Guide Vane Research Articles

Research on the Matching Characteristics of the Impellers and Guide Vanes of Seawater Desalination Pumps with High Capacity and Pressure

This paper presents the matching characteristics of impellers and guide vanes of high capacity and pressure seawater desalination pumps by using computational fluid dynamics (CFD). The single-stage pump is numerically calculated, and its external characteristics are consistent with the test results of model pump. Taking this scheme as a prototype, the research is carried out from three aspects: (i) the impeller blade outlet width; (ii) the number of impeller and guide vane blades; and (iii) the area ratio of impeller outlet to guide vane inlet. The results indicate that the blade outlet width significantly affects the pump head and efficiency. Appropriately increasing the number of guide vane blades or changing the number of impeller blades can improve efficiency and expand the high-efficiency area. Additionally, increasing the throat area of the guide vane has the opposite effect on the large flow and small flow area of the pump. An optimized hydraulic model design scheme is obtained.

Experimental and Numerical Analysis of Loss Characteristics of Cooled Transonic Nozzle Guide Vanes

Abstract This article presents high-fidelity experimental traverse measurements downstream of an annular cascade of transonic nozzle guide vanes (NGVs) from a high-pressure (HP) turbine stage. The components are heavily cooled real engine components from a modern civil gas turbine engine, operated at scaled engine conditions. Tests were conducted in the high technology readiness level (TRL) Engine Component Aerothermal (ECAT) facility at the University of Oxford. High-resolution full-area traverse measurements of local kinetic energy (KE) loss coefficient are presented in several axial planes. In particular, we present circumferential loss coefficient profiles at several radial heights, full-area traverses at three axial planes, and fully mixed-out loss calculations. The analysis of these data gives insight into particular loss structures, overall aerodynamic performance, and wake mixing rates. The effect of exit Mach number on performance is also considered. The data address a gap in the literature for the detailed analysis of traverse measurements downstream of HP NGV engine components. Experimental data are compared with steady and unsteady Reynolds-averaged Navier–Stokes (RANS) simulations, allowing benchmarking of typical computational fluid dynamics (CFD) methods for absolute loss prediction of cooled components. There is relatively limited aerodynamic performance data in the literature for heavily cooled NGVs, and this study represents one of the most comprehensive of its type.

Accommodation of Multishaft Gas Turbine Switching Control Gain Tuning Problem to Inlet Guide Vane Position

Abstract This article aims to discuss the influence of compressor inlet guide vane (IGV) position on gas turbine switching control system gain tuning problem. The distinction between IGV and normally reckoned working conditions is differentiated, and an improved double-layer linear parameter varying (LPV) model is proposed to estimate the protected parameters under various IGV positions. Controller gain tuning is conducted with single and multi-objective intellectual optimization algorithms. Simulation results reveal that normally used multi-objective optimization procedure is unnecessary and time-consuming. While with the comprehensive indicator introduced in this paper, the calculation burden can be greatly eased. This improvement is especially advantageous when tuning work is carried out under multiple IGV positions.

Numerical Investigation of Single-Row Double-Jet Film Cooling of a Turbine Guide Vane under High-Temperature and High-Pressure Conditions

Single-row double-jet film cooling (DJFC) of a turbine guide vane is numerically investigated in the present study, under a realistic aero-thermal condition. The double-jet units are positioned at specific locations, with 57% axial chord length (Cx) on the suction side or 28% Cx on the pressure side with respect to the leading edge of the guide vane. Three spanwise spacings (Z) in double-jet unit (Z = 0, 0.5d, and 1.0d, here d is the film hole diameter) and four spanwise injection angles (β = 11°, 17°, 23°, and 29°) are considered in the layout design of double jets. The results show that the layout of double jets affects the coupling of adjacent jets and thus subsequently changes the jet-in-crossflow dynamics. Relative to the spanwise injection angle, the spanwise spacing in a double-jet unit is a more important geometric parameter that affects the jet-in-crossflow dynamics in the downstream flowfield. With the increase in the spanwise injection angle and spanwise spacing in the double-jet unit, the film cooling effectiveness is generally improved. On the suction surface, DJFC does not show any benefit on film cooling improvement under smaller blowing ratios. Only under larger blowing ratios does its positive potential for film cooling enhancement start to show. Compared to the suction surface, the positive potential of the DJFC on enhancing film cooling effectiveness behaves more obviously on the pressure surface. In particular, under large blowing ratios, the DJFC plays dual roles in suppressing jet detachment and broadening the coolant jet spread in a spanwise direction. With regard to the DJFC on the suction surface, its main role in film cooling enhancement relies on the improvement of the spanwise film layer coverage on the film-cooled surface.

