Tip Vane Research Articles

Aerodynamic noise prediction and reduction of H-Darrieus vertical axis wind turbine

ABSTRACT small scale VAWTs are erected in built up areas while in these locations they will be inherently close to people. Therefore, the noise radiated from a VAWT is very significant to make an investigation. In this work we carried out numerical prediction for aerodynamic acoustics of a H-Darrieus VAWT. The URANS equations is conducted to achieve the time-accurate results. The aero-acoustics noise prediction is simulated by using FW-H equation with low-Mach number assumptions. Simulations are performed under different tip speed ratios. In order to verify the accuracy of the numerical results, mean torque coefficient is compared with the experimental data. The tip-speed ratio, wind speed, receiver distance on the OASPL, distance between the source and receivers and blades number effects are investigated in this work. In addition, this work introduced a method of adding V and S tip vanes on the blade tip to reduce the aerodynamic noise of a H-VAWT. The result showed that two types of tip vanes can weaken the tip vortex and reduce the sound pressure level (SPL) of a H-VAWT.

Collocated attitude and vibrations control for square solar sails with tip vanes

This paper is devoted to developing collocated attitude and vibrations controllers for a square solar sail spacecraft containing four pre-tensioned triangular sails supported by flexible diagonal booms and four reflective control vanes at boom tips. Since the control torques for attitude control are created by the solar radiation pressure forces on the tip vanes, the attitude control problem is effectively non-collocated. The present work identifies collocated sensing for the tip vane forces which furnishes a passive input-output model. Various controllers are developed which furnish attitude and vibrations control. A finite-element-based linear structural model is used to evaluate the developed controllers and examine the controller-structure interactions.

Coupled 3D multiphysics analysis of 325 MHz ISNS RFQ structure

Abstract A 325 MHz, 3.0 MeV Radio Frequency Quadrupole (RFQ) is being developed for 1 GeV proton accelerator for proposed Indian Spallation Neutron Source (ISNS) facility at Raja Ramanna Centre for Advanced Technology, Indore. RFQ will be a normal conducting four vane resonating structure made of Oxygen Free Electronic (OFE) copper. During high power operation of RFQ, Radio Frequency (RF) field induced heating results in temperature rise, thermal deformations and shift in resonant frequency from designed values. Therefore thermal stability of RFQ is one of the important design issues. Various RF–thermal–structural coupled multiphysics analysis methodologies for thermal management of RFQ have been attempted in past and reported in literature. However, these efforts are primarily limited to 2D simulations for a thin slice of RFQ cross section and do not addresses for longitudinal temperature rise of cooling water, distribution of frequency tuners, vane tip modulations and vane cut back at the inlet and exit of RFQ structure. This paper proposes a finite element method (FEM) based multiphysics analysis methodology for numerical simulation of RFQ structure. The methodology consists of a complete 3D-RF-fluid–thermal–structural–RF coupled analysis for predicting temperature rise, thermal deformations and frequency shift of RFQ structure due to RF heating. All analysis (electromagnetic, fluid, thermal and structural) and their coupling are carried out using a single code namely ANSYS Mechanical. The simulated results from proposed methodology are compared with published work and a maximum error of less than 7% is obtained. The numerical comparison of described methodology with other multiphysics analysis methodologies (such as importing 2D field maps and using heat transfer coefficient from empirical relations) has been carried out. The described methodology is paving the way for the design and development of ISNS RFQ structure.

Kinematics of a balanced vane pump with circular tip vanes

This paper analyzes the kinematics of the vane-cam ring mechanism in balanced vane pumps, by considering both vanes with centered and not-centered circular tip. The motion of the vane, the position of the contact point and the evolution of the pressure angle are analytically determined in reference to a generic cam ring profile. The results of the kinematic analysis are used to obtain the constraints defining the admissibility of the vane geometry, which is described in terms of tip radius, vane thickness and tip center eccentricity. A parametric study is performed to show the capabilities of the proposed formulation and the influence of the vane design parameters on its kinematics. The analysis demonstrates that the vane kinematic motion in balanced vane pumps is mainly controlled by the tip radius and the tip center eccentricity, as long as the cam ring profile is defined. The tip radius is mainly responsible for the shape of the vane motion, while the tip center eccentricity has a major influence on its timing. Furthermore the effect of the cam ring profile is evaluated by demonstrating that shape and extension of the rise and fall phases influence on the vane geometry admissibility.

