Fluid Thermal Effects Research Articles

Polarization and properties of low-frequency waves in warm magnetized two-fluid plasma

This paper presents the derivation of a general wave dispersion relation for warm magnetized plasma under the two-fluid formalism. The discussion is quite general except for the assumption of low frequency and slow phase speed, for which the displacement current is negligible, under the implicit assumption that the plasma is sufficiently dense to satisfy the condition ωpe>ωce, where ωpe and ωce denote the plasma oscillation frequency and electron gyro frequency, respectively. The present discussion does not invoke charge neutrality associated with the fluctuations although it is implicitly satisfied. The resulting dispersion relation that includes the fluid thermal effects shows that there are three eigen modes, which include those corresponding to ideal MHD, namely, fast, slow, and kinetic Alfvén waves, as well as higher-frequency modes including the ion and electron cyclotron and lower-hybrid resonances. The fluid effects in the ideal MHD wave branches are influenced by the finite Larmor radius scales, and when the wave number in the cross field direction is comparable to these values, the fluid effects become significant. It is found that the Larmor radius should be interpreted in the sense as ion-acoustic gyro-radius instead of ion thermal gyro radius only. That is, it is found that the electrons also contribute to the non-ideal effect associated with the kinetic Alfvén wave. A comprehensive explanation of the polarization of each mode is also presented. The present findings indicate that the polarity may change its sign only for the kinetic Alfvén mode branch and that such a transition is based on the propagation angle. When such a change does take place, it is found that the kinetic Alfvén wave transits to an ion-acoustic mode. For each branch, it is also found that the electric field along the ambient magnetic field is purely transverse.

The Thermal Effect of Submarine Mud Volcano Fluid and Its Influence on the Occurrence of Gas Hydrates

Mud volcanoes and other fluid seepage pathways usually transport sufficient gas for the formation of gas reservoirs and are beneficial to the accumulation of gas hydrate. On the other hand, the fluid thermal effects of mud volcanoes can constrain the occurrence of gas hydrates. Current field measurements indicate that fluid thermal anomalies impact the distribution of gas hydrates associated with mud volcanoes. However, due to the lack of quantitative analysis of the mud volcano fluid flow and thermal evolution, it is difficult to effectively reveal the occurrence of gas hydrates in mud volcano development areas and estimate their resource potential. This study took the Håkon Mosby Mud Volcano (HMMV) in the southwestern Barents Sea as the research object and comprehensively used seismic, well logging, drilling and heat flow survey data, combining the principles and methods of fluid dynamics and thermodynamics to study the fluid flow and heat transfer of a mud volcanic pathway. The space framework of the mud volcanic fluid temperature field thermal structure was established, the influence of the HMMV fluid thermal effect on gas hydrate occurrence was analyzed and the distribution and resource potential of gas hydrates in mud volcano development areas were revealed from the perspective of thermodynamics. This study provides a thermodynamic theoretical basis for gas hydrate accumulation research, exploration and exploitation under a fluid seepage tectonic environment.

Effect Of Taper Angle On Flow And Stress In Conical Shell Fluid Mixers

Hollow cylindrical flow mixers achieve a homogeneous mixture with less pressure loss and higher momentum. However, the low volume of the mixer due to the hollow creates high pressure effects and mechanical stresses on the mixer. In this study, the stresses formed on the mixer by considering the flow and thermal effects of fluids in a conical cylinder mixer at different temperatures were examined. The effect of taper angle has been studied. In the examinations carried out using the finite element method, a verification study was first made, and solution sensitivity was determined. Water as fluid in standard conditions and common steel properties as cylinder material were used. Plate thickness was chosen to be 1 mm. It seems more appropriate to use a non-conical straight model to achieve thermal equilibrium. The taper angle reduced the velocity of fluid entering the mixer. Stress concentrations were observed at the supports and a lower and decreasing stress distribution was obtained for the conical mixer while it was constant for the straight cylinder in the other regions.

