Experimental Analysis of Cavitation Phenomena on Kaplan Turbine Blades Using Flow Visualization

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Andrej Podnar ◽  
Matevž Dular ◽  
Brane Širok ◽  
Marko Hočevar
Keyword(s):  
Turbine Blades ◽  
Suction Side ◽  
Cavitation Inception ◽  
Runner Blade ◽  
Kaplan Turbine ◽  
Turbine Performance ◽  
Blade Shape ◽  
The Right ◽  
Operating Points ◽  
Acceptance Tests

In this study, a comparison of two different Kaplan turbine runners with differently shaped turbine blades was performed. The two turbines differed in the selection of the hydrofoil, the main hydrofoil parameters of which had been modified including, the position of maximum thickness and curvature and the inlet edge radius. Both turbines (unmodified and modified hydrofoils) were tested on a rig designed for low pressure model turbine acceptance tests. The effect of blade shape on cavitation inception, development, and intensity was demonstrated using computer aided visualization. Visualization was performed on the suction side of Kaplan runner blade where the shape of the blade determines cavitation inception and development. The modified Kaplan turbine reduced the cavitation phenomena, and as a result, both turbine performance and output increased for the selected operating points. This demonstrates that choosing the right turbine blade shape is key for optimal turbine performance.

Analysis of a pico tubular-type hydro turbine performance by runner blade shape using CFD

2012 ◽  
Vol 15 (4) ◽  
pp. 042031 ◽  
Author(s):  
J H Park ◽  
N J Lee ◽  
J V Wata ◽  
Y C Hwang ◽  
Y T Kim ◽  
...  
Keyword(s):  
Hydro Turbine ◽  
Tubular Type ◽  
Runner Blade ◽  
Turbine Performance ◽  
Blade Shape

The Effect of Endwall Manufacturing Variations on Turbine Performance

2014 ◽  
Author(s):  
Robert P. Grewe ◽  
Robert J. Miller ◽  
Howard P. Hodson
Keyword(s):  
Mass Flow ◽  
Turbine Blades ◽  
Casting Process ◽  
Suction Side ◽  
Vortical Structures ◽  
Leakage Flows ◽  
Turbine Performance ◽  
Secondary Flow Structure ◽  
Aero Engines ◽  
The Impact

Turbine blades and vanes of modern aero-engines are commonly manufactured by casting. The casting process often introduces slight geometry variations. In the endwall region this leads to inter-platform steps, gaps and leakage flows. This paper determines the underlying loss mechanisms associated with each of these geometric features and guides designers in minimizing their impact on efficiency. The paper shows that the presence of an inter-platform step causes a pair of vortical structures to be superimposed onto the blade existing secondary flow structure. These are shown to always increase loss. When manufacture variations are considered the optimal design intent blade is shown to be one where the suction side endwall is lower than the pressure side endwall. The paper shows that when leakage mass flow is introduced the presence of a step can either raise or reduce loss. A correlation which gives the optimal step height for a set leakage mass flow is presented. In the final part of the paper measured engine vane geometries are used to determine the impact of endwall geometry variation on turbine stage efficiency.

Experimental Investigation of the Interblade Flow in a Kaplan Runner at Several Operating Points Using Laser Doppler Anemometry

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Kaveh Amiri ◽  
Berhanu Mulu ◽  
Michel J. Cervantes
Keyword(s):  
Vortex Breakdown ◽  
Laser Doppler Anemometry ◽  
Secondary Flows ◽  
Laser Doppler ◽  
Asymmetric Flow ◽  
Vortex Rope ◽  
Runner Blade ◽  
Kaplan Turbine ◽  
Flow Through ◽  
Operating Points

This paper presents laser Doppler anemometry (LDA) measurements within the runner blade channels and at the runner outlet of a Kaplan turbine model. The model was investigated at six operating points located on two propeller curves of the turbine to study the flow condition during on-cam and off-cam operations. Main and secondary flows within and after the runner were analyzed, and the effects of the hub and tip clearances on the velocity fields within and after the runner were evaluated. Operation of the turbine at flow rates that are lower than the designed rate for the corresponding propeller curve resulted in vortex breakdown and the formation of a rotating vortex rope (RVR). The RVR formation produced an asymmetrical velocity distribution within and after the runner. The results demonstrated the occurrence of an oscillating flow with the same frequency as the vortex rope within the blade channels located upstream of the RVR. This results in an asymmetric flow through the runner and oscillating forces on the runner blades. The measured velocities indicated that the geometrical asymmetries in the runner manufacturing process resulted in various flow asymmetries at the measured sections. The asymmetries were up to 3% within the runner and 7% at the runner outlet.

scholarly journals Analysis of Bulb Turbine Hydrofoil Cavitation

2021 ◽  
Vol 11 (6) ◽  
pp. 2639
Author(s):  
Andrej Podnar ◽  
Marko Hočevar ◽  
Lovrenc Novak ◽  
Matevž Dular
Keyword(s):  
Regression Model ◽  
Flow Characteristics ◽  
Suction Side ◽  
Cavitation Number ◽  
Design Parameters ◽  
Cavitation Inception ◽  
Measuring Station ◽  
Runner Blade ◽  
Cavitation Tunnel ◽  
Bulb Turbine

