Search results
Results From The WOW.Com Content Network
Both calculate an approximation of the first natural frequency of vibration, which is assumed to be nearly equal to the critical speed of rotation. The Rayleigh–Ritz method is discussed here. For a shaft that is divided into n segments, the first natural frequency for a given beam, in rad/s , can be approximated as:
Analysis shows that there are well-damped critical speed at lower speed range. Another critical speed at mode 4 is observed at 7810 rpm (130 Hz) in dangerous vicinity of nominal shaft speed, but it has 30% damping - enough to safely ignore it. Analytically computed values of eigenfrequencies as a function of the shaft's rotation speed. This ...
Dunkerley's method [1] [2] is used in mechanical engineering to determine the critical speed of a shaft-rotor system. Other methods include the Rayleigh–Ritz method . Whirling of a shaft
In this state, lowering the back pressure increases the flow speed everywhere in the nozzle. [13] When the back pressure, p b, is lowered enough, the flow speed is Mach 1 at the throat, as in figure 1b. The flow pattern is exactly the same as in subsonic flow, except that the flow speed at the throat has just reached Mach 1.
Traffic engineers calculate the threshold of instability for a curve, and then set the advisory speed below that threshold. The sign alerts drivers to a potential hazard, and if that driver ...
For given upstream conditions at point 1 as shown in Figures 3 and 4, calculations can be made to determine the nozzle exit Mach number and the location of a normal shock in the constant area duct. Point 2 labels the nozzle throat, where M = 1 if the flow is choked.
Speed – flow diagrams are used to determine the speed at which the optimum flow occurs. There are currently two shapes of the speed-flow curve. The speed-flow curve also consists of two branches, the free flow and congested branches. The diagram is not a function, allowing the flow variable to exist at two different speeds.
The true airspeed corresponding to the critical Mach number generally decreases with altitude. The flight envelope is a plot of various curves representing the limits of the aircraft's true airspeed and altitude. Generally, the top-left boundary of the envelope is the curve representing stall speed, which increases as altitude increases.