Abstract
This paper shows influences of initial conditions on a diaphragmless shock tube operation. This facility consists of a driver tube, a driven tube and a damp tank. The driver tube has a circular cross section with diameter of 150 mm and the driven tube, a rectangular cross section (60 mm x 150 mm). The shock tube is operated by using a quick-opening pneumatic piston instead of a diaphragm. For the operation, pressure inside the pneumatic piston (piston pressure) is quickly released by opening a solenoid valve. In this paper, the initial piston pressure was chosen as a parameter to investigate effects on test flow conditions created by the shock tube. As a result, it was found that when the piston pressure at initial condition is large, piston pressure decreased more rapidly than that obtained for a small piston pressure condition, regardless of the pressure ratio of driver and the driven tube. In the condition of a constant initial operational pressure ratio and a different piston pressure, the shock Mach number was almost constant.
Highlights
It is well known that a shock tube is used for various researches including high-speed aerodynamics [1, 2]
Test flow condition of shock tube is theoretically determined by differential pressure between high pressure driver section and low pressure driven section, and arbitrary test flow conditions can be obtained by appropriate control of the initial pressure
For a large piston pressure at initial condition, piston pressure decreased more rapidly while piston moved than that obtained for a small piston pressure condition
Summary
It is well known that a shock tube is used for various researches including high-speed aerodynamics [1, 2]. The shock tube of diaphragmless type is considered as the attractive aerodynamic devices because test flow is not contaminated by the minute fragments of the film. The quick-opening pneumatic piston was installed for diaphragmless operation of our shock tube. This shock tube system has been used to investigate aerodynamic characteristics of the transonic airfoil flows, and to develop the progress flow visualization technique for the past few years. Test flow condition of shock tube is theoretically determined by differential pressure between high pressure driver section and low pressure driven section, and arbitrary test flow conditions can be obtained by appropriate control of the initial pressure. In diaphragmless shock tube, Ms becomes smaller than theoretical value because the piston opens in a finite time
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