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.

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 Fin sweep angle does not determine flapping propulsive performance

2020 ◽  
Author(s):  
Andhini N. Zurman-Nasution ◽  
Bharathram Ganapathisubramani ◽  
Gabriel D. Weymouth
Keyword(s):  
Correlation Coefficient ◽  
Large Range ◽  
Three Dimensional ◽  
Leading Edge ◽  
Potential Sweep ◽  
Sweep Angle ◽  
Propulsive Performance ◽  
Maximum Angle ◽  
And Robotics ◽  
Three Dimensional Simulations

The importance of the leading-edge sweep angle of propulsive surfaces used by unsteady swimming and flying animals has been an issue of debate for many years, spurring studies in biology, engineering, and robotics with mixed conclusions. In this work we provide results from an extensive set of three-dimensional simulations of finite foils undergoing tail-like (pitch-heave) and flipper-like (twist-roll) kinematics for a range of sweep angles while carefully controlling all other parameters. No significant change in force and power is observed for tail-like motions as the sweep angle increases, with a corresponding efficiency drop of only ≈ 2%. Similar findings are seen in flipper-like motion and the overall correlation coefficient between sweep angle and propulsive performance is 0.1-6.7%. This leads to a conclusion that fish tails or mammal flukes can have a large range of potential sweep angles without significant negative propulsive impact. A similar conclusion applies to flippers; although there is a slight benefit to avoid large sweep angles for flippers, this could be easily compensated by adjusting other hydrodynamics parameters such as flapping frequency, amplitude and maximum angle of attack to gain higher thrust and efficiency.

Three Components- and Tomographic-PIV Measurements of a Cyclone Cooling Flow in a Swirl Tube

2013 ◽  
Author(s):  
Christoph Biegger ◽  
Bernhard Weigand ◽  
Alice Cabitza
Keyword(s):  
Flow Field ◽  
Vortex Breakdown ◽  
Tracer Particle ◽  
Three Dimensional ◽  
Axial Flow ◽  
Leading Edge ◽  
Generic Model ◽  
Tube Axis ◽  
Tomographic Piv ◽  
Order Of Magnitude

Swirl cooling is a very efficient method for turbine blade cooling. However, the flow in such a system is quite complicated. In order to gain understanding of the flow structure, the velocity field in a leading edge swirl cooling chamber with two tangential inlet ducts is experimentally studied via Particle Image Velocimetry (PIV). The examined swirl tube is 1 m long and has a diameter of 50 mm. It represents an upscaled generic model of a leading edge swirl chamber. The Reynolds number, defined by the bulk velocity and the swirl tube diameter, ranges from 10,000 to 40,000, and the swirl number is 5.3. Velocity fields are measured in the center plane of the tube axis with stereo- and tomographic-PIV using two and four CCD cameras respectively. Tomographic-PIV is a three-dimensional PIV technique relying on the illumination, recording, reconstruction and cross correlation of a tracer particle distribution in a measurement volume opposed to a plane in stereo-PIV. For statistical analysis 2,000 vector maps are calculated and evaluations show a sample size of 1,000 ensembles is sufficient. Our experiment showed, that the flow field is characterized by a vortex system around the tube axis. Near the tube wall we observed an axial flow towards the outlet with a circumferential velocity component in the same order of magnitude. In contrast the vortex core consists of an axial backflow (vortex breakdown). The gained understanding of the flow field allows to predict regions of enhanced heat transfer in swirl chambers.

A scaling for vortex formation on swept and unswept pitching wings

2017 ◽  
Vol 832 ◽  
pp. 697-720 ◽  
Author(s):  
Kyohei Onoue ◽  
Kenneth S. Breuer
Keyword(s):  
Control Volume ◽  
Vortex Formation ◽  
Fluid Motion ◽  
Three Dimensional ◽  
Leading Edge ◽  
Sweep Angle ◽  
Reduced Frequency ◽  
Vortex Formation Time ◽  
The Stability ◽  
Vorticity Transport

We examine the dynamics of the leading-edge vortex (LEV) on a rapidly pitching plate with the aim of elucidating the underlying flow physics that dictates the stability and circulation of the LEV. A wide variety of flow conditions is considered in the present study by systematically varying the leading-edge sweep angle ($\unicode[STIX]{x1D6EC}=0^{\circ }$, $11.3^{\circ }$, $16.7^{\circ }$) and the reduced frequency ($f^{\ast }=0.064{-}0.151$), while keeping the pitching amplitude and the Reynolds number fixed. Tomographic particle image velocimetry is used to characterise the three-dimensional fluid motion inside the vortex core and its relation to the LEV stability and growth. A series of control volume analyses are performed to quantify the relative importance of the vorticity transport phenomena taking place inside the LEV to the overall vortex development. We show that, near the wing apex where tip effects can be neglected, the vortex develops in a nominally two-dimensional manner, despite the presence of inherently three-dimensional vortex dynamics such as vortex stretching and compression. Furthermore, we demonstrate that the vortex formation time and circulation growth are well-described by the principles of optimal vortex formation number, and that the occurrence of vortex shedding is dictated by the relative energetics of the feeding shear layer and the resulting vortex.

