Simple Nozzle Research Articles

The Theory of Pulsating Flow in Conical Nozzles

A knowledge of the dynamic characteristics of nozzles and orifices is important in many control and stability analyses of engineering devices. It is usual to assume that the instantaneous flowrate, for a given set of inlet conditions and outlet pressure, is the same as the nontransient value for the same operating conditions. Recently, in connection with the stability analysis of an externally pressurized thrust bearing, the validity of this assumption was questioned. The analysis presented in this paper was undertaken to provide an answer. The present analysis applies to any fluid, liquid, or gas flowing into a simple conical nozzle. The amplitude and phase of the mass-flux response to a sinusoidally time-varying pressure fluctuation at the nozzle exit are determined. An approximate formula is given for these quantities in terms of the nozzle throat area, the solid angle subtended by the cone, the velocity of the fluid at the nozzle throat, the acoustic velocity at the throat, and the frequency of the pressure fluctuation.

Research on Quenching to prevent Steel Plate Deformation caused by Oxygen Cutting

When cutting the mild steel plate by oxygen, some deformation remains frequently due to the effect of local heating and cooling. The influence of this deformation makes the further works difficult.Several methods to prevent this kind of deformation have been reported recently, but it seems to us that these methods do not always meet our satisfaction.For this purpose, we have discovered a new and quite interesting method, applying water quenching right after oxygen cutting, which enables us to reduce the amount of deformation almost to zero without giving any harm to the material.In this research, we found out the suitable quenching condition and investigated the influence of this process to the material.The following results are summarized from the experiment.1. According to the quenching condition, shown in TABLE 10, we could reduce the amount of deformation more than 1/10 of the one caused by ordinary oxygen cutting.2. The change in material characteristics throughout this process is out of question, namely, after electric arc welding no difference is found in material characteristics comparing with the ordinary process. On the contrary, the free edge as cut, not intended for electric arc welding, is inferior for cold bending and brittle fracture. But we can eliminate this inferiority by applying a simple additional treatment.3. To apply this process, it is not necessary to arrange any special apparatus but only a simple water nozzle with its holder, rubber water tube and some water.Therefore, this process is easy to manage and is very much economical, as for, we are possible to carry on the further works without any fairing.

Compressible Gas Flow in Nozzle taking Boundary Layer into Consideration : Part 3 Calculations of Convergent and Divergent Nozzles, and Schrielen-photo Experiments

The theoretical calculations of compressible gas flow of nozzle accompanied by laminer or turbulent boundary layer at its wall, are extended to the case of convergent and divergent nozzles in this paper, using assumptions, equations and methods similar to those of the foregoing papers, which discussed the parallel walled straight simple nozzle only. And Schrielen photographic experiments of miscellaneous nozzles of conv. div. and parallel walls are done. By the results from above calculations and experiments, there exists supersonic main flow inside the nozzle end of parallel nozzle, and though, of convergent nozzle. And in divergent nozzle, there are some cases where the acoustic line is put away from throat into the divergent part.

The Nozzle as an Accurate Water-Meter

For measuring the discharge of water in moderate quantity and under considerable pressure a simple smooth nozzle, to which an accurate pressure gauge is properly connected, forms an apparatus of great convenience and remarkable accuracy.