scholarly journals Spillage-Adaptive Fixed-Geometry Bump Inlet of Wide Speed Range

Aerospace ◽  
2021 ◽  
Vol 8 (11) ◽  
pp. 340
Author(s):  
Zonghan Yu ◽  
Guoping Huang ◽  
Ruilin Wang ◽  
Omer Musa
Keyword(s):  
Boundary Layer ◽  
Design Method ◽  
Three Dimensional ◽  
Low Speed ◽  
Flight Vehicles ◽  
Integration Pattern ◽  
Speed Range ◽  
Flexible Integration ◽  
Wide Speed Range ◽  
Future Work

In this work, a new spillage-adaptive bump inlet concept is proposed to widen the speed range for hypersonic air-breathing flight vehicles. Various approaches to improve the inlet start-ability are summarized and compared, among which the bump-inlet pattern holds the merits of high lift-to-drag ratio, boundary layer diversion, and flexible integration ability. The proposed spillage-adaptive concept ensures the inlet starting performance by spilling extra mass flow away at low speed number conditions. The inlet presetting position is determined by synthetically evaluating the flow uniformity and the low-kinetic-energy fluid proportion. The numerical results show that the flow spillage of the inlet increases with the inflow speed decrease, which makes the inlet easier to start at low speed conditions (M 2.5–6.0). The effects of the boundary layer on spillage are also studied in this work. The new integration pattern releases the flow spillage potentials of three-dimensional inward-turning inlets by reasonably arranging the inlet compression on the bump surface. Future work will focus on the spillage-controllable design method.

Novel Strategy for BLDC Motor Rotor Position Detection

2015 ◽  
Vol 772 ◽  
pp. 365-372
Author(s):  
Ling Zhi Cao ◽  
Sheng Hao Yang
Keyword(s):  
Motor Speed ◽  
Zero Crossing ◽  
Low Speed ◽  
Rotor Position ◽  
Voltage Difference ◽  
Position Detection ◽  
Position Signal ◽  
Speed Range ◽  
Terminal Voltage ◽  
Wide Speed Range

The detection of rotor position plays an important role in the motor speed-adjustment system. By analyzing the back-EMF method and its improved methods, we know the amplitude of back-EMF is too small to be detected when the motor run at low speed. A new detection method of rotor position has been proposed in this paper. It detects the zero crossing point of line terminal voltage difference to acquire the rotor position signal after a 90 degrees mechanical angle delay. The amplitude of line terminal voltage difference is large in wide speed range, so the rotor position signal can be accurately acquired in most situations. Simulation results proved that the new method can obtain the rotor position signal exactly in both high and low speed. It meets the wide speed range of motor.

Experimental and Numerical Study of a Subsonic Aspirated Cascade

2012 ◽  
Author(s):  
Antoine Godard ◽  
François Bario ◽  
Stéphane Burguburu ◽  
Francis Lebœuf
Keyword(s):  
Boundary Layer ◽  
Flow Control ◽  
Numerical Study ◽  
Design Method ◽  
Active Flow Control ◽  
Three Dimensional ◽  
Design Feature ◽  
Suction Side ◽  
Compressor Blades ◽  
Pressure Losses

This paper presents the validation of a design method for aspirated compressor blades, combining a passive separation control by blade shaping with an active flow control by aspiration. In a first part, a linear aspirated cascade designed according to this method was built and tested at low speed, without and with aspiration. The latter was only applied on the suction surfaces of the blades. Particle Image Velocimetry measurements performed at mid-span of the cascade, in the central passage, showed a complete reattachment of the separated boundary layer on the suction side of the blade. A flow deflection of approximately 65 degrees was achieved requiring an aspirated mass flow rate of 3.3%. However, boundary layer reattachment is effective in a zone centered at mid-span covering 30% of blade span. Flow visualization revealed large corner separation in the presence of aspiration. This is due to the re-establishment of strong pressure gradient on sidewalls of the cascade. No flow control was applied on these zones for optical access purpose. These secondary-flow regions reduced the diffusion occurring within the cascade by nearly 60% in comparison with the design intent. They also increased the expected level of total pressure losses measured by wake traverses downstream of the cascade. In a second part, numerical simulations of the aforementioned experiment were carried out to help the understanding of the experimental results. The simulations were able to reproduce correctly the characteristic flow features, without and with aspiration, observed and measured during the experiment. Thus, they confirmed the potential of this design method developed for aspirated compressor blades, as well as CFD capabilities to simulate the influence of technological effects like suction slots. A uniform and a non-uniform aspiration distribution along the blade span direction were considered during simulations. Suction distribution was found to have a significant impact on the control by aspiration. This design feature, in addition to flow control on endwalls, has to be taken into account in the three-dimensional design of highly loaded aspirated compressor blades.

scholarly journals Axial Flux PM In-Wheel Motor for Electric Vehicles: 3D Multiphysics Analysis

