Design of a Hot Gas Vane Motor

2004 ◽  
Author(s):  
Bo Li ◽  
Eric J. Barth ◽  
Kevin B. Fite ◽  
Michael Goldfarb
Keyword(s):  
Analytical Model ◽  
Conversion Efficiency ◽  
Motor Performance ◽  
Motor Behavior ◽  
Maximum Amount ◽  
Output Energy ◽  
Working Fluid ◽  
Direct Drive ◽  
Hot Gas ◽  
Insight Into

This paper describes the design of a hot gas vane motor. The motor is intended as a portable direct drive actuator powered by a hot gaseous working fluid as an alternative to battery-powered electromagnetic motors. The objective is thus to convert a maximum amount of enthalpy at the inlet into mechanical rotational output energy in a compact and lightweight package. The described motor incorporates a non-circular stator shape and a geometry of injection and exhaust ports to maximize conversion efficiency. An analytical model is developed to describe the torque output and efficiency of the motor. Simulations are performed to provide insight into the motor behavior and characterize the expected motor performance.

A simple analytical model of laser direct-drive thin shell target implosion

2021 ◽  
Author(s):  
Bo Yu ◽  
Tianxuan Huang ◽  
Li Yao ◽  
Chuankui Sun ◽  
Wanli Shang ◽  
...  
Keyword(s):  
Analytical Model ◽  
Thin Shell ◽  
Simple Analytical Model ◽  
Direct Drive

Interaction Between Finger Opposition Movements and Aftereffects of 1Hz-rTMS on Ipsilateral Motor Cortex

2009 ◽  
Vol 101 (3) ◽  
pp. 1690-1694 ◽  
Author(s):  
Laura Avanzino ◽  
Marco Bove ◽  
Andrea Tacchino ◽  
Carlo Trompetto ◽  
Carla Ogliastro ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Motor Performance ◽  
Magnetic Stimulation ◽  
Voluntary Movement ◽  
Motor Behavior ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Motor Task ◽  
The Other ◽  
Experimental Conditions ◽  
Opposition Movements

One-hertz repetitive transcranial magnetic stimulation (1Hz-rTMS) over ipsilateral motor cortex is able to modify up to 30 min the motor performance of repetitive finger opposition movements paced with a metronome at 2 Hz. We investigated whether the long-lasting rTMS effect on motor behavior can be modulated by subsequent engagement of the contralateral sensorimotor system. Motor task was performed in different experimental conditions: immediately after rTMS, 30 min after rTMS, or when real rTMS was substituted with sham rTMS. Subjects performing the motor task immediately after rTMS showed modifications in motor behavior ≤30 min after rTMS. On the other hand, when real rTMS was substituted with sham stimulation or when subjects performed the motor task 30 min after the rTMS session, the effect was no longer present. These findings suggest that the combination of ipsilateral 1Hz-rTMS and voluntary movement is crucial to endure the effect of rTMS on the movement itself, probably acting on synaptic plasticity-like mechanism. This finding might provide some useful hints for neurorehabilitation protocols.

Design for Manufacturability of an Off-Shore Direct-Drive Wind Generator: An Insight Into Additional Loss Prediction and Mitigation

2017 ◽  
Vol 53 (5) ◽  
pp. 4831-4842 ◽  
Author(s):  
Alberto Tessarolo ◽  
Fabio Luise ◽  
Stefano Pieri ◽  
Andrea Benedetti ◽  
Mauro Bortolozzi ◽  
...  
Keyword(s):  
Design For Manufacturability ◽  
Direct Drive ◽  
Wind Generator ◽  
Loss Prediction ◽  
Insight Into ◽  
Additional Loss

Test Results and Analytical Predictions for Rotor Drop Testing of an AMB Expander/Generator

2006 ◽  
Author(s):  
Lawrence Hawkins ◽  
Alexei Filatov ◽  
Shamim Imani ◽  
Darren Prosser
Keyword(s):  
High Speed ◽  
High Performance ◽  
Time History ◽  
Test Results ◽  
Direct Drive ◽  
Flow Loop ◽  
Low Loss ◽  
Model Predictions ◽  
Full Speed ◽  
Insight Into

A cryogenic gas expander system that incorporates a high performance, high-speed permanent magnet, direct-drive generator and low loss magnetic bearings is described. Flow loop testing to 30,000 rpm was completed at the system manufacturer’s facility in January 2005, and field installation is scheduled for October 2005. As part of the system testing, the rotor was dropped onto the backup bearings multiple times at an intermediate speed and at 30,000 rpm. Orbit and time-history data from a full speed drop and spin down are presented and discussed in detail. A transient, nonlinear rotordynamic analysis simulation model was developed for the machine to provide insight into the dynamic behavior. The model includes the dead band clearance, the flexible backup bearing support and hard stop. Model predictions are discussed relative to the test data.

