Vane Configuration Research Articles

Diverse feather shape evolution enabled by coupling anisotropic signalling modules with self-organizing branching programme

Adaptation of feathered dinosaurs and Mesozoic birds to new ecological niches was potentiated by rapid diversification of feather vane shapes. The molecular mechanism driving this spectacular process remains unclear. Here, through morphology analysis, transcriptome profiling, functional perturbations and mathematical simulations, we find that mesenchyme-derived GDF10 and GREM1 are major controllers for the topologies of rachidial and barb generative zones (setting vane boundaries), respectively, by tuning the periodic-branching programme of epithelial progenitors. Their interactions with the anterior–posterior WNT gradient establish the bilateral-symmetric vane configuration. Additionally, combinatory effects of CYP26B1, CRABP1 and RALDH3 establish dynamic retinoic acid (RA) landscapes in feather mesenchyme, which modulate GREM1 expression and epithelial cell shapes. Incremental changes of RA gradient slopes establish a continuum of asymmetric flight feathers along the wing, while switch-like modulation of RA signalling confers distinct vane shapes between feather tracts. Therefore, the co-option of anisotropic signalling modules introduced new dimensions of feather shape diversification.

CFD analysis on mixing effects of spacer grids with different dimples and sizes for advanced fuel assemblies

Abstract The thermal hydraulic characteristics of a mixing vane grid are largely dependent on the structure of key components, such as strip, spring, dimple, weld nugget, as well as the mixing vane configuration. In this paper, several types of spacer grids with different dimple shapes are modeled under subcooled boiling conditions. Prior to the application of CFD on the dimple shape analysis, the mixing effects of spacer grids were studied. After the dimple shape analysis, the side channel effect is discussed by comparing the simulation results of a 3 × 3 and a 5 × 5 spacer grid. The two phase flow CFD models in this study are validated through simple geometry showing that the calculated void fraction is in good agreement with the experimental data. The dimple comparison result shows that varying dimple structures can result in different temperatures, lateral velocities and void fraction distributions downstream of the spacer grids. Comparison of two sizes of spacer grids demonstrate that the side channel generates different flow distribution pattern in the center channel.

Numerical analysis of the steam flow field in shell and tube heat exchanger

Abstract In the paper, the results of numerical simulations of the steam flow in a shell and tube heat exchanger are presented. The efficiency of different models of turbulence was tested. In numerical calculations the following turbulence models were used: k-ε, RNG k-ε, Wilcox k-ω, Chen-Kim k-ε, and Lam-Bremhorst k-ε. Numerical analysis of the steam flow was carried out assuming that the flow at the inlet section of the heat exchanger were divided into three parts. The angle of steam flow at inlet section was determined individually in order to obtain the best configuration of entry vanes and hence improve the heat exchanger construction. Results of numerical studies were verified experimentally for a real heat exchanger. The modification of the inlet flow direction according to theoretical considerations causes the increase of thermal power of a heat exchanger of about 14%.

Effect of vane configuration on yield stress measurements of cement pastes

The reliable yield stress (τ0) measurement of cement pastes requires selection of appropriate vane configuration and thorough understanding of shear stress distribution acting on top, bottom, and sides of the vane. In this project, 11 vanes containing 2–6 blades, height/diameter ratio (H/D) varying from 2.4 to 1.5, and various shapes including cylindrical, conical, and coaxial-cylindrical were considered. The data obtained were normalized with respect to the cohesion (C) determined using the direct shear method. Test results have shown that vanes made with gradually reduced H/D and/or having conical shapes led to relatively increased τ0 values. For given H/D, the use of coaxial-cylindrical vanes resulted in abrupt breakdown of material structure along with the lowest τ0 responses. The presence of slots is believed to minimize the end effects and strengthen the assumption of shearing taking place within the suspension, which could be advantageous in τ0 measurements.

The optical design of highly efficient cold shield in IR detector based on ASAP

In order to obtain higher stray radiation suppression of a cold shield and enhance the cold shield efficiency of cooled infrared system, different configurations of the vanes inside cold shield are proposed. The effects of these configurations of vanes on stray radiation suppression are simulated and analysed by Advanced Systems Analysis Program (ASAP software), which not only trace ray by Monte Carlo method but also simulate the scattering of each surface. According to the analysis of results, vane plays an important role in the improvement of cold shield efficiency and the suppression of stray radiation. The cold shield with 6 vanes characterized by rounded-square hole, whose configuration is calculated based on the principle of laying out a set of vanes, suppresses 99.5% more stray radiation comparing to the original one without any vanes. However, considering that the cold shield with 6 vanes is complicated and difficult to fabricate, the cold shield with 3 vanes owing rounded-square hole is selected, since its stray radiation suppression level is acceptable.

