Effects of Convoluted Divergent Flap Contouring on the Performance of a Fixed-Geometry Nonaxisymmetric Exhaust Nozzle PDF Download
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Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
ISBN: 9781723949630
Category : Science
Languages : en
Pages : 76
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Book Description
An investigation was conducted in the model preparation area of the Langley 16-Foot Transonic Tunnel to determine the effects of convoluted divergent-flap contouring on the internal performance of a fixed-geometry, nonaxisymmetric, convergent-divergent exhaust nozzle. Testing was conducted at static conditions using a sub-scale nozzle model with one baseline and four convoluted configurations. All tests were conducted with no external flow at nozzle pressure ratios from 1.25 to approximately 9.50. Results indicate that baseline nozzle performance was dominated by unstable, shock-induced, boundary-layer separation at overexpanded conditions. Convoluted configurations were found to significantly reduce, and in some cases totally alleviate separation at overexpanded conditions. This result was attributed to the ability of convoluted contouring to energize and improve the condition of the nozzle boundary layer. Separation alleviation offers potential for installed nozzle aeropropulsive (thrust-minus-drag) performance benefits by reducing drag at forward flight speeds, even though this may reduce nozzle thrust ratio as much as 6.4% at off-design conditions. At on-design conditions, nozzle thrust ratio for the convoluted configurations ranged from 1% to 2.9% below the baseline configuration; this was a result of increased skin friction and oblique shock losses inside the nozzle.Asbury, Scott C. and Hunter, Craig A.Langley Research CenterCONVERGENT-DIVERGENT NOZZLES; BOUNDARY LAYER SEPARATION; WIND TUNNEL NOZZLES; WIND TUNNEL TESTS; NOZZLE FLOW; OBLIQUE SHOCK WAVES; FLOW VISUALIZATION; NOZZLE GEOMETRY; AERODYNAMIC DRAG; SKIN FRICTION; PRESSURE RATIO; FLAPS (CONTROL SURFACES)
Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
ISBN: 9781723949630
Category : Science
Languages : en
Pages : 76
Get Book Here
Book Description
An investigation was conducted in the model preparation area of the Langley 16-Foot Transonic Tunnel to determine the effects of convoluted divergent-flap contouring on the internal performance of a fixed-geometry, nonaxisymmetric, convergent-divergent exhaust nozzle. Testing was conducted at static conditions using a sub-scale nozzle model with one baseline and four convoluted configurations. All tests were conducted with no external flow at nozzle pressure ratios from 1.25 to approximately 9.50. Results indicate that baseline nozzle performance was dominated by unstable, shock-induced, boundary-layer separation at overexpanded conditions. Convoluted configurations were found to significantly reduce, and in some cases totally alleviate separation at overexpanded conditions. This result was attributed to the ability of convoluted contouring to energize and improve the condition of the nozzle boundary layer. Separation alleviation offers potential for installed nozzle aeropropulsive (thrust-minus-drag) performance benefits by reducing drag at forward flight speeds, even though this may reduce nozzle thrust ratio as much as 6.4% at off-design conditions. At on-design conditions, nozzle thrust ratio for the convoluted configurations ranged from 1% to 2.9% below the baseline configuration; this was a result of increased skin friction and oblique shock losses inside the nozzle.Asbury, Scott C. and Hunter, Craig A.Langley Research CenterCONVERGENT-DIVERGENT NOZZLES; BOUNDARY LAYER SEPARATION; WIND TUNNEL NOZZLES; WIND TUNNEL TESTS; NOZZLE FLOW; OBLIQUE SHOCK WAVES; FLOW VISUALIZATION; NOZZLE GEOMETRY; AERODYNAMIC DRAG; SKIN FRICTION; PRESSURE RATIO; FLAPS (CONTROL SURFACES)
