The diaphragms are one of the most important parts of a shock tube. At the start of an experiment the diaphragm separates the driver and driven sections. Gas tight seals are formed on each side of the diaphragm to prevent gas leaking between the two sections as they are filled and in the high-pressure shock tube the seals must be good enough to prevent helium at 10,000 psi escaping from the driver section.

The diaphragms in the high-pressure shock tube are made from sheets of soft brass. One side of the diaphragm has two mutually perpendicular grooves centered on the diaphragm cut on it.

The pressure at which a diaphragm bursts is mainly determined by the material it is made of and the depths of the grooves. We have extensively tested several different materials and developed a reliable technique for producing up to 100 diaphragms per day.

Typical characteristics for soft brass diaphragms. P5 is the pressure behind the reflected shock wave.

The diaphragms are contained and sealed, not surprisingly, in the diaphragm section of the shock tube. This part has been designed so that either the double diaphragm or single diaphragm techniques can be used.

The driver and driven section are separated by two diaphragms with a small space between the diaphragms. The driven section is filled first and then the driver section and the space between the diaphragms are filled. When the pressure in the spacer is half the difference between the driven section and the desired bursting pressure the filling is stopped. The tube is fired by reducing the pressure in the spacer section.

The driver and driven sections are separated by only one diaphragm in the single diaphragm technique. The diaphragm must be capable of withstanding large pressure differences to obtain the desired bursting pressures

Diaphragms

Burst the diaphragm by moving the cursor over it