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Technical Paper

Wavelet-Based Visualization, Separation, and Synthesis Tools for Sound Quality of Impulsive Noises

Recent applied mathematics research on the properties of the invertible shift-invariant discrete wavelet transform has produced new ways to visualize, separate, and synthesize impulsive sounds, such as thuds, slaps, taps, knocks, and rattles. These new methods can be used to examine the joint time-frequency characteristics of a sound, to select individual components based on their time-frequency localization, to quantify the components, and to synthesize new sounds from the selected components. The new tools will be presented in a non-mathematical way illustrated by two real-life sound quality problems, extracting the impulsive components of a windshield wiper sound, and analyzing a door closing-induced rattle.
Technical Paper

Wavelet-Based Visualization of Impulsive and Transient Sounds in Stationary Background Noise

Scalograms based on shift-invariant orthonormal wavelet transforms can be used to analyze impulsive and transient sounds in the presence of more stationary sound backgrounds, such as wind noise or drivetrain noise. The visual threshold of detection for impulsive features on the scalogram (signal energy content vs. time and frequency,) is shown to be similar to the audible threshold of detection of the human auditory system for the corresponding impulsive sounds. Two examples of impulsive sounds in a realistic automotive sound background are presented: automotive interior rattle in a vehicle passenger compartment, and spark knock recorded in an engine compartment.
Technical Paper

Wavelength-Agile Laser Sensors for Measuring Gas Properties in Engines

Internal combustion engines present a harsh environment for optical sensors, owing to challenges such as high pressures, multiple phases, and window fouling. Fortunately, a new class of “wavelength-agile” light sources that rapidly scan through a broad wavelength range facilitates accurate absorption spectroscopy in engines. Gas temperature and species concentrations can be monitored with fast time response (down to ∼ 1 μs). Here, two strategies for generating wavelength-agile light are introduced. We present in-cylinder results obtained by applying one of the strategies to monitor gas temperature and H2O concentration during compression in a single-cylinder optical engine operating in HCCI mode. Such data will be useful for improving the understanding of engine phenomena and offer the potential for active engine control.
Technical Paper

Warm-Up Characteristics of Surface Temperatures in an I.C. Engine Measured by Thermal Imaging Technique

The warm-up characteristics of a spark-ignition engine significantly affect fuel consumption and emissions from cars. A thermal imaging technique has been applied to measure the cylinder head surface temperature and piston surface temperature of an internal combustion engine simultaneously. The two-dimensional thermal images of the cylinder head surface temperature were viewed through an infra-red transmitting window mounted in the piston. The piston surface temperature was measured by painting black two small areas of the window's top surface. The similar thermal characteristics of the window material (silicon) to those of a normal piston and good heat transfer between the window and the piston provided realistic operation conditions. The mean and extreme values of the inlet valve, exhaust valve, two other areas of the cylinder head surface and window surface temperatures were measured from the thermal images during the first two minutes of the engine start.
Technical Paper

Wall Wetting Characterization Using an Image-Based Scattering Technique

A simple imaging technique was explored as a means for characterizing in-cylinder wall wetting in GDI engines. For technique development, a GDI fuel injector was directed vertically down on the top of a temperature controlled flat piston within a non-motored research cylinder in an experimental arrangement described previously [3, 4, 6, 7, 14]. A three-factor randomized factorial design of experiments was performed that included laser sheet level (with three treatments including 0 mm, 2 mm, and 5 mm from the piston surface), piston surface temperature (with three treatments including 100 °C, 150 °C, and 200 °C), and time after start of fuel (with five treatments including 1 ms, 2 ms, 3 ms, 4 ms, and 5 ms after start of fuel). The technique for characterizing wall-wetting differences involved subtracting the 8-bit pixel intensity values at every pixel location for one laser-illuminated scattered image from another image.
Technical Paper

Wake Structure Diagnostics of a Flapping Wing MAV

Experiments were performed to better understand the aerodynamic flow field of a flapping-wing micro air vehicle. High-resolution laser sheet flow visualization and particle image velocimetry (PIV) analyses have shown the presence of folded vortex filaments that are trailed from the tip and root of the wing, which are combined with a shed dynamic stall vortex with a strong spanwise flow toward the wing tip. This leading-edge vortex gains strength as the translational motion of the wing accelerates through mid-stroke. There is a subsequent shedding of this vortex, but with the simultaneous formation of another leading-edge vortex. The generation of the second vortex occurs before the first vortex reaches mid-chord, enhancing overall lift. This second vortex moves along the chord during supination, before finally being shed from the trailing-edge of the wing.
Technical Paper

