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Research Interests: Geology, Physics, Particle Image Velocimetry, Flow Control, Computation Fluid Dynamics, and 11 morePerformance Model, Turbulent Flow, Experimental Study, Wind Tunnel, Three Dimensional, Turbulence Model, Wake, Experimental Measurement, Pressure Measurement, Active flow control, and Model performance
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ABSTRACT A comparison between flame luminosity and non-combusting flows was made in order to better understand the effects combustion and the flame have on the fluid dynamics of a flow. A large eddy simulation (LES) of a cylinder in a... more
ABSTRACT A comparison between flame luminosity and non-combusting flows was made in order to better understand the effects combustion and the flame have on the fluid dynamics of a flow. A large eddy simulation (LES) of a cylinder in a cross flow was done at different Reynolds number in order to make the comparison between flame luminosity and non-combusting flows using OVERSET grid technology. Proper orthogonal decomposition (POD) was done for the different cases in order to compare how much energy is contained in symmetric, asymmetric, and uncorrelated POD modes. Initial results show the modal energies of the non-combusting flow do not match the modal energies of the flame luminosity.
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Experimental measurements have been performed to characterize the wake of a three-dimensional, non-conformal turret. Experiments were performed in a low-speed wind tunnel at Syracuse University using particle image velocimetry, hotwire... more
Experimental measurements have been performed to characterize the wake of a three-dimensional, non-conformal turret. Experiments were performed in a low-speed wind tunnel at Syracuse University using particle image velocimetry, hotwire anemometry and ...
Research Interests: Geology, Physics, Particle Image Velocimetry, Flow Control, Computation Fluid Dynamics, and 11 morePerformance Model, Turbulent Flow, Experimental Study, Wind Tunnel, Three Dimensional, Turbulence Model, Wake, Experimental Measurement, Pressure Measurement, Active flow control, and Model performance
Combustion modeling is an important field that is imperative for studying jet engines. A new combustion rig has been designed to create combustion models for advanced engine technology. The rig consists of two streams; one for fresh air... more
Combustion modeling is an important field that is imperative for studying jet engines. A new combustion rig has been designed to create combustion models for advanced engine technology. The rig consists of two streams; one for fresh air and another stream for vitiated air. Knowing the inlet conditions of the test section is important when doing high-resolution simulations such as large eddy simulations (LES). A simulation of the rig upstream of the test section has been performed in order to obtain the boundary conditions, which would be difficult and costly to obtain experimentally.
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In this paper, we present an experimental investigation of a supersonic rectangular nozzle with aft deck used for three-stream engines. The jet utilizes a single expansion ramp nozzle (SERN) configuration along with multiple streams,... more
In this paper, we present an experimental investigation of a supersonic rectangular nozzle with aft deck used for three-stream engines. The jet utilizes a single expansion ramp nozzle (SERN) configuration along with multiple streams, operating at a bulk flow Mj,1 = 1.6 and bypass stream Mj,3 = 1.0. This idealized representation consists of two canonical flows: a supersonic convergent-divergent (CD) jet and a sonic wall jet. Time-resolved schlieren experiments were performed up to 100 kHz. Proper orthogonal decomposition (POD), as suggested by Lumley for structure identification in turbulent flows, is applied to the schlieren images and the spatial eigenfunctions and time-dependent coefficients are related to the flow structures. This research seeks to lay a foundation for fundamental testing of multi-stream SERNs and the identification of the flow physics that dominate these modern military nozzles.
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As focused light passes through turbulent ∞ow the light is distorted and the intensity is reduced. An extended study using active ∞ow control to afiect the turbulent region over the a ∞at aperture of a 3-D hemispheric turret was conducted... more
As focused light passes through turbulent ∞ow the light is distorted and the intensity is reduced. An extended study using active ∞ow control to afiect the turbulent region over the a ∞at aperture of a 3-D hemispheric turret was conducted in the Air Force Research Laboratory’s Subsonic Aerodynamic Research Laboratory (SARL) wind tunnel at WrightPatterson Air Force Base. The SARL experiments were performed at a Mach number of :3, which gives Reynolds number on the order of 2;000;000. At these Reynolds numbers the ∞ow becomes highly complex and more challenging to study. A large database from previous work containing no control and open loop control cases provided a rich ensemble for plant model development based on low dimensional techniques such as the split-POD method of Camphouse (2007). PIV velocity data was acquired along with simultaneously sampled surface pressure data at various planes across the turret with and without control. Control authority was acquire by actuators mounted upstream of the aperture that generated a momentum ∞ux in the ∞ow around the turret. Simple proportional closed-loop control was performed using the bandpass flltered temporal POD mode coe‐cients of the surface pressure as the feedback signal. This paper shows that the active control reduced the root mean squared of the pressure ∞uctuations, shrunk the integral scales, and drove the ∞ow towards homogeneity.
