Dimensions Of Vanes Research Articles

Assessment of the effect of thermal barrier coating blockage on film cooling effectiveness: An experimental study of full-coverage turbine vane

The improved performance of turbine blades leads to increased temperature loads, thereby necessitating higher design standards for heat protection. Thermal barrier coating (TBCs) and film cooling are the predominant technologies employed for blade cooling. However, the application of thermal barrier coatings through spraying inevitably modifies the structure of film holes, resulting in deviations from the original design in film cooling. In this study, numerical calculations are used to examine the impact of TBCs blockage on coolant mixing and flow mechanisms in the film holes at typical locations on the vane surface. Additionally, models with actual engine vane dimensions were developed, and the full-coverage film cooling effectiveness (.) vanes with and without TBCs were measured using Pressure-sensitive paint (PSP). The results indicate that the impact of TBCs blockage on the cooling characteristics of cylindrical holes is more pronounced than that of laid-back fan-shaped holes. The TBCs blockage leads to a redistribution of coolant, causing a greater tendency for the coolant to flow out from the hole rows on the suction surface in the tested vane. This results in higher η on the suction surface for the vane with TBCs compared to the vane without TBCs, with a maximum increase of approximately 16.7%. For the other regions of the vane, TBCs spraying significantly reduced η at the leading edge of the vane (with a maximum reduction of approximately 52%) and slightly reduced η at the pressure surface for other regions of the vane (with a maximum reduction of approximately 7%). The application of TBCs reduces the uniformity of film coverage on vane surfaces, with a maximum reduction of approximately 22.5%.

The examination of circular and elliptical vanes under natural convection of nanofluid in a square chamber subject to radiation effects

In this paper, natural convection and radiation heat transfer of alumina-water nano-fluid in a square chamber at 45° has been simulated. The right wall of the chamber is cold, and there is a warm vane in the chamber. The vane can change form into horizontal ellipse, vertical ellipse, and circle. The other parts of the walls are insulated. The simulation was performed by using the algebraic control volume method and the SIMPLE algorithm. The effective parameters include the Rayleigh number, the radiation parameter, the nanoparticle volume percentage, and the vane dimensions. The paper focuses on finding the best vane size for maximum heat transfer. The results show that the intensification of the Rayleigh Number and addition of nanoparticles augments heat transfer. As the Rayleigh number enhances by up to 105, the Nusselt number increases up to 3 times. The intensification of nanoparticles concentration up to 4% also increases the Nusselt by 2.5% compared to water. Adding radiation heat transfer to the chamber can significantly increase heat transfer. Increasing the radiation parameter from 0 to 3 has increased the Nusselt number by more than 7 times. The Nusselt number increases with increases in both vane diameters. Nevertheless, it is strongly dependent on the horizontal diameter, and changes in the vertical diameter have little effect on the average Nusselt Number (Nuave).

Mechanical Efficiency Optimization of a Sliding Vane Rotary Compressor

This study presents the mechanical efficiency optimization of a sliding vane rotary compressor by using genetic algorithms. Relevant air properties, volume segments, vane loadings and stresses, friction forces, compression power, and power loss are calculated to determine the mechanical efficiency of a compressor. Design variables include the major axis length and minor axis length of the elliptical stator inner contour, thickness, depth and width of vanes, mechanical efficiency, rotor rotational speed, polytropic exponent, and angular locations of the inlet and outlet ports. The effects of the mutation rate, crossover rate, and population size of the genetic algorithms on these design variables are studied. The vane is thin and the variation effects of vane dimensions on the mechanical efficiency of the compressor are less significant than other design variables. Therefore, the dimensions of vanes can be eliminated as design variables. The mechanical efficiency of the compressor is 0.55. The optimum values of these design variables are recommended for further development of the compressor.

MEASUREMENT OF YIELD STRESS IN DARK CHOCOLATE USING CONTROLLED STRESS VANE METHOD

ABSTRACT The controlled stress vane method was used to measure the yield stress in dark chocolate. Three vanes with different L/D ratios and five different stress rates were used in three different chocolate formulations. The vane displacement data did not indicate a definite yield phenomenon. When the vane displacement data were transformed into a ratio of vane velocity to elapsed time, the square root of vane velocity (SV) or the cube root of displacement, a definite yield phenomenon was observed. The SV was preferred on the basis of physical considerations and the linear regression of its derived yield stress on vane dimensions, stress rate and chocolate particle size. The value of the yield stress was the least when determined for a vane height to diameter ratio of 2 and at a stress rate of 3 Pa/min using the SV transformation.

Optimization of Vane-Parameters for Gain-Frequency Response of Vane-Loaded Gyro-TWT

This paper discusses an analytical method to study the effects of the vane-parameters on the gain-frequency response of an azimuthally periodic vane-loaded cylindrical waveguide interaction structure for the gyro-traveling wave tube (gyro-TWT) amplifier in the small-orbit TE01 waveguide mode configuration. The vane-loaded gyro-TWT enables the higher gain than that of the smooth-wall device. An optimum choice of the vane dimensions causes a change in the frequency corresponding to the peak-gain.

Direct Yield Stress Measurement with the Vane Method

In the vane method for measuring the yield stress, the conventional analysis assumes that the stress is uniformly distributed on a cylindrical sheared surface to calculate the yield stress from the maximum torque and vane dimensions. By using two simple procedures, the present work shows that this assumption is justified at the moment of yielding. The yield stress calculated using the proposed methods compares favorably with that obtained with the conventional procedure. A comparison with the yield stress independently determined by other methods again confirms the usefulness of the vane technique as a simple but accurate method for direct yield stress measurement.

Rate of Shear Effects on Vane Shear Strength

A series of laboratory vane shear tests was performed on sedimented samples of kaolinite and slaked Pierre shale to determine the effects of shear rate and vane dimensions on measured strength. Results of the tests were expressed in terms of shear strength on a vertical plane and were plotted versus average shear rate. For kaolinite samples vane shear strength decreased as shear rate increased because of partial drainage occurring at slower shear rates. However, for the highly plastic Pierre shale vane, shear strength increased as shear rate increased because of undrained creep occurring at slower rates of shear. Test results for kaolinite and Pierre shale are compared to published information from other studies.

Optimum Design of a Potentially Dispersion-Free Helical Slow-Wave Circuit of a Broad-Band TWT (Short Paper)

The results of an equivalent circuit analysis are studied for a potentially dispersion-free slow-wave circuit of a TWT which consists of a dielectric-supported helix in a metal shell provided with vanes. The optimum vane dimensions are predicted, which should be helpful in broadbanding the performance of a TWT.

Evaluation and Design of Wind Vanes

Abstract Wind vane motion constants (damping ratio, natural wavelength and decay distance) are derived in a way which can accomodate both mechanical friction and the presence of a propeller. The motion is shown to be insufficiently described by a second order equation because of the way in which the aerodynamic torque changes with angle of attack. This implies that any measurements of vane constants made in the wind tunnel at initial angles of attack above 20° are not representative for the vane. Simple relations between easily measured vane dimensions and motion constants are derived, and vane motion is proved to be independent of the fin area. The WMO requirement for wind vanes is translated into motion constants and shown to be fulfilled for any vane with a damping ratio of 0.30. For turbulence measurements a certain short-wavelength reliability limit for vane-measured spectra is proposed. Experimental comparison of basic fin configurations shows the inferiority of streamlined and splayed fins. General...