Experimental determination of blast wave pressure loading, thermal radiation protection, and electrical transmission loss for parabolic antenna models in simulated nuclear blast environments.

摘要

A twelve inch diameter parabolic antenna model instrumented with eleven differential pressure sensors was tested at the Ballistics Research Laboratory of the United States Army Aberdeen Proving Ground, Maryland. Transient pressure loading was determined for 37 different antenna model angular positions with respect to the direction of the blast wave at a peak overpressure of 3.0 pounds per square inch; limited data at 4.5 and 6.0 pounds per square inch were also investigated. The first millisecond of shock wave interaction with the antenna model features the most prominent fully reversed triangular pressure pulse. A blast function, F, was developed that accurately approximates the transient behavior of the blast wave resultant force and moment loading on the antenna model. The resultant blast force on the antenna model is minimized when the axis of the paraboloid of the model is rotated 82 degrees with respect to the direction of the blast wave.; Four different thermal protective coatings were tested at the Ballistics Research Laboratory to evaluate the effects of coating color and thickness. A rating system was developed that evaluates the coatings with respect to thermal performance, coating thickness, material cost, durability, weatherability, maintainability, application cost, color selection and the ability to successfully withstand more than one thermal exposure. The white fluoroelastomer coatings, Caapcoat 1 and Caapcoat 2, achieved the highest overall rating; followed by the ablative char former, Ocean 477; colored versions of Caapcoat 2; and the ceramic tile, Cerez.; Transmission loss measurements were completed on eight different quartz-polyimide antenna models coated with Caapcoat and Ocean 477 thermal protective coatings to measure the changes in transmission loss characteristics. Swept frequency measurements were completed at three different angles of incidence before and after thermal testing across the Super High Frequency, SHF, portion of the electromagnetic frequency spectrum (7.0-8.5 {dollar}times{dollar} 10{dollar}sp9{dollar} cycles per second). The white fluoroelastomer coatings exhibited a two way transmission loss change of approximately 0.20 dB. The ablative char forming coatings exhibited a two way transmission loss of approximately 6.70 dB. Transmission loss measurements were also completed for different types of ablative char formation on Ocean 477 and for an uncoated antenna model.