Hybrid CART3D/OVERFLOW Near-Field Analysis of a Low Boom Configuration with Wind Tunnel Comparisons (Invited)

Howe, D.

doi:10.2514/6.2011-3336

Cited by 11 publications

(3 citation statements)

References 11 publications

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“…Further details are available for the Participant F submission to SBPW2 [12]. Participant G used CartOVER [48], which combines Cart3D near the body with an OVERFLOW collar grid.…”

Section: Participantsmentioning

confidence: 99%

Near Field Summary and Statistical Analysis of the Second AIAA Sonic Boom Prediction Workshop

Park

Nemec

2017

35th AIAA Applied Aerodynamics Conference

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A summary is provided for the Second AIAA Sonic Boom Workshop held 8-9 January 2017 in conjunction with AIAA SciTech 2017. The workshop used three required models of increasing complexity: an axisymmetric body, a wing body, and a complete configuration with flow-through nacelle. An optional complete configuration with propulsion boundary conditions is also provided. These models are designed with similar nearfield signatures to isolate geometry and shock/expansion interaction effects. Eleven international participant groups submitted nearfield signatures with forces, pitching moment, and iterative convergence norms. Statistics and grid convergence of these nearfield signatures are presented. These submissions are propagated to the ground, and noise levels are computed. This allows the grid convergence and the statistical distribution of a noise level to be computed. While progress is documented since the first workshop, improvement to the analysis methods for a possible subsequent workshop are provided. The complete configuration with flow-through nacelle showed the most dramatic improvement between the two workshops. The current workshop cases are more relevant to vehicles with lower loudness and have the potential for lower annoyance than the first workshop cases. The models for this workshop with quieter ground noise levels than the first workshop exposed weaknesses in analysis, particularly in convective discretization.

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“…Further details are available for the Participant F submission to SBPW2 [12]. Participant G used CartOVER [48], which combines Cart3D near the body with an OVERFLOW collar grid.…”

Section: Participantsmentioning

confidence: 99%

Near Field Summary and Statistical Analysis of the Second AIAA Sonic Boom Prediction Workshop

Park

Nemec

2017

35th AIAA Applied Aerodynamics Conference

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“…One is by providing dense meshes within the sonic boom pressure disturbance along with mesh rotation techniques 5 to align the mesh with the Mach angle, or alternatively by using solution-adaptive techniques. [6][7][8][9][10][11][12][13][14][15] Also, structured overset grid methods, 16 or hybrid methods [16][17][18][19][20] that utilize unstructured flow solutions in the near-field and a structured grid solutions in the far-field can also provide accurate on-track calculations. Grid generation tools that allow stretching of the mesh in addition to alignment to the Mach angle [21][22][23] offer smaller meshes that maintain density in the axial direction and reduce the effects of dissipation along characteristic lines.…”

Section: Courtesy Of the Boeing Companymentioning

confidence: 99%

Experimental and Computational Sonic Boom Assessment of Boeing N+2 Low Boom Models

Durston

Elmiligui

Cliff

et al. 2014

32nd AIAA Applied Aerodynamics Conference

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Near-field pressure signatures were measured and computational predictions made for several sonic boom models representing Boeing's Quiet Experimental Validation Concept (QEVC) supersonic transport, as well as for three axisymmetric calibration models. The concept was designed under a NASA Research Announcement (NRA) contract to address environmental and performance goals, specifically for low sonic boom loudness levels and high cruise efficiency, for an aircraft anticipated to enter service in the 2020-timeframe. Wind tunnel tests were conducted on the aircraft and calibration models during Phases I and II of the NRA contract from 2011 to 2013 in the NASA Ames 9-by 7-Foot and NASA Glenn 8-by 6-Foot Supersonic Wind Tunnels. Sonic boom pressure signatures were acquired primarily at Mach 1.6 and 1.8, and force and moment data were acquired from Mach 0.8 to 1.8. The sonic boom test data were obtained using a 2-in. flat-top pressure rail and a 14-in. tapered "reflection factor 1" (RF1) pressure rail. Both rails capture an entire pressure signature in one data point, and successive signatures at varying positions along or above the rail were used to improve data quality through spatial averaging. The sonic boom data obtained by the rails were validated with high-fidelity numerical simulations of offbody pressures. The test results showed good agreement between the computational and experimental data when a variety of testing techniques including spatial averaging of a series of pressure signatures were employed. The two wind tunnels generally produced comparable data. NomenclatureCAD = computer-aided design CoR = center of rotation h, h_nose = model altitude at model nose, in. h/L, h_nose_L = model altitude non-dimensionalized by model length HumidAvg = average humidity from wind tunnel sensors, ppm by weight L = model reference length, in. M = Mach number

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“…Backed by programatic investment within NASA and elsewhere, a number of simulation tools have recently become available for predicting high-fidelity pressure signals several body lengths away from an aircraft. [1][2][3][4][5][6][7][8][9][10][11] At such distances, details of the three-dimensional aircraft geometry become less important and atmospheric propagation codes [12][13][14] can be employed to model wave propagation through the atmosphere and to the ground. While several technologies have played roles in improving the effectiveness of CFD-based analysis, one of the keys has been the widespread use of adaptive mesh techniques.…”

Section: Introductionmentioning

confidence: 99%

Cart3D Simulations for the First AIAA Sonic Boom Prediction Workshop

Aftosmis

Nemec²

2014

52nd Aerospace Sciences Meeting

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Simulation results for the First AIAA Sonic Boom Prediction Workshop (LBW1) are presented using an inviscid, embedded-boundary Cartesian mesh method. The method employs adjoint-based error estimation and adaptive meshing to automatically determine resolution requirements of the computational domain. Results are presented for both mandatory and optional test cases. These include an axisymmetric body of revolution, a 69 • delta wing model and a complete model of the Lockheed N+2 supersonic tri-jet with V-tail and flow through nacelles. In addition to formal mesh refinement studies and examination of the adjoint-based error estimates, mesh convergence is assessed by presenting simulation results for meshes at several resolutions which are comparable in size to the unstructured grids distributed by the workshop organizers. Data provided includes both the pressure signals required by the workshop and information on code performance in both memory and processing time. Various enhanced techniques offering improved simulation efficiency will be demonstrated and discussed.

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Hybrid CART3D/OVERFLOW Near-Field Analysis of a Low Boom Configuration with Wind Tunnel Comparisons (Invited)

Cited by 11 publications

References 11 publications

Near Field Summary and Statistical Analysis of the Second AIAA Sonic Boom Prediction Workshop

Near Field Summary and Statistical Analysis of the Second AIAA Sonic Boom Prediction Workshop

Experimental and Computational Sonic Boom Assessment of Boeing N+2 Low Boom Models

Cart3D Simulations for the First AIAA Sonic Boom Prediction Workshop

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