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Showing 1 to 17 of 17 for “"microjet"”.
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Microjet impingement cooling of high power-density electronics
… this work, the high heat transfer capability of microjet impingement was leveraged to bring cooling directly to the backside of the electronic device. Previous experimental studies characterized the effects of geometrical factors, such as diameter, pitch, and standoff, on heat transfer …
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The stabilization and extinction of a microjet diffusion flame
The steady jet diffusion micro-flame is mathematically modeled and its extinction properties and investigated in this study. The diffusion flame of interest is one that results from the reaction of a fuel present in a weak jet issuing from a nozzle into an unbounded medium containing the oxidizer. …
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Suppression of premixed combustion dynamics utilizing microjet air injection
… thermoacoustic instabilities through the use of microjet air injection. This was done by building upon a previous combustor setup to allow the installation of several new diagnostic capabilities and the new microjets.
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Microjet based noise control of supersonic jets on carrier decks
The effectiveness of ground plane water microjet control on the noise generated by a supersonic, ideally expanded, Mach 1.5, impinging jet was determined. Using a converging-diverging nozzle with a design Mach number of 1.5, the jet was operated at temperatures ranging from 60 to 1700°F. Six …
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The reduction of supersonic jet noise using pulsed microjet injection
… control of supersonic jet noise using pulsed microjet injection at the nozzle exit. Experimental investigations were carried out using this control method on an ideally expanded Mach 1.8 jet operating at 900, 1300 and 1700'F. Six Bosch fuel injectors were modified and mounted on a toroidal …
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Suppression of thermoacoustic instabilities in a swirl combustor through microjet air injection
… to passively suppress combustion instability. Microjets inject air into the combustion chamber in the flame anchoring zone. These microjet injectors attempt to modify the flow field so as to break the feedback mechanism between the chamber acoustics and the heat release rate. Eight microjet …
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Active noise control of supersonic impinging jet using pulsed microjets
… of supersonic impinging jet flow using unsteady microjet injection. Supersonic impinging jet involves several problems such as lift loss, ground erosion, significant noise pollution, and sonic fatigue, all of which are dominated by impinging tones mainly caused by well-known phenomenon, the feed …
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Active noise control in supersonic impinging jets using pulsed microjets : actuator design, reduced-order modeling
… years, it has been demonstrated that direct microjet injection into the shear layer of the main jet disrupts the feedback loop inherent in high speed impinging jet flows, thereby significantly reduces the adverse effects. The amount of noise reduced by microjet actuation is known to be …
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Control of acoustics and store separation in a cavity in supersonic flow
… rigorously explains the role of leading edge microjets in cavity noise suppression and predicts the magnitude of noise reduction for a given control input (that is the steady pressure at which the microjets are fired). The model is validated through comparison of its noise reduction …
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Experimental and numerical investigation of cavitation erosion damage in FRP composites
… and damage mechanisms under highly localised microjet impacts. Further research was focused on finding factors affecting the resistance of FRP composites to cavitation erosion. The effects of water absorption of FRP composites, internal layup of fibres in composites, content of dissolved gas …
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The chemical effects of ultrasound
… interfaces include high speed liquid microjet impact, shock wave damage, enhanced mass transport near surfaces, and high velocity interparticle collisions.
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Active Control of Coherent Structures in an Axisymmetric Jet
… control (ANC) system that utilizes a unsteady microjet actuator on the nozzle lip in the downstream direction to produce a desired effect on the jet flow-field dynamics thereby directly affecting the source source. In contrast to the passive approach, the proposed open-loop control design will …
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Aeroacoustics Applications to Jets and Rotors
… techniques. A novel approach utilizing unsteady microjet actuation at the nozzle lip is explored to disrupt the formation of large-scale turbulent structures responsible for noise generation. High-fidelity simulations capture the unsteady flow dynamics and acoustic propagation, revealing how …
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Erosion-Corrosion of Cr3C2-NiCr High Velocity Thermal Spray Coatings
… coatings were deposited by Aerospray HVAF, GMA Microjet HVOF, Stellite Jet Kote HVOF and TAFA JP-5000 HVOF spraying under optimised conditions using agglomerated/sintered and blended powders. The prealloyed powder based coatings, characterised in terms of microhardness, porosity content and …
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Conformable Ultrasound Face Patch for Cavitation-enhanced Transdermal Cosmeceutical Delivery
… for inertial cavitation, convective mixing, and microjet formation with the application of ultrasound. Multiphysics simulation models are used to guide parameters for device design, and the modeling outputs are verified with electrical and mechanical characterization results. Subsequently, …
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Role of cavitation, surfactants, and their synergism in transdermal sonophoresis
… process of cavitation-induced microjet collapse at the skin surface, while the increased rpore values in non-LTRs are likely due to SLS perturbation, with enhanced penetration of SLS into the skin resulting from the frequency-independent process of acoustic streaming. Next, the …
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Silicon microcavity and microchannel plasma devices: spectroscopy and time-resolved optical experiments
Novel microcavity and microchannel plasma devices in Si have provided new and efficient sources of visible, ultraviolet (UV) and vacuum ultraviolet (VUV) radiation. The realization of this new platform for devices is implemented through VLSI and MEMS fabrication techniques. In this thesis, the …