http://hdl.handle.net/10057/313 Search the Channel s http://soar.wichita.edu:8080/dspace/simple-search http://hdl.handle.net/10057/2097 title: Detached-eddy simulation of turbulent flow over a wiper blade authors: Urban, Michael Patrick <br>abstract: Decreasing noise and improving efficiency is an important trend for the future jetliner industry. The predominant sources of aerodynamic noise are created from attached turbulent boundary layers (TBL) as well as separated flows. The current numerical effort will focus on geometry of a fence to crudely model a windshield wiper blade for a large jetliner. This will produce an unsteady separated flow field. The recent literature lacks some of the characteristics that would make it most useful to aircraft applications. The numerical simulations performed were validated with a backward facing step experiment at M = 0.15. The backstep geometry was then altered one feature at a time until an angled fence system was produced. All simulations except the final were performed with conditions that matched the wind tunnel experiment. The final simulation was performed at cruise conditions at 35,000 feet, with rough flight deck conditions provided by the Boeing Company. The Mach number of the incoming boundary layer flow is 0.5. Results of mean velocity fields were in excellent agreement with experiments. Turbulence intensity as well as pressure quantities agreed. Spectra of pressure fluctuations followed trends of past experiments. Pressure fluctuation magnitudes were over predicted just as many other numerical investigations in literature concluded. <br>description: Wichita State University, College of Engineering, Dept. of Aerospace Engineering <br> http://hdl.handle.net/10057/2089 title: Flight environment of the propellers on commuter aircraft authors: Dorfling, Johann <br>abstract: Data obtained from digital flight data recorders installed on a fleet of 27 Beech 1900Ds are used to assess the actual operational environment of propellers on commuter aircraft. The data consists of 910 complete flights and 589 flight hours. Aircraft operations have been separated into three ground operations categories and five flight phases. Parameters that pertain to the propellers are emphasized. Overall aircraft and subsystem usage is also considered to establish the commuter airline flight profile. Overall aircraft usage includes information on flight durations and time within each flight phase, time at various airspeeds and engine torque levels, and flap operations. Flights of commuter aircraft are shown to be of short duration, with the cruise phase accounting for the majority of airborne time. Ground phases highlight the operation of the propellers within prohibited shaft speed ranges. A noticeable length of time is shown to have been spent within these restricted ranges. The usage of reverse thrust during landing rollouts and ground operations is also considered. Reversals upon landing accounted for less than half of the total number of reverse cycles. The short duration takeoff rotation is shown to impose the most severe operating conditions on the propellers. Aerodynamic parameters indicate large inflow angles into the propeller disk, resulting in the most severe vibratory loads. Engine torque, propeller shaft speed, and airspeed are all considered as contributing factors to the large vibratory loads the propellers experience at takeoff rotation. Information pertaining to the in flight engine and propeller usage is also given, and shows no abnormal usage of these components. Cumulative frequency of occurrence of angle of attack for each of the five flight phases has been normalized per 1000 hours and per nautical mile. Each flight phase is shown to produce a unique pattern of frequency of occurrence of the angle of attack, driven by the associated airspeeds. Another aerodynamic parameter considered while in flight is the upwash angle. Upwash angle has been derived for a variety of aircraft weights and airspeeds. This parameter is shown to have a significant influence on the propeller inflow angle, especially at high aircraft weight and low airspeed conditions. The change in inflow angle due to gusts has also been extracted and normalized per 1000 hours and per nautical mile. This data is given in the form of plots of cumulative frequency of occurrence for each flight phase and altitude. Increasing altitude shows a significant reduction in the frequency and magnitude of variations in angle of attack caused by gusts. The information is presented in statistical formats that could enable the FAA, the propeller manufacturer, and the airline to better understand and control those factors that influence the structural integrity of these components. <br>description: Wichita State University, College of Engineering, Dept. of Aerospace Engineering <br> http://hdl.handle.net/10057/2088 title: The effects of sealants and surface treatments on the faying surface of swept friction stir spot welds authors: Brown, Jeremy Micah <br>abstract: The goals of this project were to determine and document the effects of sealants and surface treatments have on the ultimate strength, fatigue life, and corrosion resistance of swept Friction Stir Spot Welded (FSSW) joints. One sealant, the PRC-DeSoto PR-1432 GP and several surface treatments were examined. The surface treatments attempted were AlClad, Chromic Acid Anodization on bare sheets, and Alodine chemical conversion