The Experts below are selected from a list of 72 Experts worldwide ranked by ideXlab platform

Mark P Wernet - One of the best experts on this subject based on the ideXlab platform.

  • an experimental study of the oscillatory flow structure of tone producing supersonic impinging jets
    Journal of Fluid Mechanics, 2005
    Co-Authors: Brenda Henderson, James Bridges, Mark P Wernet
    Abstract:

    An experimental investigation into the structure of a supersonic jet impinging on a large plate is presented. Digital particle image velocimetry (DPIV), Shadowgraph Photography and acoustic measurements are used to understand the relationship between the unsteady jet structure and the production of tones for nozzle-to-plate spacings between 1 and 5 nozzle exit diameters at a nozzle–pressure ratio equal to 4. Results indicate that the instability of the jet depends on the location of the plate in the shock cell structure of the corresponding free jet and the strength of the standoff shock wave, rather than on the occurrence of recirculation zones in the impingement region. Phase-locked studies show streamwise displacements of the stand-off shock wave, a moving recirculation zone in the subsonic flow in front of the plate, and significant oscillations of both the compression and expansion regions in the peripheral supersonic flow when tones are produced. Sound is shown to be generated by periodic pulsing of the wall jet boundary resulting from periodic motion of the flow in the impingement and near-wall regions of the flow.

Juan G Santiago - One of the best experts on this subject based on the ideXlab platform.

  • mixing of a sonic transverse jet injected into a supersonic flow
    AIAA Journal, 2000
    Co-Authors: Wayne M Vanlerberghe, Juan G Santiago, Craig J Dutton, Robert P Lucht
    Abstract:

    The mixing characteristics of an underexpanded sonic jet injected into a Mach 1.6 crosse ow are studied experimentally. Shadowgraph Photography and planar laser-induced e uorescence from acetone are used to obtain temporally resolved e owe eld visualizations of a side viewof the barrel shock region, a side view of the downstream plume, and an end view cross section of the plume. Instantaneous images, mean and standard deviation images, and image-intensity probability density functions (PDFs) are used to study the mixing produced by large-scale turbulent structures. PDFs show that time-averaged mixture fraction measurements greatly overestimate the actual level of instantaneous mixing in the e owe eld. Comparisons of the instantaneous images and PDFs show the role of large-scale rolling structures and jetlike plumes in transporting coherent packets of e uid across the threedimensional shear layer formed between the jet and crosse ow. Signie cant instantaneous mixing in this e owe eld occursin the wakeregiondownstream ofthebarrel shock region and below thejetcenterline.Thecounter-rotating streamwisevortex pairin thejetplumeplaysan importantrole in the scalarmixing processes becauseit transports jet e uid down toward the wake and entrains crosse ow e uid from below up into the jet.

  • velocity measurements of a jet injected into a supersonic crossflow
    Journal of Propulsion and Power, 1997
    Co-Authors: Juan G Santiago, Craig J Dutton
    Abstract:

    This paper presents a quantitative, experimental study of a single, sonic, underexpanded, transverse, round jet injected into a Mach 1.6 crosse ow. This investigation is applicable to studies of supersonic combustors, thrust vector control of rocket nozzles, the cooling of nozzle walls, and jet reaction force prediction. Schlieren/Shadowgraph Photography and two-component, frequency preshifted laser Doppler velocimetry are used to visualize the e ow and to measure three mean velocity components, e ve of the six kinematic Reynolds stresses, and turbulent kinetic energy at over 4000 locations throughout the e owe eld. The study focuses on the transverse, midline plane and on two crosse ow planes. These measurements are used to study the size and orientation of the recirculation regions upstream and downstream of the jet; the structure and strength of the bow shock, barrel shock, and Mach disk; the structure, strength, and development of the kidney-shaped, counter-rotating vortex pair; the growth of the annular shear layer between the jet plume and the crosse ow; and the growth of the boundary layer beneath the jet. In addition, the present study provides validation data for analytical and numerical predictions of the transverse jet e owe eld.

Brenda Henderson - One of the best experts on this subject based on the ideXlab platform.

  • an experimental study of the oscillatory flow structure of tone producing supersonic impinging jets
    Journal of Fluid Mechanics, 2005
    Co-Authors: Brenda Henderson, James Bridges, Mark P Wernet
    Abstract:

    An experimental investigation into the structure of a supersonic jet impinging on a large plate is presented. Digital particle image velocimetry (DPIV), Shadowgraph Photography and acoustic measurements are used to understand the relationship between the unsteady jet structure and the production of tones for nozzle-to-plate spacings between 1 and 5 nozzle exit diameters at a nozzle–pressure ratio equal to 4. Results indicate that the instability of the jet depends on the location of the plate in the shock cell structure of the corresponding free jet and the strength of the standoff shock wave, rather than on the occurrence of recirculation zones in the impingement region. Phase-locked studies show streamwise displacements of the stand-off shock wave, a moving recirculation zone in the subsonic flow in front of the plate, and significant oscillations of both the compression and expansion regions in the peripheral supersonic flow when tones are produced. Sound is shown to be generated by periodic pulsing of the wall jet boundary resulting from periodic motion of the flow in the impingement and near-wall regions of the flow.

