L. M. Shpanin

Mathematical Modeling Study of Scroll Air Motors and Energy Efficiency Analysis—Part II

A scroll air motor, also known as a scroll expander, is a relatively new concept to pneumatic actuators. In recent years, scroll air motors have been adopted by combined heat and power boilers, uninterrupted power supply, and some other energy storage systems as a new mechatronic device for energy conversion. The paper aims to develop a complete mathematical model of the scroll air motor for dynamic characteristic and energy efficiency analysis. In Part I of the paper, the geometry description of the scroll air motor is presented and the scroll driving torque is derived. In this, Part II, the mathematical model for the scroll dynamic process is described and verified by comparing the simulated and measured results. Then, the initial analysis of scroll energy efficiency is given, which explains the scrolls high ability in energy conversion.

Current Interruption Using Electromagnetically Convolved Electric Arcs in Gases

Measurements were described as current, voltage, and local dielectric strength for a current interrupter which utilized a novel form of electromagnetically convolved electric arc in air. Experiments have been performed with various interrupter structures and operational conditions. Precurrent zero-voltage extinction peaks and post-arc local breakdown voltages have been measured and are compared with values for nonconvoluted arcs in nitrogen and SF6. An empirical relationship between the extinction peak voltage and various design and operational parameters is presented. Signatures for the various interrupter structures under different operational conditions have been obtained by using a chromatic methodology and embodying the extinction peak and a local breakdown voltage.

Control and Propulsion of an Atmospheric Pressure Plasma Ring

A new approach for the electromagnetic control and propulsion of a current carrying electric arc plasma ring is described. The essence of the approach is to form and manipulate the arc plasma outside rather than inside an electromagnetic field (B-field) producing coil so that pulsed plasma thrusts can be produced in a choice of different directions. The interaction of the electric arc, formed in atmospheric pressure air, with such B-field has been investigated. It has been shown that a stable azimuthal plasma ring can rapidly be produced by the simple process of separating two annular contacts. Pulsed plasma propulsion is obtained when the arc plasma, and B-field sustaining current is automatically reduced to zero, whereby the constraining electromagnetic forces are removed and, as a consequence, the resulting plasma ring radially expands outwards. Several different measurement techniques have been deployed for investigating the behavior of the plasma ring. These include electrical probing, B-field probing, and high-speed plus video photography. Experimental results are shown to be in good agreement with theoretical estimates based upon a Sedovs self-similar model.

RLC-Induced Current Oscillations in Convoluted Arcs With Independently Activated Magnetic Fields

Experimental results on atmospheric-pressure arc plasma convolutes in air around a polytetrafluoroethylene cylindrical shroud containing a magnetic field ( B-field) producing coil are presented. In this paper, the B-field coil is energized by a current separate from that flowing through the arc, and a separate RLC circuit was connected across the arc gap. Thus the magnitude and time duration of the B-field are independent of the arc current and the high-frequency current oscillations produced by the parallel RLC circuit. Experimental results for the time variation of the current through and voltage across the arc plasma for these different conditions are presented, along with high-speed photographs of the oscillating current arc. The effects of varying the B-field upon plasma pulsations formed by the independent B-field and RLC current oscillations are discussed.

The Production of Plasma Pulses With Convoluted Arc Columns in Atmospheric Pressure Air

Experimental results for the operation of a device which generates radially propagating pulses of plasma are reported. These are produced from a convoluted arc plasma column formed using a suitably configured magnetic field (B-field). Both quasi-steady-current and alternating-current arc plasmas in atmospheric pressure air have been studied. High-speed photographic records of the convoluted plasma column during the main arcing phase are presented along with video images of propagating plasma clouds formed when the B-field and arc current collapse. Measured time variations of current and arc voltage during the main current phase are correlated with features on the photographic records. Results are presented, showing the effect of different operating conditions upon the propagation rates of the plasma pulses.

Electromagnetically convoluted arcs for the interruption of quasi direct current

This paper describes a novel technique for interrupting direct currents (D.C.) with an electromagnetically convoluted arc in air at atmospheric pressure. Investigations are reported on the effects of using a separate current for producing the arc convolving electromagnetic field (B-field) to that being interrupted and using a separate R, L, C circuit in parallel with the arc contacts. Experimental results are presented for the time variation of currents flowing through the arc gap, the B-field coil and the parallel R, L, C circuit, along with the voltage across the arc gap.

Control and propulsion of an atmospheric pressure plasma ring

A new approach for the electromagnetic control and propulsion of a current carrying electric arc plasma ring is described. The essence of the approach is to form and manipulate the arc plasma outside rather than inside a magnetic field producing coil so that pulsed plasma thrusts can be produced in a choice of different directions. The interaction of the electric arc, formed in atmospheric pressure air, with such a magnetic field has been investigated. It has been shown that a stable azimuthal plasma ring can be rapidly produced by the simple process of separating two annular contacts. Pulsed plasma propulsion is obtained when the arc plasma and B-field sustaining current is reduced to zero whereby the constraining electromagnetic forces are removed and, as a consequence, the resulting plasma ring expands radially outwards. Several different measurement techniques have been deployed for investigating the behavior of the plasma ring. These include electrical probing, B-field probing and high-speed plus video photography. The results suggest that the plasma control and propulsion is governed by a combination of effects including ablation of the material around which the plasma ring is formed and self-pressurization related to the device geometry, as well as the electromagnetic forces. Preliminary results indicate that through the use of appropriate device geometries, the arc plasma may be propelled in axially opposite directions as well as radially.

Convoluted Arc With Flux Concentrator for Current Interruption

Further considerations are given to the use of an electromagnetic flux concentrator for arc plasma control in a rotary arc current interrupter. Such flux concentrators have been previously proposed for plasma fusion and other plasma applications. The possible extension of the proposed method for enhancing the interruption of direct currents with a rotary arc interrupter is discussed with the aid of theoretical modeling of the concentrator geometry and with its possible enhancement of ablation from the arc containing cylinders.

Further study of electromagnetically convoluted arc plasmas in atmospheric pressure air

The formation of convoluted arc plasma columns, concentric with a magnetic field (B-field) producing coil are considered. Preliminary experimental investigations are described on the effect on such electromagnetically convoluted arcs of a vertically inclined, electrically insulated plate attached to the outside of the Polytetrafluoroethylene (PTFE) cylinder containing the B-field producing coil. Experimental results are presented for the time variation of arc current and voltage along with post arc, photographic images of arc tracks on the PTFE cylinder and vertical plate, and video photographs of the plasma volume so formed. The results show that a new form of post arc plasma pulse appears to be formed with the deployment of the vertical PTFE plate.