Browse Topic: Cabin pressurization
This research analyzes the significance of air extractor on car door closing effort, especially within the context of highly sealed cabins. The goal is to measure their effectiveness in lowering pressure-induced resistance, study how the cut-out cross section and location affect performance, and its contribution to vehicle premium feel. Current vehicle design trends prioritize airtight cabin sealing for improving aerodynamic efficiency, NVH performance. This causes a problem in door closing operation. Air trapped while closing door creates transient pressure pulses. This pressure surge creates immediate discomfort to user i.e., Popping in Ears and requires high door closing force, and long-term durability problems in hinges and seals. In properly sealed cabins, air pressure resistance can contribute to 25% to 40% of total door closing force. Air extractors, usually installed in the rear quarter panels or behind rear bumpers, serve as pressure relief valves, allowing for a smoother airflow out of the cabin during such incidents. This passive system lowers door-closing effort, improves occupant experience, and safeguard structural components. A combination of CFD simulations, and real-world validations was employed to assess various air extractor configurations. Extractor size, location, flap design, and sealing levels of the vehicle were varied. Cabin pressure behavior and door closing force were evaluated under controlled and dynamic conditions. Comparative studies were also conducted across vehicle segments, including electric vehicles with high sealing requirements. Through these factors, this paper gives a holistic view to improve overall user experience as well as help to align with industry standards. The results have been backed with case studies as well as with simulation analysis to properly optimize the extractor design for new vehicles.
The passenger car segment has been extremely competitive and automotive OEMs are thriving to provide superior customer experience. Door closing is an event that requires slamming of the door with a certain velocity to get the door latched. A good latching provides that thud sound and assurance of the door getting closed for an SUV. While the door is closed, it pushes the volume of air inside the cabin. As the amount of air moved in is proportionate to the size of the door it becomes more critical for the SUV segment of vehicles to ensure the air extraction path is efficient. Else, steep pressure rise inside the cabin causes severe discomfort to the passengers sitting inside the vehicle. Current work focused on the process of simulation of cabin pressure while door closing, implementing changes based on results and validating with test results. Test results are in close correlation with simulation predictions. Also, it emphasizes that body panel changes made to improve the airflow path are extremely necessary. The outcome has been excellent, rated by jury members, and the proposed changes have been realized for production.
This SAE Aerospace Information Report (AIR) provides general information on Continuous Flow Oxygen Systems which are available, principle functions of those systems and technical approaches to be taken into account during design and realization of systems. However, particular performance specifications and detailed information of manufacturing, testing and integration of such systems is beyond the scope of this document.
Closed-cycle protective breathing apparatus, commonly referred to as rebreathers, or CCBA provide trained aircrew members or ground personnel with eye and respiratory protection from toxic atmospheres.
Environmental Control System (ECS) of an aircraft provides required temperature, pressure and air flow to the cockpit or cabin or occupied compartments for the comfortable and required conditions of the occupant. Cabin pressure control system (CPCS), one of the sub-systems of ECS, controls and maintains the cabin pressure to provide a physiologically safe environment for the occupants inside the cabin. As ECS takes engine bleed air as input, any variation in engine rpm affects the cabin pressure and further the comfortable condition inside the cabin. This paper is focused on modeling and simulation of a fighter aircraft CPCS to evaluate its performance for its entire range of operation. The system is modeled and simulated in AMESim and the dynamic behavior of the system and its components are studied. Also, this paper emphasizes the effect of transient input characteristics on the cabin pressure with the cases of extreme variation in engine rpm and aircraft altitude. For the purpose of model validation, the simulated results are compared with the actual data and found that the simulated cabin pressure profile and the dynamics of cabin pressure control valve match with the actual data. The validated system model and results can be further used in designing a better CPCS.
Pressure regulating valves are one of the indispensable components in an aircraft. Its application is found in many critical systems such as anti-icing system, cabin pressurization, propulsion system, hydraulic system etc. In this study, the simulation and dynamic analysis of a pressure regulating anti-icing valve is discussed. The valve comprises of an arrangement of sliding piston and pressure chamber to regulate the pressure. It also includes a feedback loop to achieve self-regulation. The valve includes two functional halves for robustness as well as to have some redundant functionality if some components doesn’t function optimally as the operation calls for accuracy as well as precision. The principles behind the working of this valve includes the interaction of physical domains such as mechanical and fluid dynamics. The modeling of this valve is carried out in multi-domain physical state simulation in MATLAB/SIMULINK platform. It is followed by the dynamic analysis to study the effect of each sub-component on the overall functioning of the valve. Considering this model can be used for designing as well as solving field issues, all the variables such as the diameter at various sections, friction coefficient, surface area of piston, stroke length, orifice diameter are parametric. Variables such as inlet and outlet pressure, piston displacement, flow rate and force balance at the piston are studied. The response from the dynamic model with the initial parameters shows good correlation with the design targets and the influence of key physical parameters on outlet pressure and the regulation time is presented.