Multi‐objective optimization and decision‐making of the combined control law of guide vane and pressure regulating valve for hydroelectric unit

AbstractThis paper aimed to investigate the multi‐objective optimization and decision‐making of the combined control law of guide vane (CCLGV) and pressure regulating valve (PRV) for hydroelectric unit under load rejection. Firstly, the multi‐objective optimization problem of CCLGV‐PRV is formulated. Then, a new multi‐objective gravitation search algorithm with non‐dominated screening and chaos mutation (NCMOGSA) is adopted to solve it. Moreover, an improved entropy weight method and relative objective proximity method are applied to select suitable solution. Finally, a comprehensive comparative study is carried out to reveal the mechanism between the CCLGV‐PRV and several basic parameters. The results indicate that replacing surge tank with PRV can effectively solve the contradictory between water pressure at the bottom of volute and rotational speed under load rejection. The NCMOGSA shows excellent performance in solving the multi‐objective optimization problem of CCLGV‐PRV and get a group of Pareto set. The improved entropy weight and relative objective proximity method make the final scheme clear. The rise rate of rotational speed is completely determined by the guide vane (GV), and the water pressure is jointly determined by the control law of the GV and PRV. The two‐stage closing and two‐stage opening (TCTO) is the final recommendation for CCLGV‐PRV.

Numerical Investigation of Transient Flow Characteristics in a Centrifugal Compressor Stage with Variable Inlet Guide Vanes at Low Mass Flow Rates

This study numerically investigates the beneficial effects of positive pre-swirl on the aerodynamic performance and internal flow field in a centrifugal compressor stage with variable inlet guide vanes (VIGVs) at low mass flow rates. Four positions of VIGV are considered, including 0°, 30°, 45°, and 60° angle. The latter three positions of VIGV induce positive pre-swirl. Numerical results show that as positive pre-swirl increases, the aerodynamic performance curve of the stage moves in the low mass flow rate direction. In the three cases of positive pre-swirl, there was an improvement of approximately 9.95% of stall/surge margin greater than in conditions with no pre-swirl. The regulation of IGV can effectively improve the unstable flow of the compressor stage at low mass flow rates. A low frequency that has a great influence on the internal flow of the compressor stage is found, and the unstable flow caused by low frequency is analyzed by the combination of streamline distribution, spectrum analysis, vector, entropy increase, and modal decomposition method. Meanwhile, the modal decomposition method and flow field reconstruction techniques are used to investigate the coherent flow structures caused by low frequency under different guide vane openings.

Handling Water Leaking on The Turbine Pit ULPLTA Bakaru due to Damage of the Guide Vane Part using Automatic Method with Motorized Valve

The Bakaru PLTA is the largest hydroelectric power plant in South Sulawesi with a capacity of 126 MW. To generate that much power, a lot of water is required, therefore, the Bakaru hydropower dam is designed to be able to accommodate a lot of water. In operation, the Bakaru hydropower plant consists of 2 units. However, not all units operate normally, such as unit 2. In unit 2, there is a leak that occurs in the Turbine Pit. This leak is caused by abrasion of the u-packing guide vane. With a leak in the turbine pit, more approaches are needed to dispose of the water in the turbine pit to the pit drainage. Which later developed into an infusion system that utilizes gravity to discharge water from the turbine pit in basement 2 to the drainage pit in basement 3. However, in its development, it turns out that the volume of water discharged cannot be controlled so that, it can cause a condition where one day the infusion hose does not flow and causes an increase in the water level in the turbine pit. This rise in the level of the turbine pit is dangerous for the unit. This is because water can enter the breathing hole of the bearing turbine tank and contaminate the oil so the bearing temperature is high and causes a trip or in the worst case, causing equipment damage. However, in reality, using an infusion system using human labor is still often constrained in terms of time efficiency, consistency and cost. Because every time this activity is carried out, the workers who do it are not always the same person and scheduled. Therefore the efficiency is still low. The purpose of this study was to determine the optimal method of handling the increase in water level in the turbine pit so that unit trips do not occur caused by the increase in the water level in the turbine pit. Finally, it is interesting to discuss and find a solution by relocating the handling of leaks by "using an automatic method with a motorized valve by installing a Motorized Valve on the Turbine Pit, so there are financial and non-financial benefits to be obtained. From the results of using the automatic method with a motorized valve, the results obtained are faster cycle times for handling leaks in the turbine pit so there is no stop unit due to leakage disturbances in the turbine pit.

