Automatic control of a liquid nitrogen cooled, closed-circuit, cryogenic pressure tunnel

The control system design, performance analysis, microprocesser based controller software development, and specifications for the Transonic Cryogenic Tunnel (TCT) are discussed. The control laws for the single-input single-output controllers were tested on the TCT simulator, and successfully demonstrated on the TCT

True Airspeed Measurement by Ionization-Tracer Technique

Ion bundles produced in a pulse-excited corona discharge are used as tracers with a radar-like pulse transit-time measuring instrument in order to provide a measurement of airspeed that is independent of all variables except time and distance. The resulting instrumentation need not project into the air stream and, therefore, will not cause any interference in supersonic flow. The instrument was tested at Mach numbers ranging from 0.3 to 3.8. Use of the proper instrumentation and technique results in accuracy of the order of 1 percent

Development and Application of Fire Video Image Detection Technology in China’s Road Tunnels

A large number of highway tunnels, urban road tunnels and underwater tunnels have been constructed throughout China over the last two decades. With the rapid increase in vehicle traffic, the number of fire incidents in road tunnels have also substantially increased. This paper aims to review the development and application of fire video image detection (VID) technology and their impact on fire safety in China’s road tunnels. The challenges of fire safety in China’s road tunnels are analyzed. The capabilities and limitations of fire detection technologies currently used in China’s road tunnels are discussed. The research and development of fire VID technology in road tunnels, including various detection algorithms, evolution of VID systems and evaluation of their performances in various tunnel tests are reviewed. Some cases involving VID applications in China’s road tunnels are reported. The studies show that the fire VID systems have unique features in providing fire protection and their detection capability and reliability have been enhanced over the decades with the advance in detection algorithms, hardware and integration with other tunnel systems. They have become an important safety system in China’s road tunnels

Comparison of theoretical method of the gas flow in corridors with experimental measurement in real scale

The paper describes the principles of ventilation of underground structures, tunnels and corridors. It also presents a theoretical method of assessment of corridor structures where primary monitored values are velocity of spreading, temperature and depth of forehead of smoke wave in dependance on time and distance from the centre of fire. Results predicated by a theoretical method are compared to the values measured in a real large-scale experiment conducted in the tunnel Valik on the D5 motorway in the Czech Republic. This paper evaluates a possible use of theoretical calculation for constructions of tunnels. The presented method is based on a buoyancy of flue gases. At common constructions is the buoyancy effect one of the most significant phenomena, which affects the smoke movement. The specific type of tunnel constructions is the cause of phenomena that fundamentally affect the smoke flow. The importance of a buoyancy effect decreases significantly while the openness for tunnel construstions and the effect of fire ventilation becomes the major influences. These described effects are the cause of significant variances in realized experiments and applied theoretical method. Based on mentioned important discrepancies it is impossible to recommend this presented calculation method for using of tunnel constructions. The method would require an important modification so that would take into account the specifics of tunnel constructions.Web of Science21215314

Meeting Review: Airborne Aerosol Inlet Workshop

Proceedings from the Airborne Aerosol Inlet Workshop are presented. The two central topics of discussion were the role of aerosols in atmospheric processes and the difficulties in characterizing aerosols. The following topics were discussed during the working sessions: airborne observations to date; identification of inlet design issues; inlet modeling needs and directions; objectives for aircraft experiments; and future laboratory and wind tunnel studies

Aeronautical Engineering: A continuing bibliography with indexes, supplement 185

This bibliography lists 462 reports, articles and other documents introduced into the NASA scientific and technical information system in February 1985. Aerodynamics, aeronautical engineering, aircraft design, aircraft stability and control, geophysics, social sciences, and space sciences are some of the areas covered

Aeronautical Engineering. A continuing bibliography with indexes, supplement 156

This bibliography lists 288 reports, articles and other documents introduced into the NASA scientific and technical information system in December 1982