The Orion Crew Module has a pressurized cabin of approximately 20 m3 in volume. There are a number of cold plates within the Crew Module for thermal management. An optical communication type of payload consists of electronics boxes and modems that dissipate a significant amount of heat during science operation. Generally, such payloads operate for a short term (e.g., up to one hour). If these heat-dissipating components are flown inside the Crew Module, they require heat rejection to the cold plates in the Crew Module. The waste heat is transported from the cold plate to thermal radiators located outside the Orion spacecraft. This makes such a payload thermally dependent on the Crew Module cold plates.
The pressurization system design considerations presented in this AIR deal with human physiological requirements, characteristics of pressurization air sources, methods of controlling cabin pressure, cabin leakage control, leakage calculation methods, and methods of emergency cabin pressure release.
This ARP discusses design philosophy, system and equipment requirements, and ambient conditions and design considerations for systems within the ATA 100 Specification, Chapter 21 (Reference 1). This chapter is principally concerned with passenger and crew environment and the air conditioning system that maintains this environment. The airplane air conditioning system comprises that arrangement of equipment, controls and indicators that supply and distribute air to the occupied compartments for ventilation, pressurization, and temperature and moisture control. The principal features of the system are: a A supply of fresh air from at least two sources with independent control valves b A means for heating c A means for cooling (air or vapor cycle units and heat exchangers) d A means for removing excess moisture from the air supply e A ventilation subsystem f A temperature control subsystem g A pressure control subsystem Other system components for treating cabin air such as filtration and humidification would be included, as would the ancillary functions of equipment cooling and cargo compartment conditioning. The interface with the major associated system, the pneumatic system (Chapter 36 of ATA 100), is at the inlet of the air conditioning shutoff valves. This boundary definition aligns with that in the ATA 100 Specification.
A report describes proposed systems to be installed in spacecraft to detect punctures by impinging meteoroids or debris. Relative to other systems that have been used for this purpose, the proposed systems would be simpler and more adaptable, and would demand less of astronauts' attention and of spacecraft power and computing resources. The proposed systems would include a thin, hollow, hermetically sealed panel containing an inert fluid at a pressure above the spacecraft cabin pressure. A transducer would monitor the pressure in the panel. It is assumed that an impinging object that punctures the cabin at the location of the panel would also puncture the panel. Because the volume of the panel would be much smaller than that of the cabin, the panel would lose its elevated pressure much faster than the cabin would lose its lower pressure. The transducer would convert the rapid pressure drop to an electrical signal that could trigger an alarm. Hence, the system would provide an immediate indication of the approximate location of a small impact leak, possibly in time to take corrective action before a large loss of cabin pressure could occur.
The pressurization system design considerations presented in this AIR deal with human physiological requirements, characteristics of pressurization air sources, methods of controlling cabin pressure, cabin leakage control, leakage calculation methods, and methods of emergency cabin pressure release.
The Falcon 7X features a host of new technologies, including an advanced wing design, making it Dassault's next-generation business jet. Announced at last year's Paris Air Show, the Falcon 7X will become Dassault Falcon Jet Corp.'s newest addition to its business jet product line. The number seven launches a new naming convention for the company's new generation of Falcons, with the X tag denoting the advanced technology aspects of the airplane. Key to the aircraft's technology is its all-new wing design, which features a planform 44% larger in area than that of the Falcon 900EX and an aspect ratio of 9.0 compared to 7.6. “Dassault's goal was to optimize the wing's total shape (airfoil and planform) in ways that allow structural simplification, weight and cost savings, and a generous internal volume for fuel-all while maintaining the inherently safe and pilot-friendly flying qualities traditional within the Falcon family,” said Olivier Villa, Vice President of Falcon Programs.
Compact instruments, similar in appearance to common personal pagers, have been proposed for warning aircraft crewmembers that cabin air pressure has decreased to a potentially dangerous level. An instrument of this type, called a "personal cabin pressure monitor and warning system" (PCPMWS), implements a warning protocol consistent with Federal Aviation Administration (FAA) requirements for commercial flight crews to (1) use supplemental oxygen after a 30-minute exposure to a cabin pressure altitude between 10,000 and 12,000 ft (about 3,050 and 3,660 m), or (2) immediately when the cabin pressure altitude exceeds 12,000 ft. The PCPMWS would provide both 10,000- and 12,000-ft warnings. The elapsed time between these two warning altitudes could also serve as an indication of the rate of decompression, and thus of the urgency of the situation.
This Aerospace Standard (AS) provides recommended design guidelines for composition formation, performance, testing and reliability of metal-chlorate-perchlorate class solid chemical oxygen generators, supplying oxygen at essentially ambient pressure, for aircraft whose cabin pressure altitude does not exceed 40,000 feet (12,192 m).
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