Analysis of Exhaust Plume Effects on Sonic Boom for a 59-Degree Wing Body Model

53rd AIAA Aerospace Sciences Meeting

Elmiligui

Cliff

et al. 2015

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

Section: Iiia Experimental Resultssupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

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

53rd AIAA Aerospace Sciences Meeting

Elmiligui

Cliff

et al. 2015

“…Tests were performed in a 4-foot by 4-foot supersonic wind tunnel with pressure measurements taken one diameter away from the nozzle. Study of exhaust nozzle plume effect on sonic boom has progressed from analysis and testing of an isolated nozzle 4,5 , to slot nozzles 6 and engine-wing-body models 7,8 . These studies demonstrated how the nozzle lip shock from an under-expanded nozzle plume could suppress the nozzle boat-tail expansion and reduce the trailing shock.…”

Section: Introductionmentioning

confidence: 99%

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

Zaman

Fagan

et al. 2017

Journal of Aircraft

Self 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.

“…The study of exhaust nozzle plume effect on sonic boom has progressed from analysis and testing of an isolated nozzle to analysis of slot nozzles 6 and engine-wing-body models 7,8 . These studies also demonstrated how the nozzle lip shock from an under-expanded nozzle plume could suppress the nozzle boat-tail expansion and reduce the strength of the trailing shock.…”

Section: Introductionmentioning

confidence: 99%

Cart3D Analysis of Plume and Shock Interaction Effects on Sonic Boom

33rd AIAA Applied Aerodynamics Conference

2015

A plume and shock interaction study was developed to collect data and perform CFD on a configuration where a nozzle plume passed through the shock generated from the wing or tail of a supersonic vehicle. The wing or tail was simulated with a wedge-shaped shock generator. Three configurations were analyzed consisting of two strut mounted wedges and one propulsion pod with an aft deck from a low boom vehicle concept. Research efforts at NASA were intended to enable future supersonic flight over land in the United States. Two of these efforts provided data for regulatory change and enabled design of low boom aircraft. Research has determined that sonic boom is a function of aircraft lift and volume distribution. Through careful tailoring of these variables, the sonic boom of concept vehicles has been reduced. One aspect of vehicle tailoring involved how the aircraft engine exhaust interacted with aft surfaces on a supersonic aircraft, such as the tail and wing trailing edges. In this work, results from Euler CFD simulations are compared to experimental data collected on sub-scale components in a wind tunnel. Three configurations are studied to simulate the nozzle plume interaction with representative wing and tail surfaces. Results demonstrate how the plume and tail shock structure moves with increasing nozzle pressure ratio. The CFD captures the main features of the plume and shock interaction. Differences are observed in the plume and deck shock structure that warrant further research and investigation. Nomenclature