Vane Configuration Research Articles

Impact of Blowing and Density Ratio on the Film Cooling and Heat Transfer in an Aggressive Turbine Center Frame

Abstract It was shown in the previous study that the aft purge flows from the last stage of the high-pressure turbine (HPT) have a significant film cooling potential in the downstream turbine center frame (TCF) (Jagerhofer et al., 2023, “Heat Transfer and Film Cooling in an Aggressive Turbine Center Frame,” ASME J. Turbomach., 145(12), p. 121012). The TCF is a stationary duct that guides the flow from the HPT outlet to the low-pressure turbine (LPT) inlet and is the third most thermally loaded engine component. This article investigates the impact of different purge-to-mainstream blowing and density ratios on the film cooling effectiveness and the heat transfer coefficient in the TCF. The experiments were conducted in a product-representative 1.5-stage HPT-TCF-LPT vane configuration under Mach-similarity in the Transonic Test Turbine Facility (TTTF) at TU Graz. The blowing ratio has been demonstrated to be the dominant parameter for purge film cooling in TCFs since HPT purge flows typically have very low momentum. Even at twice the nominal blowing ratio, no cooling film detachment was observed on the TCF hub or shroud surface. Varying the density ratio in the experimentally possible range delivered no significant differences in the results. With increasing purge blowing ratios, the film cooling effectiveness in the TCF increases as expected, but the heat transfer also intensifies due to the purge injection. The circumferentially averaged film cooling on the hub scales relatively well with an offset version of the well-known Hartnett correlation (Hartnett et al., 1961, “Velocity Distributions, Temperature Distributions, Effectiveness and Heat Transfer for Air Injected Through a Tangential Slot Into a Turbulent Boundary Layer,” ASME J. Heat Transfer, 83(3), pp. 293–305) that takes into account the ingress-induced premixing of the purge flow in the cavities.

Impact of Turbine-Strut Clocking and Turbine Outlet Swirl on the Heat Transfer and Film Cooling in an Aggressive Turbine Center Frame

Abstract This study focuses on the thermal impact of the clocking position of the high-pressure turbine (HPT) vanes with respect to the turbine center frame (TCF) struts and the thermal impact of the HPT outlet swirl. The TCF is a stationary duct equipped with nonturning airfoils (struts), and it connects the HPT to the low-pressure turbine (LPT). The heat transfer coefficient and the purge film cooling effectiveness are measured in an aggressive TCF for two turbine-strut clocking positions and two HPT outlet swirl levels. The measurements are carried out in a product-representative 1.5-stage HPT-TCF-LPT vane configuration under Mach similarity. The unshrouded HPT is fully purged with four individually adjustable purge flows, and the film cooling effectiveness of these purge flows in the downstream TCF is investigated. The biggest influence of turbine-strut clocking was found for the heat transfer coefficient on the struts. By clocking the HPT vanes by half a vane pitch from the thermally least to the most favorable position, a significant heat transfer reduction was achieved for both the nominal and the increased HPT outlet swirl. Increasing the HPT outlet swirl increased the flow incidence of the TCF struts and affected the heat transfer along the struts significantly. On the TCF hub, the averaged heat transfer coefficient and the averaged purge film cooling effectiveness responded relatively robustly to all imposed operating point deviations with differences of less than 2%. However, the effects on the local heat transfer and film cooling distributions on the hub were more significant.

DDPM investigation on centrifugal slurry pump with inlet and sideline configuration retrofit

The inlet and sideline configuration modifications are widely investigated to alter regional particle fluid flow conditions, considering pressure, turbulence and erosion, therefore to improve energy saving and compartment longevity of centrifugal slurry pump. This paper aims to analyse pump hydraulic and erosion characteristics with proposed pump sideline and inlet configuration retrofit by the DDPM method. Specifically, the inlet guide vane number () and angle (), and sidelining vane (SDV) curvature are investigated in quantitative manner. Accordingly, by adjusting inlet vane configuration and placement, a trade-off between wall erosion and hydraulic performance is observed. The sidelining vane (SDV) design is suggested to avoid resultant counter-current flow formulation, therefore, to mitigate turbulence induced erosion in impeller and volute. However, the SDV modification effect on pump hydraulic head and efficiency is found marginal. In general, this study offers realistic guideline for performance improvement and device upgrading of centrifugal slurry pumps.

