A Study on Precise Measurement of Spark Discharge Length in High Velocity Gas Flow Using Small Wind Tunnel

Topics below are rather undesired, but important, outcome not yet completed research on the aircraft airfoils, turbine and compressor blades, parametric design of airfoils, establishing the relationships based on the results of experiments in a wind tunnel, developing databases for determining the relationships between airfoil parameters and lift and drag coefficients. Reliable database created as a result of the research work allows to simulate the wind tunnel. Very early on, however, was necessary to extend the developed specialized software for a new applications, and it meant the need for generalization of software, e.g. for gas turbine engines, propellers, etc. But after some time it turned out, that in order to achieve the required accuracy, the changes are needed in the underlying assumptions, set decades ago. In addition, coordinate measuring machines and systems, and associated software were not always as accurate as expected. Concepts how to solve it and develop software carrying out these tasks are presented in the article. It is like to withdraw from the old path and look for a new path that will lead to the reliable data base. Processes related to air or gas flow should be similarly defined in all the specialized software applications (e.g. aircrafts and turbine engines). Accuracy (10-9 mm) achieved in virtual measurements within the integrated system can be used to verify the results of CMM and other measuring systems, provided that an appropriate software has been developed.

Download Full-text

Transitional ballistics of electric high-velocity launchers

2019 15th Hypervelocity Impact Symposium ◽

10.1115/hvis2019-092 ◽

2019 ◽

Author(s):

B. Reck ◽

S. Hundertmark ◽

R. Hruschka ◽

A. Zeiner ◽

B. Sauerwein ◽

...

Keyword(s):

High Velocity ◽

Gas Flow ◽

Mechanical Response ◽

Numerical Models ◽

Time Interval ◽

Viscous Effects ◽

Simulation Code ◽

Package Design ◽

Gun Barrel ◽

Experimental Values

Abstract The high-velocity launch of a projectile is subjected to a number of disturbances which exert an influence on the flight trajectory. In the case of sub-caliber projectiles, sabot separation is one of the critical aspects. In this work, we focus on the projectiles and the launch package of an electric railgun launch, i.e. on the behavior of the launch-package, when transitioning from the gun barrel to free-flight. This work further addresses the use of a hydrocode for creating numerical models which are capable of predicting the motion and deflection of the sabot parts during their separation from the projectile after exiting the muzzle. An earlier study showed that the air flow around the projectile and the sabot can be modeled with sufficiently high accuracy by means of a simulation code that uses an Eulerian description of the gas flow. Within a time interval of several milliseconds, just the duration that a projectile needs to enter quasi-stationary flight, viscous effects of the air or gas flow have relatively little influence on the sabot discard process. If the Eulerian gas flow is coupled with the Lagrangian structural parts, the mechanical response of the latter to the gas pressure can be complex in terms of deformation and damage, and in that way, can affect the gas flow. In this study, the hydrocode model is applied to a medium caliber launch package concept for accelerating long rod projectiles. The computed results agree well with the corresponding experimental values obtained from a launch package model test in the shock tunnel at Mach 4.5. This demonstrates that the presented hydrocode model can be used for launch package design optimizations with high confidence.

Download Full-text

High Velocity Flow Suggested by Wing Components of the Hα Line Profiles in the Selected Planetary Nebulae

Symposium - International Astronomical Union ◽

10.1017/s0074180900209637 ◽

2003 ◽

Vol 209 ◽

pp. 539-540

Author(s):

S. Tamura ◽

M. Otsuka ◽

A. Tajitsu

Keyword(s):

High Velocity ◽

Gas Flow ◽

Planetary Nebulae ◽

Gas Flows ◽

Stellar Winds ◽

Short Report ◽

Line Profiles ◽

Internal Motions ◽

Velocity Flow ◽

Gaussian Method

This is a short report on the study of internal motions of selected Planetary nebulae. We have studied this subject with both high (4 or 8 Å/mm) and intermediate (20 Å/mm) dispersion spectrographs. During the course of this work we noticed the existence of a high velocity gas flow distinct from the well known expanding gas, but with smaller velocities than stellar winds (Yadoumaru & Tamura 1994 on Abell 30; Otsuka & Tamura, 2001 on H 4-1). We present subsequent results obtained with the intermediate dispersion spectrograph about 10 selected planetary nebulae. The analyses were made by multiple Gaussian method on the emission line profiles of Hα. High velocity gas flows were recognized by a weak broad wing component.

Download Full-text

Applications of Accurate Isentropic Exponent Determination for Fuel Gas Measurement

Volume 3: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations ◽

10.1115/95-gt-037 ◽

1995 ◽

Author(s):

David J. Pack ◽

Terry J. Edwards ◽

Derek Fawcett

Keyword(s):

Natural Gas ◽

Gas Flow ◽

Precise Measurement ◽

Gas Flows ◽

Fuel Gas ◽

Isentropic Exponent ◽

Natural Gas Transmission ◽

Gas Measurement ◽

Cost Penalty

This paper discusses the determination and application of the isentropic exponent to the various thermodynamic processes found in a high pressure natural gas transmission system. Increasing demands for more precise measurement of natural gas, coupled with the need for greater efficiency and accountability of transportation and processing operations had led to our research and development efforts into the more precise measurement of gas flow, and the determination of gas thermodynamic properties including isentropic exponent. The isentropic exponent has many applications, some of which include: • the determination of the expansion factor ϵ, for calcuation of flow using an orifice or venturi type meter; • the volumetric efficiency in a reciprocating compressor; • the determination of the compression head for a centrigual compressor; • the engine power required for the set given conditions for gas compressor; • the calculation of discharge temperatures for compressors; and • the direct measurement of gas density. As can be appreciated, the application of an incorrect value for the isentropic exponent represents an error in the parameter determined. For large volume gas flows, this can translate into a significant cost penalty.

Download Full-text

New Matheson Flowmeters for simple, precise measurement of gas flow

Chemical & Engineering News ◽

10.1021/cen-v037n028.p115 ◽

1959 ◽

Vol 37 (28) ◽

pp. 115

Keyword(s):

Gas Flow ◽

Precise Measurement

Download Full-text

Synthesis of Mixed AuZn Nanoparticles by Spark Discharge Technique

MRS Advances ◽

10.1557/adv.2019.221 ◽

2019 ◽

Vol 4 (28-29) ◽

pp. 1621-1629

Author(s):

Shubhra Kala ◽

F. E. Kruis

Keyword(s):

Electron Microscopy ◽

Gas Flow ◽

Normal Pressure ◽

High Resolution Electron Microscopy ◽

Spark Discharge ◽

Scanning Mobility Particle Sizer ◽

Carrier Gas ◽

Charging Current ◽

Mixed Nanoparticles ◽

Particle Sizer

AbstractIn this study, feasibility of spark discharge technique to generate mixed metal nanoparticles is demonstrated. Two immiscible metals Au and Zn are selected to prepare AuZn mixed nanoparticles. Ignition of spark between Au and Zn electrodes under normal pressure, in the presence of carrier gas, leads to formation of mixed nanoparticles by condensation and nucleation. Online particle size-distribution is monitored by a scanning mobility particle sizer on changing carrier gas flow rate and capacitor charging current during co-sparking between Au and Zn electrodes. The technique provides flexibility to generate binary mixture of AuZn nanoparticles in the size range of 10-80 nm. Distribution of Au and Zn in the prepared mixed nanoparticles is mapped by scanning electron microscopy and high resolution electron microscopy.

Download Full-text