Computational Analysis of the Performance Characteristics of a Supercritical CO2 Centrifugal Compressor

A centrifugal compressor working with supercritical CO 2 (S-CO 2 ) has several advantages over other supercritical and conventional compressors. S-CO 2 is as dense as the liquid CO 2 and becomes difficult to compress. Thus, during the operation, the S-CO 2 centrifugal compressor requires lesser compression work than the gaseous CO 2 . The performance of S-CO 2 compressors is highly varying with tip clearance and vanes in the diffuser. To improve the performance of the S-CO 2 centrifugal compressor, knowledge about the influence of individual components on the performance characteristics is necessary. This present study considers an S-CO 2 compressor designed with traditional engineering design tools based on ideal gas behaviour and tested by SANDIA national laboratory. Three-dimensional, steady, viscous flow through the S-CO 2 compressor was analysed with computational fluid dynamics solver based on the finite volume method. Navier-Stokes equations are solved with K- ω (SST) turbulence model at operating conditions in the supercritical regime. Performance of the impeller, the main component of the centrifugal compressor is compared with the impeller with vaneless diffuser and vaned diffuser configurations. The flow characteristics of the shrouded impeller are also studied to analyse the tip-leakage effect.

Numerical study of guide vane effects on reacting flow characteristics in a trapped vortex combustor

ABSTRACTTrapped Vortex Combustor (TVC) is a simple and promising concept for flame stabilizations in aero-engines. In this concept, cavity trapped vortices are used to establish pilot flames for robust combustion performance. The main objective of this study is to numerically investigate the effects of guide vanes on the performance of a TVC installed in a small ramjet. Three dimensional steady and unsteady simulations are performed by solving the Reynolds-Averaged Navier-Stokes (RANS) equations with the commercial flow solver ANSYS FLUENT v16.1. The shear stress transport (SST) model is selected for the turbulence closure, and the eddy dissipation model (EDM) is used for the combustion modeling of gaseous propane (C3H8) fuel. In the current work, four cases are studied: (1) TVC without vanes, (2) TVC with a square-tip vane, (3) TVC with a sharp-tip vane, and (4) TVC with a sharp-tip vane and additional cavity fuel injection. Numerical results reveal that the introduction of guide vanes significantly changes the cavity vortex structure. Unlike the previous single cavity vortex, a counter-rotating dual-vortex structure is formed inside the cavity when the vane is implemented: one vortex is generated by the air jet guided by the vane and the other is the wake vortex downstream the vane. Because of the additional air introduced into the cavity by the guide vane, a fuel-lean mixture is obtained inside the cavity. This indicates fuel can be further injected inside to make full use of the air. Combustion results show that compared with the TVC without vanes, case 4 increases the combustion efficiency by 14% (to 99.3%) at the exit of combustor. Meanwhile, the combination of the sharp tip vane and cavity fuel injection only provides around 5% increase in aerodynamic drag and 3.9% in overall total pressure loss.

Effects of Tip Vanes on Aerodynamic Performance of H-Type VAWT

In order to investigate the effect of the tip vanes on the aerodynamic performance of H-type vertical axis wind turbines (H-VAWTs), adopting the method of the CFD numerical simulation to analysis blade surface pressure distribution, tip vortex and power coefficient of H-VAWTs that are installed two different kinds of tip vanes on both ends of the blade and not installed. The result showed that the tip vanes can weaken the tip vortex, increase the blade surface pressure difference and improve the power coefficient of the H-VAWT. In addition, the power coefficient of the rotor with V type tip vane was greater than that of the rotor with S type tip vane. The maximum improvement achieved was a 37.5 percent increase in power coefficient with V type tip vane and a 33 percent increase in power coefficient with S type tip vane, the tip vanes made the power augmentation of the H-VAWT.

Numerical Investigation the Effect of the Different Tip Vanes on the Loading of an H-VAWT

In this paper, the effect of the three typical tip vanes on the loading of an H-VAWT is investigated by employing the three-dimensional unsteady numerical simulation method. The results show that the both transient tangential force coefficient (CT) and normal force coefficient (Cn) have obvious change when the winglet and the V type vane is used at the blade's tip, respectively. However, in three tip vanes, the CT average value is the lowest and the CT fluctuation characteristic is the highest when the winglet is used. Although the winglet and V type vane contribute to change the transient CT and Cn, the normal force is increased too, it results in increasing fatigue loading and decreasing lifetime for H-VAWT. By comparison, the effect of the plate vane on the loading is weaker. Additionally, the winglet is advantage to improve power coefficient in the low tip speed ratio.

