Study of horizontal axis tidal turbine performance and investigation on the optimum fixed pitch angle using CFD

Abstract

Purpose The purpose of this paper is to design, investigate and optimize a horizontal axis tidal turbine (HATT) using computer-aided numerical simulation and computational fluid dynamics (CFD). This is the first step of research and development (R&D) for implementation in the Persian Gulf condition. To do so, suitable locations are reviewed. Then, the optimization is focused on determining the optimum fixed pitch angle (β) of a three-bladed HATT based on the widespread multiple reference frame (MRF) technique to calculate power and thrust coefficients at different operational rotating speeds. Design/methodology/approach To simplify the problem and reducing the computational costs due to cyclic symmetry only one blade, accordingly one-third of the whole computational domain is considered in the modeling. Due to flow’s nature involving rotating, separation and recirculation, a realizable κ-ε turbulence model with standard wall function is selected to capture flow characteristics influenced by the rotor and near the wall region. Simulations are conducted for two free-stream velocities, then compared with their dependencies through the dimensionless tip speed ratio (TSR) parameter. Findings The validation process of the simulations is carried out by the use of AeroDyn BEM code, which has been evaluated by comparing with two experimental data. As results, the highest coefficient of power is achieved at ß = 19.3° at TSR = 4 with the value around 0.41 and 0.816 for thrust coefficient. Furthermore, to comprehend the rotor’s performance and simulation method, flow characteristics due to the rise in angular velocity is discussed in detail. Moreover, the major phenomenon, cavitation occurrence, is also checked at the critical situation where it is found to be safe. Originality/value By comparing and evaluating the results to other HATTs, it implies that the proposed rotor of this study is feasible and proved by CFD evaluation at this step. However, the current rotor is awaiting a justification through experimental assessment.

Cooling Performance Analysis of Outside Fins of the Closed Circuit Axial Piston Transmission

“…Machines 2021, 9, x FOR PEER REVIEW 3 of 19 investigated with the knowledge of heat transfer path. With the aim of decreasing the maximum temperature of shell, the effects of fin height h, fin pitch p and fin thickness t on the thermal performance are studied by the means of numerical simulation, considering that the finite volume method is a useful tool [30,31]. The flow field and temperature field on the outside of the fin structure are also obtained as a guidance for improving the heat dissipation effect.…”

“…The governing equations indicating continuity, momentum and energy conservation have been illustrated in published literature many times, which are not listed in the paper. Learn from Amiri et al [30] and Alavi et al [31], the heat transfer performance is investigated through the finite volume method on the basis of the Reynolds equation and the energy equation. Besides the Realizable κ-ε turbulence model, the SIMPLE algorithm is used for pressure-velocity coupling and the least square cell-based option for the spatial discretization of the gradient.…”

Experimental Assessment of a Fixed On-Shore Oscillating Water Column Device: Case Study on Oman Sea

“…Study of renewable energies is of great importance due to the increased demand for energy and also the problems caused by fossil fuels and their limited resources [1][2][3]. As the ocean has the highest energy density among other types of renewable energies, it has received considerable *Corresponding Author Email: rshafaghat@nit.ac.ir (R. Shafaghat) attention during the recent decade [4].…”

Unsteady Aerodynamic Characteristics Simulations of Rotor Airfoil under Oscillating Freestream Velocity

“…Therefore, investigations on unsteady aerodynamic characteristics of rotor airfoil under oscillating freestream velocity are important, especially for the dynamic stall phenomenon [1,2]. To discover the physical essence of a rotor airfoil dynamic stall, a lot of research under steady freestream velocity (SFV) conditions has been accomplished by using the experimental method [3][4][5][6], theoretical method [7][8][9][10][11][12], and numerical method [13][14][15]. Hence, the dynamic stall of airfoil under SFV conditions is well-studied at present.…”