Numerical Investigation of the Effect of Rotor Blade Leading Edge Geometry on the Performance of a Variable Geometry Turbine

2012 ◽  
Author(s):  
Lei Huang ◽  
Weilin Zhuge ◽  
Yangjun Zhang ◽  
Liaoping Hu ◽  
Di Yang ◽  
...  
Keyword(s):  
Rotor Blade ◽  
Leading Edge ◽  
Flow Fields ◽  
Operating Conditions ◽  
Angle Distribution ◽  
Variable Geometry ◽  
Sweep Angle ◽  
Turbine Performance ◽  
And Performance ◽  
Blade Leading Edge

Variable geometry turbines are more and more widely used in diesel engines to meet the requirements of the stringent emission standards. The VGTs mostly operate at off-design conditions. At highly off-design conditions, there exist complex secondary flow structures and severe flow separation in the rotor passage, which deteriorate the turbine performance largely. The influence of rotor blade leading edge geometries on the VGT performance was studied by CFD simulations. The blade angle distribution along the leading edge was varied while keeping the radial-fiber rotor construction. The effects of inlet sweep angle distribution and lean angle of the blade leading edge on the turbine flow fields and performance were investigated under different operating conditions. Results show that the turbine with backswept leading edge has better performance at low U/C, while the turbine with forward swept leading edge has a higher efficiency under high flow rate conditions. With the same sweep angle distribution, the leading edge lean affects the flow fields in the rotor passage as well as the turbine performance significantly. The influence of blade lean on the turbine performance varies according to different swept blading and operating conditions.

EFFECT OF AXIAL CASING GROOVE GEOMETRY ON ROTOR-GROOVE INTERACTIONS IN THE TIP REGION OF A COMPRESSOR

2021 ◽  
pp. 1-54
Author(s):  
Subhra Shankha Koley ◽  
Huang Chen ◽  
Ayush Saraswat ◽  
Joseph Katz
Keyword(s):  
Rotor Blade ◽  
Leading Edge ◽  
Secondary Flows ◽  
Low Flow ◽  
Flow Angle ◽  
Flow Rates ◽  
Piv Measurements ◽  
Tip Leakage ◽  
Large Vortex ◽  
Blade Leading Edge

Abstract This experimental study characterizes the interactions of axial casing grooves with the flow in the tip region of an axial turbomachine. The tests involve grooves with the same inlet overlapping with the rotor blade leading edge, but with different exit directions located upstream. Among them, U grooves, whose circumferential outflow opposes the blade motion, achieve a 60% reduction in stall flowrate, but degrade the efficiency around the best efficiency point (BEP) by 2%. The S grooves, whose outlets are parallel to the blade rotation, improve the stall flowrate by only 36%, but do not degrade the BEP performance. To elucidate the mechanisms involved, stereo-PIV measurements covering the tip region and interior of grooves are performed in a refractive index matched facility. At low flow rates, the inflow into both grooves, which peaks when they are aligned with the blade pressure side, rolls up into a large vortex that lingers within the groove. By design, the outflow from S grooves is circumferentially positive. For the U grooves, fast circumferentially negative outflow peaks at the base of each groove, causing substantial periodic variations in the flow angle near the blade leading edge. At BEP, interactions with both grooves become milder, and most of the tip leakage vortex remains in the passage. Interactions with the S grooves are limited hence they do not degrade the efficiency. In contrast, the inflow into and outflow from the U grooves reverses direction, causing entrainment of secondary flows, which likely contribute to the reduced BEP efficiency.

Film-Cooling Prediction on Rotor Blade Leading Edge in 1-1/2 Turbine Stage

2008 ◽  
Vol 22 (2) ◽  
pp. 201-209 ◽  
Author(s):  
Huitao Yang ◽  
Hamn-Ching Chen ◽  
Je-Chin Han ◽  
Hee-Koo Moon
Keyword(s):  
Film Cooling ◽  
Rotor Blade ◽  
Leading Edge ◽  
Turbine Stage ◽  
Blade Leading Edge

scholarly journals Impact of mission requirements on the design of low observable UCAV configurations

2019 ◽  
Vol 91 (10) ◽  
pp. 1295-1307
Author(s):  
Eduardo Sepulveda Palacios ◽  
Howard Smith
Keyword(s):  
Low Cost ◽  
Leading Edge ◽  
Aircraft Design ◽  
Considerable Proportion ◽  
Design Environment ◽  
Sweep Angle ◽  
Content Type ◽  
Aerial Warfare ◽  
And Performance ◽  
Excess Power