Liquid–Liquid Mixing Studies in Annular Centrifugal Contactors Comparing Stationary Mixing Vane Options

Comparative studies of multiphase operation of an annular centrifugal contactor show the impact of housing stationary mixing vane configuration. A number of experimental results for several different mixing vane options are reported for operation of a 12.5 cm engineering-scale contactor unit. Fewer straight vanes give greater mixing-zone hold-up compared to curved vanes. Quantitative comparison of droplet size distribution also showed a significant decrease in mean diameter for four straight vanes versus eight curved vanes. This set of measurements gives a compelling case for careful consideration of mixing vane geometry when evaluating hydraulic operation and extraction process efficiency of annular centrifugal contactors.

Measurements of Hub Flow Interaction on Film Cooled Nozzle Guide Vane in Transonic Annular Cascade

An experimental study has been performed in a transonic annular sector cascade of nozzle guide vanes (NGVs) to investigate the aerodynamic performance and the interaction between hub film cooling and mainstream flow. The focus of the study is on the endwalls, specifically the interaction between the hub film cooling and the mainstream. Carbon dioxide (CO2) has been supplied to the coolant holes to serve as tracer gas. Measurements of CO2 concentration downstream of the vane trailing edge (TE) can be used to visualize the mixing of the coolant flow with the mainstream. Flow field measurements are performed in the downstream plane with a five-hole probe to characterize the aerodynamics in the vane. Results are presented for the fully cooled and partially cooled vane (only hub cooling) configurations. Data presented at the downstream plane include concentration contour, axial vorticity, velocity vectors, and yaw and pitch angles. From these investigations, secondary flow structures such as the horseshoe vortex, passage vortex, can be identified and show the cooling flow significantly impacts the secondary flow and downstream flow field. The results suggest that there is a region on the pressure side (PS) of the vane TE where the coolant concentrations are very low suggesting that the cooling air introduced at the platform upstream of the leading edge (LE) does not reach the PS endwall, potentially creating a local hotspot.

CFD Analysis for the Turbulent Flow Distribution in a Fuel Assembly with the Split-Type Mixing Vanes by Using the Advanced Scale-Resolving Turbulence Models

In general, the turbulent flow inside PWR (Pressurized Water Reactor) fuel assembly depends on the mixing vane configuration and the pattern of the mixing vane arrangement on the strap of the spacer grid. In this study, in order to examine the turbulent flow structure inside fuel assembly with the split-type mixing vanes, simulations were conducted with the commercial CFD (Computational Fluid Dynamics) software, ANSYS CFX R.14. Two different types of turbulence models, i.e. SAS (Scale-Adaptive Simulation)-SST (Shear Stress Transport) and DES (Detached Eddy Simulation), were used. The predicted results were compared with the measured data from the MATiS-H (Measurement and Analysis of Turbulent Mixing in Subchannels-Horizontal) test facility. Although there were locally differences between the prediction and the measurement, ANSYS CFX R.14 predicted the time averaged velocity field in the reliable level. The predicted horizontal and vertical velocity components were more in agreement with the measured data than the axial velocity component. There was no significant difference in the prediction accuracy of both turbulence models.

Sound Generated by Fan Wakes and Validation with Experiments

This paper presents a validation of the rotor-wake/stator interaction code, CAAT-S, with NASA Source Diagnostic Test (SDT) experiments. CAAT-S is a computationally efficient three-dimensional code based on the Euler equations linearized about a nonlinear rotational mean flow. It accounts for the flow swirl, the blade and fan 3D geometry and loading, and yields directly the radiated sound in terms of the duct acoustic modes. Two exit guide vane configurations, three power levels, and three blade passing frequencies (BPF) are considered. The power levels presented are taken at approach, cutback, and takeoff conditions for (a) the SDT low vane count (LVC) stator and (b) the SDT low noise (LN) stator. The mean flow and wake profiles are taken from the SDT experiments and exhibit strong radial dependencies. The reduced frequencies, based on the blade tip and speed of sound, associated with SDT data range from 15 for the 1BPF at approach power to 72 for 3 BPF at takeoff power. This produces a large number of propagating acoustic modes and makes the prediction of the vane forces and the radiated sound power a real computational challenge. Improved nonreflecting boundary conditions are developed extending the capability of CAAT-S to resolve the large number of high frequency modes, and making it suitable for turbofan engine noise prediction. CAAT-S calculated sound power level (PWL) underpredicts data by about 3 dB for both LVC and LN configurations. However, CAAT-S trend predictions are within the scatter of the experimental data. These results validate CAAT-S for moderate to high subsonic Mach numbers and over a broad range of blade passing frequencies.

