Martin Kearney-Fischer

• Lockheed Martin Corporation

Previous works have shown that subsonic jet noise radiating to aft angles can be described as a succession of independent large fluctuations (i.e. events). Building on these previous works, a model function is found that can accurately reproduce the observed spectra for jets whose aft angle noise is well described the Large-scale Similarity Spectru...

Following on previous works showing that far-field jet noise has significant intermittent aspects, the present work assumes that these intermittent events are the dominant feature of jet noise. A definition and method of detection for intermittent noise events is devised and implemented. Using a large experimental database of acoustically subsonic...

We present experimental and theoretical analyses of the response of high-speed, high-Reynolds-number, round jets to impulsive forcing with arc-filament-plasma actuators. The impulse response is obtained with forcing Strouhal numbers, based on the nozzle exit diameter and exit center line velocity, less than 0.1. The resulting phase-averaged near-fi...

Localized arc filament plasma actuators (LAFPAs) are used at the Gas Dynamics and Turbulence Laboratory (GDTL) for the purpose of controlling the shear layer development and acoustic radiation from a rectangular jet. Previous studies at the GDTL have shown these actuators to be effective at producing significant mixing enhancement and acoustic miti...

A class of plasma actuators called localized arc filament plasma actuators for high-speed and high-Reynolds-number flow and acoustic control has been developed at the Gas Dynamics and Turbulence Laboratory. Over the past several years, these high-bandwidth (0 to 200 kHz) and individually controlled actuators have been used successfully to excite th...

Building on previous work showing that far-field jet noise has significant intermittent aspects and the statistical analysis of those intermittent aspects, the present work applies the same analysis techniques to an excited jet. Using an experimental database covering several operating conditions [jet Mach number (Mj = 0.9), nozzle diameter (D = 2....

Localized arc filament plasma actuators (LAFPAs) have been developed and used at The Gas Dynamics and Turbulence Laboratory for the purpose of controlling high-speed and high Reynolds number jets. The ability of LAFPAs for use in both subsonic and supersonic jets has been explored, and experiments to date have shown that these actuators have signif...

Mach wave radiation is one of the better understood sources of jet noise. However, the exact conditions of its onset are difficult to determine and the literature to date typically explores Mach wave radiation well above its onset conditions. In order to determine the conditions for the onset of Mach wave radiation and to explore its behaviour duri...

Mach wave radiation is one of the better understood sources of jet noise. However, the exact conditions of its onset are difficult to determine and the literature to date typically explores Mach wave radiation well above its onset conditions. In order to determine the conditions for the onset of Mach wave radiation and to explore its behavior durin...

Localized arc filament plasma actuators (LAFPAs) have been used at The Gas Dynamics and Turbulence Laboratory (GDTL) for the purpose of controlling the downstream development of and noise radiation from a 1-inch (2.54-cm) nozzle exit diameter jet. The capability of LAFPAs for use in both subsonic and supersonic jets has been explored, and experimen...

Plasma actuators are used to control far-field noise in Mach 1.65 jets from contoured and conical supersonic axisymmetric nozzles (henceforth contoured and conical jets, respectively). The contoured nozzle is designed using the method of characteristics for shock-free jet. The conical nozzle has converging and diverging conical sections with a shar...

An axisymmetric perfectly expanded Mach 1.3 jet, with a Reynolds number based on the nozzle exit diameter (ReD) of 1.1 × 106 and turbulent boundary layer at the nozzle exit, was excited using localized arc filament plasma actuators over a wide range of forcing Strouhal numbers (StDF). Eight actuators distributed azimuthally were used to excite azim...

Recently, heating capabilities have been added to the free jet facility at the Gas Dynamics and Turbulence Laboratory (GDTL) of the Ohio State University using a storage-based off-line electric heater. This addition makes it possible to test the effectiveness of the localized arc filament plasma actuators (LAFPAs) for the purposes of noise mitigati...

Heating capabilities have recently been added to the free jet facility at the Gas Dynamics and Turbulence Laboratory (GDTL) of the Ohio State University using a storage-based off-line electric heater. This addition makes it possible to test the effectiveness of the localized arc filament plasma actuators (LAFPAs) for the purpose of either noise mit...

Recent developments in the heating capabilities of the free jet facility at the Ohio State University's Gas Dynamics and Turbulence Laboratory using a storage-based off-line electric heater have made it possible to test the effectiveness of the localized arc filament plasma actuators (LAFPAs) over a wide range of temperatures. These actuators have...

An active noise control work in jets from contoured and conical supersonic axisymmetric nozzles (henceforth contoured and conical jets, respectively) with plasma actuators is conducted. The Mach 1.65 contoured nozzle is designed by using the method of characteristics for shock-free jet. The Mach 1.65 conical nozzle has converging and diverging coni...

Noise mitigation has been in the forefront of research and development since the advent of jet engines. Supersonic commercial and especially supersonic military aircraft cannot take the advantages offered by large bypass ratio engines due to significant drag penalty and performance degradation. Therefore, other control techniques must be utilized t...

Recent improvements in mass spectrometry (MS) technology led to an explosive amount of MS data collected and shared. A typical liquid chromatography/mass spectrometry (LC/MS) "image" from the instrument used in this study consists of 4 GB of data. To reduce the bit rate required to code the MS data below that of the authors' previous (lossless) alg...

A novel experiment to investigate fluid dynamics in quasi-two-dimensional flows has been built. A soap film is suspended horizontally in an annular channel with a rotating outer boundary, providing mean flow shear, and a vortex array is forced electromagnetically. The experiment will investigate sheared flow stability and the effect of mean flow sh...

Measurements of forced turbulence in the presence of mean flow shear in quasi-two-dimensional flows in a circular Couette cell are underway. Initial observations indicate suppression of the turbulence by the shear, as suggested by observations of transport barriers in geostrophic flows and laboratory fusion plasmas. The apparatus generates flows in...

An experiment to study turbulence in quasi-two-dimensional flows with a controlled mean flow shear has been built. Experiments are underway to investigate the suppression of turbulent transport by sheared flow as seen in geostrophic flows and laboratory fusion plasmas. The apparatus, a circular Couette cell, uses a liquid film of dilute soap soluti...

An experiment is under construction to study turbulence in two-dimensional flows with a controlled mean flow shear. The results will shed light on the suppression of turbulent transport by sheared flow seen in geostrophic flows and laboratory fusion plasmas. The apparatus uses a liquid film of dilute soap solution suspended freely in an annular cha...