Numerical Study of Longitudinal and Transverse Flow through a screen model for a Bauer-McNett Classifier

NOTICE OF INTENT TO ISSUE A PURCHASE ORDER. The Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health (NIOSH), Division of Applied Research and Technology hereby announces its intent to issue a purchase order to the University of Cincinnati, Computational Fluid Dynamics Research Laboratory, Professor Urmila Ghia for a Numerical Study of Rotational Effects in Powder Aerosolization. Background: Techniques for investigating health hazards of inhalation or exposure to substances which are toxic to human cells depend significantly on the type of substance causing the health hazards. Two classes of such toxic substances are asbestos fibers and pharmaceutical powders. Experimental study of fiber length relative to cytotoxicity (quality of being toxic to cells) has shown that longer fibers are more toxic than fibers of length ~ 3 ?m and 4 ?m [Blake et al. (1998)]. In order to conduct experiments to evaluate the role of fiber length in cytotoxicity, we need collections of fibers separated according to their length. This is accomplished by the Baron Classifier [Deye et al. (1999)]. The input to the Baron Classifier is an aerosol of the fiber to be tested. This aerosol is generated by an orbiting Vertical Centrifuge Tube. Small glass beads coated with the powder to be aerosolized are introduced at the top of the tube. Air is fed into the tube from the top; and the combined action of the air flow and the centrifugal force acting on the beads generates the aerosol. The proposed study will analyze the lift and drag forces exerted on a single rotating bead. An appropriate simplification to the geometry will be identified, and the forces on the bead will be calculated from numerical simulations of the flow field. The study will provide vital information to NIOSH about forces acting on the beads inside the centrifuge tube, and help in obtaining a detailed understanding of the aerosolization process. In the case of powders, pharmaceutical powders in controlled quantities are actually remedies to patients, but these same powders can be toxic to workers at the pharmaceutical manufacturing plant owing to high and prolonged exposure. One way to estimate the associated health risks to these workers is by evaluating the dustiness of these powders, with dustiness being defined as the tendency of a powder to aerosolize with a given input of energy. Evaluating dustiness of a pharmaceutical powder can predict potential exposure to workers. It can also aid in the selection of manufacturing processes/operations which generate less dust for a particular substance, and can provide vital information to guide selecting/creating powders which generate less dust. A device used to evaluate dustiness of a pharmaceutical powder is the Rotating Drum dustiness tester [Hjemsted and Schneider (1996) and Breum (1999)]. The proposed CFD study will numerically investigate the flow inside the Rotating Drum dustiness tester, and examine the aerosolization of the powder during the operation of this tester. A comprehensive description of the flow aerodynamics associated with operation of this instrument will help NIOSH to extend their work to different powders of interest. Objectives: The overall goal of the proposed effort is to numerically investigate the effects of rotation on the aerosolization process. This will be pursued via the following two objectives, using Computational Fluid Dynamics (CFD) tools: (1) to study the canonical problem of flow of an air stream over a rotating bead on a surface, and determine the forces on the bead, to investigate the forces acting on powder-coated beads in the vertical centrifuge tube aerosol generator; (2) to study the fluid flow in the Rotating Drum dustiness tester, which is equipped with baffles on the inside of its periphery to enhance the movement of powder agglomerates and their consequent break-up. Introduction: The proposed study of the effects of rotation on aerosolizaton will consist of two parts. The first part will conduct a numerical investigation of the forces acting on a rotating bead, and the second will pursue the CFD analysis of the Rotating Drum dustiness tester. Responsible sources that believe they possess the expertise and capabilities identified above are encouraged to submit to the Contracting Officer within 15 days from the posting date of this notice, their written item description/item characteristics and pricing information in the format they choose, not to exceed 10 pages. Please forward the item description and pricing information to Margaret L. Mooney, CDC NIOSH, 626 Cochrans Mill Road, Pittsburgh, PA 15236, Reference 2012-Q-14846. All vendors must be registered in the Central Contractor Registry (CCR) prior to an award of a federal contract. The website is: www.ccr.gov. The Government will review any/all item descriptions and pricing information submitted and determine if other qualified sources do exist that could provide this requirement. Information received in response will be used solely for the purpose of determining whether to conduct a competitive procurement. If no affirmative responses are received within 15 days, in accordance with FAR 13.106-1(b)(1), negotiations will be conducted with Professor Urmila Ghia at the University of Cincinnati, Computational Fluid Dynamics Research Laboratory, Department of Mechanical, Industrial and Nuclear Engineering, Cincinnati, OH 45221-0072 as the only source and a purchase order will be issued without any additional notices being posted.