EXPERIMENTAL STUDY OF PRESSURE DROP AND HEAT TRANSFER IN A U-BEND CHANNEL WITH VARIOUS GUIDE VANES AND RIBS

An experimental study was conducted to investigate pressure drop and heat transfer in a U-bend section with various configurations of guide vanes and two kinds of rib shapes on the outer wall. Ten guide vane types were tested. Results highlight that the use of special guide vanes can reduce the pressure drop penalty up to a maximum of 31%. However, guide vanes are usually associated with heat transfer reduction. To further enhance heat transfer, transverse and V-shaped ribs were attached on the outer wall. Thermal performance evaluation showed that the 45 degrees V-shaped downstream-pointing ribs coupled with guide vane configuration 5 give the best thermal performance. The results of this study can be employed to improve the internal design of modern gas turbine blade cooling systems. (Less)

A validated design methodology for a closed-loop subsonic wind tunnel

A systematic investigation into the design and simulation of flow parameters in a closed-loop wind tunnel was carried out using Computational Fluid Dynamics (CFD). The analytical model for estimating pressure losses were directed as input boundary conditions. Full-scale model of the entire wind tunnel was considered instead of the conventional approach, in which only test section flow is simulated. This allowed for optimisation of flow quality not only in the test section but also the flow in the entire circuit. Analysis of the guide vane configurations showed that test section flow quality was more affected by flow conditions in upstream than downstream sections. Hence, special attention must be given while designing the vanes at upstream turns particularly corners in line with the test section. Validation of the test section with block model showed that CFD was able to replicate wind tunnel measurements of velocity, turbulence intensity and pressure coefficient with error below 10%.

Numerical investigation of fluid flow and heat transfer characteristics on the aerodynamics of ventilated disc brake rotor using CFD

Ventilated brake discs are used in high speed vehicles. The brake disc is an important component in the braking system which is expected to withstand and dissipate the heat generated during the braking event. In the present work, an attempt is made to study the effect of vane-shape on the flow-field and heat transfer characteristics for different configurations of vanes and at different speeds numerically. Three types of rotor configurations circular pillared, modified taper radial and diamond pillar vanes were considered for the numerical analysis. A rotor segment of 20? was considered for the numerical analysis due to its rotational symmetry. The pre processing is carried out with the help of ICEM-CFD and analysis is carried out using ANSYS CFX 12.1. The three dimensional flow through the brake rotor vanes has been simulated by solving the appropriate governing equations viz. conservation of mass, momentum and energy using the commercial CFD tool, ANSYS CFX 12. The predicted results have been validated with the results available in the literature. Circular pillar rotor vanes are found to have more uniform pressure and velocity distribution which results in more uniform temperature drop around the vanes. The effect of number and diameter of vanes in the circular pillared rotor is studied and the geometry is optimized for better mass flow and heat dissipation characteristics.

Determination of appropriate configuration of submerged vanes using fuzzy TOPSIS optimization

Submerged vanes are river-training structures installed vertically in front of intake ports to exclude sediment at water intakes. The performance of submerged vanes depends on their dimensions, configuration and shape. This study was aimed at numerically investigating the effect of vane configuration on sedimentation in a 90° intake from a straight channel, and determine an appropriate configuration for installing the vanes. Simulations were done using the FLUENT mathematical model, and the fuzzy technique order performance by similarity to ideal solution multi-objective optimization method was used for choosing the appropriate configuration. All simulations were done for the three discharge ratios of 0.11, 0.16 and 0.21. The results showed that a longitudinal distance of nine times the vane height, a transverse distance of three times the vane height and 25° angle of attack are the appropriate parameters for the configuration of submerged vanes to control sediment in front of intake ports.

