Effects of Blade Tip Profile Based on NACAAirfoil on Aerodynamic Performance of Low Aspect Ratio Radial-inflow Turbine

This work outlines a procedure for simulating the flow field within multistage turbomachinery, which includes the effects of unsteadiness, compressibility, and viscosity. The associated modeling equations are the average passage equation system, which governs the time-averaged flow field within a typical passage of a blade row embedded within a multistage configuration. The results from a simulation of a low aspect ratio stage and one-half turbine will be presented and compared with experimental measurements. It will be shown that the secondary flow field generated by the rotor causes the aerodynamic performance of the downstream vane to be significantly different from that of an isolated blade row.

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Sailing Downwind: Aerodynamic Performance of the Velella Sail

Journal of Experimental Biology ◽

10.1242/jeb.158.1.117 ◽

1991 ◽

Vol 158 (1) ◽

pp. 117-132

Author(s):

LISBETH FRANCIS

Keyword(s):

Natural Selection ◽

Wind Tunnel ◽

Aspect Ratio ◽

Hydrodynamic Force ◽

Center Of Pressure ◽

Aerodynamic Force ◽

Aerodynamic Performance ◽

Polar Plot ◽

Low Aspect Ratio

Using a wind tunnel built over a shallow pool and methods devised for measuring the performance of yacht sails, I describe aerodynamic performance in situ for the sailor-by-the-wind, Velella velella. By contrast with designers of the modern yacht mainsail, natural selection has apparently favored stability and seaworthiness over performance to windward. The Velella sail is a low aspect ratio airfoil with an unusually flat polar plot. Primarily a drag-based locomotory structure, this thin, leaf-like sail generates maximum force when oriented at attack angles between 50° and 90°. In the wind tunnel, free-sailing animals spontaneously assumed stable orientations at attack angles ranging from 28° to 87° and sailed with their hulls approximately broadside to the apparent flow of oncoming water. At these angles, aerodynamic force on the sail is asymmetrical, with the center of pressure upwind of the sail midline. Since aerodynamic force on the sail is balanced at equilibrium by hydrodynamic force on the hull, this orientation must be caused by asymmetrical forces acting on surface and underwater parts as the wind drags the animal along the surface of the water.

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Tip Flow Fields in a Low Aspect Ratio Transonic Compressor

Volume 1: Turbomachinery ◽

10.1115/95-gt-089 ◽

1995 ◽

Cited By ~ 2

Author(s):

P. Russler ◽

D. Rabe ◽

B. Cybyk ◽

C. Hah

Keyword(s):

Shock Wave ◽

Aspect Ratio ◽

Flow Field ◽

High Frequency ◽

High Performance ◽

Flow Structures ◽

Transonic Compressor ◽

Low Aspect Ratio ◽

Laser Data ◽

Blade Tip

Experimental data and computational predictions are used to characterize the tip flow field of a high performance, low aspect ratio, transonic compressor. Flow structures near the first stage blade tip are monitored experimentally using two different data acquisition schemes. High frequency pressure and laser fringe anemometry data are used to experimentally define the tip flow structure. The high frequency pressure data were acquired with an array of pressure transducers mounted in the rotor casing. Laser data were acquired through a window in the same position. The transducer and laser data adequately define the shock structure at the tip. Both the movement of the shock wave in the blade passage during changes in compressor loading and the interaction between the shock wave and the tip leakage vortex are detected. Similar flow structures and compressor loading effects are numerically predicted using a three-dimensional Navier-Stokes algorithm. A fundamental understanding of the flow field at the blade tip is obtained using these three complementary methods.

