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The first part of the combustor is an increase in area (diffuser) to slow the air from the compressor because too high an entry velocity to a duct with heat addition (a combustor) would cause unacceptably high pressure losses. The velocity is still too high for a flame to be held in place so a sheltered combustion zone (known as the primary ...
Turbojets have a low propulsive efficiency below about Mach 2 [citation needed] and produce a lot of jet noise, both a result of the very high velocity of the exhaust. Modern jet propelled aircraft are powered by turbofans. These engines, with their lower exhaust velocities, produce less jet noise and use less fuel.
While a turbojet engine uses all of the engine's output to produce thrust in the form of a hot high-velocity exhaust gas jet, a turbofan's cool low-velocity bypass air yields between 30% and 70% of the total thrust produced by a turbofan system. [25]
A diffuser is "a device for reducing the velocity and increasing the static pressure of a fluid passing through a system”. [1] The fluid's static pressure rise as it passes through a duct is commonly referred to as pressure recovery. In contrast, a nozzle is used to increase the discharge velocity and lower the pressure of a fluid passing ...
Displacement ventilation systems supply air directly to the occupied zone.The air is supplied at low velocities to cause minimal induction and mixing. This system is used for ventilation and cooling of large high spaces, such as auditorium and atria, where energy may be saved if only the occupied zone is treated rather than trying to control the conditions in the entire space.
The Ferrari F40 sports car has "NACA style" side and hood scoops.. It is especially favored in racing car design. [4] [5] Sports cars featuring prominent NACA ducts include the Ferrari F40, the Lamborghini Countach, the 1996–2002 Dodge Viper, the 1971–1973 Ford Mustang, the 1973 Pontiac GTO, the 1979 Porsche 924 Turbo, the Maserati Biturbo, the Nissan S130, and the Porsche 911 GT2.
The velocity of air through a register is usually kept low enough so that it is masked by background noise. (Higher ambient levels of background noise, such as those in restaurants, allow higher air velocities.) On the other hand, air velocity must be high enough to achieve the desired temperature. [6] Registers are a critical part of the HVAC ...
Volume flow rate (cubic meters per second) = duct area (square meters) × flow velocity (meters per second) In aviation, airspeed is typically measured in knots. In weather stations with high wind speeds, the pitot tube is modified to create a special type of anemometer called pitot tube static anemometer. [9]