Quiet Spike Prototype Aerodynamic Characteristics from Flight Test

Freund, Donald; Howe, D.; Simmons, Frank; Schuster, L. S.

doi:10.2514/6.2008-125

Cited by 9 publications

(5 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Post-test analysis has been performed to analyze differences between test data and CFD predictions. The purpose of this report is (1) to present the wind tunnel test results, (2) to make comparisons to the pre-test CFD results, and (3) to make comparisons to post-test CFD analysis. The present work studies the effects of the nozzle exhaust plume and the contribution to the right hand portion of the sonic boom N-wave.…”

Section: Introductionmentioning

confidence: 99%

Exhaust Nozzle Plume Effects on Sonic Boom Test Results for Isolated Nozzles

Castner

2010

28th AIAA Applied Aerodynamics Conference

View full text Add to dashboard Cite

Reducing or eliminating the operational restrictions of supersonic aircraft over populated areas has led to extensive research at NASA. Restrictions were due to the disturbance of the sonic boom, caused by the coalescence of shock waves formed off the aircraft. Recent work has been performed to reduce the magnitude of the sonic boom N-wave generated by airplane components with focus on shock waves caused by the exhaust nozzle plume. Previous Computational Fluid Dynamics (CFD) analysis showed how the shock wave formed at the nozzle lip interacts with the nozzle boat-tail expansion wave. An experiment was conducted in the 1-by 1-ft Supersonic Wind Tunnel at the NASA Glenn Research Center to validate the computational study. Results demonstrated how the nozzle lip shock moved with increasing nozzle pressure ratio (NPR) and reduced the nozzle boat-tail expansion, causing a favorable change in the observed pressure signature. Experimental results were presented for comparison to the CFD results. The strong nozzle lip shock at high values of NPR intersected the nozzle boat-tail expansion and suppressed the expansion wave. Based on these results, it may be feasible to reduce the boat-tail expansion for a future supersonic aircraft with under-expanded nozzle exhaust flow by modifying nozzle pressure or nozzle divergent section geometry. Nomenclatureβ nozzle boat tail angle, ° D test nozzle diameter, in. NPR nozzle pressure ratio = P t /P ∞ P local static pressure, psia P t total pressure in nozzle, psia P ∞ free stream static pressure, psia ΔP/P (P -P ∞ )/P ∞ t time, sec x axial distance from jet simulator nosecone tip, in. y distance from nozzle centerline, in. IntroductionNASA has been conducting extensive research programs to reduce the sonic boom signature caused by supersonic flight speeds. Current aircraft flight restrictions, allowing supersonic flight over water only, are due to the disturbance caused by the sonic boom. The sonic boom is generated by coalescing shock waves formed by aircraft components, which generate an N-wave. A sample N-wave sonic boom signature is shown in Figure 1. The N-wave consists of a rise in pressure versus time as the aircraft 'bowwave' passes over an observer, followed by a reduction in pressure, and finally a return to atmospheric Complementary work is desired to reduce the sonic boom signature in the aft portion of the sonic boom N-wave, which in turn would decrease the peak-to-peak magnitude and result in a reduced sonic boom. This can be accomplished by aircraft shaping, and through study of how aft components, such as the tail, nacelles, and nozzles contribute to the right hand portion of the sonic boom N-wave.Previous work on exhaust nozzle contribution to sonic boom included a report by Putnam and Capone (Ref. 3), and another by Barger and Melson (Ref. 4). In the work by Putnam and Capone, nozzles were tested from a fully expanded Mach 1.7 nozzle to a fully expanded Mach 2.9 nozzle. Their study was conducted in a wind tunnel, where near-field pressure measurements we...

show abstract

Section: Introductionmentioning

confidence: 99%

Exhaust Nozzle Plume Effects on Sonic Boom Test Results for Isolated Nozzles

Castner

2010

28th AIAA Applied Aerodynamics Conference

View full text Add to dashboard Cite

show abstract

“…Recent studies to develop aircraft with acceptable sonic boom noise include programs such as the Quiet Spike 1 and the Shaped Sonic Boom Demonstrator (SSBD) 2 that achieved reduced intensity of the forward portion of the pressure signature. Research was also done to reduce the contribution from aft components including the nozzle exhaust.…”

