Chris Riedel

Free vibration analysis of planar curved beams by wave propagation

In this paper, a systematic approach for the free vibration analysis of a planar circular curved beam system is presented. The system considered includes multiple point discontinuities such as elastic supports, attached masses, and curvature changes. Neglecting transverse shear and rotary inertia, harmonic wave solutions are found for both extensional and inextensional curved beam models. Dispersion equations are obtained and cut-off frequencies are determined. Wave reflection and transmission matrices are formulated, accounting for general support conditions. These matrices are combined, with the aid of field transfer matrices, to provide a concise and efficient method for the free vibration problem of multi-span planar circular curved beams with general boundary conditions and supports. The solutions are exact since the effects of attenuating wave components are included in the formulation. Several examples are presented and compared with other methods.

Improvement of an LS-DYNA Fuel Delivery Module (FDM) Crash Simulation

This paper proposes and evaluates improvements to a crash simulation of a fuel delivery module in a fuel tank. The simulations were performed in ANSYS/LS -DYNA. Deviations between the original simulation and test data were studied and reasons for the deviations hypothesized. These reasons stemmed from some of the simplifying assumptions of the model. Improvements consisted of incorporating plasticity and strain rate effects into the material models. Performance criteria were also directly incorporated into the material models such that non-performing portions of the model could be deactivated during the simulation. Finally, solid-fluid interactions were added into the simulation to include the momentum transfer from fuel to the fuel delivery module. It was previously thought that effects of a crash would be most severe on the module when the fuel tank was empty and the module was full with fuel. This was challenged because momentum transfer from fuel to the modules exterior was thought to be significant when the tank is half full. The new simulation demonstrates a half full tank is indeed the worst case.

Diesel Spray Analysis

Light scattering based particle sizing techniques have the advantage of nonintrusively measuring sizes of emulsions and dispersions. Depending on the parameters involved, there are several techniques that can be used and a choice of the most convenient method can be made. When the particles are large, Fraunhofer Diffraction Pattern Analysis (FDPA) can be employed in measuring particle-sizing distributions. The design of a high quality diesel engine would involve an understanding of the disintegration mechanism, spray penetration, and spray motion. It is the objective of this paper to implement the FDPA laser diffraction method to determine spray penetration and droplet mean diameters, for single injection of diesel fuel with synchronized time that will allow time dependent studies.Copyright

Analysis of Sauter Mean Diameter (SMD) for Fuel Sprays

The spray-tip penetrations and the drop sizes of intermittent fuel sprays were measured by using a modified pulsed optical spray sizer. The average spray tip speeds were determined from simultaneously recorded needle lift signals and obscuration traces. The speeds of a sequence of fuel pulses injected at ∼103 Hz were analyzed to elucidate penetration mechanisms. A correlation that relates penetration distance to time, pressure drop across the nozzle, fuel density, and ambient gas density was obtained. The temporal variations of drop size in penetrating pulses of sprays were measured. The concentration of drops were calculated by combining drop size and obscuration data. The Sauter mean diameter of penetrating fuel drops increased with an increase of the chamber pressure and decreased with an increase of the injection pressure.Copyright

Spray Size Evolution of Diesel Sprays

Variations of fuel spray characteristics during cyclic operation is directly correlated to efficient operation of an engine. Measurements of drop size distribution and drop concentration under transient conditions during injection are difficult. A very rapid and synchronized measurement technique is necessary for sectional and temporal analysis of an intermittent spray during approximately 50 ms after each injection. A pulsed-spray sizer based on Fraunhofer diffraction pattern analysis was modified so that the repeatability of each injection can be determined by an obscuration-trace measurement. The sizer with a built-in adjustable delay was synchronized to the needle-lift of the injector and the drop size data were captured over 20 microseconds. For every single injection, the attenuation of the transmitted beam monitoring the arrival, the duration, and the drop concentration in the spray was recorded and stored on a digital scope. A solenoid controlled the position of the rack on the fuel line and ensured single injection. The obscuration-trace was used as a “fingerprint” in testing the reproducibility of successive injections. Drop size measurements were statistically averaged over many reproducible cycles.© 2006 ASME

Spray Penetration and Drop Size Studies of Diesel Fuels

Understanding the disintegration mechanism, spray penetration, and spray motion is of great importance in the design of a high quality diesel engine. The atomization process that a liquid would undergo as it is injected into a high-temperature, high-pressure air, is investigated in this work. The purpose of this study is to gain further insight into the atomization mechanism, the variation over time in droplet size distribution and spray penetration. This is done based on effect of chamber pressure, injection pressure, and type of fuel. A laser diffraction method is used to determine droplet mean diameters, single injection with synchronized time mechanism allowed the time dependent studies. Obscuration signals are obtained through a digital oscilloscope from which arrival time of spray can be measured. The spray penetration correlation obtained is compared to other correlation’s obtained from different other techniques used in the literature.Copyright

Spray Penetration and Drop Size Analysis

Understanding the disintegration mechanism, spray penetration, and spray motion is of great importance in the design of a high quality diesel engine. The atomization process that a liquid would undergo as it is injected into a high-temperature, high-pressure air, is investigated in this work. The purpose of this study is to gain further insight into the atomization mechanism, the variation over time in droplet size distribution and spray penetration. This is done based on the effects of chamber pressure, injection pressure, and type of fuel. A laser diffraction method is used to determine droplet mean diameters, single injection with synchronized time mechanism allowed the time dependent studies. Obscuration signals are obtained through a digital oscilloscope from which arrival time of spray can be measured. A spray penetration correlation is reported.Copyright

Determination of Particle Size Distribution Using Laser Diffraction Technique

Understanding the disintegration mechanism, spray penetration, and spray motion is of great importance in the design of a high quality diesel engine. The atomization process that a liquid would undergo as it is injected into a high-temperature, high-pressure air, is investigated in this work. The purpose of this study is to gain further insight into the atomization mechanism, the variation over time in droplet size distribution and spray penetration. This is done based on effect of chamber pressure, injection pressure, and type of fuel. A laser diffraction method is used to determine droplet mean diameters, single injection with synchronized time mechanism allowed the time dependent studies. Obscuration signals are obtained through a digital oscilloscope from which arrival time of spray can be measured. The spray penetration correlation obtained is compared to other correlation’s obtained from different other techniques used in the literature.Copyright