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Snapshot Proper Orthogonal Decomposition (POD) is a useful tool applied to many different flows. This technique is used mainly for turbulent flows to find the most energetic structures, but it can also be used to extract dominant... more
Snapshot Proper Orthogonal Decomposition (POD) is a useful tool applied to many different flows. This technique is used mainly for turbulent flows to find the most energetic structures, but it can also be used to extract dominant structures in any type of data. The method usually involves using multiple snapshots in time at one spatial location. However, a problem that can arise is when some of the data is not available in some of the snapshots due to obstructions. Several techniques have been investigated for creating data to fill in where it is missing. An example test case of a plunging NACA 0012 airfoil is used to access the efficiency and accuracy of the various fill-in techniques.
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We analyze time-resolved schlieren images of the near-field of a 3-stream supersonic jet. The primary jet operates in the vicinity of Ma = 1.6, and the images are collected at the rate of 50 to 400 kfps. We analyze transverse-axial images... more
We analyze time-resolved schlieren images of the near-field of a 3-stream supersonic jet. The primary jet operates in the vicinity of Ma = 1.6, and the images are collected at the rate of 50 to 400 kfps. We analyze transverse-axial images by constructing time series from more than 400 points selected for their possible significance, based on a qualitative analysis of the schlieren images. The points are grouped along the various shear layers and in the near-field outside the jet. We examine in turn the power spectra and cross-correlations between points. Overall qualitative and quantitative trends in both spectra and correlation are noted, revealing a strong dependence of both on transverse and axial location in the flow field. Defining features in the spectra give insight into the frequency bands which will be more closely analyzed in future phases of this study. The results from this preliminary study point to the validity of using time-resolved schlieren imaging as a non-intrusive experimental method to generate time series, to which a range of analysis methods is applicable.
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A rectangular single-expansion ramp nozzle (SERN) with an aft deck is used to model the exhaust from a three-stream engine. At the nozzle exit two unmixed streams exist. The first is assumed to be a perfectly mixed flow of core and fan... more
A rectangular single-expansion ramp nozzle (SERN) with an aft deck is used to model the exhaust from a three-stream engine. At the nozzle exit two unmixed streams exist. The first is assumed to be a perfectly mixed flow of core and fan streams operating at a nozzle pressure ratio of 4.25 and the second is the tertiary stream operating at a nozzle pressure ratio of 1.89. Above the aft deck, the two unmixed streams merge into the jet plume. Complementary simulation and experimental data were acquired for this geometry. Simulation data were obtained using the Naval Research Laboratory’s (NRL’s) jet engine noise reduction (JENRE) code. Experimental data were gathered in the Syracuse University anechoic chamber. The experimental and computational approaches provided similar results, giving confidence in both the simulation and the newly modified test facility. Using the newly acquired data the flow and acoustics were investigated and a trade study was performed, which found a potential “low noise” condition.
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Particle image velocimetry and near-field pressure were collected for an axisymmetric, Mach 0.6 jet. Some of the pressure sensors were in between the laser sheet and camera, causing occlusions in the particle image velocimetry data. Using... more
Particle image velocimetry and near-field pressure were collected for an axisymmetric, Mach 0.6 jet. Some of the pressure sensors were in between the laser sheet and camera, causing occlusions in the particle image velocimetry data. Using ideas from the data fusion community, these occluded regions could be repaired. In this case, the particle image velocimetry data could be fused with the knowledge that the velocity field was symmetric about the center axis using a new technique called fused proper orthogonal decomposition, which is inspired by gappy proper orthogonal decomposition and image/wavelet fusion. Using this technique, 90% of the missing data could be estimated with 10% error.