Performance of A Triboelectric Nanogenerator Utilising Coconut Husk Layer

Triboelectric nanogenerators, known as TENGs, offer great potential as versatile energy harvesting devices. In recent years, there has been a rise in TENG designs that prioritize compatibility with sustainable biomaterials, leading to new possibilities in green technology. The novelty of this work lies in its pioneering exploration of utilizing sustainable biomaterials, particularly coconut husk, within the field of Tribo-electric nanogenerators (TENGs). This study focuses on evaluating and characterizing coconut husk as TENG material considering factors such as rotational speed, vane count, and coarseness, all of which influence the output potential of the B-TENG. The B-TENG model employed in this research operates on a rotational sliding mode, featuring a biobased material layer of coconut husk, a layer of PTFE, and copper as electrodes. The B-TENG has a diameter of 100 mm with varying vane configurations (3-vane, 4-vane, and 5-vane). The sliding mode demonstrated impressive versatility, yielding output voltages spanning from 0.73 V to 4.0 V across rotational speeds of 200 RPM to 1400 RPM. Remarkably, the 5-vane fine-grained coconut husks achieved a maximum power of 121.10 mW at 10 Ohm and a power density of 3.84 mW/cm2. This research carries global significance, contributing to the advancement ofenergy harvesting technology. Its applications range from harnessing the motion of human bodies to rotating machineries in any industry.

Mach 3.5 Compression Corner Control Using Microvortex Generators

An experimental investigation has been performed to examine the effect of vortex generators (VGs) on a compression corner flow separation. Experiments are conducted at Mach 3.5 along a 23° compression corner with turbulent inflow boundary-layer and Reynolds number 27×104 based on the 6.2-mm boundary-layer thickness. Micro-ramp, standard ramped-vane, and inverted ramped-vane VGs all cause the separation line to ripple and become more three-dimensional, but none eliminate it altogether. Vane-type VGs produce a stronger control effect than micro-ramps. Inverted vanes tend to generate large areas of near-wall low-momentum flow that locally increase separation length, making standard vane configurations more effective at reducing separation size. Velocimetry measurements show that the VG-induced vortices remain coherent and capable of exchanging momentum within the boundary-layer, even downstream of the interaction. Enhanced flow three-dimensionality causes an intensification of areas of increased and decreased momentum downstream of reattachment, resulting in significant flow distortion. Increased near-wall turbulent fluctuations are observed upstream of the interaction in areas where separation length is reduced. These findings are used to propose a mechanism of VG control, highlighting the role of VGs in enhancing mixing in the separated shear layer, leading to earlier reattachment and an overall reduction in separation length.

A Study of the Hydrodynamic Characteristics of Two-Dimensional Tandem Cascades

In comparison to single-row cascades, tandem cascades offer the advantages of reduced losses and enhanced operational capabilities, making them widely employed in compressor applications. However, current research on tandem cascades in hydraulic equipment remains relatively limited. In order to explore the potential application of two-dimensional tandem cascade structures in hydrodynamics and investigate their performance differences from single-row cascades, this study proposes a design scheme for a tandem cascade based on an existing single-row cascade design. Numerical simulation technology is utilized to compare and analyze the impact of these two designs on various flow losses under identical working conditions. The results indicate that compared to single-row vanes, the vane configuration of a serial-row design can better reduce losses and increase the pressure difference between the upper and lower surfaces of the vanes, thereby enhancing their load-bearing capacity and stability. This research finding is expected to provide valuable insights for future water pump design and optimization.

The effect of a tandem vane crossover diffuser configuration on the performance of a MGT mixed flow compressor

Due to the inherent geometric restrictions of a micro gas turbine (MGT) mixed flow compressor design, diffuser design has a major impact on compressor performance and operating range. Vaned diffusers are often preferred to vaneless diffusers in MGT compressor designs due to better efficiency and pressure recovery, albeit at the expense of operating range. A numeric investigation of the effect of a tandem vane crossover diffuser configuration on the performance and operating range of a MGT mixed flow compressor stage is presented. Three baseline test compressors, covering a wide range of design speeds, mass flow rates and meridional exit angles, are designed with a single vane crossover diffuser. For each of the three baseline compressors, the crossover diffuser design is modified to feature various tandem vane configurations. The tangential shift of the second vane row relative to the first row is evaluated. Additionally, relative first and second vane row lengths are evaluated. The performance (efficiency and pressure ratio) and operating range of the modified diffuser configurations are compared to the baseline configurations. It is shown that a 75% second vane row tangential shift configuration displays the best overall performance, regardless of the relative vane length. It is further shown that an appropriate vane length depends on the design requirement.

