Session: 10-02: Alternative Energy Conversion Technology (including Wind, Geothermal, Hydro, and Ocean)

Paper Number: 131428

131428 - Evaluation and CFD Based Improvements of Reactive Reversible Blade Turbine 

Abstract: 

A Reactive Reversible Blade Turbine (RRBT) is a cross-flow type turbine design with multiple movable blades that pivot around their local axes to hydraulically balance the blade forces while passing through the negative drag portion of the flow regime. The RRBT allows the blades to react to the negative drag and freely rotate in a way that hydraulically balance the pressure loading. The blades "slice" through the water in a reverse motion, returning to a neutral position and resting against a stop, resulting in reduced resistance on the opposite side of the turbine shaft during rotation. This allows for a significant reduction of the negative drag during the single rotation of the turbine, which improves the power coefficients compared to the current state of the art and allows the turbine to operate at a slow-moving current. Although the design is simple, there is a broad design optimization space that can impact the performance and development of this turbine for various applications.

This paper focuses on developing a numerical approach to enhance the RRBT performance through its reactive blade operation and exploration of the design parameters. The numerical model employs a sliding mesh technique to simulate the blade motion, enabling an analysis of flow dynamics and performance estimation of a single blade around one full revolution. The predicted power coefficient of 0.21, using computational fluid dynamics (CFD), aligns well with the experimentally predicted value of 0.2 at a 0.32 Tip Speed Ratio (TSR). Further investigation focuses on gaining a deeper understanding of turbine performance concerning changes in blade profile, blade angles, blade widths, and scaling effects. The design space exploration study reveals that the blade angle (blade rotation stopper position to load the blade with positive torque) has a substantial impact on turbine performance, particularly in shifting the peak power coefficient with the tip speed ratio. As the blade angle increases, the power coefficient rises, peaking at around 72°, followed by a decrease as the blade angle further increases. Further exploration focuses on the comparison study of effect of different blade widths and profiles on power output of this turbine. It is essential to note that these findings are based on the analysis of a single blade, without considering reactive modes for all data points. Despite the design's simplicity and its potential for commercialization in slow-moving water environments, additional investigation and experimental validation are necessary to comprehensively assess the performance of the proposed design modifications.

Presenting Author: Abhay Patil Research Engineer At Southwest Research Institute

Presenting Author Biography: Abhay Patil is a Senior Research Engineer at the Southwest Research Institute.

Authors:

Abhay Patil Research Engineer At Southwest Research Institute
Kelsi Katcher SwRI
Tim Allison SWRI
Scot Cummings Creektides Energy and Power