Three-Dimensional Turbulent Flow in the Tip Region of an Axial Compressor Rotor Passage at a Near Stall Condition

2001 ◽  
Author(s):  
Hongwei Ma ◽  
Haokang Jiang
Keyword(s):  
Turbulent Flow ◽  
Large Scale ◽  
Three Dimensional ◽  
Axial Flow ◽  
Leading Edge ◽  
Rotating Stall ◽  
Suction Surface ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Compressor Rotor

This paper presents an experimental study of the three-dimensional turbulent flow field in the tip region of an axial flow compressor rotor passage at a near stall condition. The investigation was conducted in a low-speed large-scale compressor using a 3-component Laser Doppler Velocimetry and a high frequency pressure transducer. The measurement results indicate that a tip leakage vortex is produced very close to the leading edge, and becomes the strongest at about 10% axial chord from the leading edge. Breakdown of the vortex periodically occurs at about 1/3 chord, causing very strong turbulence in the radial direction. Flow separation happens on the tip suction surface at about half chord, prompting the corner vortex migrating toward the pressure side. Tangential migration of the low-energy fluids results in substantial flow blockage and turbulence in the rear of a rotor passage. Unsteady interactions among the tip leakage vortex, the separated vortex and the corner flow should contribute to the inception of the rotating stall in a compressor.

Three-Dimensional Relief in Turbomachinery Blading

1990 ◽  
Vol 112 (4) ◽  
pp. 587-596 ◽  
Author(s):  
A. R. Wadia ◽  
B. F. Beacher
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Axial Flow ◽  
Leading Edge ◽  
Two Dimensional ◽  
Suction Surface ◽  
Airfoil Surface ◽  
Flow Angle ◽  
Edge Loading ◽  
Cascade Analysis

The leading edge region of turbomachinery blading in the vicinity of the endwalls is typically characterized by an abrupt increase in the inlet flow angle and a reduction in total pressure associated with endwall boundary layer flow. Conventional two-dimensional cascade analysis of the airfoil sections at the endwalls indicates large leading edge loadings, which are apparently detrimental to the performance. However, experimental data exist that suggest that cascade leading edge loading conditions are not nearly as severe as those indicated by a two-dimensional cascade analysis. This discrepancy between two-dimensional cascade analyses and experimental measurements has generally been attributed to inviscid three-dimensional effects. This article reports on two and three-dimensional calculations of the flow within two axial-flow compressor stators operating near their design points. The computational results of the three-dimensional analysis reveal a significant three-dimensional relief near the casing endwall that is absent in the two-dimensional calculations. The calculated inviscid three-dimensional relief at the endwall is substantiated by airfoil surface static pressure measurements on low-speed research compressor blading designed to model the flow in the high-speed compressor. A strong spanwise flow toward the endwall along the leading edge on the suction surface of the airfoil is responsible for the relief in the leading edge loading at the endwall. This radial migration of flow results in a more uniform spanwise loading compared to that predicted by two-dimensional calculations.

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 Stator Design on Stator Boundary Layer Flow in a Highly Loaded Single-Stage Axial-Flow Low-Speed Compressor

2000 ◽  
Vol 123 (3) ◽  
pp. 483-489 ◽  
Author(s):  
Jens Friedrichs ◽  
Sven Baumgarten ◽  
Gu¨nter Kosyna ◽  
Udo Stark
Keyword(s):  
Axial Flow ◽  
Leading Edge ◽  
Single Stage ◽  
Swept Wing ◽  
Sweep Angle ◽  
Low Speed ◽  
Overall Performance ◽  
Layer Flow ◽  
Stator Design ◽  
Highly Loaded

The paper describes an experimental investigation of the stator hub and blade flow in two different stators of a highly loaded single-stage axial-flow low-speed compressor. The first stator (A) is a conventional design with blades of rectangular planform. The second stator (K) is an unconventional, more advanced design with blades of a special planform, characterized by an aft-swept leading edge with increasing sweep angle toward hub and casing. The experimental results show that stator K exhibits a much better hub performance than stator A, finally leading to a better overall performance of stage K compared to stage A. The better hub performance of stator K is, primarily, the result of a planform effect of the newly introduced blades with an aft-swept leading edge and the aerodynamics of an aft-swept wing.

Sign in / Sign up

Export Citation Format

Share Document