Arsenio Dimanlig

Helios Prediction of Blade-Vortex Interaction and Wake of the HART II Rotor

In this paper, we present the validation of the multi-disciplinary rotorcraft simulation code Helios for its ability to predict the blade-vortex interactions(BVI) and the rotor wake in the descending flight. Helios uses a dual-mesh paradigm with unstructured mesh near the body and Cartesian mesh in the o-body. The trim of the rotorcraft and the elastic blade deformations are modeled using the loose-coupling with RCAS comprehensive model. Three test conditions baseline, minimum noise and minimum vibration are used for the validation. Helios predictions for the baseline case which has strong BVI on both the advancing and retreating side are compared to the measured data, OVERFLOW 2/CAMRAD II and FUN3D/CAMRAD II predictions. The minimum noise and minimum vibration case predictions are compared to the measured data. Helios predictions compare favorably with the current state-of-the art codes. Cartesian-based unsteady adaptive mesh refinement (AMR) is applied in the o-body flow field to understand the eect of AMR on the prediction of the wake field.

Flow Field Measurements in the Cell Culture Unit

Abstract: The cell culture unit (CCU) is being designed to support cell growth for long‐duration life science experiments on the International Space Station (ISS). The CCU is a perfused loop system that provides a fluid environment for controlled cell growth experiments within cell specimen chambers (CSCs), and is intended to accommodate diverse cell specimen types. Many of the functional requirements depend on the fluid flow field within the CSC (e.g., feeding and gas management). A design goal of the CCU is to match, within experimental limits, all environmental conditions, other than the effects of gravity on the cells, whether the hardware is in microgravity (μg), normal Earth gravity, or up to 2g on the ISS centrifuge. In order to achieve this goal, two steps are being taken. The first step is to characterize the environmental conditions of current 1g cell biology experiments being performed in laboratories using ground‐based hardware. The second step is to ensure that the design of the CCU allows the fluid flow conditions found in 1g to be replicated from microgravity up to 2g. The techniques that are being used to take these steps include flow visualization, particle image velocimetry (PIV), and computational fluid dynamics (CFD). Flow visualization using the injection of dye has been used to gain a global perspective of the characteristics of the CSC flow field. To characterize laboratory cell culture conditions, PIV is being used to determine the flow field parameters of cell suspension cultures grown in Erlenmeyer flasks on orbital shakers. These measured parameters will be compared to PIV measurements in the CSCs to ensure that the flow field that cells encounter in CSCs is within the bounds determined for typical laboratory experiments. Using CFD, a detailed simulation is being developed to predict the flow field within the CSC for a wide variety of flow conditions, including microgravity environments. Results from all these measurements and analyses of the CSC flow environment are presented and discussed. The final configuration of the CSC employs magnetic stir bars with angled paddles to achieve the necessary flow requirements within the CSC.

Multidisciplinary Coupling for Active Flapped Rotors

To address the complex multidisciplinary nature of rotorcraft analysis, high-fidelity computational fluid and structural dynamics models have been developed for an advanced technology, active flap rotor. Comparisons are made between computational fluid dynamics/ computational structural dynamics, comprehensive (lifting-line, free-wake) analyses, and experimental data for the Boeing Smart Material Actuated Rotor Technology (SMART) rotor. A phase sweep of a 2/rev flap input is investigated in relation to the zero flap deflection baseline. Changes in performance, aerodynamic and structural loads, vibration, and noise are shown.

Advancing State-of-the-Art Unsteady, Multidisciplinary Rotorcraft Simulations

To address the complex multidisciplinary nature of rotorcraft analysis, high-fidelity computational fluid and structural dynamics models have been developed to investigate a range of challenging rotorcraft issues. First, an advanced technology, active flap rotor (Boeing SMART) is investigated, and performance, aerodynamic and structural loads, vibration, noise prediction and flow physics mechanisms are shown. The rotor model includes complex and detailed flap and flap-gap modeling. Second, analyses on an advanced dynamics model (ADM) research configuration rotor investigate regressing lag mode (RLM) aero elastic instabilities. Tightly-coupled computational fluid dynamics (CFD)/computational structural dynamics (CSD) stability calculations show noticeable improvement over lower fidelity methods. Third, the state-of-the-art capability of CFD methods to directly predict low frequency in-plane noise on realistic lifting rotors is benchmarked for the first time. In all cases, comparisons are made between CFD/CSD, comprehensive analyses, and experimental data. Taken together, these works offer an important advancement in rotorcraft analysis capability for advanced technology rotor configurations under study for future Army rotorcraft, and highlight future needs in next-generation rotorcraft analysis software.