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The behavior of vaporous hydrogen peroxide (VHP) was examined in clean, room-scale galvanized steel (GS) and polyvinylchloride-coated steel air ducts, to understand how it might be used to decontaminate larger ventilation systems. VHP injected into the GS duct decreased in concentration along the length of the duct, whereas VHP concentrations in the polyvinylchloride coated duct remained essentially constant, suggesting that VHP decomposed at the GS surface. However, decomposition was reduced at lower temperatures (approximately 22 degrees C) and higher flow rates (approximately 80 actual cubic meter per hour). A computational fluid dynamics model incorporating reactive transport was used to estimate surface VHP concentrations where bioaerosol contamination is likelyto reside, and also showed that VHP decomposition was enhanced at bends within the duct, compared to straight sections. Use of G. stearothermophilus indicators, in conjunction with model estimates, indicated that a concentration-contact time of approximately 100 mg/L H2O2(g) x min was required to achieve a 6 log reduction of indicator spores in clean GS duct, at 30 degrees C. When VHP is selected for building decontamination, this work suggests the most efficacious strategy may be to decontaminate GS ducting separately from the rest of the building, as opposed to a single decontamination event in which the ventilation system is used to distribute VHP throughout the entire building.

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This article summarizes the capabilities and development of the Helios version 2.0, or Shasta, software for rotary wing simulations. Specific capabilities enabled by Shasta include off-body adaptive mesh refinement and the ability to handle multiple interacting rotorcraft components such as the fuselage, rotors, flaps and stores. In addition, a new run-mode to handle maneuvering flight has been added. Fundamental changes of the Helios interfaces have been introduced to streamline the integration of these capabilities. Various modifications have also been carried out in the underlying modules for near-body solution, off-body solution, domain connectivity, rotor fluid structure interface and comprehensive analysis to accommodate these interfaces and to enhance operational robustness and efficiency. Results are presented to demonstrate the mesh adaptation features of the software for the NACA0015 wing, TRAM rotor in hover and the UH-60A in forward flight.

This paper presents an overview of new capabilities in the Helios v3, or Rainier, highfidelity rotorcraft simulation software. Key new capabilities include the addition of DES turbulence modeling in the near-body solver and RANS in the off-body solver, introduction of Richardson extrapolation-based error control to automate off-body AMR, and runtime parallel partitioning of near-body grids. We also report on advances made in Helios to support loose-coupling rotor-fuselage and multi-rotor configurations. The paper describes these capability enhancements in detail and provides validation results and computational performance metrics for the model TRAM rotor, HART-II, and UH-60A configurations.

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a range of critical steady forward flight conditions. Comparisons with available flight test data are provided for all of the predictions. The Helios framework combines multiple solvers and multiple grid paradigms (unstructured and adaptive Cartesian) such that the advantages of each paradigm is preserved. Further, the software is highly automated for execution and designed in a modular fashion to minimize the burden on both the users and developers. The technical approach presented herein provides details of all of the participant modules and the interfaces used for their integration into the software framework. The results composed of sectional aerodynamic loading and wake visualizations are presented. Solution-based adapative mesb refinement, a salient feature of tbe Helios framework, is explored for all flight conditions and comparisons are provided for both aerodynamic loading and vortex wake structure with and without adaptive mesh reflnement. I. IntroductionT HE Helios software framework is designed and developed by the Department of Defense (DoD)-sponsored High Performance Computing Institute for Advanced Rotorcraft Modehng and Simulation. Improvements in usability, accuracy, and efficiency were the principal metrics used in the design and development of Helios. To this end, Helios provides several novel features that are different from the existing state-of-the-art solver. These include 1) a multicode unstructured/Cartesian dual-mesh Computational Fluid Dynamics (CFD) solver architecture [1], 2) the capability for solution adaption and high-order accuracy in the off-body solver [2], 3) an automated and parallel overset grid assembling capability with implicit hole cutting [3], 4) an unstructured patch force-based fluid-structure interiace [4], and 5) a Python-based software integration framework that supports seamless and efficient data exchange between component modules [1].

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