Comparison of Film Cooling Performance for Different Purge Slot Configurations in a Cylindrical and State-of-the-Art Nozzle Guide Vane

Abstract This comparative study is concerned with the advances in nozzle guide vane (NGV) design developments and their influence on endwall film cooling performance by injecting coolant through the purge slot. This experimental study compares the film cooling effectiveness and the aerodynamic effects for different purge slot configurations on both a flat and an axisymmetrically contoured endwall of a NGV. While the flat endwall cascade was equipped with cylindrical vanes, the contoured endwall cascade consisted of modern NGVs, which represent state-of-the-art high-pressure turbine design standards. Geometric variations, e.g., the slot width and injection angle, as well as different blowing ratios were realized. The mainstream flow parameters were set to meet real engine conditions with regard to Reynolds and Mach numbers. Pressure-sensitive paint was used to determine the adiabatic film cooling effectiveness. Five-hole probe measurements were performed to measure the flow field in the vane wake region. For a more profound insight into the origin of the secondary flows, oil dye visualizations were carried out. The results show that the advances in NGV design have a significantly positive influence on the distribution of the coolant. This has to be attributed to lesser disturbance of the coolant propagation by secondary flow for the optimized NGV design, since the design features are intended to suppress the formation of secondary flow. Therefore, it is advisable to take these effects into account when designing the film cooling system of a modern high-pressure turbine.

Influence of Swirl Clocking on the Performance of Turbine Stage with Three-Dimensional Nozzle Guide Vane

The effect of the swirl clocking on three-dimensional nozzle guide vane (NGV) is investigated using computational fluid dynamics. The research reports the loss characteristics of leaned and swept NGVs and the influence of swirl clocking. The three-dimensional NGVs are built by stacking the same 2D profile along different linear axes, characterized by different angles with respect to the normal or radial direction: ε = −12° ~ +12° for the leaned and γ = −5° ~ +10° for the swept airfoils. A total of 40 models are analyzed to study the effects of lean and sweep on aerodynamic performance. To investigate the influence of swirl clocking, the analysis cases include the center of the swirl that was positioned at the leading edge as well as the middle of the passage. The prediction results show that the relationship of the changes in mass flow rate and throat area are not monotonic. Further observation confirms the redistribution of loading and flow angle under different lean and sweep angles; thus, three-dimensional design is a key influencing factor on aerodynamic performance. In the presence of swirl clocking, NGV performance is changed significantly and the findings offer new insight and opportunities to improve three-dimensional NGV airfoil design.

Optimization Study of Guide Vanes for the Intake Fan-Duct Connection Using CFD

The connection between an intake fan and a ventilation shaft must be designed in such a way that it minimizes the energy waste due to singularity losses. As a result, the questions of which radius of curvature to use and if guide vanes have to be included need to be answered. In that case, the variables such as the number, upstream and downstream penetration length, radius of curvature, and width of the vanes, need to be defined. Although this work is oriented to mine ventilation, these questions are usually valid in other engineering applications as well. The objective of this study is to define the previously mentioned variables to determine the optimal design combination for the radius/diameter relationship (r/D). Computational fluid dynamics was used to determine the shock loss factor of seven elbow curvature ratios for a 3 m diameter duct and fan, with and without guide vanes to estimate the best performing configuration and, therefore, to maximize the fan airflow volume. The methodology used consisted of initially developing models in 2D geometries, to optimize the meshing and the CPU use, and studying separately the number of vanes, upstream and downstream penetration, radius of curvature, and width of the vanes for each curvature ratio (r/D). Then, the best-performing variable combinations for each curvature ratio were selected to be simulated and studied with the 3D geometries. The application of the guide vane designs for three-dimensional simulated geometries is presented, first without and then with guide vanes, including the shock loss factors obtained. The methodology and obtained results allowed quantifying the energy savings and to reduce the CFD simulations steps required to optimize the design of the elbow and guide vanes. The results obtained cannot be used with elbows in exhaust fans, because fluid dynamics phenomena are different.