The effects of swirler vane configurations on the vortex-mixing interaction and combustion stability in a low-emission combustor

Particle Image Velocimetry (PIV) measurements and Large Eddy Simulation (LES) simulations are conducted for non-reacting and reacting flows to investigate the effects of swirler vane configurations on the vortex-mixing interaction and combustion stability in a low-emission tower-type coaxial-staged combustor (LETCC). Results show that the LES simulation results agree well with the experimental data. The combustor without vane lobes exhibits large mixture fraction bubbles in the inner shear layer (ISL) in non-reacting flow, and shows unstable combustion in reacting flow. Adding lobes to the first main stage swirler vanes eliminates instability factors in both non-reacting flow and reacting flow. Adding lobes to the second main stage swirler vanes suppresses mixture fraction bubbles in the ISL, but forms large areas with low mixture fraction in the outer shear layer (OSL) and outer recirculation zone (ORZ) in non-reacting flow, and induces localized flame extinction and re-ignition within the ORZ in reacting flow, leading to combustion instability.

The multi-objective optimisation design of outlet guide vanes of diagonal flow fan based on sobol sensitivity analysis

Diagonal flow fans offer substantial energy-saving potential and find broad application across various sectors. Their performance relies heavily on factors like outlet guide vanes and spacing relative to moving blades. However, research into enhancing fan performance through optimized guide vanes and spacing remains limited. In this study, we focus on improving the accuracy of predicting the internal flow field of diagonal flow fans. This paper incorporate rotation and curvature effects using the Large Eddy Simulation (LES) model and introduce stress terms with helicity constraints to create a non-linear subgrid-scale model. This refined model enables more precise numerical simulations. By employing accurate simulations, we optimize the outlet guide vane configuration and conduct sensitivity analysis. We utilize a Radial Basis Function (RBF) model coupled with the Sobol method for this purpose. The optimized guide vane design exhibits enhanced resistance to airflow separation compared to the original, resulting in notable reductions in flow losses within the grille channel. Experimental tests are performed on the diagonal flow fan both before and after optimization. At the specified operating point, the second guide vane optimization leads to a 1.28 m3/min increase in fan flow, a 4.33% rise in total pressure efficiency, and a 2.2 dB noise reduction. These findings underscore the accuracy of the helicity correction model in predicting diagonal flow fan behavior. The multi-objective optimization approach, combining the RBF proxy model with the Sobol method, proves highly reliable. It offers valuable design insights for similar fans and establishes a credible design methodology.

Effect of a curved turning vane on the heat transfer and fluid flow of four-pass internal cooling channels of gas turbine blades

This numerical study examined the effects of a curved turning vane on the heat transfer and pressure loss of a four-pass internal cooling channel. Three-dimensional omega-based Reynolds stress (RSM-ω) turbulence model equations were used in the computation process. Three different curved turning vane configurations were studied using a simple, without a turning vane under stationary and rotating conditions for Reynolds numbers between 20,000 and 60,000 and a rotation number of 0.042. The numerical results showed good agreement with previous experimental data. Under both stationary and rotating conditions, the curved turning vane in a hub turn reduced the pressure drop significantly compared to the conventional turning vanes. Although a curved turning vane attenuated overall heat transfer, the local heat transfer increased it in particular regions, such as the hub turn and the fourth turn of cooling passages, particularly in cases with smaller radii. Coolant flow through the hub turn of the serpentine channel can reduce recirculation, separation, and flow impingement, which are unfavorable factors of pressure loss, owing to the semi-circular configuration of the curved turning vane. Regarding the rotating conditions, four-pass channels with a smaller radius of a curved turning vane provide better overall cooling performance.

Laboratory investigations on hydraulic jump characteristics using submerged vanes and adverse slope

Hydraulic jumpis a phenomenon with destructive effects on the river bed and downstream the hydraulic structures. This study, based on experimental findings, presents a new method that can be used to prevent the detrimental impacts of the hydraulic jump downstream of hydraulic structures and to design optimal structures. In this empirical research, 135 experiments were conducted in an experimental flume where submerged vanes with angles of attack of 30 and 60°, as a novel intuitive method, were used with two different configurations and adverse slopes (0, −1.5% and −3%) to control hydraulic jump in the range of 4.58 < Fr1 < 9.14. Based on the obtained results, the sequent depth and length of the hydraulic jump were, at most, decreased by 26.6% and 31.9%, respectively, with increasing the angle of attack of submerged vanes and the adverse slope of the bed. Also, the energy loss increased up to 7.7% in the case of φ = 60°, d = 0.2 m, and S = −3%. To calculate the sequent depth and length of the hydraulic jump, new equations were expressed through the analysis of the effects associated with the angle of attack, adverse slope, and vane configuration. All data resulting from proposed equations were then compared and validated with the experimental data.

