Localized arc filament plasma actuators were used to control pressure fluctuations in a cavity with a depth of 12.7 mm and length-to-depth ratio of 4.86. The rear wall of the cavity is inclined 30 deg with respect to the upstream flow, and the cavity length is 61.7 mm. Five actuators were uniformly distributed along the span of the cavity, 1 mm upstream of the cavity leading edge. Experiments were conducted in a flow with a Mach number of 0.6 and a Reynolds number based on the cavity depth of 2 × 10 5. Forcing was conducted quasi-two-dimensionally (all actuators operated in phase) and threedimensionally (actuators operated out of phase). The objective of the research was twofold: first, to demonstrate that the peak tone as well as the broadband pressure fluctuations can be suppressed in a strongly resonating cavity, and second, the resonance can be re-established and the peak tone as well as the broadband pressure fluctuations can be amplified in a weakly resonating cavity. Time-resolved pressure and particle-image-velocimetry measurements were used to assess the effectiveness of the actuators and to explore the physics of the flow. Although both quasi-two-dimensional and threedimensional controls were successful in controlling the flow, the control was less sensitive to forcing frequency change in the latter in achieving the first objective. The results also showed that, although there are many forcing frequency options in achieving the first objective, the options are limited to frequencies near the dominant (even though weak) Rossiter modes in re-establishing the feedback in a weakly resonating cavity.

No abstract

This work develops an understanding of the flow mechanisms that induce vibrations on automotive side view mirrors. The unsteady nature of the flow over side view mirrors causes unsteady aerodynamic load distributions and flow-induced vibrations on the mirror assembly. These vibrations generate blurred rear-view images and higher noise levels, affecting the mirror functionality and passenger comfort. Certain geometrical design features of side view mirrors can exacerbate the flow-induced vibration levels of the mirror assembly significantly. This work quantifies the impact of these design features on the vibration amplitude, develops a methodology for testing mirror vibrations in a small, low-speed wind tunnel using only the mirror of interest, and delves into the interactions between the bluff body mirror geometry and its wake. Two similar side view mirror designs were investigated in this work by using laser-based vibrometry, flow visualization, particle image velocimetry, hot film anemometry, and surface stress sensitive film techniques. The magnitude of the vibrations was found to depend on the level of excursion in the dynamic location of flow separation, particularly when characteristic flow frequencies couple with the mirror housing natural frequency.

The primary objective of this research is to develop an understanding of the flow mechanisms which induce side-view mirror vibrations. The unsteady nature of the flow over side-view mirrors causes unsteady aerodynamic load distributions and flow-induced vibrations on the mirror assembly. These vibrations generate blurred rear-view images and higher noise levels, affecting the safety and comfort of the passengers. Geometrical design features of side-view mirrors exacerbate the flow-induced vibration levels of the mirror assembly significantly. This work quantifies the impact of these design features on the vibration amplitude; develops a methodology for testing mirror vibrations in a small, low-speed wind tunnel using only the mirror of interest; and delves into the interactions between the bluff body mirror geometry and its wake. Two similar side-view mirror designs, a baseline design and a turn-signal design, were investigated. The baseline mirror has a sharp-edged corner near the trailing edge, while the turn-signal design has an edge with an increased radius of curvature for the tip profile. A laser-based vibration measurement technique was developed and used to quantify vibration levels. Flow visualization, Particle Image Velocimetry (PIV), Constant Temperature Anemometry (CTA), and Surface Stress Sensitive Film (S3F) techniques were used to understand the separation characteristics over the mirrors since the time-dependent changes in separation location directly affect the unsteady loading on the mirror. The flow over the turn signal mirror with larger tip radius has larger excursions in the separation location, a wider wake, increased unsteadiness, and higher vibration levels. Results at the high Reynolds numbers for these test conditions indicate the absence of a discrete vortex shedding frequency. However, vortical structures in the wake are correlated with unsteady movement of the separation location.

Battelle's Hydroflex™ liquid-liquid extraction technology has been demonstrated for the remediation of metal and sulfate laden acid mine/acid rock drainage waters, removing sulfate to below 250 mg/L. In addition to the processed mine water, the process also produces a concentrated metal sulfate liquid byproduct and a concentrated sodium sulfate liquid byproduct. These byproducts have potential for use in the softening of flowback and produced waters in the Marcellus and Utica shale plays prior to reuse in hydraulic fracturing. This paper reports on Phase 1 of a Department of Energy project, which is preliminary qualification and design work for the full scale demonstration of a 378 liter per minute (100 gallon per minute) HydroFlex TM system to process Acid Mine/Acid Rock Drainage (AMD/ARD) water for use by the Oil and Gas industry. Initial range finding tests indicate that sulfate can be reduced to below 50 milligrams per liter (mg/L) in a single extraction stage, but that non carbonate hardness in the AMD/ARD makes the extraction process sensitive to over-mixing with organic entrainment within the processed water. Optimization of mixing and other extraction conditions in batch and continuous testing will be done to ensure production of water meeting the requirements of the oil and gas industry, as provided by industry and regulatory stakeholders.