Optimal interstage liner design: A parametric study

The current trends for next generation turbofan engines are towards shorter nacelles and increased distances between the fan and the outlet guide vanes. This leads to an overall reduction in lined surface areas as well as an increase in the relative importance of the interstage liner, which is the liner placed between the rotor blades and the stator vanes. So far most of the efforts have been on liners for intakes and bypass ducts. The interstage is different in that the liner is subject to a mean flow with a strong swirl component and shear. The focus of this paper is on the effect of swirling flow on optimal liner attenuation in the interstage region. A broadband source downstream at the Outlet Guide Vanes (OGV) consisting of all propagating modes with equal power in each mode is used. Optimum impedance plots are generated for approach and take-off mean flow conditions. The effect of swirl on liner optimum resistance and reactance and optimum insertion loss is observed for a frequency range characteristic of real turbofan engines.

Leakage Vortex Progression through a Guide Vane’s Clearance Gap and the Resulting Pressure Fluctuation in a Francis Turbine

A clearance gap (CG) between guide vanes (GVs) and facing plates exists at both ends of a Francis turbine and allows the opening angle to be adjusted for varying operating conditions. Leakage flow is induced through this gap due to the pressure difference between the two sides of the guide vanes. While some research works have used qualitative approaches to visualize and predict the strength of a leakage vortex (LV), this paper presents a method for quantifying vortices along a trajectory. In this paper, a prototype high-head Francis runner with specific speed of 85.4 is considered as a reference case. A systematic investigation across both space and time is carried out, i.e., analysis of the spatial temporal progression of LV for three operating conditions. While travelling from the CG to runner leading edge, LV evolution and trajectory data are observed and the values of vorticity and turbulent kinetic energy are calculated for the LV trajectory. Frequency spectrum analyses of pressure oscillations in the vaneless space, runner blade, and draft tube are also performed to observe the peak pressure pulsation and its harmonics. Unsteady fluctuations of the runner output torque are finally studied to identify the patterns and magnitudes of torque oscillations.

Effect of Guide Vane on Turbulence Characteristics for Single-Phase Flow through a 90-Degree Pipe Bend

The present study expresses the turbulent flow characteristics through a 90° pipe bend using a numerical ‎method by determining the solutions for Reynolds Averaged Navier-Stokes (RANS) expression using the k-ω ‎‎(SST) turbulence model. For that purpose, numerical analysis has been carried out by solving RANS equations ‎using ANSYS FLUENT 16.2, considering incompressible fluid in turbulent flow conditions. Simulations have ‎been carried out for three different Reynolds number ranging from 1×105 to 10×105 at three different bend ‎curvature ratios (Rc/D = 1, 1.5, and 2). Pipe bends with guide vane are generally used where flow separation ‎and space problem makes an issue in mechanical design. The presence of guide vane inside the bend ‎positively suppressed the flow separation and presence of cross-flow which can cause the engine to run off ‎design, thus reducing the engine efficiency. So, to observe the effect of guide vane and its position on ‎turbulence characteristics, four different positions of guide vane inside the bend are considered in the present ‎study. At first, an analysis was led to make sure that the results obtained from the present numerical model are ‎reliable and in line with previous results obtained from similar published experiments and numerical work. ‎Research has been conducted to find out the impact of Reynolds number, bend curvature ratio and position of ‎guide vane on different turbulence characteristics namely; turbulent kinetic energy, turbulent intensity, and ‎wall shear stress at bend outlet position. In general, the turbulent intensity is found larger for the lower bend ‎curvature ratio at the inner wall curvature side. Results for turbulent kinetic energy have similarities in results ‎with turbulent intensity. Significantly, the wall shear stress represented a strong dependency on the ‎circumferential angle at the bend outlet cross-section, and curvature ratio rather than Reynolds number and ‎guide vane positions‎‎.

