Supersonic Gas Nozzle Pressure Ratio Optimization in Powder Metallurgy
Maintaining nozzle pressure ratio within supersonic design boundaries guarantees negative tip aspiration, eliminating melt reflux and maximizing fine powder yield.
Shock Diamond
Meaning
Flow visualization standards use the presence of standing wave patterns to identify supersonic gas velocities in exhaust streams. Observing a shock diamond in a battery vent plume indicates that the internal pressure of the cell has reached a critical level during a thermal runaway event. These patterns are created by the interaction of expansion waves and oblique shocks with the atmosphere.
Pressure Differential
Standing waves form when the pressure of the gas at the nozzle exit differs from the ambient pressure, creating the Pressure Differential of shock diamond formation. Gas expands rapidly upon exit and then contracts as the pressure waves reflect off the jet boundary. The appearance of these structures confirms that the internal cell pressure exceeded the atmospheric pressure by a specific ratio determined by gas properties.
Velocity Calculation
Distance between the nodes of the visible structures provides the data required for the Velocity Calculation of shock diamond spacing. This measurement correlates with the speed of the escaping gas relative to the speed of sound. Safety researchers use this data to model the physical force of the jet on surrounding battery pack components.
Thermal Intensity
Analyzing the color and brightness of the flow helps determine the Thermal Intensity of shock diamond presence in a fire. Luminous intensity suggests a high energy release rate and extreme temperatures within the gas stream. This optical evidence provides a method for assessing the severity of a venting event without the use of physical sensors.