coating on bare sheets. Bare sheets without a surface treatment were also evaluated to establish a baseline comparison. Ultimate lap shear testing was based on the unguided NASM 1312-4 2-spot weld coupon configuration and the guided NASM 1312-21 4-spot weld coupon configuration. Results indicated that the sealants and surface treatments decreased the joint strength of the individual spot welded joints a relatively small amount compared to the bare material strength. However, the sealant’s adhesive properties can potentially compensate for this loss if there is sufficient sealant coverage. The guided NASM 1312-21 4-spot weld coupon configuration was used for fatigue testing. Uniform amplitude fatigue tests were conducted with a variety of load levels to generate a load-life curve. The sealants and surface treatment seemed to have no effect on fatigue life at medium to low fatigue load levels. However, at high fatigue load levels, the sealants and surface treatments were slightly detrimental. The fatigue lives of the swept FSSW coupons was less than those of the NAS 1097 AD4 riveted coupons at the medium to low loads. However, the swept FSSW coupons were not optimized for fatigue and may improve under such conditions. The results of the corrosion testing indicated that the integrity of the sealant was not compromised by the swept FSSW. Generally, the surface treatments were not affected by the FSSW operation except where the tools displaced the surface and on the anvil side of the coupon in the heat affected zone. Since these areas are more vulnerable to corrosion, some protection should be added after welding. In general, the results of this project show that swept FSSW can successfully weld through sealants and surface treatments with only a minimum loss of the ultimate strength or fatigue life of the joint. The FSSW operation can be performed while maintaining most of the corrosion resistance. <br>description: Wichita State University, College of Engineering, Dept. of Aerospace Engineering <br> http://hdl.handle.net/10057/2087 title: Exploratory flight loads investigation of the p-2v aircraft in aerial firefighting operations authors: Bramlette, Richard B. <br>abstract: An exploratory analysis has been performed on a small number of flights of the P-2V aircraft operating in the firefighting mode as opposed to the anti-submarine and search-and-rescue operations for which it was designed. The data consists of 38 flights from the 2005 and 2007 fire seasons, for the same aircraft, totaling approximately 35 flight hours. Each flight has been divided into two ground and five flight phases and analyzed separately, with emphasis on the loads and atmospheric turbulence experienced by the aircraft. Some aircraft usage data has also been extracted and shown. Aircraft usage information in terms of operating altitudes and airspeeds, as well as maximum loads and V-n diagrams, have been examined for each flight phase. Flight loads for each phase have been separated into gusts and maneuvers using the “Two-Second Rule” and have been normalized per 1000 hours and per nautical mile. Atmospheric gust velocities for each phase have also been extracted and presented in both forms. Finally, the resultant gust and maneuver flight loads have been compared with standard design gust loads and Mil-8866 maneuver loads. A number of general trends have been observed by comparing the phases before and after the release of retardant. It has been shown that the release of retardant weight would significantly decrease wing loading and thus both the cruise speed and response to atmospheric turbulence. This has been demonstrated as being caused by weight by showing the levels of atmospheric turbulence to be the same before and after the drop. The effect of the changing weight on loads has also been examined in detail. The decrease in the weight of the aircraft during the taxi after the drop has been shown to increase the frequency of all loads as well as their severity compared to taxi loads prior to the drop. A similar effect has been highlighted for the cruise phases before and after the drop. Maneuver loads while delivering the retardant have been shown to be the highest in both sets of data. However, a significant part of the increased vertical acceleration is believed to be due to the change of mass while releasing the retardant and not due to maneuvering of the aircraft as is commonly believed to be. The derived and continuous gust velocities are shown not to be remarkably different before and after the release of retardant. The results suggest that the atmospheric turbulence is largely the same before and after the drop with a trend of lower severity at higher altitudes. Comparisons of the results with the military standards for design gust and maneuver loads are provided and show that lower-magnitude accelerations can be as much as 10 times more frequent than design conditions predicted. This is not deemed to pose a threat to exceeding the limit load factor for the airframe, but it can lead to a lower than expected fatigue life for the aircraft. These results indicate that these aircraft are operated in environments different from those for which they were designed. Therefore, maintenance schedules developed for their naval missions may not be applicable for their operation as firefighters. <br>description: Wichita State University, College of Engineering, Dept. of Aerospace Engineering <br>