N+2 Low Boom Wind Tunnel Model Design and Validation

Morgenstern, John M.; Buonanno, Michael; Norstrud, Nicole

doi:10.2514/6.2012-3217

Cited by 16 publications

(8 citation statements)

References 8 publications

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“…The most challenging requirement for both N+2 and N+3 is the sonic boom noise level (based on linear theory) should be between 65 to 70 dBPL. NASA contracted Boeing [8,9] and Lockheed Martin [24] to conduct design of N+2 supersonic airplane. Both the designs have good aerodynamic performance, but the sonic boom levels are at about 80-85dBPL [9,10,11], still quite distanced from the targeted 65 to 70 dBPL.…”

Section: Sonic Boommentioning

confidence: 99%

Analysis of a Low Boom Supersonic Flying Wing Preliminary Design

Gan

Zha

2015

53rd AIAA Aerospace Sciences Meeting

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This paper presents the numerical analysis of a low boom supersonic bi-directional flying wing (SBiDir-FW) preliminary design to demonstrate the advantages of the concept. The mission requirements include cruise Mach number of 1.6, cruise altitude around 50kft, payload of 100 passengers, and a range of 4000nm. The gross takeoff weight is about 197kLb. The configuration is a flying wing symmetric about both the longitudinal and span axes. The sweep angle varies from 82 • at the very leading edge to 78 • at the tip. Two designs with same sweep angles and planform shapes are presented by varying airfoil meanline angle distributions to achieve different overpressure signatures and L/D ratios. The first design D82-78.4 achieves an L/D of 8.16, C L of 0.54, and the ground sonic boom noise level of 71.7PLdB. The second design D82-78.8 increases the C L and L/D with C L =0.60 and L/D = 8.54, while keeping a low level of ground sonic boom at 71.9PLdB by cruising at a little higher altitude of 52kft. A typical near field overpressure signature has a strong shock wave followed by a strong expansion in the overall process of expansion. The strong shockexpansion is mostly canceled out by themselves during the process of the wave propagation to ground. The designs indicate that the overpressure signature and aerodynamic efficiency are very sensitive and controllable by the variation of meanline angle distributions of the airfoils. This is an important relationship between the geometry parameters and the sonic boom/aerodynamic efficiency so that a design optimization strategy can be developed. All the designs with varied meanline angle distributions in this paper are conducted manually. With the encouraging results achieved so far, it is believed that the NASA's N+2 and N+3 goal to have ground sonic boom below 70PLdB for a supersonic civil transport is close to reach if a systematic design optimization is conducted.

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Section: Sonic Boommentioning

confidence: 99%

Analysis of a Low Boom Supersonic Flying Wing Preliminary Design

Gan

Zha

2015

53rd AIAA Aerospace Sciences Meeting

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“…Previous work by NASA, such as the Shaped Sonic Boom Demonstrator 1 (SSBD), the Quiet Spike 2 , and the NASA N+2 vehicle studies 3,4 , studied how the sonic boom signatures can be reduced with aircraft shaping. Further work was desired to understand the contribution of the nozzle exhaust plume to the sonic boom signature from the aft portion of a supersonic vehicle.…”

Section: Introductionmentioning

confidence: 99%

Plume and Shock Interaction Effects on Sonic Boom in the 1-foot by 1-foot Supersonic Wind Tunnel

Castner

Elmiligui

Cliff

et al. 2015

53rd AIAA Aerospace Sciences Meeting

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The desire to reduce or eliminate the operational restrictions of supersonic aircraft over populated areas has led to extensive research at NASA. Restrictions are due to the disturbance of the sonic boom, caused by the coalescence of shock waves formed by the aircraft. A study has been performed focused on reducing the magnitude of the sonic boom N-wave generated by airplane components with a focus on shock waves caused by the exhaust nozzle plume. Testing was completed in the 1-foot by 1-foot supersonic wind tunnel to study the effects of an exhaust nozzle plume and shock wave interaction. The plume and shock interaction study was developed to collect data for computational fluid dynamics (CFD) validation of a nozzle plume passing through the shock generated from the wing or tail of a supersonic vehicle. The wing or tail was simulated with a wedgeshaped shock generator. This test entry was the first of two phases to collect schlieren images and off-body static pressure profiles. Three wedge configurations were tested consisting of strut-mounted wedges of 2.5degrees and 5-degrees. Three propulsion configurations were tested simulating the propulsion pod and aft deck from a low boom vehicle concept, which also provided a trailing edge shock and plume interaction. Findings include how the interaction of the jet plume caused a thickening of the shock generated by the wedge (or aft deck) and demonstrate how the shock location moved with increasing nozzle pressure ratio. Nomenclature D= test nozzle outer diameter, inches NPR = nozzle pressure ratio, Pt / P∞ P = local static pressure, psia Pt = total pressure in nozzle, psia P∞ = free stream static pressure, psia ΔP/P = normalized static pressure, (P -P∞)/ P∞ x = axial distance from jet simulator nozzle exit plane, inches y = vertical distance from nozzle centerline, inches

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“…REMENDOUS advances in research related to low-boom supersonic configurations have been made in the past few years. References after 2010 include validation of CFD methods for computing off-body pressure distributions 1-10 by using novel wind tunnel measurement techniques, [11][12][13][14][15][16][17] new methods for design of low-boom supersonic configurations, [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] and development of low-boom supersonic concepts that include nacelles and some mission constraints. [28][29][30][31][32][33][34][35][36][37][38][39][40][41] One of the remaining technical challenges in development of low-boom supersonic concepts is the difficulty of knowing when to continue work on the current configuration layout for a trimmed low-boom design and when to move on with a more promising concept.…”

Section: Introductionmentioning

confidence: 99%

Feasibility of Supersonic Aircraft Concepts for Low-Boom and Flight Trim Constraints

2015

33rd AIAA Applied Aerodynamics Conference

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This paper documents a process for analyzing whether a particular supersonic aircraft configuration layout and a given cruise condition are feasible to achieve a trimmed lowboom design. This process was motivated by the need to know whether a particular configuration at a given cruise condition could be reshaped to satisfy both low-boom and flight trim constraints. Without such a process, much effort could be wasted on shaping a configuration layout at a cruise condition that could never satisfy both low-boom and flight trim constraints simultaneously. The process helps to exclude infeasible configuration layouts with minimum effort and allows a designer to develop trimmed low-boom concepts more effectively. A notional low-boom supersonic demonstrator concept is used to illustrate the analysis/design process.

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N+2 Low Boom Wind Tunnel Model Design and Validation

Cited by 16 publications

References 8 publications

Analysis of a Low Boom Supersonic Flying Wing Preliminary Design

Analysis of a Low Boom Supersonic Flying Wing Preliminary Design

Plume and Shock Interaction Effects on Sonic Boom in the 1-foot by 1-foot Supersonic Wind Tunnel

Feasibility of Supersonic Aircraft Concepts for Low-Boom and Flight Trim Constraints

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