GS0911 垂直軸揚力型風車における翼端渦抑制用固定板に関する研究

A wingtip vortex is one factor contributing to the drag that occurs to a wing. We proposed using stationary plates instead of conventional wingtip vortex restraint devices such as tip vanes. In this research, the prototype plates that were designed had three diameters: 75, 150, and 250 mm. The windmill performance with these plates was investigated experimentally. The distance from the windmill blades to the plates was 10 mm. The apparatus used in this experiment were a Gottingen-type wind tunnel, tachometer, manometer, and pitot tube. As the results showed, the windmill with the 250 mm diameter plates had the best performance in the test conditions. In addition, the performance with plates was better than the performance without plates.

Numerical simulation on effect of pressure distribution of wind turbine blade with a tip vane

It is important to study the pressure distribution on the blade and in the adjacent area while searching the power augmentation theory with adding a tip vane to the wind turbine. This paper shows the CFD simulation relationship of the pressure distribution on the rotor blade and in the adjacent area, after calculating the pressure of the different chordwise and spanwise point on the blade with the tip vane-V(8.8×8) and without the tip vane under tip speed ratio λ 4.5. Combining the isobaric section figure in certain location, it can be seen that the tip vane improve the pressure difference between pressure and suction surface. The most influenced zone is found and these can further display the power augmentation theory of the wind turbine using the tip vane. The simulation calculation was based on N-S equations. 3-D, steady, implicit solver was chosen. Turbulence model was k-ω SST. Discretization scheme is SECOND ORDER UPWIND. Pressure-velocity coupling was a typical SIMPLE scheme. In the whole grid system, two-divided grid formation was adopted, that is, inner region and outer region. Inner region including rectangular solid blade and neighboring, outer region is semi-cylinder. There were together 720,000 nodes with tetra-prism unstructured mesh.

Rotor Configuration Effects on the Performance of a HAWT With Tip-Mounted Mie-Type Vanes

In this paper, the relationships between the power augmentation of a HAWT due to Mie-type tip vane application and other factors influencing the efficiency of a wind turbine such as the blade aspect ratio, number of blades, blade pitch angle and Reynolds number are investigated. Experiments were carried out in a wind tunnel with an open, 3.6 m diameter, test section. Rotor models included two- and three-blade upwind turbines with four sets of blades with different aspect ratios. With the rotor blades tested, a maximum power augmentation of about 14.5% was achieved due to Mie vane application. The relationships between power augmentation due to the Mie vane and the above factors are investigated. It is found that the application of a tip-mounted Mie vane results in a larger increase in maximum power coefficient for rotors with smaller aspect ratios and for lower wind speeds. Surface oil film and surface tuft visualization methods were used to detect the flow patterns at the blade tip. Addition of the Mie vanes causes significant changes in flow behavior near the blade tip, resulting in additional blade lift.

Power Augmentation of a HAWT by Mie-type Tip Vanes, considering Wind Tunnel Flow Visualisation, Blade-Aspect Ratios and Reynolds Number

Wind tunnel results are reported concerning the effects of blade aspect ratio and Reynolds number on the performance of a horizontal axis wind turbine (HAWT) with Mie-type1 tip attachments. The flow behaviour around the blade tips and the Mie-type tip vanes is presented. Detailed surface oil film visualization and velocity measurements around the blade tips, with and without Mie vanes, were obtained with the two-dimensional, Laser-Doppler Velocimetry method. Experiments were performed with rotors having blades with different aspect ratio and operating at different Reynolds numbers. The properties of the vortices generated by the Mie vanes and the blade tips were carefully studied. It was found that increased power augmentation by Mie vanes is achieved with blades having smaller aspect ratio and smaller Reynolds number.

The effects of propeller tip vane on flow-field behavior

This paper investigates the effects of attaching a tip vane to a propeller blade on the development and propagation of a tip vortex. The study employed a two-bladed propeller operating with and without a tip vane. Evaluation of the tip vortex was studied by using both smoke-wire flow visualization, hot wire anemometer, and strain gauge load-cell techniques. The mean velocity distributions and the velocity unsteadiness data as well as thrust, input power and efficiencies were obtained. Experiments were repeated at various rotating speeds ranging from 2000 to 5000 rpm.

