Velocity meter

Head meters with velocity compensation. The signal from the head meter, which is proportional to pV", is divided by the signal from a velocity meter to give a signal proportional to the mass flow rate. 

The easiest thing to do is to get the pump curve from the manufacturer because it has the NPSHr listed at different flows. Nowadays, you can get the pump curve on the Internet with an e-mail to the manufacturer, you can send a fax, or request the curve in the mail or with a local call to the pump representative or distributor. If you wanted to verify the NPSHr on your pump, you ll need a complete set of instrumentation a barometer gauge, compound pressure gauges corrected to the centerline of the pump, a flow meter, a velocity meter, and a thermometer. Definitely, it s easier to get the curve from your supplier. 

Figure 9-62. Flooding data for structured packings as reported by Billet [109]. Numbers following packing type indicate specific surface area in m /m. Reproduced by pennis-sion of the American Institute of Chemical Engineers, Fair, J. R. and Bravo, J. L., Chemical Engineering Progress, V. 86, No. 1 (1990) p. 19 all rights reserved. Note, Uq = vapor velocity, meters/sec.

Other flowmeters are in common use which operate on principles differing from head flowmeters. Mechanical flowmeters have primary elements which contain moving parts. These flowmeters include rotameters, positive displacement meters and velocity meters. Electromagne-... 

Other commonly used mechanical flowmeters are velocity meters. 

Velocity Meters Velocity meters measure fluid velocity. Examples include electromagnetic, propeller, turbine, ultrasonic Doppler, ultrasonic transit time, and vortex meters. Section 8 describes the principles of operation of electromagnetic, turbine, ultrasonic, and vortex flowmeters. 

Other important classes of velocity meters include electromagnetic flowmeters and ultrasonic flowmeters. Both are described in Sec. 8. 

Air stream Velocity. Meter/Sec. Air stream Temp.. °C. Fuel Drag Coeff. Unignited Ignited Ratio of Drag Coeff. Ignited/U nignited Reynolds No.b... 

Kostiuk et al. [40] measured experimentally the flow field of the vertical co-axial turbulent impinging streams with a two-component Laser Doppler velocity meter. The opposing gas streams were ejected from two burner nozzles, which were designed to produce a uniform axial velocity profile at their exits. The turbulence in the flow was generated by a perforated plate located at the end of the contraction section in each nozzle. The air velocity at the exit of the nozzle was varied from 4.1 to 11.4 m s and... 

Air and gaseous S02 in the required ratio enter Mixer 6 to mix fully with each other, and the resulting pseudo flue gas is divided into two equal streams to enter Absorber 7. The air flow rate is adjusted by a butterfly valve in the pipeline and measured with a Pitot tube-pressure difference meter and that of S02 by the rotameter 5. The total gas flow rate is also monitored by a wind velocity meter of DF-3 type at the gas outlet of the reactor. For each run, gas-samplings are made at both inlet and outlet of the reactor, and the S02 concentrations in the samples are measured with the Iodine-quantitative method, a standard and authentic method of determining the integral amount of S02 absorbed in the reactor. 

For many locations, flow could be easily measured (i.e., using a bucket and stopwatch). For other locations where it was not possible to measure flow directly the sum of individual upstream flows was used as an estimate. For several of the main pipes entering the treatment plan, a velocity meter was used to estimate flows. In these cases the velocity, pipe diameter and depth of water within the pipe were used to calculate flow. There were a total of four sampling events. Initially, all samples were to be collected under dry conditions to maximize contaminant... 

After it is confirmed that the flow in the vessel has attained a steady state under a fixed Re, the velocity fluctuations are measured at the fixed impeller discharge flow region by using an electrode reaction velocity meter. The measured ESD is fitted by the new ESD defined by Eq. (4.7). 

There is a need to distinguish at this point how the shear rate in the impeller zone differs from the shear rate in the tank zone. To do this, however, one must carefully define shear rate and the corresponding concepts of macroscale shear rate and microscale shear rate. When one studies the localized fluid velocity through utilization of a small dimension probe, or as is currently used, a laser Doppler velocity meter device, one sees that at any point in the... 

Flow Meters. A wide variety of instruments are available for measuring the fl ow rates of liquids and gases in closed-tube systems. Four general types are (1) differential-pressure devices, (2) variable-area devices, (3) velocity meters, and (4) mass meters. Important examples of each type are listed in Table 3, which contains information on the range of volume fl ow rates Q covered by a given style of instrument as well as the accuracy and range for any individual meter. 

Velocity meters measure the velocity v of fluid flow in a pipe of known cross section, thus yielding a signal linearly proportional to the volume flow rate Q. Mass meters provide signals directly proportional to the mass flow rate m = pQ, where p is the mass density. Coriolis meters, which are true mass meters, can be used only for liquids. Thermal-type flow meters use a heating element and determine the rate of heat transfer, which is proportional to the mass flow rate. This type of device is used mostly for gas measurements, but liquid flow designs are also available. 

Other background on turbulent velocity parameters is given by Cutter (3) who calculated several parameters from photographs of flow patterns in a mixing vessel. He found that the RMS velocity fluctuation was primarily related to energy dissipation. His measurement scale In making these photographic studies could be quite different from the scale velocities from the hot wire velocity meter reported here, so that a direct comparison of these results with those of Cutter has not been made in this paper. 

Another parameter which can be measured by the hot wire velocity meter technique is a dissipation length. 

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