Search Results

The threat of Chemical Warfare (CW) may have increased even as the nuclear threat may have decreased. Terrorists and threatening countries can easily convert factories or use only a van to manufacture chemical weapons. However, no current operational U.S. military aircrafts are designed with any type of CW defense. Nuclear, Biological, and Chemical (NBC) filters will be used in the future Environmental Control Systems. The filters have advanced from the low pressure type to high pressure in semi-closed system such as the V-22 aircraft and closed loop system. A simplified Integrated Closed Environmental Control System (ICECS) has been developed in a joint U.S./Canada program to meet environmental threats. The initial effort demonstrates the advantages of the closed loop vapor cycle over an open air environmental control system.

The Dynamic Environment Simulator (DES), a man-rated centrifuge, was used to support testing of the Integrated, Closed Environmental Control System (ICECS). DES drive and support systems were modified to satisfy ICECS power, cooling and control requirements. Digital control of the DES drive systems allowed ICECS exposure to acceleration magnitudes approaching 10 G for extended periods. During latter phases of testing, G profiles were customized as indicated by the results to completely determine ICECS system dynamics. The DES provided a flexible, low cost test bed with all test objectives satisfied on time and on budget.

Advanced centrifugal compressor vapor cycle refrigeration systems are being tested extensively in the laboratory before they are introduced to new affordable fighter aircraft. It was determined that further testing was needed to establish the effects on a centrifugal compressor system due to high and rapidly varying G forces encountered during fighter aircraft maneuvers. Flight weight aircraft vapor cycle components were tested up to 4Gx, 4Gy and 9GZ on the Air Force Armstrong Laboratory Dynamic Environment Simulator Centrifuge Facility under the Integrated Closed Environmental Control System (ICECS) Program at Wright-Patterson AFB, Ohio. The tests demonstrated that a properly designed digital controlled integrated vapor cycle system will operate in the variable G field (9GZ) of a fighter aircraft. It showed that heat exchangers can be designed with minimum effect to gravity “G” fields. The future for vapor cycle systems in new affordable aircraft looks promising.

Vapor cycle environmental control systems are being designed for efficient electronic cooling on advanced fighter aircraft. A vapor cycle system, employing a two-phase refrigerant, must be able to operate in a variety of attitudes in a variable-gravity flight environment. In order to verify operation of an agile aircraft's vapor cycle system prior to flight test, the Air Force is upgrading the Armstrong Laboratory's Dynamic Environment Simulator centrifuge. This paper will discuss the facility, the types of testing that will be used to simulate flight loads, and the design of vapor cycle components which will allow them to operate in a variable-G environment.

Vapor cycle refrigeration units are being developed for expanded applications on aircraft and future spacecraft. These units offer advantages in high efficiency, closed system operation, high flux cooling, close temperature control, and long-term dependability. This paper provides an overview of approaches to vapor cycle compressor design for achieving high reliability and long life. Different types of compressors are reviewed, and descriptions are given for new innovations such as magnetic bearings, variable speed motors, and magnetic couplings.