Amir Khalid - One of the best experts on this subject based on the ideXlab platform.

  • Dynamic Behavior of Rapeseed Oil Spray in Diesel Engine
    2020
    Co-Authors: Azwan Sapit, Mohd Faisal Hushim, Azahari Razali, M Jaat, Akmal Nizam, Amir Khalid
    Abstract:

    Abstract. Fuel-air mixing is important process in diesel combustion which significantly affects the combustion and emission of diesel engine. Due to the nature of biomass fuel that has high viscosity and high distillation temperature, the condition and furthermore the improvement of atomization process is very important. This study investigates the atomization characteristics and droplet dynamic behaviors of diesel engine spray fueled by rapeseed oil (RO). Optical observation of RO spray was carried out using Shadowgraph Photography technique. Single nano-spark Photography technique was used to study the characteristics of the rapeseed oil spray while dual nano-spark Shadowgraph technique was used to study the spray droplet behavior. Using in-house image processing algorithm, the images were processed and the boundary condition of RO spray also was studied. The results show that RO has very poor atomization due to the high viscosity nature of the fuel. This is in agreement with the results from spray droplet dynamic behavior studies that shows due to the high viscosity, the droplets are large in size and travel downward, with very little influence of entrainment effect due to its large kinematic energy

  • Study on Spray Characteristics and Spray Droplets Dynamic Behavior of Diesel Engine Fueled by Rapeseed Oil
    'EDP Sciences', 2014
    Co-Authors: Azwan Sapit, Mohd. Azahari Razali, Mohd Faisal Hushim, Mas Fawzi Mohd Ali, Amir Khalid, Bukhari Manshoor
    Abstract:

    Fuel-air mixing is important process in diesel combustion. It directly affects the combustion and emission of diesel engine. Biomass fuel needs great help to atomize because the fuel has high viscosity and high distillation temperature. This study investigates the atomization characteristics and droplet dynamic behaviors of diesel engine spray fueled by rapeseed oil (RO). Optical observation of RO spray was carried out using Shadowgraph Photography technique. Single nano-spark Photography technique was used to study the characteristics of the rapeseed oil spray while dual nano-spark Shadowgraph technique was used to study the spray droplet behavior. The results show that RO has very poor atomization due to the high viscosity nature of the fuel. This is in agreement with the results from spray droplet dynamic behavior studies that shows due to the high viscosity, the droplets are large in size and travel downward, with very little influence of entrainment effect due to its large kinematic energy

Craig J Dutton - One of the best experts on this subject based on the ideXlab platform.

  • mixing of a sonic transverse jet injected into a supersonic flow
    AIAA Journal, 2000
    Co-Authors: Wayne M Vanlerberghe, Juan G Santiago, Craig J Dutton, Robert P Lucht
    Abstract:

    The mixing characteristics of an underexpanded sonic jet injected into a Mach 1.6 crosse ow are studied experimentally. Shadowgraph Photography and planar laser-induced e uorescence from acetone are used to obtain temporally resolved e owe eld visualizations of a side viewof the barrel shock region, a side view of the downstream plume, and an end view cross section of the plume. Instantaneous images, mean and standard deviation images, and image-intensity probability density functions (PDFs) are used to study the mixing produced by large-scale turbulent structures. PDFs show that time-averaged mixture fraction measurements greatly overestimate the actual level of instantaneous mixing in the e owe eld. Comparisons of the instantaneous images and PDFs show the role of large-scale rolling structures and jetlike plumes in transporting coherent packets of e uid across the threedimensional shear layer formed between the jet and crosse ow. Signie cant instantaneous mixing in this e owe eld occursin the wakeregiondownstream ofthebarrel shock region and below thejetcenterline.Thecounter-rotating streamwisevortex pairin thejetplumeplaysan importantrole in the scalarmixing processes becauseit transports jet e uid down toward the wake and entrains crosse ow e uid from below up into the jet.

  • velocity measurements of a jet injected into a supersonic crossflow
    Journal of Propulsion and Power, 1997
    Co-Authors: Juan G Santiago, Craig J Dutton
    Abstract:

    This paper presents a quantitative, experimental study of a single, sonic, underexpanded, transverse, round jet injected into a Mach 1.6 crosse ow. This investigation is applicable to studies of supersonic combustors, thrust vector control of rocket nozzles, the cooling of nozzle walls, and jet reaction force prediction. Schlieren/Shadowgraph Photography and two-component, frequency preshifted laser Doppler velocimetry are used to visualize the e ow and to measure three mean velocity components, e ve of the six kinematic Reynolds stresses, and turbulent kinetic energy at over 4000 locations throughout the e owe eld. The study focuses on the transverse, midline plane and on two crosse ow planes. These measurements are used to study the size and orientation of the recirculation regions upstream and downstream of the jet; the structure and strength of the bow shock, barrel shock, and Mach disk; the structure, strength, and development of the kidney-shaped, counter-rotating vortex pair; the growth of the annular shear layer between the jet plume and the crosse ow; and the growth of the boundary layer beneath the jet. In addition, the present study provides validation data for analytical and numerical predictions of the transverse jet e owe eld.