was injected into a transverse high velocity gas stream. The back pressures and gas velocities were adjusted independently to control the drop Weber numbers. The Weber numbers used in the experiments were 72, 148, 270, 532. High-magnification photographs and conventional spray field photography revealed the microscopic breakup mechanisms and the parent drop trajectory in the high velocity flow field, respectively. Drop sizes were measured using a Phase/Doppler particle analyzer. The experimental results were used to test and assess spray models in the KIVA3 code. The breakup model considered Kelvin-Helmholtz (K-H) instability mechanisms to account for secondary drop breakup. The computations show good agreement with experimental results of parent drop trajectories and for the spatial drop size distributions which result from secondary breakup at high gas densities. At low gas densities, it is concluded that the use of K-H model to predict drop breakup may not be justified.<br/>