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Modern diesel engines typically utilize pulse-turbocharging where an increase in exhaust gas transport efficiency is achieved at the expense of creating a highly unsteady flow through the turbine which may have a detrimental effect on turbine performance. As the turbocharger plays a major role in the performance and emissions of the engine system, the characterization of on-engine turbocharger aerodynamics is critical. Thus, this paper is directed at the investigation of the turbocharger turbine volute inlet flowfield on an in-line, six cylinder, diesel engine. Specifically, Particle Image Velocimetry (PIV), a quantitative non-intrusive whole flowfield measurement technique, is used to perform a detailed study of the on-engine pulsating flowfield at the volute inlet of the twin-entry turbocharger turbine.

The flow-induced pressure fluctuations in a door gap cavity model were investigated experimentally using a quiet wind tunnel facility. The cavity cross-section dimensions were typical of road vehicle door cavities, but the span was only 25 cm. One cavity wall included a primary bulb rubber seal. A microphone array was used to measure the cavity pressure field over a range of flow velocities and cavity configurations. It was found that the primary excitation mechanism was an “edge tone” phenomenon. Cavity resonance caused amplification around discrete frequencies, but did not cause the flow disturbances to lock-on. Possible fluid-elastic coupling related to the presence of a compliant wall was not significant. A linear spectral decomposition method was then used to characterize the cavity pressure in the frequency domain, as the product of a source spectral distribution function and an acoustic frequency response function.

The lack of effective and efficient communication between pilots and maintenance technicians has been recognized as a problem in general aviation by both members of the industry and academia. The goal of this paper is to provide an accounting of the impact that communication between maintenance technicians and pilots, or the lack thereof, can have upon both the bottom line and the experience of those who operate within the general aviation arena. The researchers interviewed and observed maintenance technicians and pilots in general aviation operations to identify what members on both sides of the communication process identified as being problematic and troubling. Several of the major barriers to communication, as well as several strategies to overcome those barriers, are discussed.

The identification of the propulsion noise of turbofan engines plays an important role in the design of low-noise aircraft. The noise generation mechanisms of a typical turbofan engine are very complicated and it is not practical, if not impossible, to identify these noise sources efficiently and accurately using numerical or experimental techniques alone. In addition, a major practical concern for the measurement of acoustic pressure inside the duct of a turbofan is the placement of microphones and their supporting frames which will change the flow conditions under normal operational conditions. The measurement of acoustic pressures on the surface of the duct using surface-mounted microphones eliminates this undesirable effect. In this paper, a generalized acoustical holography (GAH) method that is capable of estimating aeroacoustic sources using surface sound pressure is developed.

This paper describes sensors and systems developed, or under development, by researchers at Purdue University including: an automated soil nutrient mapping system; a real-time acoustic soil texture sensor; an improved, real-time soil organic matter (SOM) sensor; a real-time soil compaction sensor; and an animal manure application monitoring and control system. Issues to consider for sensor use and development, criteria for evaluating the potential for successful sensor implementation, and likely future sensors for site-specific crop management (SSCM) are also discussed.

The relationship of slip resistance (or coefficient of friction) to safe climbing system maneuvers on high profile vehicles has become an issue because of its possible connection to falls of drivers. To partially address this issue, coefficients of friction were measured for seven of the more popular fabricated metal step materials. Evaluated on these steps were four types of shoe materials (crepe, leather, ribbed-rubber, and oil-resistant-rubber) and three types of contaminant conditions (dry, wet-water, and diesel fuel). The final factor evaluated was the direction of sole force application. Results showed that COF varied primarily as a function of sole material and the presence of contaminants. Unexpectedly, few effects were attributible to the metal step materials. Numerous statistical interactions suggested that adequate levels of COF are more likely to be attained by targeting control on shoe soles and contaminants rather than the choice of a particular step material.

Structural sound transmission through primary bulb (PB) sealing systems was investigated. A two-degrees-of-freedom analytical model was developed to predict the sound transmission characteristics of a PB seal assembly. Detailed sound transmission measurements were made for two different random excitations: acoustic and aerodynamic. A reverberation room method was first used, whereby a seal sample installed within a test fixture was excited by a diffuse sound field. A quiet flow facility was then used to create aerodynamic pressure fluctuations which acted as the excitation. The space-averaged input pressure within the pseudo door gap cavity and the sound pressure transmitted on the quiescent side of the seal were obtained in each case for different cavity dimensions, seal compression, and seal designs. The sound transmission predictions obtained from the lumped element model were found to be in reasonable agreement with measured values.

Acoustic array techniques are presented as alternatives to intensity measurements for source identification in automotive and industrial environments. With an understanding of the advantages and limitations described here for each of the available methods, a technique which is best suited to the application at hand may be selected. The basic theory of array procedures for Nearfield Acoustical Holography, temporal array techniques, and an Inverse Frequency Response Function technique is given. Implementation for various applications is discussed. Experimental evaluation is provided for tire noise identification.

The turbocharger, consisting of a radial or axial flow turbine and an radial flow compressor presents perhaps one of the most challenging tasks to the turbomachinery designer. Due to the necessity of speed changes in the diesel engine, the turbocharger transits a wide variety of operating points in its normal operation. During an engine speed acceleration or deceleration there will be a lag in the required air delivery to the engine, resulting in increased smoke emission and limiting the power delivered by the engine. In order to investigate the dynamic performance of a turbocharged engine, an essential first step must be the development of an adequate model for transient characteristics of the turbocharger. One of the significant problems that must be overcome for the modeling effort to be successful is a detailed experimental description of the transient performance of the device.

Most airline maintenance human factors training programs miss the mark when it comes to producing optimal behavioral and procedural changes among participating maintenance professionals. While there are many causes for training outcomes which are less than desired and anticipated, principal among these are the failure of most programs to address the pragmatic learning needs of those technicians as adult learners. Attention to andragogical principles such as clear learning goals, readily apparent relevance and direct applicability of material, immediate feedback, learner directed inquiry and self assessment can contribute greatly to achieving optimal results. A program currently under development at Purdue University utilizes a combination of classroom instruction, group discussion, and learner participation in aviation maintenance scenarios as a method for improving human factors education.

It is generally agreed that adequate resolution is required to reproduce the structure of spray and gas jets in numerical computations. It has not been clarified what this resolution should be although it would appear reasonable to assume that it should be such that the physical scales of the problem are resolved. In the case of a jet, this implies that near the orifice, the jet diameter has to be resolved since this is the appropriate length scale. It is shown in this work that if such a resolution is not used in computing transient jets, the structure of the jet is not reproduced with adequate accuracy. In fact, unexpected, erroneous and misleading dependence on ambient turbulence length and time scales will be predicted when the initial ambient turbulence diffusivity is small relative to the jet diffusivity. When the ambient turbulence diffusivity is of the same order as the jet diffusivity or greater, entrainment rates are significantly underpredicted.