Section: Introductionmentioning

confidence: 99%

Wedge Shock and Nozzle Exhaust Plume Interaction in a Supersonic Jet Flow

Castner

Zaman

Fagan

et al. 2014

52nd Aerospace Sciences Meeting

View full text Add to dashboard Cite

Fundamental research for sonic boom reduction is needed to quantify the interaction of shock waves generated from the aircraft wing or tail surfaces with the nozzle exhaust plume. Aft body shock waves that interact with the exhaust plume contribute to the near-field pressure signature of a vehicle. The plume and shock interaction was studied using computational fluid dynamics and compared with experimental data from a coaxial convergent-divergent nozzle flow in an open jet facility. A simple diamond-shaped wedge was used to generate the shock in the outer flow to study its impact on the inner jet flow. Results show that the compression from the wedge deflects the nozzle plume and shocks form on the opposite plume boundary. The sonic boom pressure signature of the nozzle exhaust plume was modified by the presence of the wedge. Both the experimental results and computational predictions show changes in plume deflection.

show abstract

“…23 The Quiet Spike was a joint program with Gulfstream Aerospace and NASA Dryden Flight Research Center in which the concept of an extendable nose spike for sonic boom minimization was investigated. 24 In supersonic flight tests with a spike mounted on F-15B aircraft, the typical N-shaped pressure wave was reduced to a series of small shocks. However, this design is intended for a small civil transport carrying 8-14 passengers.…”

Section: Introductionmentioning

confidence: 99%

Supersonic Bi-Directional Flying Wing, Part II: Conceptual Design of A High Speed Civil Transport

Espinal

Lee

Sposato

et al. 2010

48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

View full text Add to dashboard Cite

This report designs a supersonic passenger transport using a novel supersonic bi-directional (SBiDir) flying wing (FW) concept that achieves low sonic boom, low wave drag, and high subsonic performance. For supersonic flight, the planform is designed to achieve optimum aspect ratio, span, and sweep angle to minimize wave drag. For subsonic mode, the airplane will be rotated 90° so that the side of the airplane during supersonic flight becomes the front of the airplane. The sweep angle of the LE at subsonic mode is significantly reduced and the aspect ratio is considerably increased by (L/b) 2 where L is the airplane length, and b is the span. This will allow the airplane to have high subsonic performance with short takeoff and landing distance and low stall velocity due to low wing loading. The airfoil suggested is symmetric about the 50% chord location with both sharp leading edge (LE) and sharp trailing edge (TE). The whole 3-D configuration is symmetric about the longitudinal and lateral planes. As the demonstration of concept, the AOA=0° is selected as the low boom design point. A flat pressure surface of the airfoil used as the isentropic compression surface is employed to cancel the downward shock and sonic boom. Diminished take off noise will be achieved by attaining a low stall velocity and mounting the engines on the upper part of the airplane in order to shield the jet noise. A novel LE radial air injection to delay LE stall is suggested to avoid using the conventional LE slats system, which is heavy and complicated. The calculation shows that the 90° rotation can be done in 3 to 5 seconds with a very small centrifugal acceleration. The rotation transitional time will be short enough not to lose lift and the acceleration is so small that no passenger discomfort will be created. This design has the mission requirements of a cruise f Mach 1.6, a range of 2,000 nautical miles, a payload of 70 passengers and a takeoff field length of 2,471 feet. 1 The sonic boom overpressure propagated to ground was found to be 0.3 psf at AOA=0°.

show abstract

Quiet Spike Prototype Aerodynamic Characteristics from Flight Test

Cited by 9 publications

References 5 publications

Exhaust Nozzle Plume Effects on Sonic Boom Test Results for Isolated Nozzles

Exhaust Nozzle Plume Effects on Sonic Boom Test Results for Isolated Nozzles

Wedge Shock and Nozzle Exhaust Plume Interaction in a Supersonic Jet Flow

Supersonic Bi-Directional Flying Wing, Part II: Conceptual Design of A High Speed Civil Transport

Contact Info

Product

Resources

About