Which parameters are dimensionless?

Which parameters are dimensionless?

Dimensionless Parameter

• Energy Engineering.
• Viscosity.
• Thermal Conductivity.
• Boundary Condition.
• Prandtl Number.
• Reynolds’ Number.

Why are dimensionless parameters used in the analysis of pumps?

The dimensionless equations were useful to determine which discharge should be adopted so that the system would be more efficient hydro and energetically and, also, to determine how much more energy would be consumed in the case of alteration of the point of operation of the pump by a throttling valve.

How many dimensionless parameters Characterise the system?

six dimensionless numbers

Is specific speed dimensionless?

Specific Speed is a dimensionless rating of pump discharge performance derived from an equation involving shaft speed, flow rate and differential head at a pump’s Best Efficiency Point. It is an important factor used in the design and selection of pumps and impellers.

What is pump specific speed?

Specific speed is an index used to predict desired pump or turbine performance. i.e. it predicts the general shape of a pumps impeller. It is this impeller’s “shape” that predicts its flow and head characteristics so that the designer can then select a pump or turbine most appropriate for a particular application.

Which pump has highest specific speed?

Centrifugal pump

Which pump has low specific speed?

centrifugal pump

How do you calculate pump speed?

Example – Specific Speed for a Pump with different units

1. US gpm, ft. Ns(US gpm, ft) = (1760 rev/min) (1500 gal/min)1/2 / (100 ft)3/4
2. British gpm, ft. Ns(British gpm, ft) = (1760 rev/min) (1249 gal/min)1/2 / (100 ft)3/4
3. m3/h, m. Ns(m3/h, m) = (1760 rev/min) (340 m3/h)1/2 / (30.5 m)3/4
4. liter/min, m.

What is suction specific speed?

Suction specific speed is an index number for a centrifugal pump similar to discharge specific speed and is used to define its suction characteristic. It is constant for a given pump, regardless of pump speed. For pumps of normal design, values of “S” vary from 6,000 to 12,000.

What is the unit of specific speed?

RPM

How do you calculate the speed of a centrifugal pump?

We must divide N by 9.55 to convert to radians/second. Q must be divided by 449 to convert to ft3/second and H must be multiplied by 32.2. The result tells us that to convert from U.S. units to dimensionless values requires that the U.S. values for NS be divided by 2,735.

What is overall efficiency of centrifugal pump?

The centrifugal pump converts mechanical energy into hydraulic energy (flow, velocity and pressure), and the AC motor converts electrical energy into mechanical energy. Many medium and larger centrifugal pumps offer efficiencies of 75 to 93 percent and even the smaller ones usually fall into the 50 to 70 percent range.

What is priming of a centrifugal pump?

Priming simply means preparing or getting something ready for operation. For a centrifugal pump to work properly, you need to fill it up with water. When everything is right, a standard (non-self-priming) centrifugal pump looks like this. The pump will resume operation once the air is removed.

What is specific speed of Pelton turbine?

The optimum value of the overall efficiency of a Pelton turbine depends both on the values of the specific speed and the speed ratio. The Pelton wheels with a single jet operate in the specific speed range of 4-16, and therefore the ratio D/d lies between 6 to 26 as given by the Eq. (15.25b).

How can you increase the efficiency of a Pelton turbine?

To maximise efficiency the jet must hit precisely the centre of each Pelton bucket. That way the jet gives the maximum drive to each bucket as noted earlier in the design of the buckets that the rotation of the turbine depends on the water jet velocity.

What is the efficiency of Pelton turbine?

Pelton turbines can reach up to 95% efficiency, and even on ‘micro’ scale systems 90% peak efficiency is achievable. Also the efficiency is maintained at a high level even for part-flow rates, mainly because of the low-loss design of the spear-jet.

What is the efficiency of Kaplan turbine?

The hydraulic efficiency of a Kaplan turbine is 95%, the mechanical efficiency is 93% and the volumetric efficiency is assumed to be 100%.

How much power can a Pelton wheel produce?

16.89 watts

Why Pelton wheel is used for high heads?

These turbines are generally used for sites with heads greater than 300 meters. The water in a Pelton turbine is moving quickly (high velocity head, figure 2) and the turbine extracts energy from the water by slowing the water down, which makes this an impulse turbine.

How much power can a small water wheel produce?

Microhydropower systems usually generate up to 100 kilowatts of electricity. Most of the hydropower systems used by homeowners and small business owners, including farmers and ranchers, would qualify as microhydropower systems.

How do you calculate water flow in Litres per minute?

The easiest way to get a fairly accurate measure of your water flow rate is to time yourself filling up a bucket. So for example if you fill up a 10 litre bucket in 1.5 minutes, then your flow rate will be: 10/1.5 = 6.66 Litres per minute. Don’t get confused between flow rate and pressure.

What is 1 bar in Litres per minute?

119.24