Wake Imaging System Applications at the Boeing Aerodynamics Laboratory

The wake imaging system (WIS) for rapid mappings of wind tunnel model flowfields is described and a summary of recent results is presented. Three different types of systems are discussed. These are: Photographic WIS in low-speed wind tunnels. Computer graphics WIS in transonic wind tunnels. Flying strut traverser for large low-speed wind tunnels. In addition, progress toward developing a low intrusive WIS for high-pressure transonic wind tunnels and for flight test applications is described.
Technical Paper


This paper gives an overview of the actual work performed in the field of welding of automotive polymeric components at the Laser Zentrum Hannover e.V. (LZH). Laser beam sources at different wavelengths are applied, e.g. highly efficient diode laser systems and diode pumped Nd:YAG-laser operating in quasi-continuous wave mode. Welding velocities up to several m/min can be reached, dependent on material composition, absorption characteristic, thickness and average laser output power. Furthermore, capabilities of a thermographic system for material’s qualification related to their weldability will be presented by investigations of different plastic components. Experimental results for thermographic process control during the welding process are presented as well.

WDM LAN Standard

This standard, consisting of five documents, applies to designers, suppliers, and users of optical network services, systems, and components within mobile military and commercial aerospace platforms. The standard applies to any optical network which uses Wavelength Division Multiplexing in any optical media.

WAM Pressure-Viscosity Coefficient Measurement

The lubricant performance capability for aero propulsion drive systems is derived from the physical properties of the oil and performance attributes associated with the chemical properties of the oil. Physical properties, such as viscosity, pressure-viscosity coefficient and full-film traction coefficient are inherent properties of the lubricating fluid. Chemical attributes are critical for the formation of protective boundary lubricating films on the surfaces to prevent wear and scuffing. These attributes are also associated with surface initiated fatigue (micropitting). To assure performance and to provide required information for engineering design, methodology for at least five oil properties are being studied: (1) pressure-viscosity coefficient, (2) full-film traction coefficient, (3) scuffing resistance, (4) wear resistance; and (5) micropitting propensity.
Technical Paper

Vortex Developments Over NACA 0015 Airfoil with Trailing Edge Jet

The flow over a NACA 0015 airfoil with a trailing edge jet (jet flap) is investigated using computational and experimental capabilities to determine the influence of the jet on vortex developments over the airfoil. The computational modeling of steady flow at a Reynolds number of 43,000 at fifteen and twenty degrees indicates that as the jet mass flow rate is increased, the trailing edge jet suppresses vortex development, and in some cases, reattaches the flow. Experimental visualization shows the suppression of vortex structures in both steady and accelerating flow. The trailing edge jet may thus be a possibility for vortex control.
Technical Paper

Volatile Removal Assembly Flight Experiment and KC-135 Packed Bed Experiment: Results and Lessons Learned

The Volatile Removal Assembly (VRA) is a high temperature catalytic oxidation process that will be used as the final treatment for recycled water aboard the International Space Station (ISS). The multiphase nature of the process had raised concerns as to the performance of the VRA in a micro gravity environment. To address these concerns, two experiments were designed. The VRA Flight Experiment (VRAFE) was designed to test a full size VRA under controlled conditions in micro gravity aboard the SPACEHAB module and in a 1-g environment and compare the performance results. The second experiment relied on visualization of two-phase flow through small column packed beds and was designed to fly aboard NASA's micro gravity test bed plane (KC-135). The objective of the KC-135 experiment was to understand the two-phase fluid flow distribution in a packed bed in micro gravity.
Technical Paper

Visualization techniques to identify and quantify sources and paths of exterior noise radiated from stationary and nonstationary vehicles

In recent years, Nearfield Acoustical Holography (NAH) has been used to identify stationary vehicle exterior noise sources. However that application has usually been limited to individual components. Since powertrain noise sources are hidden within the engine compartment, it is difficult to use NAH to identify those sources and the associated partial field that combine to create the complete exterior noise field of a motor vehicle. Integrated Nearfield Acoustical Holography (INAH) has been developed to address these concerns: it is described here. The procedure entails sensing the sources inside the engine compartment by using an array of reference microphones, and then calculating the associated partial radiation fields by using NAH. In the second part of this paper, the use of farfield arrays is considered. Several array techniques have previously been applied to identify noise sources on moving vehicles.
Technical Paper

