Since the 1940s, the study of supersonic and hypersonic flow has posed significant challenges due to the variable aerodynamic characteristics and alterations in air properties at such high speeds. Hypervelocity wind tunnels have been instrumental in addressing gaps in this field, yet no existing facility can fully replicate true hypersonic conditions. The primary obstacle lies in sustaining the high enthalpies and targeted total conditions necessary for authentic supersonic and hypersonic environments. This paper focuses on the development of a mixing manifold section for a high enthalpy, long-duration hypervelocity wind tunnel designed to provide clean airflow and accurately replicate true hypervelocity conditions for extended run times. Research was done over a wide range of both computational designs and their experimental counterparts to determine the most effective design that replicates the conditions needed for the full wind tunnel.

A supersonic wind tunnel, with a 20" x 20'" test section cross sectional area, was designed and constructed at the Techsburg Wind Tunnel Facility in order to determine the lift and drag on irregularly shaped fragments in supersonic flow. Prior to beginning the wind tunnel design process, a blowdown analysis model was created in order to determine the influence of a number of parameters on tunnel run time and test gas properties throughout the tunnel circuit. The design of the settling chamber, test section, supersonic nozzles, diffuser, and exhaust are presented in this thesis. Diffuser performance has a large influence on wind tunnel efficiency and run time. Therefore, significant efforts should be taken in order to attain the highest possible pressure recovery within the diffuser. The design of wind tunnel components, as well as their stress analysis, was conducted using SolidWorks. The control valve and silencer were sized and selected for the expected tunnel operating conditions. Since the control valve tends to encompass a significant portion of the overall tunnel cost, care must be taken to ensure it has a large enough flow capacity to produce the desired test conditions. Also, attempts must be made to accurately predict the total pressure loss through the silencer, since this loss can have a large impact on the total pressure ratio necessary to produce the design Mach number. Upon completion of the design process, the supersonic wind tunnel was assembled, and shakedown testing was conducted. During shakedown testing it was determined that the wind tunnel was capable of producing Mach 2 flow in the test section. Following shakedown testing, a flow survey was conducted in order to ensure uniform Mach number flow exists throughout the region occupied by the fragments. Based on the flow survey it was determined that within the middle 60% of the test section, the average Mach number was 1.950 and varied by only 0.56% within this region. Two irregularly shaped fragments were tested at Mach 2 flow, over an effective 360° pitch sweep, with wind tunnel runs performed every 10 degrees. Based on the measured force data for both fragments, the lift appeared to follow a sinusoidal curve, with minimum values at 0, 90, and 180° balance pitch angle, and maximum values occurring around 45 and 135° pitch angle. The drag force was observed to follow a gradual curve with minimum values at 0 and 180° balance pitch angle, as expected since the fragment presented area is generally least in this orientation. The maximum drag was found to occur at a balance pitch angle of 90°, once again as expected since the fragment presented area is generally greatest at this angle. It was also observed that the fragment drag tended to be greater for a fragment orientation which places the concave side of the fragment into the direction of the flow. / Master of Science

As a part of the revitalization of the supersonic wind tunnel maintained by the Aerospace Engineering Department of Mississippi State University, a new data acquisition and control system became incumbent. Previous data acquisition and control systems used in the operation of the supersonic wind tunnel made use of now outdated hardware and functioned with two central processing units; one processor was used for recording system response, while the other monitored and controlled the tunnel. A new system is required to provide adequate rapid real-time control, along with rapid acquisition of raw tunnel feedback or response data and tunnel pressure data all implemented on one computer processor. The data acquisition and control program that was developed provides synchronized data storage and control output commands, while providing the operator with all essential information and checklists required for running the tunnel. The program is a general user interface developed from previously implemented data acquisition and control systems to perform all predetermined tasks while minimizing operator front panel inputs. When the supersonic wind tunnel repair is completed, the compiled data acquisition and control program will be implemented in the operation of the tunnel. This paper details the development of the supersonic wind tunnel data acquisition and control system employed in the revitalization project. Without the information on the details of the data acquisition and control program, any future editing of the control system source codes will be a laborious task.

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