scholarly journals Numerical investigations of hydrodynamic performance of hydrofoils with leading-edge protuberances

2015 ◽  
Vol 7 (7) ◽  
pp. 168781401559208 ◽  
Author(s):  
Chang Cai ◽  
Zhigang Zuo ◽  
Shuhong Liu ◽  
Yulin Wu
Keyword(s):  
Leading Edge ◽  
Hydrodynamic Performance ◽  
Numerical Investigations

The effect of leading-edge droop on the performance of cavitating hydrofoil in an oscillating environment

2009 ◽  
Vol 223 (10) ◽  
pp. 2331-2339
Author(s):  
K Park ◽  
H Sun ◽  
S Lee
Keyword(s):  
Leading Edge ◽  
Hydrodynamic Performance ◽  
Control Surface ◽  
Navier Stokes ◽  
Two Phase ◽  
Sheet Cavitation ◽  
Maximum Angle ◽  
Oscillating Motion ◽  
Drag Ratio ◽  
Cavitating Hydrofoil

The hydrodynamics of cavitating hydrofoil in oscillating motion are important in the aspect of the performance and hydro-elasticity of the control surface of the ship. The effect of leading-edge droop is numerically studied in the oscillating hydrofoil with cavitation. A two-phase incompressible Navier—Stokes solver is used to compute the cavitation flow. The hydrodynamic performance of the baseline hydrofoil is compared with that of the fixed droop and the variable droop hydrofoil. The droop models delay the separation behind the sheet cavitation near the maximum angle of attack. When the pitch goes down, the drooped models suppress the collapse of the sheet cavitation. Therefore, they result in the improved hydrodynamic performance against the baseline model through the oscillation cycle. Among the three hydrofoils, the variable droop showed the smallest change of the lift-to-drag ratio.

Numerical Investigation of an Elastomer-Piezo-Adaptive Blade for Active Flow Control of a Nonsteady Flow Field Using Fluid–Structure Interaction Simulations

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Tien Dat Phan ◽  
Patrick Springer ◽  
Robert Liebich
Keyword(s):  
Flow Control ◽  
Active Flow Control ◽  
Leading Edge ◽  
Material Behavior ◽  
Fluid Structure ◽  
Numerical Investigations ◽  
Pulsed Detonation ◽  
Stator Blade ◽  
Suitable Concept ◽  
Active Flow

In order to prevent critical effects due to pulsed detonation propulsion, e.g., incidence fluctuations, an elastomer-piezo-adaptive stator blade with a deformable front part is developed. Numerical investigations with respect to the interaction of fluid and structure including the piezoelectric properties and the hyperelastic material behavior of an elastomer membrane are conducted in order to investigate the concept of the elastomer-piezo-adaptive blade for developing the best suitable concept for subsequent experiments with a stator cascade in a wind tunnel. Results of numerical investigations of the structure-dynamic and fluid mechanical behavior of the elastomer-piezo-adaptive blade by using a novel fluid–structure-piezoelectric-elastomer-interaction simulation (FSPEI simulation) show that the latent danger of a laminar flow separation at the leading edge at incidence fluctuations can be prevented by using an adaptive blade. Therefore, the potential of the concept of the elastomer-piezo-adaptive blade for active flow control is verified. Furthermore, it is essential to consider the interactions between fluid and structure of the transient FSPEI simulations, since not only the deformation of the adaptive blade affects the flow around the blade, the flow has a significant effect on the dynamic behavior of the adaptive blade, as well.

scholarly journals Hydrodynamic performance evaluation of a tidal turbine with leading-edge tubercles

2016 ◽  
Vol 117 ◽  
pp. 246-253 ◽  
Author(s):  
Weichao Shi ◽  
Roslynna Rosli ◽  
Mehmet Atlar ◽  
Rosemary Norman ◽  
Dazheng Wang ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Leading Edge ◽  
Hydrodynamic Performance ◽  
Tidal Turbine

scholarly journals Numerical study on the steady suction active flow control of hydrofoil in the profile of the blended-wing-body underwater glider

2021 ◽  
Vol 39 (4) ◽  
pp. 801-809
Author(s):  
Xiaoxu Du ◽  
Lianying Zhang
Keyword(s):  
Flow Control ◽  
Numerical Study ◽  
Active Flow Control ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Hydrodynamic Performance ◽  
Flow State ◽  
Underwater Glider ◽  
Blended Wing Body ◽  
Active Flow

The hydrodynamic performance of the blended-wing-body underwater glider can be improved by opening a hole on the surface and applying the steady suction active flow control. In order to explore the influence law and mechanism of the steady suction active flow control on the lift and drag performance of the hydrofoil, which is the profile of the blended-wing-body underwater glider, based on the computational fluid dynamics (CFD) method and SST k-ω turbulence model, the steady suction active flow control of hydrofoil under different conditions is studied, which include three suction factors: suction angle, suction position and suction ratio, as well as three different flow states: no stall, critical stall and over stall. Then the influence mechanism in over stall flow state is further analyzed. The results show that the flow separation state of NACA0015 hydrofoil can be effectively restrained and the flow field distribution around it can be improved by a reasonable steady suction, so as to the lift-drag performance of NACA0015 hydrofoil is improved. The effect of increasing lift and reducing drag of steady suction is best at 90° suction angle and symmetrical about 90° suction angle, and it is better when the steady suction position is closer to the leading edge of the hydrofoil. In addition, with the increase of the suction ratio, the influence of steady suction on the lift coefficient and drag coefficient of hydrofoil is greater.