scholarly journals Analytic model of comet ionosphere chemistry

2018 ◽  
Vol 616 ◽  
pp. A59 ◽  
Author(s):  
Erik Vigren
Keyword(s):  
Analytical Model ◽  
Dissociative Recombination ◽  
Flow Speed ◽  
Rate Coefficients ◽  
Ion Composition ◽  
Free Electrons ◽  
Ion Removal ◽  
Simplifying Assumptions ◽  
Computational Simplicity ◽  
Insight Into

Context. We consider a weakly to moderately active comet and make the following simplifying assumptions: (i) The partial ionization frequencies are constant throughout the considered part of the coma. (ii) All species move radially outward with the same constant speed. (iii) Ion-neutral reactions affect the chemical composition of the ions, but ion removal through dissociative recombination with free electrons is negligible. Aims. We aim to derive an analytical model for the radial variation of the abundances of various cometary ions. Methods. We present two methods for retrieving the ion composition as a function of r. The first method, which has previously been used frequently, solves a series of coupled differential equations. The new method introduced here is based on probabilistic arguments and is analytical in nature. Results. For a pure H2O coma, the resulting closed-form expressions yield results that are identical to the standard method, but are computationally much less expensive. Conclusions. In addition to the computational simplicity, the analytical model provides insight into how the various abundances depend on parameters such as comet production rate, outflow speed, and reaction rate coefficients. It can also be used to investigate limiting cases. It cannot easily be extended to account for a radially varying flow speed or dissociative recombination in the way a code based on numerical integrations can.

Microscale Boiling Heat Transfer Near the Meniscus

2005 ◽  
Author(s):  
Brenda E. Haendler ◽  
David C. Walther ◽  
Dorian Liepmann ◽  
Albert P. Pisano
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Temperature Profile ◽  
Infrared Camera ◽  
Intake Manifold ◽  
Working Fluid ◽  
Bulk Temperature ◽  
Heating Source ◽  
Portable Power ◽  
Insight Into

Results are presented experimentally measuring the localized temperature profile due to microscale boiling of a silicon-Pyrex bonded wafer with a 100 μm deep, 500 μm wide and six mm long microchannel. Experiments were performed using an infrared camera equipped with a magnifying lens. By using a camera, the dynamic temperature profile is shown from the inside channel all the way out to where the temperature of the wafer reaches the bulk temperature of the heating source. Temperature profiles are shown for both water and methanol as the working fluid applying between five and twenty degrees Celsius of superheat to the bulk wafer. Using these results, a discussion of the relevant heat transfer modes and nondimensional numbers is given to gain insight into the range of influence that phase change in a microchannel has on the temperature of the wafer. Additionally, discussion is given about modeling of microscale phase change using a commercial fluid dynamics software package. The importance of these results with respect to implementation into the fuel intake manifold for a micro engine based portable power system is also discussed.

The Confined-Discharge Plasma Generator With Local Fluid Constriction

1972 ◽  
Vol 94 (4) ◽  
pp. 818-823 ◽  
Author(s):  
J. R. Mahan ◽  
C. J. Cremers
Keyword(s):  
Energy Conversion ◽  
Conversion Efficiency ◽  
Discharge Plasma ◽  
Fluid Dynamic ◽  
Plasma Generator ◽  
Energy Conversion Efficiency ◽  
Axial Position ◽  
Working Fluid ◽  
The Mean ◽  
Cold Gas

Normally the energy conversion efficiency of a confined-discharge plasma generator is inversely related to the mean enthalpy of the effluent plasma jet. The present paper describes a technique for increasing both the energy conversion efficiency, defined as the net fraction of the electrical power input transferred to the working fluid, and the mean enthalpy, defined as the net energy transferred to the working fluid per unit mass. A portion of the working fluid is introduced to the discharge through a narrow circumferential slit in the confining duct wall. Heat transfer and fluid dynamic effects associated with this high velocity inflow of cold gas cause the local discharge column to become highly constricted. Concomitant with this local fluid constriction (LFC) is a sharp increase in the local power density, resulting in enhanced energy transfer to the cold gas. Experimental results suggest that for optimum operation the gas injection slit should be located slightly upstream of the axial position where the discharge becomes thermally fully developed.

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