Dynamics of jet flows in a vortex tube

The results of experimental studies of the pressure gradient field near the axis are presented, and the change in the pitch of the screw structure of gas flows is determined.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 53, No. 6, pp. 906–911, December, 1987.     

Experimental investigation of the working process in a vortex tube

The authors present the results of an experimental investigation of the temperature separation process in the chamber of an energy separation vortex tube.     

Study of a finned two-chamber vortex tube

A two-chamber module of a multichamber vortex-type cold-air machine is examined in four operating regimes.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 55, No. 3, pp. 363–366, September, 1988.     

Experimental investigation of vortex tube refrigerator with a divergent hot tube

Energy separation performance of vortex tube can be improved by using a divergent hot tube. Experiments are carried out to investigate the influence of the geometrical parameters on vortex tube refrigeration capacity by using nitrogen as the working fluid. In this work, the parameters are focused on the divergence angle of hot tube, length of divergent hot tube and number of nozzle intakes. Experimental results present that there is an optimum angle for obtaining the highest refrigeration performance, and 4° is the optimal candidate under our experimental conditions. Divergent tube length which exceeds a critical length has slight effect on the refrigeration capacity. The critical length to diameter ratio is L/D = 12 in our experiment. Increasing number of nozzle intakes increases the sensitivity of temperature reduction and can obtain the highest possible temperature reduction. Moreover, similarity relations for the prediction of the cold exit stream are presented and confirmed by the experimental data.     

Unstable gas flow modes in a Ranque vortex tube

The phenomenon of excitation of developed low- and high-frequency regular pressure fluctuations in the vortex tube of energy separation is experimentally established.     

Investigation of the parameters of a vortex flow inside a Ranque-Hilsch tube

Experimental data are presented on the parameters of a vortex flow, measured along a Ranque-Hilsch tube in adiabatic and nonadiabatic conditions. Graphs are given showing the variation of the thickness of the external stream, the temperature, and the heat transfer coefficient along the tube.     

Performance characteristics of energy separation in a steam-operated vortex tube

Energy separation performance of a steam-operated vortex tube is experimentally investigated, and some reasonable criteria and expressions to estimate the energy separation performance are also introduced. The performance characteristics defined by the above expressions are the same as those of ideal gas in the high superheated region, and are well expressed independently of the degree of superheat, total mass flow rate and discharge resistance. When steam is in the wet region at the nozzle outlet, the performance considerably decreases because of the energy waste from moisture vaporization. And no energy is separated when the dryness fraction is less than approximately 0.98. Some technical data including the optimum operating conditions are also offered.     

Experimental study on a simple Ranque-Hilsch vortex tube

The Ranque-Hilsch vortex tube is a device by which cold gas can be generated using compressed gas. To understand the cooling mechanism of this device, it is necessary to know the pressure, temperature, and velocity distributions inside the tube. In order to investigate this, a simple vortex tube is built and nitrogen is used as its working fluid. A special Pitot tube is used for the measurement of the pressure and velocity. This Pitot tube consists of a capillary which has only one hole in the cylinder wall. With this Pitot tube, the pressure and velocity fields inside the tube were measured. In the same way, the temperature field was measured with a thermocouple. The results of three different entrance conditions are compared here. With the measurements results, the analysis based on the two thermodynamic laws has been made. It is found that rounding off the entrance has influence on the performance of the vortex tube. The secondary circulation gas flow inside the vortex tube can be enhanced and enlarged, the performance of the Ranque-Hilsch vortex tube improved.     

Influence of inner rifling on the efficiency of a vortex tube

The results are presented on experimental studies of cylindrical vortex tubes having inner rifling of the hot end.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 35, No. 2, pp. 218–220, August, 1978.     

Effect of self-oscillations on the hydraulic resistance of a vortex tube

It has been established experimentally that the hydraulic loss increases as tangential self-oscillations develop in a swirled flow.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 37, No. 7, pp. 59–64, July, 1979.     

Observation of large-scale hydrodynamic structures in a vortex tube and the Ranque effect

The existence of large-scale structures in the form of a vortical double helix in a swirling Ranque flow is observed for the first time. The structure of the vortical double helix is visualized in real time by the method of Hilbert bichromatic filtering. The experimental result is interpreted on the basis that the most probable physical mechanism for the spatial energy separation in the gas flow (i.e., for the so-called Ranque effect) is viscous heating of the gas in a thin boundary layer at the walls of the vortex chamber and the adiabatic cooling at the center owing to the formation of an intense vortex braid near the axis. Pis’ma Zh. Tekh. Fiz. 23, 84–90 (December 12, 1997)     

Characteristics of a vortex tube with detwisting of cold flow

The results of an experimental investigation of a vortex tube with a detwister installed in the cold-flow branch are presented.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 57, No. 1, pp. 38–41, July, 1989.     