The influence of a bulb runner blade hydrofoil shape on flow characteristics around the blade was studied. Experimental work was performed on a bulb turbine measuring station and a single hydrofoil in a cavitating tunnel. In the cavitation tunnel, flow visualization was performed on the hydrofoil’s suction side. Cavitation structures were observed for several cavitation numbers. Cavitation was less intense on the modified hydrofoil than on the original hydrofoil, delaying the cavitation onset by several tenths in cavitation number. The results of the visualization in the cavitation tunnel show that modifying the existing hydrofoil design parameters played a key role in reducing the cavitation inception and development, as well as the size of the cavitation structures. A regression model was produced for cavitation cloud length. The results of the regression model show that cavitation length is dependent on Reynolds’s number and the cavitation number. The coefficients of determination for both the existing and modified hydrofoils were reasonably high, with R2 values above 0.95. The results of the cavitation length regression model also confirm that the modified hydrofoil exhibits improved the cavitation properties.

Larval and juvenile development of the Iceland cockle Ciliatocardium ciliatum (Fabricius, 1780) (Bivalvia: Cardiidae)

2020 ◽  
Vol 324 (2) ◽  
pp. 242-251
Author(s):  
L.P. Flyachinskaya ◽  
P.A. Lezin
Keyword(s):  
Lateral Position ◽  
Larval Shell ◽  
Subtidal Zone ◽  
Larval Stages ◽  
Posterior Shoulder ◽  
Blade Shape ◽  
The Right ◽  
Lateral Structures ◽  
Juvenile Development ◽  
Concentric Structure

The paper considers the development of Ciliatocardium ciliatum from the stage of straight hinge to juvenile. In the White Sea the spawning of C. ciliatum begins at the end of June, larvae at different stages of development occur in plankton until the end of September. The earliest of the larvae found had shell lengths of 123–130 µm. The paper first examined the anatomy and structure of the larval shell of C. ciliatum. During the development, the main stages of organogenesis were described and special attention was paid to the formation of the digestive and muscular systems. The digestive system begins to function when the larva reaches a size of 170–180 µm. The digestive gland has a two-blade shape and is shifted to the right side. The foot is formed at a size of 230 µm, the gill rudiments appear when the larva reaches 270 µm. The development of the larval shell and larval hinge of the mollusc is considered in detail. The development of the larval shell of C. ciliatum is similar to the development of other family members. Throughout all the larval stages, the shell has a rounded shape with a low umbos, and the prodissoconch II has a clearly visible concentric structure. The C. ciliatum larval hinge is characterized by weak differentiation and the absence of pronounced cardinal teeth typical for other Cardiidae. However, the lateral structures of the castle – ridges and flanges – are well developed. The ligament begins to form at a size of 240–250 µm and occupies a lateral position. The settlement of the cockle takes place in September in the subtidal zone. After the metamorphosis, a large radial sculpture is formed on the dissoconch and a number of small spikes are formed at the rib of the posterior shoulder.

scholarly journals Review of Icing Effects on Wind Turbine in Cold Regions

2018 ◽  
Vol 72 ◽  
pp. 01007 ◽  
Author(s):  
Faizan Afzal ◽  
Muhammad S. Virk
Keyword(s):  
Wind Turbine ◽  
Structural Integrity ◽  
Turbine Blades ◽  
Leading Edge ◽  
Added Mass ◽  
Cold Climate ◽  
Ice Accretion ◽  
Wind Turbine Blades ◽  
Turbine Performance ◽  
Ice Shedding

This paper describes a brief overview of main issues related to atmospheric ice accretion on wind turbines installed in cold climate region. Icing has significant effects on wind turbine performance particularly from aerodynamic and structural integrity perspective, as ice accumulates mainly on the leading edge of the blades that change its aerodynamic profile shape and effects its structural dynamics due to added mass effects of ice. This research aims to provide an overview and develop further understanding of the effects of atmospheric ice accretion on wind turbine blades. One of the operational challenges of the wind turbine blade operation in icing condition is also to overcome the process of ice shedding, which may happen due to vibrations or bending of the blades. Ice shedding is dangerous phenomenon, hazardous for equipment and personnel in the immediate area.

Experimental and Numerical Investigation on the Performance of a Family of Three HP Transonic Turbine Blades

2004 ◽  
Author(s):  
D. Corriveau ◽  
S. A. Sjolander
Keyword(s):  
Flow Velocity ◽  
Turbine Blades ◽  
Suction Side ◽  
Experimental Results ◽  
Base Pressure ◽  
Suction Surface ◽  
Trailing Edge ◽  
Lower Base ◽  
Shock System ◽  
Transonic Turbine

