Construction

The hot water test facility mainly consists of a thrust frame, the hot water pressure tank (content: 2.8 litres) and a laval nozzle. The pressure tank can be covered with a special isolation in order to reduce the heating time. During operation a thrust sensor, two temperature sensors and two pressure sensors are used. All electronic components of the test facility are installed in a box that is mounted to the thrust frame. For an effective discharge of the hot pressurized water, the laval nozzle must be attached to the bottom of the tank, because at the end of the discharge process only gravity forces water to come out of the tank. Otherwise residual water would remain in the tank. If the hot water rocket motor is accelerated by movement, this restriction is not necessary.
 

Fig. 1: Construction of the AQUARIUS hot water test facility

The distilled water is heated by means of three heating resistor elements with an overall performance of 1,800 Watts. With adapted nozzles, thrust values of 500 to 600 Newtons can be obtained. Thrust duration depends on the nozzle throat diameter. A duration of 10 seconds and more is typical for small nozzles. The frame of the test facility is made of welded sectional steel. In addition, the construction is equipped with wheels for transport reasons.