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The purpose of this paper is to investigate and compare the effects of rod and vane-type vortex generators for wind turbine applications. In large wind turbine rotors, an attached flow at all sections along the span direction is difficult to achieve which leads to an increase in aerodynamic losses, noise generation, and fatigue stress. Therefore, flow control strategies such as vortex generators (VGs) are beneficial to improve performance.

The benefits of the application of rod-type vortex generators (RVGs) to control flow separation on a wind turbine airfoil are assessed numerically using computational fluid dynamics (CFD). The validation of the computational model is conducted against the experimental data available for the DU96-W-180 wind turbine airfoil equipped with 44 RVGs. In addition, a revised wind tunnel angle of attack (AoA) calibration procedure (based on CFD) is proposed that is applicable for separated flows. A comparison of the RVGs to the conventional vane-type vortex generators (VVGs) is presented for inflow velocity of 30 m/s and AoA leading to significant flow separation. A parametric evaluation of the geometric characteristics of both types of VGs is conducted to quantify the generated streamwise vortices.

The comparison of the induced flow structures and aerodynamic efficiency enhancements proves that RVGs may be used as an alternative to the more conventional VVGs applied on wind turbine blades for boundary layer separation control.

A new type of VG (rod) has been investigated and compared against conventional VG (vanes) for wind turbine applications.

Helicopter rotor blades are usually aerodynamically limited by the severe conditions present in every revolution: strong shock wave boundary layer interaction on the advancing side and dynamic stall on the retreating side. Therefore, different flow control strategies might be applied to improve the aerodynamic performance.

The present research is focussed on the application of passive rod vortex generators (RVGs) to control the flow separation induced by strong shock waves on helicopter rotor blades. The formation and development in time of the streamwise vortices are also investigated for a channel flow.

The proposed RVGs are able to generate streamwise vortices as strong as the well-known air-jet vortex generators. It has been demonstrated a faster vortex formation for the rod type. Therefore, this flow control device is preferred for applications in which a quick vortex formation is required. Besides, RVGs were implemented on helicopters rotor blades improving their aerodynamic performance (ratio thrust/power consumption).

A new type of vortex generator (rod) has been investigated in several configurations (channel flow and rotor blades).

The simulations of grid-resolved rod vortex generators (RVGs) require high computational cost and time. Additionally, the computational mesh topology must be adjusted to rods geometries. The purpose of this study is to propose the new source term model for RVG.

The model was proposed by modification of Bender, Anderson, Yagle (BAY) model used to predict flows around different type of vortex generators (VGs) – vanes. Original BAY model was built on lifting line theory. The proposed model was implemented in ANSYS Fluent by means of the user-defined function technique. Additional momentum and energy sources are imposed to transport equations.

The computational results of source term model were validated against experimental data and numerical simulation results for grid-resolved rod. It was shown that modified BAY model can be successfully used for RVG in complex cases. An example of BAY model application for RVG on transonic V2C airfoil with strongly oscillating shock waves is presented. Aerodynamic performance predicted numerically by means of both approaches (grid resolved RVG and modeled) is in good agreement, what indicates application opportunity of the proposed model to complex cases.

Modified BAY model can be used to simulate the influence of RVGs in complex real cases. It allows for time/cost reduction if the location or distribution of RVG has to be optimized on a profile, wing or in the channel.

In the paper, the new modification of BAY model was proposed to simulate RVGs. The presented results are innovative because of original approach to model RVGs.

The purpose of this paper is to describe numerical investigations focused on the reduction of separation and the aerodynamic enhancement of wind turbine blades by a rod vortex generator (RVG).

A flow modelling approach through the use of a Reynolds-averaged Navier–Stokes solver is used. The numerical tools are validated with experimental data for the NREL Phase VI rotor and the S809 aerofoil. The effect of rod vortex generator’s (RVG) configuration on aerofoil aerodynamic performance, flow structure and separation is analysed. RVGs’ chordwise locations and spanwise distance are considered, and the optimum configuration of the RVG is applied to the wind turbine rotor.

Results show that streamwise vortices created by RVGs lead to modification of flow structure in boundary layer. As a result, the implementation of RVGs on aerofoil has proven to decrease the flow separation and enhance the aerodynamic performance of aerofoils. The effect on flow structure and aerodynamic performance has shown to be dependent on dimensions, chordwise location and spanwise distribution of rods. The implementation of devices with the optimum configuration has shown to increase aerodynamic performance and to significantly reduce separation for selected conditions. Application of rods to the wind turbine rotor has proven to avoid the spanwise penetration of flow separation where applied, leading to reduction of flow separation and to aerodynamic enhancement.

The proposed RVGs have shown potential to enhance the aerodynamic performance of wind turbine rotors and profiles, making devices an alternative solution to the classical vortex generators for wind turbine applications.

To investigate the heat transfer enhancement performed by installing a rectangular plate turbulator for internal flow modification induced by vortex shedding.

The large eddy simulation (LES) and SIMPLE‐C method coupled with preconditioned conjugate gradient methods have been applied to the turbulent flow field and heat transfer enhancement of mixed convection in a block‐heated channel.

