Performance Improvement of a Negative-Pressurized Isolation Room for Infection Control

Negative-pressurized isolation rooms have been approved effectively and applied widely for infectious patients. However, the outbreak of COVID-19 has led to a huge demand for negative-pressurized isolation rooms. It is critical and essential to ensure infection control performance through best practice of ventilation systems and optimum airflow distribution within isolation rooms. This study investigates a retrofitting project of an isolation room to accommodate COVID-19 patients. The field measurement has been conducted to ensure the compliance with the design specification from the CDC of Taiwan. The pressure differentials between negative-pressurized isolation rooms and corridor areas should be at least 8 Pa, while the air change rate per hour (ACH) should be 8–12 times. Computational fluid dynamics (CFD) is applied to evaluate the ventilation performance and contamination control. Different layout arrangements of exhaust air have been proposed to enhance the ventilation performance for infection control. A simple projected air-jet curtain has been proposed in the simulation model to enhance extra protection of medical staff. The resulting ventilation control revealed that the contamination control can be improved through the minor adjustment of exhaust air arrangement and the application of an air-jet curtain.

On the Jet Curtain Over Water

The problem of two planar or two-dimensional jets of nonviscous, incompressible, weightless fluid flowing from two nozzles installed symmetrically with respect to a vertical axis onto the surface of an immobile heavy liquid is considered. The flow pattern represents a simple model of a jet curtain of an air-cushion vehicle. The complete theoretical solution to the problem is found—in a thin-jet approximation and under the assumption that the height of the nozzles with respect to the undisturbed surface of the liquid is fixed. The special case of a single nozzle is also considered. Some experimental observations of an air jet flowing from an individual slotted nozzle onto a water surface are presented, and an explanation of the flow mechanism is proposed for the vertical nozzle. In essence, the corresponding process of flow has to be random.

Jet Curtain Flameholder for Aircraft Afterburners

The similarity of flow behind V-gutter flameholders and the proposed jet curtain flameholders has been demonstrated from flow visualization studies. The effective blockage of jet curtain flameholders can be varied by varying the jet pressure ratio. The jet curtain flameholder gives the same stability limits as the V-gutter if the mixture strength in the recirculation zones is identical, while it has negligible cold pressure loss. Thus, the use of the jet curtain flameholder offers the possibility of significant reduction in overall weight of an aircraft for a given range, if the afterburning duration is short.