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Investigation of the Aerodynamic Performance of Small Axial Turbines

Journal of Engineering for Power ◽

10.1115/1.3445739 ◽

1973 ◽

Vol 95 (4) ◽

pp. 326-332 ◽

Cited By ~ 13

Author(s):

J. S. Ewen ◽

F. W. Huber ◽

J. P. Mitchell

Keyword(s):

Aspect Ratio ◽

Tip Clearance ◽

Low Aspect Ratio ◽

Turbine Efficiency ◽

Design Variables ◽

Paper Cover ◽

Blade Tip ◽

Design Velocity ◽

Axial Turbines ◽

Cooling Air

This paper describes results of an experimental investigation of small axial turbine performance characteristics. Included are test data on the effects of the following design variables on small turbine aerodynamic efficiency: (a) blade height, (b) vane endwall contouring, (c) blade reaction, (d) blade tip clearance, (e) stage work, and (f) vane and blade airfoil row solidity. In addition, the effects of vane, blade, and disk cooling air injection on turbine efficiency are presented. The turbines evaluated were single stage, low aspect ratio configurations sized for airflows of 8 pps (3.63 kg/sec) or less and designed for inlet temperatures in the 2200-to-2500 deg F (1204-to-1371 deg C) range. The efficiency data presented in the paper cover both design and off-design velocity and pressure ratios. These data illustrate that relatively high efficiencies can be obtained in small, low aspect ratio axial turbines with an optimum design.

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Efficiency improvement of a CAES low aspect ratio radial inflow turbine by NACA blade profile

Renewable Energy ◽

10.1016/j.renene.2019.02.034 ◽

2019 ◽

Vol 138 ◽

pp. 1214-1231 ◽

Cited By ~ 1

Author(s):

Xing Wang ◽

Wen Li ◽

Xuehui Zhang ◽

Yangli Zhu ◽

Zhitao Zuo ◽

...

Keyword(s):

Aspect Ratio ◽

Efficiency Improvement ◽

Blade Profile ◽

Low Aspect Ratio ◽

Radial Inflow Turbine

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Computational Investigation of Flow Structure and Aerodynamic Performance in Low Aspect Ratio Revolving Plates at Low Reynolds number

52nd Aerospace Sciences Meeting ◽

10.2514/6.2014-1453 ◽

2014 ◽

Cited By ~ 1

Author(s):

CHENGYU LI ◽

Haibo Dong

Keyword(s):

Reynolds Number ◽

Aspect Ratio ◽

Flow Structure ◽

Low Reynolds Number ◽

Aerodynamic Performance ◽

Computational Investigation ◽

Low Aspect Ratio ◽

Low Reynolds

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An Aerodynamic Design Method to Improve the High-Speed Performance of a Low-Aspect-Ratio Tailless Aircraft

Applied Sciences ◽

10.3390/app11041555 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1555

Author(s):

Zhongyuan Liu ◽

Lie Luo ◽

Binqian Zhang

Keyword(s):

Aspect Ratio ◽

High Speed ◽

Design Method ◽

Aerodynamic Performance ◽

Pitching Moment ◽

Aerodynamic Design ◽

Linear Superposition ◽

Low Aspect Ratio ◽

Drag Ratio ◽

Lift To Drag Ratio

This paper puts forward an aerodynamic design method to improve the high-speed aerodynamic performance of an aircraft with low-aspect-ratio tailless configuration. The method can ameliorate the longitudinal moment characteristics of the configuration by designing and collocating the key section airfoils with the constrains of fixed parameters of planform shape and capacity. Firstly, the effect of twisting the wing, fore-loading and aft-reflexing key section airfoils on the high-speed aerodynamic performance of the configuration is evaluated by high-fidelity numerical methods, and quantified by defining trimming efficiency factors. Then, a linear superposition formula is obtained by analyzing the effect rule of trimming efficiency factor, and based on the formula the design and collocation methods of key section airfoils are achieved. According to the methods, a trimmed configuration is obtained. The results of computational fluid dynamics (CFD) and wind tunnel tests show that the trimmed configuration has smaller zero-lift pitching moment and higher available lift-to-drag ratio than the initial configuration at cruise, besides the trimmed configuration achieves the design principle raised for tailless configuration, which can be described as the zero-pitching moment, cruising design lift coefficient, and maximum lift-to-drag ratio are coincident. In addition, at off-design conditions, the trimmed configuration shows favorable drag divergence characteristics, satisfactory aerodynamic characteristics at medium-altitude maneuvering condition, and good stall and pitching-moment performance at low speed state.

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