Unsteady flowfield simulation of ducted prop-fan configurations

Janus, J.; Horstman, Howard; Whitfield, David L.

doi:10.2514/6.1992-521

Cited by 13 publications

(7 citation statements)

References 6 publications

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“…Fig. 6a shows a slice of the density field juxtaposed with the body of the turbine [16]. The regions of interest are the leading and trailing edges of the blade and the tip of the propeller.…”

Section: Resultsmentioning

confidence: 99%

“…Previous volume compression methods include predictive methods [11], fractal methods [3], vector quantization (VQ) [28], Discrete Cosine Transform (DCT) [42], wavelets [9], [13], [16], [26], [27], [32], [34], [38], [39], [40], and Gaussian pyramids [12]. The predictive method (followed by Huffman coding) reported in [11] provided sufficient improvement over the standard UNIX utilities like gzip, but did not provide a high level of compression.…”

Section: Introductionmentioning

confidence: 99%

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Structure-significant representation of structured datasets

Machiraju

Zhu

Fry

et al. 1998

IEEE Trans. Visual. Comput. Graphics

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Numerical simulation of physical phenomena is now an accepted way of scientific inquiry. However, the field is still evolving, with a profusion of new solution and grid-generation techniques being continuously proposed. Concurrent and retrospective visualization are being used to validate the results, compare them among themselves and with experimental data, and browse through large scientific databases. There exists a need for representation schemes which allow access of structures in an increasing order of smoothness (or decreasing order of significance). We describe our methods on datasets obtained from curvilinear grids. Our target application required visualization of a computational simulation performed on a very remote supercomputer. Since no grid adaptation was performed, it was not deemed necessary to simplify or compress the grid. In essence, we treat the solution as if it were in the computational domain. Inherent to the identification of significant structures is determining the location of the scale coherent structures and assigning saliency values to them [22], [23]. Scale coherent structures are obtained as a result of combining the coefficients of a wavelet transform across scales. The result of this operation is a correlation mask that delineates regions containing significant structures. A spatial subdivision (e.g., octree) is used to delineate regions of interest. The mask values in these subdivided regions are used as a measure of information content. Later, another wavelet transform is conducted within each subdivided region and the coefficients are sorted based on a perceptual function with bandpass characteristics. This allows for ranking of structures based on the order of significance, giving rise to an adaptive and embedded representation scheme. We demonstrate our methods on two datasets from computational field simulations. Essentially, we show how our methods allow the ranked access of significant structures. We also compare our adaptive representation scheme with a fixed blocksize scheme.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structure-significant representation of structured datasets

Machiraju

Zhu

Fry

et al. 1998

IEEE Trans. Visual. Comput. Graphics

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“…It must also accurately simulate the flow field with varying high gradient features, such as shock waves, contact discontinuities, rapid expansions, shear layers, etc. The solution algorithm developed for this project is based upon the structured algorithm developed by Whitfield et al [23,24] that is an implicit Newton-relaxation scheme with an approximate LU factorization and Roe flux-difference splitting. Implicit algorithms with Roe flux-difference splitting have been successfully developed by others for single element type unstructured grids.…”

Section: Fig 42 Edge Area and Volume Contributions For Vertex Basementioning

confidence: 99%

“…The flux-Jacobians required for Newton's method need not be exact and can be approximated without any loss in accuracy. Efficiency can be improved by using flux-Jacobians from a flux splitting scheme rather than those from the flux-difference splitting scheme used to determine the residual [23,24]. The system of equations that result from the Newton-linearization is solved using a modified two-pass approximate LU factorization scheme.…”

Section: Edge Area Edge Volumementioning

confidence: 99%

“…These equations need not be solved exactly and can be solved approximately without any degradation in accuracy. This implicit approach has been used successfully with structured grids for steady and unsteady viscous flow fields at the ERC [23,24]. Time steps corresponding to CFL values in the thousands have been obtained with structured grids on fairly complex configurations.…”

Section: Edge Area Edge Volumementioning

confidence: 99%

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Computational Simulation of Unsteady, Viscous, Hypersonic Flow about Flight Vehicles with Store Separation

Marcum¹

2001

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Public reporting burden for this collection of information n estimated to average 1 hour per response, including gathering and maintaining the data needed, and completing and reviewing the collection of information. «a »(«91 «aw ABSTRACT (Maximum 200 words)This project describes a research project to develop a computational capability to accurately and efficiently simulate unsteady, three-dimensional, hypersonic, viscous flow fields about realistic flight vehicle configurations with separating stores and/or components. Unstructured grid technology with an advanced implicit high-resolution flow field, solution algorithm is utilized as the basis for this computational capability. The solution algorithm uses an implicit Newton-relaxation scheme with approximate LU factorization and Roe flux-difference splitting. A new unstructured grid generation procedure labeled Advancing-Front/LocalReconnection (AFLR) was developed that significantly improves the state-of-theart. This procedure uses an iterative point placement scheme. New points are generated using advancing-front type point placement and the connectivity is optimized with iterative local-reconnection. The combined efficiency, quality, and robustness for AFLR are a substantial improvement over existing techniques. Unsteady and steady flow fields about complex flight vehicles with separating components were simulated to demonstrate, test, and validate the overall computational procedure. SUBJECT TERMScomputational fluid dynamics, unstructured grid generation

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A 3D Linearized Euler Analysis for Blade Rows Part 1: Aerodynamic and Numerical Formulations

Montgomery¹,

Verdon²

1998

Unsteady Aerodynamics and Aeroelasticity of Turbomachines

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Unsteady flowfield simulation of ducted prop-fan configurations

Cited by 13 publications

References 6 publications

Structure-significant representation of structured datasets

Structure-significant representation of structured datasets

Computational Simulation of Unsteady, Viscous, Hypersonic Flow about Flight Vehicles with Store Separation

A 3D Linearized Euler Analysis for Blade Rows Part 1: Aerodynamic and Numerical Formulations

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