Map Width Enhancement Technique for a Turbocharger Compressor

This paper presents an investigation of map width enhancement and the performance improvement of a turbocharger compressor using a series of static vanes in the annular cavity of a classical bleed slot system. The investigation has been carried out using both experimental and numerical analysis. The compressor stage used for this study is from a turbocharger unit used in heavy duty diesel engines of approximately 300 kW. Two types of vanes were designed and added to the annular cavity of the baseline classical bleed slot system. The purpose of the annular cavity vane technique is to remove some of the swirl that can be carried through the bleed slot system, which would influence the pressure ratio. In addition to this, the series of cavity vanes provides a better guidance to the slot recirculating flow before it mixes with the impeller main inlet flow. Better guidance of the flow improves the mixing at the inducer inlet in the circumferential direction. As a consequence, the stability of the compressor is improved at lower flow rates and a wider map can be achieved. The impact of two cavity vane designs on the map width and performance of the compressor was highlighted through a detailed analysis of the impeller flow field. The numerical and experimental study revealed that an effective vane design can improve the map width and pressure ratio characteristic without an efficiency penalty compared to the classical bleed slot system without vanes. The comparison study between the cavity vane and noncavity vane configurations presented in this paper showed that the map width was improved by 14.3% due to a significant reduction in surge flow and the peak pressure ratio was improved by 2.25% with the addition of a series of cavity vanes in the annular cavity of the bleed slot system.

Heat-Transfer Characteristics of a Non-Rotating Two-Pass Rectangular Duct With Various Guide Vanes in the Tip Turn Region

The present study investigated convective heat transfer inside a two-pass rectangular duct with guide vanes in the turning region. The objective was to determine the effect of the guide vanes on blade-tip cooling. The duct had a hydraulic diameter (Dh) of 26.67 mm and an aspect ratio (AR) of 5. The duct inlet width was 80 mm, and the distance between the tip of the divider and the tip wall of the duct was also 80 mm. Various guide vane configurations were used in the turning region. The Reynolds number (Re), based on the hydraulic diameter, was held constant at 10,000. The naphthalene sublimation technique was used to determine the detailed local heat-transfer coefficients, using the heat-and mass-transfer analogy. The results indicate that guide vanes in the turning region enhance heat transfer in the blade-tip region. The guide vane on the second-pass side of the turning region had higher heat transfer than the guide vane on the first-pass side. Strong secondary flow enhanced heat transfer in the blade-tip region. Dean vortices induced by the guide vanes pushed the high-momentum core flow toward the tip wall, and heat transfer was increased in the turning region, but decreased in the second passage. Consequently, a guide vane on the second-pass side of the turning region generates high-heat-transfer rates on the tip surface, and can also increase the thermal performance factor in a two-pass duct.

Flow Measurements Using Particle Image Velocimetry in the Ultracompact Combustor

The potential for the ultracompact combustor (UCC) lie in future research to reduced fuel consumption and improved engine performance. Velocity measurements performed on the UCC test rig at the Air Force Institute of Technology revealed flow patterns and time-averaged turbulence statistics for data taken burning hydrogen fuel in a straight and a curved cavity vane configuration. Over an equivalence ratio from 0.7 to 1.5, the straight vane configuration showed spanwise velocity decreased linearly with distance from the cavity vane over the width of the main channel. Increasing the flow rates and holding the equivalence ratio and ratio of cavity to main airflow rates constant, flow velocities in the main channel showed an increase with the curved circumferential configuration but a decrease with the straight circumferential configuration. Turbulence intensity is expected to be a major contributing factor, specifically since measured at 15% and 21% in the main channel for the straight and curved configurations, respectively. The results also show how the radial vane cavity (RVC) created strong vorticity throughout the main flow supporting a recirculation zone for mixing. Peak vorticity occurred farthest from the cavity vane suggesting the angle of the radial vane cavity is effective in generating increasing flow rotation.

Impact of a multi-splitter vane configuration on the losses in a 1.5 turbine stage

This study presents the influence of a multi-body architecture on the aerodynamic performance of a low-pressure stator. The novel design has been studied numerically in a one-and-a-half stage turbine by means of a three-dimensional Reynolds-averaged Navier–Stokes simulation. This numerical research compares the behaviour of low-pressure stator composed of two different vanes against a conventional axisymmetric single airfoil row. The computational fluid dynamics predictions were calibrated using experimental aerodynamic measurements. Loss generation mechanisms were evaluated for the conventional and multi-splitter cascades at nominal and off-design conditions. At design conditions, the novel stator and conventional designs show comparable performances. However, the performance is drastically reduced at off-design conditions due to the sensitivity of the structural vanes to flow incidence. This article addresses the performance limitation for the multi-splitter vane configuration and presents a new tool to analyse the non-uniform flow conditions associated with such novel design. This procedure should help researchers in addressing any non-axisymmetric design.