A Novel Vane-twisted Conformal Diffuser for Compact Centrifugal Compressors

Compact aero-engines that use centrifugal compressors are in high demand due to their small size and cost-effectiveness. However, limited improvements in the aerodynamic performance of centrifugal impellers have led to a greater focus on improving the performance of diffusers. This paper introduces a novel vane conformal diffuser designed to match an impeller with a high pressure ratio. The diffuser utilizes a unique design method that creates transitions from a two-dimensional meridian to a three-dimensional configuration, to achieve a twisted design for the vane and hub. Eventually an integrated vane configuration is formed from the radial section to the bend and axial sections. The novel diffuser significantly reduces the radial size of the entire compressor compared with a conventional vaned diffuser. Different cross-section area distributions are studied to explore the reasonable static pressure recovery ability of the diffuser. To validate the new concept, the diffusers of two existing high-pressure centrifugal compressors are redesigned using the novel conformal diffuser configuration. The numerical results show that the aerodynamic performances of the two redesigned centrifugal compressors are improved in terms of both the total pressure ratio and the isentropic efficiency compared with their counterparts. These results demonstrate the effectiveness and applicability of the developed design method for the novel conformal diffuser.

Comparison of Secondary Flow Characteristics in Mixed-Flow Turbine between Nozzleless and Symmetric Nozzle Vane Angles under Steady-State Flow at Full Admission

In industrial applications, radial or mixed-flow turbines are frequently used in energy recovery systems, small turbines for producing power, and turbochargers. The implementation of radial or mixed-flow turbines helps to maintain high efficiency at a large range of pressure ratios by reducing the overall turbine losses and secondary flow losses. Numerous findings on secondary flow development research adopting double-entry turbines can be obtained in the public domain, except asymmetric volute, which is less well-researched. The focus of the present work is to investigate the evolution of secondary flows and their losses in a mixed-flow turbine used in an asymmetric volute turbine, by employing an experimentally validated three-dimensional computational fluid dynamics (CFD). The flow topology is analyzed to explain the formation and evolution of flow separations at the pressure, suction, and hub surfaces. As the opening angle of the nozzle vane increases, the incidence angle falls into the positive range while the maximum pressure difference between the shroud and hub decreases by about 40%. The results also show that the development of secondary flow accounts for the majority of losses and induced the centrifugal pressure head influence. The presence of symmetric nozzle vanes in both large and small scrolls is also found to have a significant detrimental effect on the turbine efficiency, which is 4% lower than the nozzleless case. Furthermore, significant flow separation is observed in the symmetrical nozzle vane configuration as opposed to that of nozzleless. In addition, the centrifugal pressure head indicated by the maximum pressure difference between the hub and shroud influences the overall turbine efficiency, as the symmetrical nozzle vane arrangement is introduced with two different turbine rotational speeds of 30 K rpm and 48 K rpm.

Effect of Different Guide Vane Configurations on Flow Field Investigation and Performances of an Axial Pump Based on CFD Analysis and Vibration Investigation

Effect of Different Guide Vane Configurations on Flow Field Investigation and Performances of an Axial Pump Based on CFD Analysis and Vibration Investigation

Role of moveable guide vane with various configurations in controlling the vortex-induced vibration of twin-box girder suspension bridges: An experimental investigation

The purpose of this paper is to investigate the effects of a moveable guide vane with various configurations (i.e., horizonal length and stiffness) in controlling the vortex-induced vibration (VIV) of a long-span suspension bridge with twin-box girder. First, a series of VIV tests of the 1:50 scaled ratio of sectional model with various guide vane configurations were performed. The vertical and torsional displacements of the twin-box girder as well as the vertical response of the windward and leeward guide vane measured to analyze the movement characteristics of the main girder and guide vanes, respectively. The test results show that, the moveable guide vane could significantly reduce the maximum vertical and torsional displacement responses of the main girder with an immovable guide vane or without a guide vane, especial under the most unfavorable wind attack angle of +3°. In addition, a moveable guide vane with relatively low stiffness could produce a better outcome of VIV control. Furthermore, the increase of the horizontal length of the guide vane could have a negative impact on the VIV control of the bridge. Importantly, the maximum vertical amplitude of the moveable guide vane is generally larger than that of the main girder, indicates that the leeward guide vane could play an important role in the VIV suppression when the stiffness of the guide vane is over certain threshold (e.g., 19 g/mm).

