An experimental investigation involving the design, fabrication, and testing of an ambient sampling inlet and two additional Stokes-scaled inlets is presented here. Testing of each inlet was conducted at wind speeds of 2, 8, and 24 km/h (0.55, 2.22, and 6.67 m/s), and characterized for particle sizes between 5 and 20 µm AD. The base-line ambient sampling inlet, which operates at 100 L/min, was developed to interface with a Circumferential Slot Virtual Impactor aerosol concentrator. The inlet displays wind-speed independent characteristics with a penetration above 90% for a nominal particle size of 10 µm AD for all wind speeds. Particles up to 11.5 µm AD are sampled through this inlet with a penetration above 80% at all wind speeds. In an effort to test the validity of Stokes scaling to assist in the design of inlets, two additional inlets were designed to accommodate design flow rates of 400 L/min and 800 L/min, with the 100 L/min unit as the base inlet. Scaling was achieved by applying a Stokes scaling factor to selective parameters, such as inlet aspiration gap, annular gap, window height, and the rise which is the vertical distance extending from the lower flange to the base of the window. The scaled inlets display wind independent penetration characteristics close to 95% for a nominal particle size of 10 µm AD. The scaled inlets also have the ability to sample particles up to a size of 13 µm AD with a penetration in excess of 80% at all wind speeds. Observations from the plots of penetration against the Stokes number based on the free stream velocity suggest that it is insufficient to use only Stokes-scaling for inlet design. A modified velocity ratio defined for omnidirectional inlets was incorporated into a summary of results obtained for all combinations of BSI units and wind speeds. Also, a correlation equation based on the Stokes number and a modified velocity ratio was developed as a model for predicting performance among the BSI family of inlets. This correlation used in unison with Stokes-scaling provides promise for predicting performance and improving the overall design process of inlets.

New bioaerosol sampling inlets were designed and tested that have nominal exhaust flow rates of 100 L/min to 400 L/min, and which have internal fractionators and screens to scalp large, unwanted particles and debris from the transmitted size distribution. These units consist of the same aspiration section, which is a 100 L/min Bell Shaped Inlet (BSI-100), and different pre-separators. The pre-separators are called the IRI-100 (Inline Real Impactor) with an exhaust flow rate of 100 L/min, the IRI-400 (exhaust flow rate of 400 L/min), the IVI-300 (Inline Virtual Impactor for a flow rate of 300 L/min) and the IVI-400. These units were tested in a wind tunnel at speeds of 2, 8, and 24 km/hr with particle sizes between 3 and 20 μm AD (aerodynamic diameter). The units show wind independent characteristics over the range of wind speeds tested. The aspiration section of the BSI-100 has greater than 85% penetration for particle sizes ≤ 10 μm AD. The IRI-100, IRI-400, IVI-300 and IVI-400, when combined with the BSI-100 all provide cutpoints of 11 ± 0.5 μm AD.

New bioaerosol sampling inlets were designed and tested that have nominal exhaust flow rates of 100 L/min to 400 L/min, and which have internal fractionators and screens to scalp large, unwanted particles and debris from the transmitted size distribution. These units consist of the same aspiration section, which is a 100 L/min Bell Shaped Inlet (BSI-100), and different pre-separators. The pre-separators are called the IRI-100 (Inline Real Impactor) with an exhaust flow rate of 100 L/min, the IRI-400 (exhaust flow rate of 400 L/min), the IVI-300 (Inline Virtual Impactor for a flow rate of 300 L/min) and the IVI-400. These units were tested in a wind tunnel at speeds of 2, 8, and 24 km/hr with particle sizes between 3 and 20 μm AD (aerodynamic diameter). The units show wind independent characteristics over the range of wind speeds tested. The aspiration section of the BSI-100 has greater than 85% penetration for particle sizes ≤ 10 μm AD. The IRI-100, IRI-400, IVI-300 and IVI-400, when combined with the BSI-100 all provide cutpoints of 11 ± 0.5 μm AD.

An experimental investigation involving the design, fabrication, and testing of an ambient sampling inlet and two additional Stokes-scaled inlets is presented here. Testing of each inlet was conducted at wind speeds of 2, 8, and 24 km/h (0.55, 2.22, and 6.67 m/s), and characterized for particle sizes between 5 and 20 µm AD. The base-line ambient sampling inlet, which operates at 100 L/min, was developed to interface with a Circumferential Slot Virtual Impactor aerosol concentrator. The inlet displays wind-speed independent characteristics with a penetration above 90% for a nominal particle size of 10 µm AD for all wind speeds. Particles up to 11.5 µm AD are sampled through this inlet with a penetration above 80% at all wind speeds. In an effort to test the validity of Stokes scaling to assist in the design of inlets, two additional inlets were designed to accommodate design flow rates of 400 L/min and 800 L/min, with the 100 L/min unit as the base inlet. Scaling was achieved by applying a Stokes scaling factor to selective parameters, such as inlet aspiration gap, annular gap, window height, and the rise which is the vertical distance extending from the lower flange to the base of the window. The scaled inlets display wind independent penetration characteristics close to 95% for a nominal particle size of 10 µm AD. The scaled inlets also have the ability to sample particles up to a size of 13 µm AD with a penetration in excess of 80% at all wind speeds. Observations from the plots of penetration against the Stokes number based on the free stream velocity suggest that it is insufficient to use only Stokes-scaling for inlet design. A modified velocity ratio defined for omnidirectional inlets was incorporated into a summary of results obtained for all combinations of BSI units and wind speeds. Also, a correlation equation based on the Stokes number and a modified velocity ratio was developed as a model for predicting performance among the BSI family of inlets. This correlation used in unison with Stokes-scaling provides promise for predicting performance and improving the overall design process of inlets.

No description available.

Thesis (M.S.)--University of North Carolina at Wilmington, 2004. / Includes bibliographical references (leaves : 104).

Thesis (M.S.)--University of North Carolina at Wilmington, 2004. / Includes bibliographical references (leaves : [48]-52).

Thesis (M.S.)--University of Delaware, 2008. / Principal faculty advisor: Timothy E. Targett, College of Marine & Earth Studies. Includes bibliographical references.

No description available.

Fresh water entering the inlets moves seaward, mixing with and entraining salt water from below. On the assumption that horizontal advection of salt is balanced by vertical diffusion, the magnitude and variation in time and space of the diffusion coefficient are determined by numerical evaluation of the differential equation describing this process. A method of systematically smoothing the data is established by solving the differential equation analytically. These solutions yield further information on the diffusion coefficient which is found to be nearly constant in the upper reaches of an inlet but increases rapidly towards the mouth in the brackish layer. A technique is developed for determining the total fresh water inflow to the inlets using precipitation observations and available river flow measurements. The results indicate that a significant proportion of fresh water enters from the sides at all times. The importance of this in theoretical studies is emphasized. The results are also analyzed for a possible relationship between inlet dimensions and intensity of mixing. A new method, based on the heat budget, is developed to determine the mean seaward movement of the brackish layer. This method is also applied to determine the depth from which salt water is entrained into the surface layer. / Science, Faculty of / Physics and Astronomy, Department of / Graduate