Effect of Turning Vane Configurations on Heat Transfer and Pressure Drop in a Ribbed Internal Cooling System

The ribbed serpentine blade cooling system is a typical configuration in the modern gas turbine airfoil. In this study, experimental and the numerical efforts were carried out to investigate the local heat transfer and pressure drop distribution of a ribbed blade cooling system with different configurations in the turn region. A test rig containing a ribbed rectangular U-duct with a 180 deg round turn was built in Tsinghua University for this study. The transient liquid crystal method was applied to get the heat transfer distribution. Nine test cases with three turn configurations under three Reynolds numbers were carried out in the experiment. Pressure was measured along the duct in order to determine the influence of turning vane configurations on pressure drop. The test cases were also analyzed numerically based on Reynolds-averaged Navier-Stokes (RANS) with three different turbulence models: the k-ε model, the SST reattachment model, and the Omega Reynolds stress (ORS) turbulence model. Both the experimental and numerical results showed a significant influence of the turning vane configuration on the heat transfer and pressure drop in the convective cooling channel. Among the three configurations, the loss coefficient of turn in configuration 2 was lowest due to the introduction of turning vane. Even the ribs were added in the turn region of configuration 3, the loss coefficient and friction factor are reduced by 23% and 17.5%, respectively. Meanwhile, the heat transfer in baseline configuration is still the highest. As the introduction of turning vane, the heat transfer in the region after turn was reduced by 35%. In configuration 3, the heat transfer in the turn region was enhanced by 15% as the ribs installed in the turn region. In the before turn region, the pressure drop and heat transfer was not influenced by the turn configuration. All the turbulence models captured the trend of heat transfer and pressure drop distribution of three test sections correctly, but all provide overpredicted heat transfer results. Among the models, the ORS turbulence model provided the best prediction. While aiming at high heat transfer level and low pressure drop, it is suggested that a suitable turn configuration, especially with the turning vane and/or the ribs, is a promising way to meet the conflicted requirements of the heat transfer and pressure drop in the convective cooling system.

Experimental investigation of hinged and spring loaded rolling piston compressors pertaining to a turbo rotary engine

Abstract Hinged rolling piston compressor of a new thermodynamic cycle Pars engine promises high performance figures such as single stage high compression levels and higher volume flow discharge with competitively low input power and torque. The pumping characteristic of the present engine compressor unit has been increased by the implementation of a spring less vane configuration. The reciprocating vane which is usually operated by spring compression in air conditioning and refrigeration unit has been replaced by a hinge vane mechanism. At high speeds, the conventional spring loaded vane which is forced against the eccentrically moving rotor periphery does disconnect and starts rocking. With the new configuration, this mishap has been eliminated and subsequently resulting compressor pressure leaks have been avoided. Compressor experiments have been carried out at predetermined rotor speeds and compressed volume flow amounts and required shaft powers have been measured and derived accordingly. Experimentally determined pressure–volume relations have been compared with isentropic, isothermal, isochoric compressions as well as isobaric process. It is seen that at lower speeds, hinged vane compression is half way between isentropic and isochoric compressions whereas at high speed the compression process approaches further isochoric compression behavior. The isentropic compression efficiency of the hinged vane compressor is around 85% for pressures reaching 9 atm.

The Effect of Turning Vanes on Pressure Loss and Heat Transfer of a Ribbed Rectangular Two-Pass Internal Cooling Channel

Gas turbine blades are usually cooled by using ribbed serpentine internal cooling passages, which are fed by extracted compressor air. The individual straight ducts are connected by sharp 180 deg bends. The integration of turning vanes in the bend region lets one expect a significant reduction in pressure loss while keeping the heat transfer levels high. Therefore, the objective of the present study was to investigate the influence of different turning vane configurations on pressure loss and local heat transfer distribution. The investigations were conducted in a rectangular two-pass channel connected by a 180 deg sharp turn with a channel height-to-width ratio of H/W=2. The channel was equipped with 45 deg skewed ribs in a parallel arrangement with e/dh=0.1 and P/e=10. The tip-to-web distance was kept constant at Wel/W=1. Spatially resolved heat transfer distributions were obtained using the transient thermochromic liquid crystal technique. Furthermore static pressure measurements were conducted in order to determine the influence of turning vane configurations on pressure loss. Additionally, the configurations were investigated numerically by solving the Reynolds-averaged Navier–Stokes equations using the finite-volume solver FLUENT. The numerical grids were generated by the hybrid grid generator CENTAUR. Three different turbulence models were considered: the realizable k-ε model with two-layer wall treatment, the k-ω-SST model, and the v2-f turbulence model. The results showed a significant influence of the turning vane configuration on pressure loss and heat transfer in the bend region and the outlet pass. While using an appropriate turning vane configuration, pressure loss was reduced by about 25%, keeping the heat transfer at nearly the same level in the bend region. An inappropriate configuration led to an increase in pressure loss while the heat transfer was reduced in the bend region and outlet pass.