College of Engineering

Mechanical Engineering Seminar

Date(s): 11/29/2012 11:00 AM - 11/29/201212:00 PM
Location: Textile Building, Room 101E Conference Room
Contact: Dr. Sankha Bhowmick sbhowmick@umassd.edu 508-999-8619
Mechanical Engineering

The Mechanical Engineering Department is pleased to announce a SEMINAR on November 29, 2012 from 11am - 12pm in Textile 101E.

SPEAKER: Mr. Prasun Chatterjee, MS student of the UMD Mechanical Engineering Department

TOPIC: ANALYSIS OF A DIFFUSER-SHROUDED HIGH-SOLIDITY VERTICAL AXIS TURBINE USING COMPUTATIONAL FLUID DYNAMICS

ABSTRACT:

Vertical axis turbines (VATs) excel over horizontal axis turbines in their independent flow direction. VATs that operate in an enclosure, e.g., a diffuser shroud, are reported to have efficiencies that exceed the Betz limit of 59.3%. Ducted VATs also are advantageous over unducted VATs in terms of torque fluctuation reduction on the rotor blades. A diffuser-shrouded, 3-blade, high-solidity VAT with NACA 633-018 airfoils is modeled in 2-D using the commercial software ANSYS-FLUENT. Incompressible, unsteady, segregated, implicit, and 2nd-order in time and space solver is implemented in association with the Spalart-Allmaras and SST k-ω turbulence models with a reasonable computational cost. High-solidity, unducted VATs, e.g., 40% with NACA 633-018 airfoils are approximately 33% efficient at low-tip-speed ratios. A diffuser-shrouded VAT with the same solidity is analyzed over tip speed ratios ranging from 1 to 2. The aim is to optimize the diffuser shape in two ways. First, by determining a suitable diffuser contraction ratio in order to redirect the flow at the proper angle of attack relative to the rotor airfoil; and second, by considering the diffuser wall as an array of small airfoils separated by slots. The numerical model investigates Venturi-effect enhancement of the flow, mitigation of flow separation due to adverse pressure gradients, slot spacing effect on the diffuser boundary layer and flow bleed, and the impact of localized pressure recovery on VAT efficiency. A comparison will be made with an unducted 2-D VAT model in order to assess the wake structure, flow separation at the turbine rotor, torque distribution and turbine efficiency over a range of tip speed ratios.

Mr. Chatterjee's advisor is Dr. Raymond Laoulache.

All are welcome, and light refreshments will be served.

First year MNE-MS students are required to attend; all other MNE students are encouraged to attend.

For more information please contact Dr. Sankha Bhowmick, Seminar Coordinator, sbhowmick@umassd.edu, 508-999-8619. Thank you!


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