Comparative Performance of New Surface Roughness Element and Pin fin in Converging Channel for Gas Turbine Application

Thermal performance of a novel surface roughness element, named as Double 45 Dimple (D45D), is compared with pin-fin element in a converging channel with rectangular cross section and presented. The Surface Roughness Element (SRE) is derived by combining protrusion & dimple in a particular fashion such that area available for transfer of heat increases. The objective of this study is to demonstrate the applicability of D45D element channel for trailing edge channel of a typical nozzle guide vane where typically pin-fin element is used. New cooling configuration of Nozzle Guide Vane (NGV) with D45D element is also proposed. All thermal and flow related results are derived using validated CFD approach with EARSM turbulence model for a typical value of Reynolds number. From this investigation, it is found that D45D element provides remarkable improvement in the averaged as well as heat transfer in local region for the corresponding surface which makes it a candidate for trailing edge channel cooling application.

Effect of the Reynolds Number and Clearance Flow on the Aerodynamic Characteristics of a New Variable Inlet Guide Vane

Recently, a new type of low-loss variable inlet guide vane (VIGV) was proposed for improving a compressor’s performance under off-design conditions. To provide more information for applications, this work investigated the effect of the Reynolds number and clearance flow on the aerodynamic characteristics of this new type of VIGV. The performance and flow field of two representative airfoils with different chord Reynolds numbers were studied with the widely used commercial software ANSYS CFX after validation was completed. Calculations indicate that, with the decrease in the Reynolds number Rec, the airfoil loss coefficient ω and deviation δ first increase slightly and then entered a high growth rate in a low range of Rec. Afterwards, a detailed boundary-layer analysis was conducted to reveal the flow mechanism for the airfoil performance degradation with a low Reynolds number. For the design point, it is the appearance and extension of the separation region on the rear portion; for the maximum incidence point, it is the increase in the length and height of the separation region on the former portion. The three-dimensional VIGV research confirms the Reynolds number effect on airfoils. Furthermore, the clearance leakage flow forms a strong stream-wise vortex by injection into the mainflow, resulting in a high total-pressure loss and under-turning in the endwall region, which shows the potential benefits of seal treatment.

Influence of tilt angle and the number of guide vane blades towards the Savonius rotor performance

Additional guide vane (GV) to the Savonius rotor is used to overcome the low rotor efficiency. This study is experimentally carried out to know the influence of guide vane in improving two blades Savonius rotor performance. There were four designs of guide vane which are 4, 5, 6 blades and installed at different tilt angles, which were 0°, 20°, 40°, and 60°. The experiment was done under wind speed of 5.9 m/s, 7.0 m/s, 8.1 m/s, 9.3 m/s and 10.4 m/s. The results show that the 6 blades of GV at a 60° tilt angle attained the best Cp, which was 0.0279 at the tip speed ratio of 0.53. The Cp increased up to 40% with six blades of GV. Wind direction identified significantly affected the rotor performance. The rotor performed best on the wind direction of 0° attained Cp of 0.079, but when the wind direction was modified on 30°, the rotor with 6 GV attained Cp of 0.0153 did not perform better than without GV that produced Cp of 0.0166. The guide vanes improve the Savonius rotor performance compared to the rotor without a guide vane. However, the wind direction also needs to be considered no less important factor affecting the Savonius rotor performance.

The Combined Influences of Hot Streak and Swirl on the Cooling Performances of C3X Guide Vane with or without TBCs

This paper studied the combined influences of the hot streak and swirl on the cooling performances of the NASA C3X guide vane coated with or without thermal barrier coatings (TBCs). The results show that: (1) Even under uniform velocity inlet conditions, the hot streak core can be stretched as it impinges the leading edge which causes higher heat load on the suction side of the forward portion. (2) The swirl significantly affects circumferential and radial migration of the hot streak core in the NGV passage. On the passage inlet plane, positive swirl leads to a hotter tip region on the suction side. In comparison, negative swirl leads to a hotter hub region on the pressure side. (3) Under the influence of swirl, migration of coolant improves the coverage of film cooling close to the midspan, while in the regions close to the hub and tip end-wall, the overall cooling performance decreases simultaneously. (4) In the regions with enough internal cooling, the cooling effectiveness increment is always larger than that in other regions. Besides, the overall cooling effectiveness increment decreases on the region covered by film cooling for the coated vane, especially in the region with negative local heat flux.