Numerical Investigation of Bionic Rudder With Leading-Edge Protuberances

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Hongtao Gao ◽  
Wencai Zhu
Keyword(s):  
Electron Microscopy ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Hydrodynamic Performance ◽  
Spanwise Direction ◽  
Flow Mechanism ◽  
Suction Surface ◽  
Edge Profile ◽  
Drag Ratio ◽  
Lift To Drag Ratio

The duck's webbed feet are observed by using electron microscopy, and observations indicate that the edges of the webbed feet are the shape of protuberances. Therefore, the rudder with leading-edge protuberances is numerically studied in the present investigation. The rudder has a sinusoidal leading-edge profile along the spanwise direction. The hydrodynamic performance of rudder is analyzed under the influence of leading-edge protuberances. The present investigations are carried out at Re = 3.2 × 105 and 8 × 105. In the case of Re = 3.2 × 105, the curves of lift coefficient illustrate that the protuberant leading-edge scarcely affects the lift coefficient of bionic rudder. However, the drag coefficient of the bionic rudder is markedly lower than that of the unmodified rudder. Therefore, the lift-to-drag ratio of the bionic rudder is obviously higher than the unmodified rudder. In another case of Re = 8 × 105, the advantageous behavior of the bionic rudder with leading-edge protuberances is mainly performed in the post-stall regime. The flow mechanism of the significantly increased efficiency by the protuberant leading-edge is explored. It is obvious that the pairs of counter-rotating vortices are presented over the suction surface of bionic rudder, and therefore, the flow is more likely to adhere to the suction surface of bionic rudder.

Hydrodynamics and Flow Characterization of Tuna-Inspired Propulsion in Forward Swimming

2019 ◽  
Author(s):  
Junshi Wang ◽  
Huy Tran ◽  
Martha Christino ◽  
Carl White ◽  
Joseph Zhu ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Leading Edge ◽  
Underwater Vehicle ◽  
Numerical Approach ◽  
Primary Objective ◽  
Computational Effort ◽  
The Body ◽  
Hydrodynamic Performance ◽  
Immersed Boundary ◽  
Ring Structures

Abstract A combined experimental and numerical approach is employed to study the hydrodynamic performance and characterize the flow features of thunniform swimming by using a tuna-inspired underwater vehicle in forward swimming. The three-dimensional, time-dependent kinematics of the body-fin system of the underwater vehicle is obtained via a stereo-videographic technique. A high-fidelity computational model is then directly reconstructed based on the experimental data. A sharp-interface immersed-boundary-method (IBM) based incompressible flow solver is employed to compute the flow. The primary objective of the computational effort is to quantify the thrust performance of the model. The body kinematics and hydrodynamic performances are quantified and the dynamics of the vortex wake are analyzed. Results have shown significant leading-edge vortex at the caudal fin and unique vortex ring structures in the wake. The results from this work help to bring insight into understanding the thrust producing mechanism of thunniform swimming and to provide potential suggestions in improving the hydrodynamic performance of swimming underwater vehicles.

Edge Matching: Part II — Numerical Investigations

2005 ◽  
Author(s):  
J. Chen ◽  
L. C. Ji
Keyword(s):  
Axial Compressor ◽  
Flow Simulation ◽  
Leading Edge ◽  
Spatial Relation ◽  
Single Stage ◽  
Numerical Investigations ◽  
Edge Matching ◽  
Blade Row ◽  
Em Theory ◽  
Effective Degree

Edge Matching (EM), presented in accompanying paper [1], may make it manipulable to utilize time-accurate unsteady flow simulation in daily design of multistage turbomachinery. The spatial relation between a blade trailing edge and the leading edge of the sequent blade row is taken into account in improving turbomachinery performance. This paper presents numerical investigations to further illustrate and validate the EM theory and its implementations. A single stage transonic axial compressor and a single stage steam turbine are modified with EM. Numerical results show that EM might provide an effective degree of freedom (DOF) for unsteady design of turbomachinery.

scholarly journals Numerical analysis of a leading edge tubercle hydrofoil in turbulent regime

2019 ◽  
Vol 878 ◽  
pp. 292-305 ◽  
Author(s):  
Blanca Pena ◽  
Ema Muk-Pavic ◽  
Giles Thomas ◽  
Patrick Fitzsimmons
Keyword(s):  
Numerical Analysis ◽  
Turbulent Flow ◽  
Flow Regime ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Main Flow ◽  
Hydrodynamic Performance ◽  
Turbulent Regime ◽  
Transitional Regime ◽  
Turbulent Flow Regime

This paper presents a numerical performance evaluation of the leading edge tubercles hydrofoil with particular focus on a fully turbulent flow regime. Efforts were focused on the setting up of an appropriate numerical approach required for an in-depth analysis of this phenomenon, being able to predict the main flow features and the hydrodynamic performance of the foil when operating at high Reynolds numbers. The numerical analysis was conducted using an improved delayed detached eddy simulation for Reynolds numbers corresponding to the transitional and fully turbulent flow regimes at different angles of attack for the pre-stall and post-stall regimes. The results show that tubercles operating in turbulent flow improve the hydrodynamic performance of the foil when compared to a transitional flow regime. Flow separation was identified behind the tubercle troughs, but was significantly reduced when operating in a turbulent regime and for which we have identified the main flow mechanisms. This finding confirms that the tubercle effect identified in a transitional regime is not lost in a turbulent flow. Furthermore, when the hydrofoil operates in the turbulent flow regime, the transition to a turbulent regime takes place further upstream. This phenomenon suppresses a formation of a laminar separation bubble and therefore the hydrofoil exhibits a superior hydrodynamic performance when compared to the same foil in the transitional regime.

Sign in / Sign up

Export Citation Format

Share Document