Provides information about heat transfer performance indicating that heat transfer performance can be affected by various width‐to‐height ratio of turbulator and Grasehof numbers with a constant Reynolds number. The results show that the installation of turbulator in cross‐flow above an upstream block can effectively enhance the heat transfer performance by suitable width‐to‐height ratio of turbulator and Grasehof numbers.

It is limited to two‐dimensional mean flow for the turbulent vortex‐shedding flow past a long square cylinder.

A very useful source of information and favorable advice for people developing heat transfer enhancement for electronic devices.

The results of this study may be of interest to engineers attempting to develop thermal control of electronic devices and to researchers interested in the turbulent flow‐modification aspects of heat transfer enhancement of mixed convection in a vertical channel.

This paper aims to describe a proposal for an innovative method of normal shock wave–turbulent boundary layer interaction (SBLI) and shock-induced separation control.

The concept is based on the introduction of a tangentially moving wall upstream of the shock wave and in the interaction region. The SBLI control mechanism may be implemented as a closed belt floating on an air cushion, sliding over two cylinders and forming the outer skin of the suction side of the airfoil. The presented exploratory numerical study is conducted with SPARC solver (steady 2D RANS). The effect of the moving wall is presented for the NACA 0012 airfoil operating in transonic conditions.

To assess the accuracy of obtained solutions, validation of the computational model is demonstrated against the experimental data of Harris, Ladson & Hill and Mineck & Hartwich (NASA Langley). The comparison is conducted not only for the reference (impermeable) but also for the perforated (permeable) surface NACA 0012 airfoils. Subsequent numerical analysis of SBLI control by moving wall confirms that for the selected velocity ratios, the method is able to improve the shock-upstream boundary layer and counteract flow separation, significantly increasing the airfoil aerodynamic performance.

The moving wall concept as a means of normal shock wave–turbulent boundary layer interaction and shock-induced separation control has been investigated in detail for the first time. The study quantified the necessary operational requirements of such a system and practicable aerodynamic efficiency gains and simultaneously revealed the considerable potential of this promising idea, stimulating a new direction for future investigations regarding SBLI control.

A numerical study has been conducted for the characteristics of the periodically fully developed turbulent flow and heat transfer in a channel with transverse opposite‐positioned fins. The Reynolds number range is 2 × 10⁴ to 7 × 10⁴. K‐ε model and wall function method were adopted during the calculation. The influence of the thermal boundary condition of the fin to the heat transfer has been verified. For the studied configuration the prominent feature that differs from the similar laminar heat transfer is the phenomenon of secondary peak of the Nusselt number distribution. Assessment of heat transfer enhancement under the constraint of the same pump power reveals that the effect of the configuration of the relative fin height, e/H, equal to 0.1 is superior to those of e/H equal to 0.15 and 0.2. Comparing with the results of the channel with rod disturbances, the studied configuration possesses nearly the same heat transfer enhancement effect. Transient simulations to cases with big fin have also been conducted to assure the validity of the steady algorithm.

For flow around elongated bluff bodies, flow separations would occur over both leading and trailing edges. Interactions between these two separations can be established through acoustic perturbation. In this paper, the flow and the acoustic fields of a D-shaped bluff body (length-to-height ratio L/H = 3.64) are investigated at height-based Reynolds number Re = 23,000 by experimental and numerical methods. The purpose of this paper is to study the acoustic feedback in the interaction of these two separated flows.

The flow field is measured by particle image velocimetry, hotwire velocimetry and surface oil flow visualization. The acoustic field is modeled in two dimensions by direct aeroacoustic simulation, which solves the compressible Navier–Stokes equations. The simulation is validated against the experimental results.

Separations occur at both the leading and the trailing edges. The leading-edge separation point and the reattaching flow oscillate in accordance with the trailing-edge vortex shedding. Significant pressure waves are generated at the trailing edge by the vortex shedding rather than the leading-edge vortices. Pressure-based cross-correlation analysis is conducted to clarify the effect of the pressure waves on the leading-edge flow structures.

The understanding of interactions of separated flows over elongated bluff bodies helps to predict aerodynamic drag, structural vibration and noise in engineering applications, such as the aerodynamics of buildings, bridges and road vehicles.

This paper clarifies the influence of acoustic perturbations in the interaction of separated flows over a D-shaped bluff body. The contribution of the leading- and the trailing-edge vortex in generating acoustic perturbations is investigated as well.

In an aircraft of the rotary wing type, a suspension rig, a rotatable wing assembly comprising a plurality of blades of aerofoil cross‐section rotatably mounted on said suspension rig adapted to lift said aircraft when said wing assembly is rotated, each of said blades having at least one jet orifice along its trailing edge, a series of rocket units and a manifold common to all rocket units integrally mounted upon said rotatable wing assembly, solid‐fuel rocket charges within said rocket motors, fluid conducting passages connecting the common manifold with the jet orifices in the blades, and means for igniting and expending said solid‐fuel rocket charges in sequence.