Research on aerodynamic characteristics of two-stage axial micro air turbine spindle for small parts machining

In order to meet the requirements of output torque, efficiency and compact shape of micro-spindles for small parts machining, a two-stage axial micro air turbine spindle with an axial inlet and outlet is proposed. Based on the k-ω turbulence model of SST, the flow field and operation characteristics of the two-stage axial micro air turbine spindle were studied using computational fluid dynamics (CFD) combined with an experimental study. We obtained the air turbine spindle under different working conditions of the loss and torque characteristics. When the inlet pressure was 300 KPa, the output speed of the two-stage turbine was 100,000 rpm, 9% higher than that of a single-stage turbine output torque. The total torque reached 6.39 N·mm, and the maximum efficiency of the turbine and the spindle were 42.2% and 32.3%, respectively. Through the research on the innovative structure of the two-stage axial micro air turbine spindle, the overall performance of the principle prototype has been significantly improved and the problems of insufficient output torque and low working efficiency in high-speed micro-machining can be solved practically, which laid a solid foundation for improving the machining efficiency of small parts and reducing the size of micro machine tool.

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Experimental Results of Full Scale Air-Cooled Turbine Tests

Journal of Engineering for Power ◽

10.1115/1.3446100 ◽

1976 ◽

Vol 98 (1) ◽

pp. 103-113

Author(s):

H. Nouse ◽

A. Yamamoto ◽

T. Yoshida ◽

H. Nishimura ◽

K. Takahara ◽

...

Keyword(s):

Axial Flow ◽

Aircraft Engine ◽

Aerodynamic Characteristics ◽

Experimental Results ◽

Test Results ◽

Test Apparatus ◽

Two Stage ◽

Turbine Cooling ◽

Turbine Performance ◽

Air Turbine

In order to investigate several problems associated with the turbine cooling, an air-cooled two-stage axial flow turbine for an aircraft engine application was designed. Aerodynamic characteristics of the two-stage turbine without coolants were obtained first from the cold air turbine tests, and predictions of the turbine performance with supplying of coolants were made using the test results. Following these experiments, cooling tests of the first stage turbine were conducted in the range of turbine inlet gas temperatures lower than 1360 K by the another test apparatus. The descriptions of the turbine and the two test apparatus and the experimental results of the two test turbines are presented. The performance prediction, coolant effects and Reynolds number effect on the turbine performance are also described.

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Development of High-Speed Gas Bearings for High-Power Density Microdevices

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.1498273 ◽

2002 ◽

Vol 125 (1) ◽

pp. 141-148 ◽

Cited By ~ 32

Author(s):

F. F. Ehrich ◽

S. A. Jacobson

Keyword(s):

Power Density ◽

High Power ◽

High Speed ◽

Single Crystal Silicon ◽

Small Scale ◽

Crystal Silicon ◽

Gas Bearings ◽

Electromagnetic Devices ◽

Air Turbine ◽

Micro Machine

A 4.2-mm diameter silicon rotor has been operated in a controlled and sustained manner at rotational speeds greater than 1.3 million rpm and power levels approaching 5 W. The rotor, supported by hydrostatic journal and thrust gas bearings, is driven by an air turbine. This turbomachinery/bearing test device was fabricated from single-crystal silicon wafers using micro-fabrication etching and bonding techniques. We believe this device is the first micro-machine to operate at a circumferential tip speed of over 300 meters per second, comparable to conventional macroscale turbomachinery, and necessary for achieving high levels of power density in micro-turbomachinery and micro-electrostatic/ electromagnetic devices. To achieve this level of peripheral speed, micro-fabricated rotors require stable, low-friction bearings for support. Due to the small scale of these devices as well as fabrication constraints that limit the bearing aspect ratio, the design regime is well outside that of more conventional devices. This paper focuses on bearing design and test, and rotordynamic issues for high-speed high-power micro-fabricated devices.