Experimental results concerning the performance of three high-pressure (HP) transonic turbine blades having fore-, aft- and mid-loadings have been presented previously by Corriveau and Sjolander [1]. Results from that study indicated that by shifting the loading towards the rear of the airfoil, improvements in loss performance of the order of 20% could be obtained near the design Mach number. In order to gain a better understanding of the underlying reasons for the improved loss performance of the aft-loaded blade, additional measurements were performed on the three cascades. Furthermore, 2-D numerical simulations of the cascade flow were performed in order to help in the interpretation of the experimental results. Based on the analysis of additional wake traverse data and base pressure measurements combined with the numerical results, it was found that the poorer loss performance of the baseline mid-loaded profile compared to the aft-loaded blade could be traced back to the former’s higher rear suction side curvature. The presence of higher rear suction surface curvature resulted in higher flow velocity in that region. Higher flow velocity at the trailing edge in turn contributed to reducing the base pressure. The lower base pressure at the trailing edge resulted in a stronger trailing edge shock system for the mid-loaded blade. This shock system increased the losses for the mid-loaded baseline profile when compared to the aft-loaded profile.

scholarly journals Chronology of the Swords with Ring Pommel from the Maeotian Sites on the Right Bank of Kuban River

2020 ◽  
pp. 164-182
Author(s):  
Natalya Limberis ◽  
◽  
Ivan Marchenko ◽  
Keyword(s):  
Type Ii ◽  
Wide Range ◽  
Blade Shape ◽  
Kuban River ◽  
The Right

The article focuses on the chronological analysis of the Maeotian burials, which contained ring-topped swords. Nowadays, there is a wide range of dating of this type of weapon starting from the 1st century BC until the 2nd century AD. Recently, as a result of new excavations, the collection of swords of this type extracted from the Maeotian sites on the right bank of the Kuban river has increased significantly, and it has become possible to clarify their chronology in the region. There were found two types of swords and daggers with a ring pommel (62 pieces): I – with a straight barshaped cross-guards; II – no cross-guards. There are also 2 types of blade shape. Swords with a bar-shaped (45 pieces) prevail quantitatively as a result of those excavations. Swords of this type were discovered only in the necropolis of the Spornoye settlement. On the contrary, there was only a single dagger of type II among 11 swords found at the Elizavetinskaya cemetery No. 2. Most of the well-dated assemblages come from the cemeries of the Spornoye, Starokorsunskaya No. 2 and Elizavetinskaya No. 2 settlements. Only two swords are classified as the earliest pieces, which can be referred to the first half of the 1st century BC, according to the accompanying inventory. Another 8 assemblages are dated around the 1st century BC. It is typical of burials containing swords of the 1st century AD to show the presence of fibulae (“Aucissa” type, enamel-less hinged type, etc.), glass cast skyphos and other dating objects, which help to specify the chronology of the assemblages in many cases. Five burials belong to the first half of the 1st century AD, other 11 burials are dated back to the second half of the 1st century AD. The chronology of the rest assemblages is questionable, but only a few burials can be dated to the beginning – the first half of the 2nd сentury AD. The swords with ring pommel of the Maeotians from the right Kuban bank prevail in the period from the 1st century BC – the beginning of the 2nd century AD. The latter, most probably indicates that this type of swords with s straight cross-guard was borrowed from the Sarmatians.

Optimization of an Axial Turbine Stage for Aerodynamic Inlet Blockage

2011 ◽  
Author(s):  
Mohammad Arabnia ◽  
Vadivel K. Sivashanmugam ◽  
Wahid Ghaly
Keyword(s):  
Pressure Loss ◽  
Suction Side ◽  
Loss Coefficient ◽  
Von Mises Stress ◽  
Optimization Approach ◽  
Design Point ◽  
Pressure Loss Coefficient ◽  
Design Variables ◽  
Blade Shape ◽  
Von Mises

This paper presents a practical and effective optimization approach to minimize 3D-related flow losses associated with high aerodynamic inlet blockage by re-stacking the turbine rotor blades. This approach is applied to redesign the rotor of a low speed subsonic single-stage turbine that was designed and tested in DLR, Germany. The optimization is performed at the design point and the objective is to minimize the rotor pressure loss coefficient as well as the maximum von Mises stress while keeping the same design point mass flow rate, and keeping or increasing the rotor blade first natural frequency. A Multi-Objective Genetic Algorithm (MOGA) is coupled with a Response Surface Approximation (RSA) of the Artificial Neural Network (ANN) type. A relatively small set of high fidelity 3D flow simulations and structure analysis are obtained using ANSYS Workbench Mechanical. That set is used to train and to test the ANN models. The stacking line is parametrically represented using a quadratic rational Bezier curve (QRBC). The QRBC parameters are directly related to the design variables, namely the rotor lean and sweep angles and the bowing parameters. Moreover, it results in eliminating infeasible shapes and in reducing the number of design variables to a minimum while providing a wide design space for the blade shape. The aero-structural optimization of the E/TU-3 turbine proved successful, the rotor pressure loss coefficient was reduced by 9.8% and the maximum von Mises stress was reduced by 36.7%. This improvement was accomplished with as low as four design variables, and is attributed to the reduction of 3D-related aerodynamic losses and the redistribution of stresses from the hub trailing edge region to the suction side maximum thickness area. The proposed parametrization is a promising one for 3D blade shape optimization involving several disciplines with a relatively small number of design variables.

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