Aerodynamic stand is designed to test full-sized ice-forming aerosol generators on the ground conditions. The stand allows to define ice-forming efficiency — the number of active particles from the unit weight of the composition or solution — at different temperatures of supercooled clouds when the generator is in blowing their air flow rates up to 30 m/s.
Composition of the stand
The stand includes:
1. The open type wind tunnel
2. The cloud chamber
3. Aerosol dilution system
4. Aerosol sampling system
5. Attachment system and ignite aerosol generator
6. Purification system from aerosols
7. The system of registration of ice crystals.
The wind tunnel is designed to create an air flow blowing aerosol generator and includes:
• fan pressure;
• working part of a diameter of 0.3 m and a length of 1.5 m;
• cone diameter of 0.5 m and a length of 2 m;
• exhaust pipe diameter of 0.3 m and a length of 8 m;
• baffle diameter of 0.1 m;
• pressure tube and micromanometer;
• mounting system of the generator in the test section.
Cloud chamber 8 is designed to create a model fog with a given temperature of cooling. Seating capacity is 125 liters. The cloud chamber is provided with a fan, a lighting and temperature measurement of fog and steam generator.
Aerosol dilution system is designed to dilute the initial concentration of aerosol in the wind tunnel and it includes:
• sampler with volume of 2 L
• aerosol cubes volume of 125 L and 1000 L, with the fan located inside to mix the air.
Aerosol sampling system consists of:
• suction comb, located perpendicular to the direction of air flow
• blower providing continuous sampling of the aerosol wind tunnel
The registration system is designed to capture and further calculation of ice crystals in the cloud chamber and includes:
• optical microscope.
Working volume of the cloud chamber placed in it thermostats and other equipment.
• The diameter of the cross section of the working parts of the mashine- 0.3 m;
• Air speed – up to 30 m/s;
• Temperature range of supercooled fog – from -10C to — 250C;
• The dilution factor is the aerosol concentration – up to 70;
• Minimum and maximum measured value of the output ice-forming particles – 107 and 1017g-1;
• The duration of a single measurement – about 40 minutes;
• The mean square error of one measurement of ice-forming particles of 1 gram of pyrotechnic composition at -100C – no more than ± 120%;
• Power consumption – no more than 1 kW/h.
PRINCIPLE OF MEASUREMENT OUTPUT OF ICE-FORMING PARTICLES
The measuring principle is to determine the number of ice crystals that form when introduced into supercooled water fog known sample aerosol produced in the operation of the generator ice-forming aerosols in the air stream. Airflow with specified characteristics is created in the wind tunnel.
Fog is created in the working volume of the cloud chamber by jets of hot water steam. The quantity of ice crystals created is evaluated by measuring the number of crystals that fell to the floor unit area of cloud chamber. Capture of crystals produced in mikrotermostat preserving ice crystals within a sufficient time to count them with an optical microscope.
Efficiency of ice-forming compounds developed in RUSSIA involving the Agency