Visualization of the Scavenging Flow of Small Two-Stroke Cylinders

Experimental methods are needed to understand unsteady three-dimensional flows. They also become an important tool where geometrical details or the complexity of the applied model would require an over-proportional numerical effort to investigate a scavenging flow. The experimental method presented in this paper applies visualization techniques to analyze the scavenging flow of small two-stroke cylinders. The principle at work is based on similarity laws, which transfer the dimensions of an actual engine into an enlarged model. The modular set-up allows fast modifications of the port geometry and detailed visualization of the flow coming out of individual transfer ports of multiple port cylinders by using different dyes. Results are presented as movies, which give a very graphic impression of the unsteady three-dimensional flow inside the cylinder.
Technical Paper

Visualization of the Qualitative Fuel Distribution and Mixture Formation Inside a Transparent GDI Engine with 2D Mie and LIEF Techniques and Comparison to Quantitative Measurements of the Air/Fuel Ratio with 1D Raman Spectroscopy

Mie-Scattering and laser induced exciplex fluorescence (LIEF) were used to visualize the distribution of liquid fuel and fuel vapor inside an optical accessible one-cylinder research engine with gasoline direct injection (GDI). Using a tracer which was developed especially for the environments of gasoline combustion engines, LIEF enables an extensive separation between liquid and vapor phase and delivers a signal proportional to the equivalence ratio. Simultaneous images of LIEF and Mie scattering proof the high quality of the phase separation using this tracer concept. The mixture formation process will be shown exemplary at one operation point with homogeneous load and another with stratified load. First results of determining the air/fuel ratio by means of linear Raman spectroscopy will be presented and compared with the two-dimensional qualitative distribution of the fuel vapor (LIEF).
Technical Paper

Visualization of the Gas Flow Field within a Diesel Particulate Filter Using Magnetic Resonance Imaging

In recent years magnetic resonance imaging (MRI) has been shown to be an attractive method for fluid flow visualization. In this work, we show how MRI velocimetry techniques can be used to non-invasively investigate and visualize the hydrodynamics of exhaust gas in a diesel particulate filter (DPF), both when clean and after loading with diesel engine exhaust particulate matter. The measurements have been used to directly measure the gas flow in the inlet and outlet channels of the DPF, both axial profiles along the length and profiles across the channel diameter. Further, from this information we show that it is possible to indirectly ascertain the superficial wall-flow gas velocity and the soot loading profiles along the filter channel length.
Technical Paper

Visualization of the Flow Inside the Transfer Channels of Small Two-Stroke Cylinders

A method is presented which allows the investigation of the flow inside the cylinder and the transfer channels of small two-stroke cylinders under the condition of an expanded time scale by using the similarity laws. A test rig has been designed to incorporate the application of visualization techniques as well as quantitative measurement systems like LDV or PIV. The results obtained by this method are needed to understand the complex nature of the three-dimensional flow inside the cylinder and can be used to verify CFD calculations. Moreover, modifications can be applied to the model in an easy and fast manner, which enables the designer to examine various versions during the early stage of the development process.
Technical Paper

Visualization of the Cavitating Flow inside the Nozzle Hole Using by Enlarged Acrylic Nozzle

In this study, it is purpose to make clear the effect of cavitation phenomenon on the spray atomization. In this report, the cavitation phenomenon inside the nozzle hole was visualized and the pressure measurements along the wall of the nozzle hole were carried out by use of 25-times enlarged acrylic nozzle. For the representatives of regular gasoline, single and two-component fuels were used as a test fuel. In addition, various cavitating flow patterns same as experimental conditions were simulated by use of Barotropic model incorporated in commercial code of Star-CD scheme, and compared with experimental results.
Technical Paper

Visualization of a Fired Two-Stroke Chain Saw Engine Running at Idle Speed by Dynamic Neutron Radiography

Dynamic neutron radiography is a non-destructive inspection method. It provides different attenuation contrast compared, e.g., to common X-ray imaging. This allows neutrons to penetrate centimeter thick layers of metals while fuel or lubricants can still deliver good visibility. With beam cross sections between 3 cm and 30 cm (squared), neutron radiography is an ideal tool for the visualization of running combustion engines. Here we report on an experiment that demonstrates the feasibility to visualize a fired two-stroke chain saw engine running at idle speed (~ 3000 rpm). A sequence of single frames of the running engine was recorded and combined into a movie which provides a view into the moving parts of the engine, the combustion chamber and the crank case.