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2107
Author(s):  
Andrea Credo ◽  
Marco Tursini ◽  
Marco Villani ◽  
Claudia Di Lodovico ◽  
Michele Orlando ◽  
...  
Keyword(s):  
Motor Behavior ◽  
Thermal Analyses ◽  
Three Dimensional ◽  
Axial Flux ◽  
Compact Structure ◽  
Radial Flux ◽  
Speed Range ◽  
Wide Speed Range ◽  
3D Problem ◽  
Transmission Gear

The Axial Flux Permanent Magnet (AFPM) motor represents a valid alternative to the traditional radial flux motor due to its compact structure; it is suitable for in-wheel applications so that the transmission gear can be suppressed. The modeling of the motor is a purely Three-Dimensional (3D) problem and the use of 3D finite element tools allows the attainment of accurate results taking also into account the effects of the end-windings. Moreover, a 3D multiphysics analysis is essential to evaluate not only the motor performance and its thermal behavior, but also the electromagnetic forces acting on the surfaces of the stator teeth and of the magnets that face the air gap. Moreover, as the vehicle’s motors often work in variable-speed conditions, the prediction of vibrations and noise for electric motors over a wide speed range is usually necessary. The paper presents a double-sided AFPM motor for a small pure electric vehicle; the basic drive architecture includes four axial flux motors installed directly inside the vehicle’s wheels. The aim is to propose advanced and integrated electromagnetic, vibroacoustic and thermal analyses that allow the investigation of the axial flux motor behavior in a detailed and exhaustive way.

Aerodynamics of Boundary Layer Ingesting Fans

2014 ◽  
Author(s):  
E. J. Gunn ◽  
C. A. Hall
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Low Speed ◽  
Turbofan Engines ◽  
Unsteady Separation ◽  
Fuel Burn ◽  
Boundary Layer Interaction ◽  
Flow Features ◽  
Structure Strength ◽  
Transonic Fan

Boundary Layer Ingesting (BLI) turbofan engines could offer reduced fuel burn compared with podded engines, but the fan stage must be designed to run continuously with severe inlet distortion. This paper aims to explain the fluid dynamics and loss sources in BLI fans running at a cruise condition. High-resolution experimental measurements and full-annulus unsteady CFD have been performed on a low-speed fan rig running with a representative BLI inlet velocity profile. A three-dimensional flow redistribution is observed, leading to an attenuation of the axial velocity non-uniformity upstream of the rotor and to non-uniform swirl and radial angle distributions at rotor inlet. The distorted flow field is shown to create circumferential and radial variations in diffusion factor with a corresponding loss variation around the annulus. Additional loss is generated by an unsteady separation of the casing boundary layer, caused by a localised peak in loading at the rotor tip. Non-uniform swirl and radial angles at rotor exit lead to increased loss in the stator due to the variations in profile loss and corner separation size. An additional CFD calculation of a transonic fan running with the same inlet profile is used to show that BLI leads to wide variations in rotor shock structure, strength and position and hence to loss generation through shock-boundary layer interaction, but otherwise contained the same flow features as the low-speed case. For both fan geometries, BLI was found to reduce the stage efficiency by around 1–2% relative to operation with uniform inlet flow.

Low speed aerodynamic performance analysis of vortex lift waveriders with a wide-speed range

2019 ◽  
Vol 161 ◽  
pp. 209-221 ◽  
Author(s):  
Zhen-tao Zhao ◽  
Wei Huang ◽  
Li Yan ◽  
Tian-Tian Zhang ◽  
Shi-bin Li ◽  
...  
Keyword(s):  
Performance Analysis ◽  
Aerodynamic Performance ◽  
Low Speed ◽  
Speed Range ◽  
Wide Speed Range

Drag Reduction of a Cylinder/Endwall Junction Using the Iceformation Method

1993 ◽  
Vol 115 (1) ◽  
pp. 26-32 ◽  
Author(s):  
R. S. LaFleur ◽  
L. S. Langston
Keyword(s):  
Boundary Layer ◽  
Design Method ◽  
Three Dimensional ◽  
Control Parameters ◽  
Cylinder Wake ◽  
Adaptive Selection ◽  
Vortex Model ◽  
Optimal Contour ◽  
Flow Visualizations ◽  
High Reynolds

The iceformation design method was used to reduce the drag of a juncture between a cylinder and flat endwall. Ice was formed on a subfreezing flat endwall in a warmer laminar water flow. The ice shape was influenced by and altered the three-dimensional separated boundary layer and the cylinder wake. Preliminary experiments were used to indicate control parameter relationships. An adaptive selection theory was used to determine optimal control parameters. A sample optimal contour was generated and tested for juncture drag performance. High Reynolds number wind tunnel drag tests showed that the iceform contour had an average of 18 percent lower drag than a flat plate juncture given the same upstream boundary layer conditions. Flow visualizations showed that the iceform contour produced three larger diameter vortices compared to the laminar four vortex model of Baker (1979).

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