Table of Contents
What is a critical pressure ratio?
The critical pressure ratio is the ratio of the downstream pressure to the upstream pressure at which the flow becomes sonic. Below the critical pressure ratio, the mass flow rate is constant for a given upstream pressure. The flow is choked, and it does not change if the downstream pressure is decreased.
How do you find the critical pressure ratio?
The critical pressure ratio formula for the nozzle is given by,
- Critical pressure ratio = PcPo=(2n+1)nn−1.
- PcPo=(2n+1)nn−1.
- =(21.41+1)1.411.41−1.
- PcPo=(2n+1)nn−1.
- =(21.135+1)1.1351.135−1.
What is critical pressure ratio in nozzle?
The ratio of the pressure at the section where sonic velocity is attained to the inlet pressure of a nozzle is called the critical pressure ratio. It happens at Mach number equals 1.
What is the critical pressure ratio of a convergent nozzle?
Hence from the above two definitions we can say that critical pressure ratio is defined as ratio of outlet pressure to the inlet pressure of the nozzle only when mass flow rate per unit area is maximum.
How do you calculate critical flow?
Plates in Axial Flow This allows us to define a critical flow velocity Uc, beyond which there exists at least one unstable wave of wavenumber k. By means of equation (6.99), it is thus found that Uc = (T/mp)1/2 if ; for T = 0 and , however, Uc = 0.
What is nozzle ratio?
The ratio of the nozzle total to static pressure ratio is called the nozzle pressure ratio (NPR). Nozzle Pressure Ratio: NPR = pt8 / p8 = pt8 / p0. Considering the energy equation for the nozzle, the specific total enthalpy is equal to the static enthalpy plus the square of the exit velocity divided by two.
How is the critical velocity formula derived?
The fluid’s Critical Velocity can be calculated using the Reynolds number, which characterizes the flow of streamlined or turbulent air….Dimensional formula of:
- Reynolds number (Re) = M0L0T0.
- Coefficient of viscosity (𝜂) = M1L-1T-1.
- Radius (r) = M0L1T0.
- The density of fluid (⍴) = M1L-3T0.
What is critical depth formula?
The governing equation for critical depth computation is [1](1) Q 2 g = A 3 B , where is the discharge given to compute the corresponding critical depth, is the gravitational acceleration, is the cross section area, and is the top width at the water surface.
What is the critical pressure ratio for initially dry saturated steam?
0.546
For dry saturated steam, pressure ratio is 0.546. For wet steam, it is 0.577.
What is blade efficiency?
The blade efficiency is the ratio of the work done on the blades to the energy supplied to the fluid. The efficiency of the stage.
What is De level turbine?
De Laval turbine is an impulse turbine, in which steam impinges upon revolving blades from a flared nozzle. The flare of the nozzle causes expansion of the steam, and hence changes its pressure energy into kinetic energy. An enormous velocity (30,000 revolutions per minute in the 5 H.P.
What is Rayleigh line and Fanno line?
Fanno and Rayleigh line, when plotted on h-s plane, for same mass velocity G, intersect at 1 and 2.as shown in fig. All states of Fanno line have same stagnation temperature or stagnation enthalpy, and all states of Rayleigh line have same stream thrust F / A.
What is meant by expansion ratio?
The expansion ratio of a liquefied and cryogenic substance is the volume of a given amount of that substance in liquid form compared to the volume of the same amount of substance in gaseous form, at room temperature and normal atmospheric pressure.
What is the another name of converging nozzle?
Clarification: Another name of converging nozzle is Subsonic Nozzle.
What is the relation between critical velocity and Reynolds number?
Critical velocity is the speed and direction at which the flow of a liquid through a tube changes from smooth to turbulent. Determining the critical velocity depends on multiple variables, but it is the Reynolds number that characterises the flow of the liquid through a tube as either turbulent or laminar.