Rotating cowling

The invention concerns a cowling for aircraft propulsion systems of the counterrotating propeller type. The cowling includes a pair of mounting rings located fore and aft of a propeller array. Removable panels extend between the mounting rings and contain openings through which the propeller blades extend

The effect of face velocity, pleat density and pleat orientation on the most penetrating particle size, pressure drop and fractional efficiency of HEPA filters

The increasing need for clean air in critical industrial applications has highlighted the importance of the role of air filters in providing improved air quality. Actual performance of air filters installed in air handling units and in the intake of gas turbines tends to deviate from the performance predicted by laboratory results. Therefore, accurate filter performance prediction is important to estimate filter lifetime, and to reduce energy and maintenance operating costs. To ensure that the desired efficiency of a HEPA filter is attained, the effects of face velocity, pleat density and pleat orientation on the Most Penetrating Particle Size (MPPS) of pleated HEPA filters must be examined. This paper compares the effects of varying these parameters on the MPPS. The paper also presents the initial pressure drop response and fractional efficiency curves using DEHS testing according to DIN 1822 for vertical and horizontal pleat orientations. It analyzes the underlying reasons causing surface area losses for different flow rates, pleat density and orientation as well as the effects on filter permeability. The tests conducted in this study used full scale HEPA pleated V-shaped filters from Heating Ventilation and Air Conditioning (HVAC) and gas turbine applications

Physical and chemical characterization of Kuwaiti atmospheric dust and synthetic dusts: effects on the pressure drop and fractional efficiency of HEPA filters.

The importance of clean air to the indoor air quality affecting the well-being of human occupants and rising energy consumption has highlighted the critical role of air filter performance. Actual performance of air filters installed in air handling units in Kuwait tends to deviate from the performance predicted by laboratory results. Therefore, accurate filter performance prediction is important to estimate filter lifetime, and to reduce energy and maintenance operating costs. To ensure appropriate filter selection for a specific application, particulate contaminants existing in Kuwaiti atmospheric dust were identified and characterized. This paper compares the physical and chemical characterization of Kuwaiti atmospheric dust with the available commercial synthetic dusts. It also tests full scale HEPA pleated V-shaped filters used in Heating Ventilation and Air Conditioning (HVAC) and gas turbine applications. The effects of different synthetic dust types and their particle size distributions on the pressure drop and fractional efficiency using DEHS testing according to DIN 1822 is studied

The effect of pleat count and air velocity on the initial pressure drop and fractional efficiency of HEPA filters

The importance of clean air to the well-being of people and industrial applications has highlighted the critical role of air filters performance. Accurate filter performance prediction is important to estimate filter lifetime and reduce energy and maintenance operating costs. To ensure appropriate filter selection for a specific application, the effect of pleat count and surface area on filter design and performance has been investigated. This paper examines the effects of air velocity on permeability during operation of HEPA pleated V-shaped filters, and the effect of pleat count on the initial pressure drop and fractional efficiency using DEHS testing according to DIN 1822. An empirical equation for predicting the efficiency of the filter is suggested

Flow Properties of Tailored Net-Shape Thermoplastic Composite Preforms

A novel thermoplastic programmable preforming process, TP-P4, has been used to manufacture preforms for non-isothermal compression molding. Commingled glass and polypropylene yarns are deposited by robot onto a vacuum screen, followed by a heat-setting operation to stabilize the as-placed yarns for subsequent handling. After an optional additional preconsolidation stage, the preforms are molded by preheating and subsequent press forming in a shear edge tool. The in- and out-of-plane flow capabilities of the material were investigated, and compared to those of 40 wt% Glass Mat Thermoplastics (GMTs). Although the TP-P4 material has a fiber fraction of 60 wt%, the material could be processed to fill 77mm deep ribs with a thickness of 3mm, indicative of complex part production. The pressure requirements for out-of-plane flow were shown to depend on the fiber length and fiber alignment. Segregation phenomena were found to be less severe with TP-P4 than with GMT materia

Rapid Processing of Net-Shape Thermoplastic Planar-Random Composite Preforms

A novel thermoplastic composite preforming and moulding process is investigated to target cost issues in textile composite processing associated with trim waste, and the limited mechanical properties of current bulk flow-moulding composites. The thermoplastic programmable powdered preforming process (TP-P4) uses commingled glass and polypropylene yarns, which are cut to length before air assisted deposition onto a vacuum screen, enabling local preform areal weight tailoring. The as-placed fibres are heat-set for improved handling before an optional preconsolidation stage. The preforms are then preheated and press formed to obtain the final part. The process stages are examined to optimize part quality and throughput versus processing parameters. A viable processing route is proposed with typical cycle times below 40s (for a plate 0.5 × 0.5m2, weighing 2kg), enabling high production capacity from one line. The mechanical performance is shown to surpass that of 40wt.% GMT and has properties equivalent to those of 40wt.% GMTex at both 20°C and 80°

The Moral Economy of Heroin in ‘Austerity Britain’

This article presents the findings of an ethnographic exploration of heroin use in a disadvantaged area of the United Kingdom. Drawing on developments in continental philosophy as well as debates around the nature of social exclusion in the late-modern west, the core claim made here is that the cultural systems of exchange and mutual support which have come to underpin heroin use in this locale—that, taken together, form a ‘moral economy of heroin’—need to be understood as an exercise in reconstituting a meaningful social realm by, and specifically for, this highly marginalised group. The implications of this claim are discussed as they pertain to the fields of drug policy, addiction treatment, and critical criminological understandings of disenfranchised groups

VOID EVOLUTION DURING STAMP-FORMING OF THERMOPLASTIC COMPOSITES

SUMMARY: A thermoplastic stamp-forming process has been investigated using glass fibre (GF), carbon fibre (CF), and hybrid carbon-glass fibre fabric materials. For monolithic GF/PA6 and CF/PA66 materials, stamping pressure was the dominating variable to achieve high mechanical properties, low void contents, and minimal void content distributions across the stamped part. Use of a hybrid flow core material composed of CF/PA66 textile skins and a GF/PA66 random fibre core reduced this tendency such that tool temperature dominated the process. The increased local flow of the core layer accommodated the varying local superficial fabric density. Use of the flow core did not significantly affect flexural properties, but with a 29% and 17% drop in tensile modulus and strength. A substantial cost saving resulted from the use of a hybrid glass and carbon structure. In mould cycle times of 30s resulted for 3mm thick parts