Experimental investigation of the effects of threefold type Ranque-Hilsch vortex tube and six cascade type Ranque-Hilsch vortex tube on the performance of counter flow Ranque-Hilsch vortex tubes

In this study, performances of Ranque-Hilsh Vortex Tubes (RHVTs) were experimentally investigated under three different situations based on inlet pressure and the ratio of mass flow rate of the cold stream to the mass flow rate of the inlet stream (ξ). 1st situation is the conventional RHVT. 2nd situation is the threefold cascade type RHVT. Here three RHVTs were used. 3rd situation deals with the six cascade type RHVT. In this case, six RHVTs were used. When all the test results under P_i = 360 kPa and P_i = 400 kPa pressure conditions are compared, it is found that the best performance occurs at the 3rd situation. Moreover, the performance of the 3rd situation at P_i = 400 kPa pressure is higher than that at P_i = 360 kPa. Maximum values of ΔT and ξ are obtained as 67.6 °C and 0.9 for 3rd situation.     

Parametric and internal study of the vortex tube using a CFD model

A computational fluid dynamics (CFD) model is used to investigate the energy separation mechanism and flow phenomena within a counter-flow vortex tube. A two-dimensional axi-symmetric CFD model has been developed that exhibits the general behavior expected from a vortex tube. The model results are compared to experimental data obtained from a laboratory vortex tube operated with room temperature compressed air. The CFD model is subsequently used to investigate the internal thermal-fluid processes that are responsible for the vortex tube's temperature separation behavior. The model shows that the vortex tube flow field can be divided into three regions that correspond to: flow that will eventually leave through the hot exit (hot flow region), flow that will eventually leave through the cold exit (cold flow region), and flow that is entrained within the device (re-circulating region). The underlying physical processes are studied by calculating the heat and work transfers through control surfaces defined by the streamlines that separate these regions. It was found that the energy separation exhibited by the vortex tube can be primarily explained by a work transfer caused by a torque produced by viscous shear acting on a rotating control surface that separates the cold flow region and the hot flow region. This work transfer is from the cold region to the hot region whereas the net heat transfer flows in the opposite direction and therefore tends to reduce the temperature separation effect. A parametric study of the effect of varying the diameter and length of the vortex tube is also presented.     

Unsteady free-convection heat transfer during vortex flow in a horizontal tube

We conducted a theoretical and experimental investigation of the hydrodynamic structure and unsteady free-convection heat transfer in a round horizontal tube under different conditions of the second kind. During the experiment the Grashof number varied from Gr=1.54·10⁵ to Gr=7.9·10⁵. Using the interferometric method we investigated the distribution of the temperature field for different structures of free-convection flow in the tube.Academic Scientific Complex A. V. Luikov Heat and Mass Transfer Institute of the Academy of Sciences of Belarus, Minsk. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 68, No. 1, pp. 3–8, January–February, 1995.     

Empirical equation for the index of refraction of seawater

We have determined an empirical equation for the index of refraction of water as a function of temperature, salinity, and wavelength at atmospheric pressure. The experimental data selected by Austin and Halikas ["The index of refraction of seawater," SIO Ref. 76-1 (Scripps Institution of Oceanography, La Jolla, Calif., 1976)] were fitted to power series in the variables. A ten-parameter empirical equation that reproduces the original data to within its experimental errors was obtained.     

Photon-echo novelty filter for measuring a sudden change in index of refraction

An optical novelty filter with phase-conjugate photon echoes is constructed to measure a sudden change in the index of refraction of a transparent medium. This novelty filter is set up as a Michelson interferometer and employs a europium-doped crystal as a phase-conjugate mirror. The filter is sensitive to the sudden change in index of refraction when the phase-conjugate echo experiences a different path length from the first laser excitation pulse in a photon-echo experiment. Using a Pockels cell as a pure phase modulator, we demonstrate that the filter can resolve a sudden phase change occurring on a nanosecond time scale with an accuracy and resolution close to 5°.     

Distribution of volume-averaged parameters of vortex flow over the energy separation chamber of a vortex tube with supplemented flow

The profiles of averaged circular and axial velocity components, temperature, and pressure are measured in the axisymmetric channel of the energy separation chamber of a vortex tube with the introduction of additional flow in the near-axis zone on the side cross section where throttle is located.Rybinsk Aviation Engineering Institute. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 62, No. 4, pp. 534–538, April, 1992.