Numerical analysis of flow characteristics of a swirl-stabilized premixed burner with different swirl vane configurations

Numerical analysis of flow characteristics of a swirl-stabilized premixed burner with different swirl vane configurations

Hydraulic Performance of a Francis Turbine with a Variable Draft Tube Guide Vane System to Mitigate Pressure Pulsations

The present paper demonstrates a proof-of-concept by introducing a variable guide vane system in the draft tube of a high-head Francis model turbine. The aim is to examine the hydraulic performance of the turbine while mitigating the pressure pulsations in the draft tube. The guide vanes can rotate about an axis up to ±45°. The pressure pulsations mitigation studies were performed at lower- and upper-part loads. The hydraulic performance was examined at all operating ranges within the turbine head. There were six guide vane configurations considered between ±45°. The findings demonstrate that the highest efficiency loss with a guide vane configuration that mitigates the pressure pulsations is marginal, with modest improvements at the best efficiency point. The pressure pulsations are 100% mitigated at the lower part load, and there is a maximum decrement in the pressure pulsations up to 80% at the upper part load. The study demonstrates that such a system can improve the operational flexibility of the hydro-turbine by mitigating the pressure pulsations and marginally affecting its hydraulic performance.

Performance study of savonius style wind turbines in a solar chimney power plant under guided flow environment

With the uprise in global population and rapid industrialisation in developing nations, increasing energy demand to compensate for societal and industrial needs is inevitable. However, popular energy resources such as gas, petroleum, and coal, on which the global energy mix is heavily reliant, induce environmental pollution and global warming. Thus, clean energy sources, such as wind and solar, are increasingly sought to mitigate these adverse environmental effects and identify alternative sustainable and renewable energy technologies. The existing literature suggests minimal research has been conducted on the turbine component of the solar chimney power plant (SCPP). The present research proposes the study of a vertical axis wind turbine (VAWT), namely the Savonius-style wind turbine (SSWT), for power augmentation in the SCPP under the influence of guide vanes and shields that are installed in the solar collector area. A two-dimensional numerical analysis is performed using the ANSYS Fluent software. The SSWT and SCPP models used in the simulations were validated using numerical and experimental results from previous literature data. The angle of the guide vanes was varied while the dimensions of the SCPP model and the energy extractor considered were kept constant. The optimum turbine performance was identified based on the flow analysis and the power output of the rotary component from different guide vane configurations. The present study shows an overall improvement in the turbine’s performance coefficient and power output under the influence of the guide vane and shield in the SCPP. The turbine with the guide vane and shield at an angle of 45° enhanced the performance by 22.22% and power output by 22.25% compared to the turbine without the guide vane and shield.

Performance Characteristics of In-Line Oil Separator with Various Airfoil Vane Configurations of the Axial-Flow Swirl Generator

Recently, as the industry develops, global energy consumption has been increasing. Power generation using various energy sources is used to meet energy consumption. The demand for renewable energy resources is increasing as well as the demand for fossil fuels. However, fossil fuel reserves offshore are limited, and the continued resource development is causing the depletion of fossil fuels. Accordingly, there is a demand for resource development not only offshore but also in the deep sea. In order to efficiently separate water and oil, it is necessary to study a compact in-line oil separator. In this study, the oil–water separation characteristics according to various airfoil vane configurations of the in-line type oil separator are numerically calculated. The maximum camber and location of the maximum camber of the NACA(National Advisory Committee for Aeronautics) airfoil model were selected as design parameters. As a result, the maximum separation efficiency of 63.9% was predicted when the maximum camber value was 13.51% and the maximum camber position was 50%.

Effects of supersonic nozzle guide vanes on the performance and flow structures of a rotating detonation combustor

The integration of a rotating detonation combustor with downstream nozzle guide vanes is a crucial early step prior to the full implementation of the rotating detonation turbine engine. The present study aims to elucidate the flow structures introduced by this integration and provide guidance for the application of rotating detonation turbine engines. A numerical investigation on a rotating detonation combustor with three supersonic guide vane configurations is conducted and compared to a baseline case without any nozzle guide vane. Integrating nozzle guide vanes into the rotating detonation combustor increases the detonation strength and its pressure gain capability, resulting in a higher outlet total pressure for the greater thrust potential. The results show that the total pressure drops mainly in the attached oblique shock region rather than the nozzle guide vane passages. Moreover, the detonation intensity and the shock structures in nozzle guide vane passages influence the total pressure gain performance for multiple configurations. Compared to others, the aligned configuration is preferred for future design due to the optimal comprehensive performance of unsteadiness damping, flow conditioning, total pressure gain, and useful work production. Furthermore, a shock structure termed rake-type shock envelope is identified for the first time. The propagating detonation forces the reflected shock waves from the leading edges of the vanes to move circumferentially, yielding this dynamic shock system. This suggests that the propagating detonation guarantees no normal shocks upstream of the nozzle guide vanes, and therefore the typical unstarting issue for turbines is prevented.