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Shock diamonds are the bright areas seen in the exhaust of this statically mounted Pratt & Whitney J58 engine on full afterburner.. Shock diamonds (also known as Mach diamonds or thrust diamonds, and less commonly Mach disks) are a formation of standing wave patterns that appear in the supersonic exhaust plume of an aerospace propulsion system, such as a supersonic jet engine, rocket, ramjet ...
If under or overexpanded then loss of efficiency occurs. Grossly overexpanded nozzles have improved efficiency, but the exhaust jet is unstable. Conventional nozzles become progressively more underexpanded as they gain altitude. [1]
Figure 1: A de Laval nozzle, showing approximate flow velocity increasing from green to red in the direction of flow Density flow in a nozzle. A rocket engine nozzle is a propelling nozzle (usually of the de Laval type) used in a rocket engine to expand and accelerate combustion products to high supersonic velocities.
However, after the shock the flow in the jet is subsonic. [13] Lowering the back pressure further causes the shock to bend out into the jet (figure 1e), and a complex pattern of shocks and reflections is set up in the jet that create a mixture of subsonic and supersonic flow, or (if the back pressure is low enough) just supersonic flow.
Jet noise may be reduced by adding features to the exit of the nozzle which increase the surface area of the cylindrical jet. Commercial turbojets and early by-pass engines typically split the jet into multiple lobes. Modern high by-pass turbofans have triangular serrations, called chevrons, which protrude slightly into the propelling jet.
XRS-2200 linear aerospike engine for the X-33 program being tested at the Stennis Space Center. The aerospike engine is a type of rocket engine that maintains its aerodynamic efficiency across a wide range of altitudes. [1]
Jet fires impinged on vessels, pipework and firewalls. Under these conditions the fireproofing material was compromised within a few minutes rather than one to two hours, which had been specified. Even without direct impingement, the high thermal radiation emitted by jet flames also affected plant and would have been fatal to personnel. [2]
Contour animation of the mole fraction variation (from 0.025 to 0.05) of a Natural Gas jet as it impinges a steel tank done through CFD.. A high pressure jet is a stream of pressurized fluid that is released from an environment at a significantly higher pressure than ambient pressure from a nozzle or orifice, due to operational or accidental release. [1]