Purpose The purpose of this paper is to characterise the effects of mission and performance parameters on the design space of low observable subsonic unmanned combat aerial vehicles (UCAVs) operating in typical Hi-Lo-Hi ground strike missions. Design/methodology/approach Conceptual design methodologies appropriate to low observable, tailless UCAVs have been integrated into a multidisciplinary aircraft design environment, GENUS, developed at Cranfield University’s aircraft design group. A basic Hi-Lo-Hi mission is designed and a baseline configuration is established through the GENUS framework. Subsequently, an evolutionary optimiser and a robust gradient-based optimiser are used to obtain convergent design solutions for various leading edge sweep angles, mission ranges, cruise Mach numbers and other operational constraints. Findings The results indicate that performance constraints, specifically in the form of specific excess power (SEP), have a large influence on the overall sizing of subsonic tailless UCAVs. This requirement drives the engine sizing, which represents a considerable proportion of the empty and gross mass of the vehicle. Cruise Mach number studies show that no significant advantages exist for operating at low speeds while maintaining performance requirements consistent with combat missions. There is a drastic increase in the vehicle’s mass and thrust requirements for flight speeds above Mach 0.8, with low sweep configurations showing a more pronounced effect. Increases in the range are not overly dependent on the leading edge sweep angle. Top-level radar cross section (RCS) results also favour configurations with higher leading edge sweep angles, especially from the nose-on aspect. Finally, research and development costs are shown to be directly linked to engine size. Originality/value This research shows the use of an integrated aircraft design environment that incorporates aerodynamics, performance, packaging and low observability aspects into the optimisation loop. Through this methodology, this study supports the efforts towards characterising and establishing alternate visions of the future of aerial warfare through the use of low cost, survivable unmanned platforms in network-centric cooperative tasks.

Kinematic Analysis of 3-D Swept Shock Surfaces in Axial Flow Compressors

2000 ◽  
Vol 123 (3) ◽  
pp. 490-500 ◽  
Author(s):  
Peng Shan
Keyword(s):  
Three Dimensional ◽  
Axial Flow ◽  
Leading Edge ◽  
Research Field ◽  
High Loading ◽  
Kinematic Characteristic ◽  
Sweep Angle ◽  
Quantitative Classification ◽  
Axial Flow Compressors ◽  
Blade Leading Edge

This paper is part II of a comprehensive study on the blade leading edge sweep/bend of supersonic and transonic axial compressors. The paper explores and analyzes the kinematic characteristic variables of three-dimensional (3-D) swept shock surfaces. In the research field studying the sweep aerodynamics of axial flow compressors and fans, many types of high loading swept blades are under intensive study. So, in both direct and inverse design methods and experimental validations, an accurate grasp of the sweep characteristic of the blade’s 3-D swept shock surface becomes of more concern than before. Associated with relevant blading variables, this paper studies the forward and zero and backward sweeps of shock surfaces, defines and resolves every kind of useful sweep angle, obtains dimensionless sweep similarity factors, suggests a kind of method for the quantitative classification of 3-D shock structures, and proposes the principle of 3-D shock structure measurements. Two rotor blade leading edge shock surfaces from two high loading single stage fans are analyzed and contrasted. This study is the foundation of the kinematic design of swept shock surfaces.

Numerical Modeling of the Effects of Leading-Edge Erosion and Trailing-Edge Damage on Wind Turbine Loads and Performance

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Francesco Papi ◽  
Lorenzo Cappugi ◽  
Sebastian Perez-Becker ◽  
Alessandro Bianchini
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Prolonged Exposure ◽  
Leading Edge ◽  
Future Generation ◽  
Operating Conditions ◽  
Wind Speeds ◽  
And Performance ◽  
Lift And Drag ◽  
The Impact

Abstract Wind turbines operate in challenging environmental conditions. In hot and dusty climates, blades are constantly exposed to abrasive particles that, according to many field reports, cause significant damages to the leading edge. On the other hand, in cold climates similar effects can be caused by prolonged exposure to hail and rain. Quantifying the effects of airfoil deterioration on modern multi-MW wind turbines is crucial to correctly schedule maintenance and to forecast the potential impact on productivity. Analyzing the impact of damage on fatigue and extreme loading is also important to improve the reliability and longevity of wind turbines. In this work, a blade erosion model is developed and calibrated using computational fluid dynamics (CFD). The Danmarks Tekniske Universitet (DTU) 10 MW Reference Wind Turbine is selected as the case study, as it is representative of the future generation wind turbines. Lift and Drag polars are generated using the developed model and a CFD numerical setup. Power and torque coefficients are compared in idealized conditions at two wind speeds, i.e., the rated speed and one below it. Full aero-servo-elastic simulations of the turbine are conducted with the eroded polars using NREL's BEM-based code OpenFAST. Sixty-six 10-min simulations are performed for each stage of airfoil damage, reproducing operating conditions specified by the IEC 61400-1 power production DLC-group, including wind shear, yaw misalignment, and turbulence. Aeroelastic simulations are analyzed, showing maximum decreases in CP of about 12% as well as reductions in fatigue and extreme loading.