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The Effects of Different Support Forms on the Aerodynamic Characteristics of the High-Speed Train Model

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.246-247.461 ◽

2012 ◽

Vol 246-247 ◽

pp. 461-465

Author(s):

Bao Yu Li ◽

Xi Zhuang Shan ◽

Zhi Gang Yang

Keyword(s):

Flow Field ◽

High Speed ◽

Aerodynamic Characteristics ◽

Operating Conditions ◽

High Speed Train ◽

Reference Velocity ◽

Computational Fluid Dynamics Cfd ◽

Aerodynamic Parameters ◽

Support Interference ◽

Good Support

By the method of computational fluid dynamics (CFD), this paper calculates the aerodynamic parameters of one complex high-speed train model which adopts different support forms when the reference velocity is 70m/s under different operating conditions. It also analyses the support interference mechanism from the point of flow field structure. The results show that the distributed cylinder support form causes least interference on the model, while the single big cylinder support forms change the flow field structures much which leads to much change of the aerodynamic parameters of the model. The distributed cylinder support form can be applied as a good support form for the high-speed train wind tunnel tests.

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Transverse Vibration Response of a Super High-Speed Elevator under Air Disturbance

International Journal of Structural Stability and Dynamics ◽

10.1142/s0219455419501037 ◽

2019 ◽

Vol 19 (09) ◽

pp. 1950103 ◽

Cited By ~ 5

Author(s):

Zhe Yang ◽

Qing Zhang ◽

Ruijun Zhang ◽

Luzhong Zhang

Keyword(s):

Working Conditions ◽

Transverse Vibration ◽

High Speed ◽

Aerodynamic Characteristics ◽

Minor Effect ◽

Guide Rail ◽

Vibration Acceleration ◽

Lagrange Principle ◽

Computational Fluid Dynamics Cfd ◽

A Minor

For a super high-speed elevator running in a hoistway, it will encounter air flows at high speed. The transverse force and pitching moment generated by the air intensify the transverse vibration of the elevator. In this paper, by fully considering the guide rail excitation and air disturbance, the transverse vibration of a super high-speed elevator under different working conditions is examined. Based on the Lagrange principle, a four degree-of-freedom (DOF) model is adopted for the transverse vibration of the elevator. Combined with computational fluid dynamics (CFD), the effects of various parameters corresponding to different working conditions on the aerodynamic forces acting on the transverse surfaces (the surfaces facing the guide rail) of the car is analyzed. Finally, the Newmark-[Formula: see text] method is employed to analyze the effect of air disturbances on the transverse vibration acceleration of the car under different working conditions. The results show that when the car is symmetrically positioned, the aerodynamic characteristics on both transverse surfaces of the car also appear to be symmetric. The operating speed and the distance between the car’s transverse surface and the hoistway wall (DCH) have a minor effect on the transverse vibration of the car, and the car is basically in a state of forced balance in the transverse direction. However, once the car deviates from the symmetric position, the balance will be violated, and the transverse resultant force and moment of the car will increase with the increase in the deviation amount. Among all these factors, the influence of the rotation angle on the elevator’s vibration acceleration is the most significant.

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Yaw Galloping of a TLWP Platform Under High Speed Currents by Analytical Methods and its Comparison With Experimental Results

Volume 1: Offshore Technology ◽

10.1115/omae2017-61909 ◽

2017 ◽

Author(s):

Francisco Lamas ◽

Miguel A. M. Ramirez ◽

Antonio Carlos Fernandes

Keyword(s):

High Speed ◽

Production Systems ◽

Experimental Tests ◽

Experimental Results ◽

Analytical Methodology ◽

New Approach ◽

Laboratory Facilities ◽

Polynomial Curve ◽

Computational Fluid Dynamics Cfd ◽

Cfd Analyses

Flow Induced Motions are always an important subject during both design and operational phases of an offshore platform life. These motions could significantly affect the performance of the platform, including its mooring and oil production systems. These kind of analyses are performed using basically two different approaches: experimental tests with reduced models and, more recently, with Computational Fluid Dynamics (CFD) dynamic analysis. The main objective of this work is to present a new approach, based on an analytical methodology using static CFD analyses to estimate the response on yaw motions of a Tension Leg Wellhead Platform on one of the several types of motions that can be classified as flow-induced motions, known as galloping. The first step is to review the equations that govern the yaw motions of an ocean platform when subjected to currents from different angles of attack. The yaw moment coefficients will be obtained using CFD steady-state analysis, on which the yaw moments will be calculated for several angles of attack, placed around the central angle where the analysis is being carried out. Having the force coefficients plotted against the angle values, we can adjust a polynomial curve around each analysis point in order to evaluate the amplitude of the yaw motion using a limit cycle approach. Other properties of the system which are flow-dependent, such as damping and added mass, will also be estimated using CFD. The last part of this work consists in comparing the analytical results with experimental results obtained at the LOC/COPPE-UFRJ laboratory facilities.

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