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Characterization of Supersonic Flow Around a Hemispherical Model

Title: Characterization of Supersonic Flow Around a Hemispherical Model.
Name(s): Carnrike, Daniel Andrew, author
Kumar, Rajan, (Professor of Mechanical Engineering), professor directing thesis
Cattafesta, Louis N., committee member
Collins, E. (Emmanuel), committee member
Florida State University, degree granting institution
College of Engineering, degree granting college
Department of Mechanical Engineering, degree granting department
Type of Resource: text
Genre: Text
Master Thesis
Issuance: monographic
Date Issued: 2017
Publisher: Florida State University
Place of Publication: Tallahassee, Florida
Physical Form: computer
online resource
Extent: 1 online resource (75 pages)
Language(s): English
Abstract/Description: Propagation of laser beams through complex flow field caused by radar system housing has been an important topic for many years dating back to the mid 1960s. Applications for radar systems range from missile defense, directed energy to target designation and tracking. Complications are introduced when laser systems are no longer stationed on the ground, but instead mounted on airplanes traveling at subsonic, transonic and supersonic speeds. Housing systems have been developed with a variety of different designs with some designs more optimal for decreasing laser aberrations than others. The work presented strives to characterize flow around a hemispherical configuration (D = 10.16 cm) for a turret housing system in the supersonic flow regime. Multiple diagnostic tests were conducted at the Florida Center for Advanced Aero-Propulsion in the Polysonic Wind Tunnel Facility. Shadowgraph visualization, surface oil flow visualization, static pressure and unsteady pressure data characterized the complicated supersonic flow field around a hemisphere. Observations were conducted at Mach 2 while Reynolds number changed, ReD = 1.8 ∗ 106 and ReD = 3.6 ∗ 106. Complex shock system consisting of a lambda shock and detached bow shock were observed upstream of the hemisphere center through shadowgraph images. While a shock-let system was developed between the foot of the lambda shock and the detached bow shock from the unsteady boundary layer shockwave interaction. Surface oil flow visualization accented the development of an axisymmetric horseshoe vortex and the presence of a secondary shock location upstream of the hemisphere. A centerline static pressure distribution quantified the visualization techniques. A stagnation point of 30◦ was observed on the body for both ReD case. While, flow separation occurred at slightly different locations on the hemisphere; flow separated at 103◦ for ReD = 1.8∗106 and 107◦ for the ReD = 3.6 ∗ 106. Location of flow separation is further strengthen by the unsteady pressure data as the energy fluctuations are less on the separation line for the different Re cases. The study found that flow structures for different ReD cases were similar, except for the strength of the different flow features; as the flow feature magnitudes were greater for ReD = 3.6 ∗ 106 case. Also observed from the unsteady pressure measurement data, the wake structure behind the hemisphere were different in nature as the wake structure for the ReD = 1.8 ∗ 106 case was larger than the ReD = 3.6 ∗ 106 case. Planar Particle Image Velocimetry was conducted in the Pilot Wind Tunnel Facility at the Florida Center for Advanced Aero-Propulsion on a dynamically similar flow (M = 2,ReD = 1.8∗106). Planar PIV for different Z/D planes were also measured on a D = 19.05 mm hemisphere, which highlighted the presence of an expansion fan at the apex of the hemisphere with decreasing effects on the external flow field as flow moved further away from the centerline of the hemisphere. The results presented in this work characterized supersonic flow around a hemisphere and has laid the groundwork for the development of active or passive flow control techniques in order to minimize flow structures, which ultimately lead to less aero-optical aberrations.
Identifier: FSU_FALL2017_Carnrike_fsu_0071N_14262 (IID)
Submitted Note: A Thesis submitted to the Department of Mechanical Engineering in partial fulfillment of the requirements for the degree of Master of Science.
Degree Awarded: Fall Semester 2017.
Date of Defense: November 9, 2017.
Keywords: Characterization, Flow, Hemisphere, Supersonic
Bibliography Note: Includes bibliographical references.
Advisory Committee: Rajan Kumar, Professor Directing Thesis; Louis N. Cattafesta, III, Committee Member; Emmanuel G. Collins, Committee Member.
Subject(s): Mechanical engineering
Aerospace engineering
Persistent Link to This Record:
Host Institution: FSU

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Carnrike, D. A. (2017). Characterization of Supersonic Flow Around a Hemispherical Model. Retrieved from