Study of Flow Characteristics inside Francis Turbine Draft Tube with Adjustable Guide Vanes

Numerical investigation was performed on a semi-model (one stay vane, two guide vanes, one runner passage inclusive of one main and one splitter blade, and the draft tube) of a high-head Francis turbine model with adjustable guide vanes in the draft tube. The motive of the present study is to investigate the possibility to mitigate the rotating vortex rope (RVR) formed at part load operating condition. Each guide vane in the draft tube consists of two hydrofoils. The upper hydrofoil is adjustable according to the flow angles leaving the runner. The lower hydrofoil is stationary and corresponds to the flow angle at best efficiency point (BEP).The factors considered while designing these guide vanes were a) number of guide vanes, b) chord length, c) span and d) position in the draft tube. The preliminary results indicate that the RVR pressure amplitude was suppressed by 97% compared to the reference model with no guide vanes at part load (PL) operating condition. An 8.7% increment in the draft tube pressure recovery was obtained which indicates that implementation of the guide vanes in the draft tube could positively impact the turbine efficiency beside the mitigation of the pressure pulsations at PL operation.

Numerical Investigation of a Radially Cooled Turbine Guide Vane Using Air and Steam as a Cooling Medium

Gas turbine performance is closely linked to the turbine inlet temperature, which is limited by the turbine guide vanes ability to withstand the massive thermal loads. Thus, steam cooling has been introduced as an advanced cooling technology to improve the efficiency of modern high-temperature gas turbines. This study compares the cooling performance of compressed air and steam in the renowned radially cooled NASA C3X turbine guide vane, using a numerical model. The conjugate heat transfer (CHT) model is based on the RANS-method, where the shear stress transport (SST) k−ω model is selected to predict the effects of turbulence. The numerical model is validated against experimental pressure and temperature distributions at the external surface of the vane. The results are in good agreement with the experimental data, with an average error of 1.39% and 3.78%, respectively. By comparing the two coolants, steam is confirmed as the superior cooling medium. The disparity between the coolants increases along the axial direction of the vane, and the total volume average temperature difference is 30 K. Further investigations are recommended to deal with the local hot-spots located near the leading- and trailing edge of the vane.

Effects of Inlet Guide Vanes on the Performance and Stability of an Aeronautical Centrifugal Compressor

Abstract A research centrifugal compressor stage designed and built by Safran Helicopter Engines is tested at three inlet guide vanes (IGV) stagger angles. The compressor stage includes four blade rows: axial inlet guide vanes, a backswept splittered impeller, a splittered vaned radial diffuser (RD), and axial outlet guide vanes (OGVs). The methodology for calculating the performance is detailed, including the consideration of humidity in order to minimize errors related in particular to operating atmospheric conditions. The shift of the surge line toward lower mass flow rate as the IGV stagger angle increases highly depends on the rotation speed. The surge line shift is very small at low rotation speeds, whereas it significantly increases at high rotation speeds. A first-order stability analysis of the impeller and diffuser sub-components shows that the diffuser (resp. impeller) is the first unstable component at low (resp. high) rotation speeds. This situation is unaltered by increasing the IGV stagger angle. At low rotation speeds below a given mass flow rate, rotating instabilities (RI) at the impeller inlet are detected at zero IGV stagger angle. Their occurrence is conditioned by the relative flow angle at the tip of the leading edge of the impeller. As the IGV stagger angle increases, the mass flow decreases to maintain a given inlet flow angle. Therefore, the onset of the rotating instabilities is delayed toward lower mass flow rates. At high rotation speeds, the absolute flow angle at the diffuser inlet near surge decreases as the IGV stagger angle increases. As a result, the flow is highly alternate over two adjacent channels of the radial diffuser beyond the surge line at IGV stagger angle of 0 deg.