Power Augmentation of a Horizontal Axis Wind Turbine Using a Mie Type Tip Vane: Velocity Distribution Around the Tip of a HAWT Blade With and Without a Mie Type Tip Vane

Power augmentation and velocity measurements in the wake of a HAWT blade with Mie type tip vane (a tip device on the main blade) are presented. The maximum Cp with a Mie type tip vane is found to be 15 percent larger than that without the Mie type tip vane. Power augmentation caused by the Mie type tip vane is mainly due to the reduction of tip vortex and the diffusing effect by the Mie type tip vane. The effects of a Mie type tip vane are quantitatively verified by the velocity distributions around the tip of the main blade. The velocity distribution was measured by three-dimensional hot wire probes, which measured the axial, radial, and tangential velocity components. The circulation distributions along the main blade with a Mie type tip vane and without a Mie type tip vane were obtained from the measured velocity distributions. A strong reduction of bound vorticity is found for the main blade tip without the Mie type tip vane, whereas the bound vorticity persists on the main blade tip with the Mie type tip vane.

Power Augmentation Effects of a Horizontal Axis Wind Turbine With a Tip Vane—Part 1: Turbine Performance and Tip Vane Configuration

This paper describes the experimental results of output power augmentation of a horizontal axis wind turbine with a tip vane. In order to find the relationship between the performance of the turbine and the configuration of the tip vane, various types and sizes were used. It was found that V-type and S-type tip vanes can improve turbine performance. Also, the dimensions of V- and S-type tip vanes were investigated. The maximum improvement achieved was a 25 percent increase in power in an existing wind turbine without a tip vane.

Power Augmentation Effects of a Horizontal Axis Wind Turbine With a Tip Vane—Part 2: Flow Visualization

This paper presents a discussion of the physics of the flow discussed in our first report (Shimizu, Y. et al., 1990). By visualizing the flow around the tip vane, the following results were drawn: 1) The strength of the tip vortex, the induced drag and turbulence on the blade tip can be diminished with a tip vane. 2) The inflow rate to the rotary surface of wind turbine can be increased with the tip vane.

Rotation Speed Control of Horizontal-Axis Wind Turbine by Tip Vane.

This paper describes the rotation speed control of a horizontal-axis wind turbine. A tip vane has the excellent capability of improving the performance of the horizontal-axis wind turbine. Also, we found that the rotation speed of the wind turbine is controlled by changing the sweep angle of the tip vane. The relationships among the sweep angle of the tip vane, the change of wind speed and the rotor speed are investigated. As a result, a method to maintain constant rotor speed for changing wind speed, by means of an electromechanical apparatus, is developed.

Velocity distribution around the tip vane of HAWT blade.

Power augmentation of HAWT with tip vane has been achieved at Mie University. This reason are mainly considered due to the reduction of the tip vortex and the diffuser effect by the tip vane. However, these effects has not been verified quantitatively. To get the detailed structure of the wake of a rotor model with tip vane, the near wake measurements have been performed. In these measurements, a three dimensional hot wire probe was used to measure the three velocity components : axial, radial and tangential component. The result of measurements revealed the preceding effects of the tip vane. Some other phenomena of the tip vane have been verified.

Rotation Speed Control of Horizontal Axis Wind Turbine by Tip Vane.

The paper describes about the rotation speed control of horizontal axis wind turbine by tip vane. Tip vane has the excellent ability to improve the performance of horizontal axis wind turbine. Also, we found that the rotation speed of wind turbine is controlled by the change of sweep angle of tip vane. The relationships among the sweep angle of tip vane, the change of wind speed and the rotor speed are investigated. As the results, the method to keep the constant rotor speed by means of electro-mechanical apparatus is developed, when wind speed changed.

Power Augmentation of Horizontal Axis Wind Turbine with Tip Vane. 3rd Report, In Case of Taper Blade.

Output of horizontal axis wind turbine is improved by tip vane. This paper describes the results when the taper blade are used to the wind turbine. Comparing 1st report with 3rd one, the power coefficient on the turbine with the taper blade is more larger than that on one with the equi-chord length. The maximum power coefficient reaches to 0.48 in case of the taper blade. Also, this paper describes the effects of setting angles of tip vane to the tip main blade.