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Nigel Taylor

Publications and source records attributed to Nigel Taylor.

5 records
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Requirements and Challenges for CFD Validation within the High-Lift Common Research Model Ecosystem

The High-Lift Common Research Model (CRM-HL) ecosystem is envisioned to become an industry standard set of test cases for high-lift aerodynamics prediction, with data generated providing a strong foundation for CFD validation. Since its original development, preliminary wind tunnel tests have been conducted to further understand and configure the geometry, and several more are in the planning phases. It is anticipated that the data generated in these tests will be used extensively by the CFD community for research, development, and validation of new techniques that yield more accurate results. To derive the maximum benefit from planned wind tunnel testing, data acquisition will be focused in several key areas to address specific shortcomings in CFD predictive capabilities. Significant challenges currently exist in areas including, but not limited to, characterizing high-lift flow phenomena, quantifying effects due to configuration changes, understanding wind tunnel and model installation effects, and establishing data uncertainty. This paper will discuss the current state-of-the-art in high-lift CFD prediction, key limitations of current CFD methods and tools, establishing a validation dialog between test and CFD practitioners, and the flow phenomena of highest interest, in an effort to begin to address these challenges. To this end, it is expected that the data generated from CRM-HL tests will form a strong foundation for future predictive capability.

Adam M Clark↗
NASA NTRSDate not supplied

CFD Validation Experiments: Toward a Broader Perspective

The current literature considers a CFD validation experiment synonymously with a particular type of wind tunnel test. By drawing on the experience of the authors, this paper makes a case for broadening the definition to include a more balanced and synergistic exploitation of computational and physical testing techniques. The concept of validation dialog is introduced which, together with technique verification, is considered a key enabler in the pursuit of an improved CFD predictive capability. An outline of a lifecycle for a CFD validation experiment is also proposed to consolidate the thinking. The result, it is reasoned, will encourage improved engagement with a broader range of stakeholders and wider recognition of the value of the outcomes of what might otherwise be considered studies of lesser importance. In turn, this is expected to encourage the adoption of more systematic approaches to complex problems, such that they are more readily broken down into smaller, more focused endeavors, while at the same time making such activities easier to fund.

CFD↗
NASA NTRSDate not supplied

HLPW-4/GMGW-3: Wall-Modeled LES and Lattice-Boltzmann Technology Focus Group Workshop Summary

A summary of the nine submissions to the Wall-Modeled LES and Lattice-Boltzmann(WMLESLB) Technical Focus Group (TFG) at the 4th High lift Prediction Workshop is provided. The focus of this TFG was to assess the current capabilities of WMLES and Lattice-Boltzmann methods on a complex high-lift configuration across a wide range of angles of attack. Preliminary analysis of the submitted data suggests that>250𝑀spatial degrees of freedom are needed to accurately predict pitching moments at high angles of attack due to large pressure gradients present on the outboard slat and main element for𝛼 >17◦(corrected for free-air).While some scatter is reported in pitching moments at the low-angles of attack (𝛼 <11◦) - likely caused by differences in flap separation possibly due to low Reynolds number effects - excellent agreement is observed between the submissions near the𝐶𝐿,max state. Objective superiority over steady state RANS can be seen in terms of lack of excess outboard separation; a majority of the good quality WMLES and LB submissions predict wedge-shaped separation patterns consistent with the experimental oil flow. Differences in the onset of stall mechanism in the free-air configuration for𝛼 >20◦is reported with two distinct topologies observed. Topology A is characterized by the onset of corner-flow separation which progressively grows to produce a pitch break in free-air with an angle of attack increase from𝛼=20.55◦to𝛼=21.47◦+𝜖where𝜖is a small perturbation (varying between submissions and likely to be within±0.3◦). Topology Bis characterized by boundary layer weakness emanating from the inboard side of the wing-pylon juncture substantially larger than any weakness in the wing-body juncture (due to corner-flow);submissions in this category do not show any tendency for occurrence of a pitch break for the free-air configuration within the vicinity of𝛼=21.47◦. The in-tunnel simulations submitted by3 participants using different discretizations, grids and closure models show excellent agreement with the experiment in terms of a) integrated loads, b) surface flow-topology, and c) mechanism for the onset of inboard stall. Further evidence is provided to demonstrate both qualitative and quantitative superiority of all 3 WMLES submissions over a single steady state RANS submission to the workshop.

TTT↗