How do you find the power number in a Reynolds number?

How do you find the power number in a Reynolds number?

Based on the relationship between the power number and Reynolds number (power curve) of a rotationally reciprocating impeller operated at A=π/2, the power number is decreased inversely proportional to Reynolds number at Re<10 and then becomes constant at Re> 40 (Senda et al., 2015) .

What does power number mean in mixing?

Power Number is a dimensionless parameter based on the power in Watt consumed by the agitating rotor = impellers for the SUB and turbines for the SUF.

What is power number and modified Reynolds number?

A modified Reynolds number is defined for a power-law fluid as(5.63)RePL=DV¯ρs1K(4n3n+1)n(8V¯D)1−nthen equation 5.62 gives(5.64)fPL=16RePLfor laminar flow of a power-law fluid.

How do you find the power of a number?

Power number can be obtained by using the power number curves that are corresponding to the related impellers or calculated by the correlations. The main correlations are the Nagata correlation and Kamei and Himoka correlation to calculate the power number.

How do you find the power number of an impeller?

Power = Np * n3 * d5 * sg * K The value of the dimensionless power number (Np) depends on several factors including impeller design, number of impellers and location within a tank, tank baffling and fluid viscosity. Typically the power number is shown for mixing in fully turbulent flow.

What should be the value of impeller Reynolds number for laminar and turbulent regime in a bioreactor?

Actually, the transition between laminar and turbulent flow occurs not at a specific value of the Reynolds number but in a range usually beginning between 1,000 to 2,000 and extending upward to between 3,000 and 5,000.

What is power of a number?

The power (or exponent) of a number says how many times to use the number in a multiplication. It is written as a small number to the right and above the base number. In this example the little “2” says to use 8 two times in a multiplication: 82 = 8 × 8 = 64.

What is power number in fermentation?

The power number Np (also known as Newton number) is a commonly used dimensionless number relating the resistance force to the inertia force.

What is the power number/Reynolds number curve?

Power number/Reynolds number curve for the power consumption of impellers. For gas-liquid operations there is another relationship called the K factor which relates the effect of gas rate on power level. Figure 7.26 illustrates a typical K factor plot that can be used for estimation.

Does the power number–Reynolds number relationship change under turbulent conditions?

Assume that at the low gas used, power number–Reynolds number relationship will not be affected and that under fully turbulent conditions, the power number is equal to 6.

What is the power number of the shaft?

The power number is a function of Reynolds number and is constant for Reynolds number greater than 10,000. From the power number, calculate shaft power with: (16-3)P = NPρN3D5 gc

How does the blade angle affect the power number?

For pitched-blade turbines, changing the blade angle, θ, changes the power number by: For pitched-blade turbines, the elevation of the impeller above the tank bottom has a small effect on power number: If there are multiple impellers on a shaft, the power numbers may or may not be additive, depending on impeller type and spacing.