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Showing 1 to 20 of 27 for “"unsteady pressure"”.
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Unsteady pressure and vorticity fields in blade-vortex interactions
The unsteady interaction of a vortex core with a NACA 0015 airfoil is studied in two dimensions. A two-component, three-beam Helium-Neon laser-Doppler Velocimetry system is used to take data in a water tunnel. Ensemble-averaged velocity fields are obtained in the region of the leading edge of the …
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UNSTEADY PRESSURE MEASUREMENTS IN A SUPERSONIC INLET DURING UNSTART SIMULATIONS
Unsteady pressure behavior during inlet unstart is a critical factor in understanding the performance and stability of supersonic systems. This thesis will investigate the unsteady pressure measurements within a supersonic inlet during unstart. By using a model developed by Ben Nikaido, Kulites …
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Tip clearance and angle of attack effects upon the unsteady response of a vibrating flat plate in crossflow
… clearance and angle of attack upon the mid-span unsteady pressure response of a vibrating flat plate was investigated experimentally. Unsteady pressure measurements were taken for a variety of incidence angles, vibration frequencies and tip clearances over a Mach number range of 0.2 to 0.6. It …
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Rotor/Fuselage Unsteady Interactional Aerodynamics: A New Computational Model
A new unsteady rotor/fuselage interactional aerodynamics model has been developed. This model loosely couples a Generalized Dynamic Wake Theory (GDWT) to a Navier-Stokes solution procedure. This coupling is achieved using a newly developed unsteady pressure jump boundary condition in the …
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Mean Loading and Turbulence Scale Effects on the Surface Pressure Fluctuations Occurring on a NACA 0015 Airfoil Immersed in Grid Generated Turbulence
Detailed surface pressure measurements have been made on a NACA 0015 immersed in two grid generated homogenous flows at Re = 1.17 x 10⁶ for a = 0°, 4°, 8°, 12°, 16°, and 20°. The goal of this measurement was to reveal and highlight mean loading and turbulence scale effects on surface pressure …
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Correlation between Unsteady Loading and Tip Gap Flow Occurring in a Linear Cascade with Simulated Stator-Rotor Interaction
… and the tip blade loading were made using static pressure taps. The tip loading shows that the minimum suction surface pressure coefficient increases in magnitude linearly up to a tip clearance of 7.9% chord. Unsteady pressure was measured on the pressure and suction surfaces at the tip of two …
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Characterization of unsteady loading due to impeller-diffuser interaction in centrifugal compressors
… simulations are used to characterize the unsteady impeller blade loading due to imipeller-diffuser interaction in centrifugal compressor stages. The capability of simulations are assessed by comparing results against unsteady pressure and velocity measurements in the vaneless space. …
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Numerical Simulation of Pressure Wave Supercharger with Pockets Operating at Different Speeds
Pressure wave supercharger is an application of wave rotor technology that utilizes compression waves produced by high-pressure engine exhaust gas to compress the fresh intake air within the channels. The phenomena within the wave rotor channels are governed by compression and expansion waves …
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Active noise control in supersonic impinging jets using pulsed microjets : actuator design, reduced-order modeling
… The most energetic spatial mode of the unsteady pressure along the nozzle diameter is captured using the POD, which in turn is used to determine the distribution of microjet intensity along the nozzle exit. Preliminary experimental results from a STOVL supersonic jet facility at Mach 1.5 …
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Understanding the Impact of a Serrated Trailing Edge on the Unsteady Hydrodynamic Field
… was found that there may be differences in the unsteady surface pressure over serrated edges in one-sided flows as compared to two-sided flows, like on that of an airfoil, most notably in relation to the magnitude of the unsteady pressure on the serrations. In the wall jet and in agreement with …
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Investigation of Pulse Detonation Engine Flow Conditions for Turbomachinery Integration
<p>Pressure gain combustion has been known to be more thermodynamically efficient than its constant pressure counterpart, which employs deflagration. Integration of pressure gain combustors into gas turbine engines has been and still is one of the most important challenges facing the gas turbine …
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A study on flow development in an APU-style inlet and its effect on centrifugal compressor performance
… steadiness was achieved by tuning the pressure controller using a PID control method and utilizing multi-layer screens downstream of the APU inlet. Less than 1% relative unsteadiness was achieved for full range operation.</p> <p>The flow field inside the rectangular-sectioned 90? bend …
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Further studies of unsteady gas flow in the manifolds of multi-cylinder automobile engines
… an investigation into the general principles of unsteady flow in pipe systems, with analysis of specific flow regions in the manifolds of a carburetted, four-stroke, automotive engine. The unsteady flow calculation is effected by the method of characteristics under the assumption of …
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Post-stall hysteresis and flow field unsteadiness on an NACA 0012 airfoil
… on an NACA 0012 airfoil at Rec = 1.0 × 10^6. Unsteady pressure measurements were acquired to evaluate the performance of the airfoil, and a hysteresis loop was identified in the vicinity of the airfoil Cl,max. Two fundamentally different flow regimes were observed at post-stall angles of …
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Turbine inlet non-uniformities and unsteady mechanisms
… chord downstream of the trailing edge. Near the pressure surface, the wake stagnation pressure increases by up to 42% above the freestream stagnation pressure. The mechanisms identified are a localized reduction in flow-through time for wake fluid near the pressure surface, compared to the …
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Experimental Sensitivity Analysis and Control of Thermoacoustic Systems in the Linear Regime
… arise due to feedback between acoustic waves and unsteady heat release rate when the fluctuating heat release rate is sufficiently in phase with the unsteady pressure. The primary aim of designers is to design linearly stable thermoacoustic systems in which these dangerous oscillations do not …
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Asymptotic approximations for the sound generated by aerofoils in unsteady subsonic flows
This thesis considers the sound generated by unsteady perturbations interacting with solid aerofoils in background steady flows, in an attempt to further develop analytic models for the noise generated by blades within turboengines. Specifically, high-frequency unsteady gust and sound wave …
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An Experimental Investigation of Unsteady Surface Pressure on Single and Multiple Airfoils
This dissertation presents measurements of unsteady surface pressure on airfoils encountering flow disturbances. Analysis of measurements made on an airfoil immersed in turbulence and comparisons with inviscid theory are presented with the goal of determining the effect of angle of attack on an …
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Forced response of a centrifugal compressor stage due to the impeller-diffuser interaction
The unsteady pressure field experienced by a centrifugal compressor stage can be dominated by of the impeller-diffuser interaction. The energy of the unsteady field, under certain aerodynamic and structural conditions, is capable of forcing the rotating impeller blades to vibrate excessively to the …
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An Investigation of Controlled Oscillations in a Plasma Torch for Combustion Enhancement
… influence on the induced shock structure. The unsteady nitrogen-fed torch was integrated with the flush walled 4-hole aerodynamic ramp injector using hydrogen and hydrocarbon fuels at the University of Virginia Aerospace Research Lab (ARL) heated Mach 2 supersonic flow. Unsteady pressure …
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