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Showing 1 to 16 of 16 for “"Microjets"”.
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Active control of supersonic impingement tones using microjets
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003.
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Direct numerical simulation of microjets for turbulent boundary layer control
A direct numerical simulation approach is used to simulate an array of MEMS slot jets in a turbulent boundary layer for the purposes of flow control. Initial studies were used to first ascertain the correctness of the model and give insight into the performance characteristics of the devices. To …
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Active noise control of supersonic impinging jet using pulsed microjets
… used for active control is composed of pulsed microjets, utilizing a fraction of mass flow rate needed with steady microjets. Two means of producing pulsed microjet were introduced; one with a rotating cap, pulsing at 16 - 100Hz, and the other developed based on the principle of Hartmann tube, …
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Pulsed plasma microjets: a new tool for the investigation of plasma kinetics and molecular spectroscopy
We report on the development of a new laboratory tool which is suitable both for generating and quickly cooling short-lived molecules, and also for studying the kinetics and dynamics that take place at the rotational level during the expansion process. By integrating a microplasma device with a …
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Active noise control in supersonic impinging jets using pulsed microjets : actuator design, reduced-order modeling
… this paper, two active control strategies using microjets are suggested to maintain a uniform, reliable, and optimal reduction of these tones over the entire range of operating conditions. In the first method, a quasi-closed loop control strategy is proposed using steady microjet injection and …
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Microjet based noise control of supersonic jets on carrier decks
… at temperatures ranging from 60 to 1700°F. Six microjets were installed in the ground plane in a circular configuration at a radial spacing of 1.53 nozzle diameters, and an angle of 0 and 300 to tangential. Baseline and control temperature readings at the ground plane and acoustic readings at …
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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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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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Suppression of premixed combustion dynamics utilizing microjet air injection
… several new diagnostic capabilities and the new microjets.
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The reduction of supersonic jet noise using pulsed microjet injection
… data were also collected from the jet while the microjets were injecting steadily at a constant pressure. The results led to the following two conclusions: for injection at a given mass flow rate, noise reductions are higher with pulsed injection compared to the steady case, and for injection at …
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Evaluation of the sonically induced narrowing of nuclear magnetic resonance spectra of solids
… between acoustically induced cavitation microjets and particles.
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Aeroacoustics Applications to Jets and Rotors
… dynamics and acoustic propagation, revealing how microjets alter the dominant frequency modes of coherent structures. Through Spectral Proper Orthogonal Decomposition (SPOD), the study identifies the impact of actuation on the energy distribution across the frequency spectrum. Results demonstrate …
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Effectiveness of a Serpentine Inlet Duct Flow Control Scheme at Design and Off-Design Simulated Flight Conditions
… control technique using air injection through microjets at 1% of the inlet mass flow rate was developed by Lockheed Martin to improve the quality of the flow exiting the inlet duct. Both the inlet duct and the flow control technique were examined at cruise condition and off-design simulated …
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Ultrasound-assisted synthesis and processing of carbon materials
… fracture occur due to the shockwaves and microjets formed from asymmetric bubble collapse at extended surfaces. The chemical and physical effects of ultrasound have been studied as an adjunct to the traditional chemical pretreatment of lignocellulosic biomass for ethanol production. …
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Nanoparticle formation and coating using supercritical fluids
Jet breakup phenomenon and nanoparticle formation The focus of this dissertation is to study the SAS process to manufacture nanoparticles with minimum agglomeration, controlled size and size distribution. Solution jet breakup and solvent evaporation into supercritical fluid (SC CO_2) is studied …
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Modeling, design, and fabrication of pulsed fluidic micro-actuators
The forced vibration of a thin flexible plate or membrane in a sealed cavity with a small opening can cause fluid to be pumped into and out-of the cavity. At particular frequencies and amplitudes of vibration, a streaming of vortex rings can occur near the orifice. These vortex rings move under …