Kinematic Analysis of 3-D Swept Shock Surfaces in Axial Flow Compressors

2000 ◽  
Author(s):  
Peng Shan
Keyword(s):  
Axial Flow ◽  
Leading Edge ◽  
Research Field ◽  
High Loading ◽  
Kinematic Characteristic ◽  
Sweep Angle ◽  
Quantitative Classification ◽  
Experimental Validations ◽  
Axial Flow Compressors ◽  
Blade Leading Edge

This paper is Part II of a comprehensive study on the blade leading edge sweep/bend of supersonic and transonic axial compressors. The paper explores and analyses the kinematic characteristic variables of 3-D swept shock surfaces. In the research field called sweep aerodynamics of axial flow compressors and fans, many types of high loading swept blades are under an intensive study. So, in both the direct/inverse design methods and the experimental validations, the accurate grasp of the sweep characteristic of the blade’s 3-D swept shock surface becomes more concerned than before. Associated with relevant blading variables, this paper studied in uniformity the forward and zero and backward sweeps of shock surfaces, defined and resolved every kind of useful sweep angle, obtained dimensionless sweep similarity factors, suggested a kind of method for the quantitative classification of 3-D shock structures, proposed the principle of 3-D shock structure measurements. Two rotor blade leading edge shock surfaces from two high loading single stage fans are analysed and contrasted. This study is the foundation of the kinematic design of swept shock surfaces.

scholarly journals Design fabrication and performance analysis of length morphing rotor blade

2018 ◽  
Vol 7 (3.3) ◽  
pp. 139
Author(s):  
G Saravanan ◽  
Vinoth Kumar Annamalai ◽  
N Bharath ◽  
Antonio Kevin ◽  
G Rahul Teja ◽  
...  
Keyword(s):  
Rotor Blade ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Blade Element Theory ◽  
Weight Variation ◽  
Design Variables ◽  
Thrust Efficiency ◽  
Length Variable ◽  
And Performance ◽  
Maximum Thrust

The present work deals with helicopter theory involving the study, design and fabrication of the helicopter rotor blades with the length-morphing mechanism. The research of the rotor blades has enabled in a proper understanding of the aerodynamics and design of the same. The thrust produced by a blade is proportional to its area, and for every motor RPM, maximum thrust efficiency is achieved for a discrete length of the rotor blade. Facing this complexity, designers compute an optimal length for the average motor RPM while designing the heli-copter blades. Acknowledging the challenges, Length-Morphing rotor blades targeting maximum thrust efficiency for each motor RPM was developed with the aid of knowledge in Blade Element Theory. The rotor blade was designed and fabricated to be driven by the centrifugal force from the motor. The rotor blade was divided into fixed inboard section and sliding outboard part in a span-wise direction. The analy-sis was carried out to study and comprehend the operating conditions of the length-variable rotor during revolutions and to derive the design variables of extension-spring and rotor weight. Variation of thrust concerning the length of the rotor blade was studied, and the setup was fabricated. The project aims to enable maximum rotor blade thrust efficiency for each RPM of the motor by varying the length of the rotor blade and computing the performance characteristics of the same.  

Improving Vibration Response of Radial Turbine in Variable Geometry Turbochargers With CFD Analysis

2021 ◽  
Author(s):  
Bipin Gupta ◽  
Toyotaka Yoshida ◽  
Shinji Ogawa ◽  
Yosuke Danmoto ◽  
Takashi Yoshimoto
Keyword(s):  
Safety Factor ◽  
Surface Pressure ◽  
Leading Edge ◽  
Operating Conditions ◽  
Wake Flow ◽  
Leakage Flow ◽  
Variable Geometry ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Nozzle Vane

Abstract Recent advancements in internal combustion engine for efficient fuel combustion, such as application of miller cycle, where the closing of engine intake valve is purposely delayed to provide more cooling of air-fuel mixture during compression stroke for better engine efficiency, has led to a requirement for turbochargers to function at a wider operating range and higher compression ratio. One of the methods which have been largely accepted is the use of variable geometry turbochargers. As compared to diesel engine, operating conditions for gasoline engine require the turbine to operate at higher exhaust temperature, which increases the risk of damaging the rotor. This paper discusses a detailed flow analysis of the effect of tip leakage and nozzle vane wake flow on surface pressure distribution of the turbine rotor, especially at the severe condition when vane trailing edge and rotor leading edge are in proximity. It was observed in steady and unsteady CFD simulations that the origination and propagation of tip leakage flow can be varied depending on the blade loading at the rotor leading edge, and the major interaction of nozzle wake can be switched from pressure surface to suction surface as rotor blade crossed a nozzle vane, which can drastically affect the alternating aerodynamic stresses. The sensitivity to this phenomenon has been evaluated by calculating the safety factor. The authors modified the rotor design to weaken the effect of tip leakage flow in order to suppress variations in rotor surface pressure as it crosses the nozzle vane. It significantly reduced the alternating stress and increased the safety factor at vibration mode 2 from 0.3 to 9.3 and mode 3 from 0.6 to 3.2 respectively.

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