Thermal characteristics testing and thermal error modeling on a worm gear grinding machine considering cutting fluid thermal effect

The coolant absorbing cutting heat has strong influence on thermal behaviors for high precision machine tool using flood cooling technique. However, the majority of applied thermal error compensation models are without considering cutting fluid thermal effect, which results in poor simulation accuracy of thermal deformation. This paper experimentally investigated the effect of coolant temperature on the thermal characteristics of a worm gear precision grinding machine. Experiments were carried out under three conditions: no-load with coolant, no-load with heated coolant, and load test. Moreover, a real-time thermal error compensation model was theoretically developed and validated based on the experimental data involving the cutting fluid thermal effect. The results show that the temperature distribution of the machine tool was more uniform and the temperature gradient was decreased when the grinding heat was partially considered using heated coolant, which indicates that coolant can positively affect the thermal behavior if it is controlled to flow correctly. The thermal error compensation model was built based on the optimal four temperature variables and with a high accurate prediction and robustness. For the no-load operating conditions, the maximum absolute errors and mean absolute errors are 2.7 μm and 1.5 μm respectively. For the load operating conditions, the prediction accuracy of the model built by no-load measuring data is also greatly improved because the grinding heat is partially considered by heated coolant in the no-load test. And the maximum prediction error is 13.0% when the influence of the feed drive system adjustment is considered.

A thermal characteristic analytic model considering cutting fluid thermal effect for gear grinding machine under load

The cutting fluid has a great influence on the thermal behavior of machine tools using flood cooling technique. But majority of machine tools thermal models are without considering the cutting fluid absorbing grinding heat and its effect on the thermal behavior. In this paper, a thermal-structure coupling finite element model considering the cutting fluid thermal influence was developed and a special measurement system was established, and a series of load experiments were carried out to validate this model. The simulation results and experimental data are in good agreement. The thermal behavior of the machine tool has been estimated using the proposed thermal models. The effect of coolant and machining position on thermal deformation was also analyzed. The results show that larger temperature gradient occurred in the X- and Z-directions of the whole machine because cutting fluid absorbing grinding heat and lead to ambient temperature rise of machine tool enclosed housing. The combined effect of the X- and Z-direction thermal deformation causes the column and the workpiece column obviously appear “backwards” distortion. The coolant channels of bed can be designed to be symmetrically distributed around the motorized spindle in the X-direction to further reduce the thermal deformation.

A Simplified Approach to Modeling Thermal Effects in Wet Clutch Engagement: Analytical and Experimental Comparison

The simplified isothermal model for wet clutch engagement previously developed by Berger, Sadeghi, and Krousgrill (Berger, E. J., Sadeghi, F., and Krousgrill, C. M., 1996, “Analytical and Numerical Modeling of Engagement of Rough, Permeable, Grooved Wet Clutches,” ASME J. Tribol., 119, p. 143) was extended to include fluid thermal effects. The modified Reynolds and thermal diffusion equations were simultaneously solved to obtain torque and temperature characteristics during wet clutch engagement. The modified Reynolds equation was integrated using the Adams-Gear scheme and the alternating direction implicit method (ADI) finite difference technique was used to solve the thermal diffusion equation. The model was used to study the effects of speed, temperature, and load on the torque transfer and lubricant temperature variation during wet clutch engagement. A comparison of thermal and isothermal results indicates that the thermal model generally predicts a longer engagement time and smaller peak torque than the isothermal model. Comparison of analytical and experimental results indicates that including fluid thermal effects in the model is critical for achieving good correlation between analytical and experimental results. [S0742-4787(00)01501-0]

Thermal effects of metamorphic fluids in subduction zones

In subduction zones, large volumes of fluid are released from the subducting slab during prograde metamorphism of hydrated oceanic crust. Once released, metamorphic fluids tend to migrate upward owing to buoyancy. Fluid migration can affect the thermal structure of a subduction zone by (1) advecting heat and (2) causing retrograde (hydration, carbonation) reactions in the hanging wall. Under most P - T conditions, the volumetric heat capacities of H 2 O and rocks are similar; therefore, the thermal effects of fluid migration and uplift are comparable. Calculations suggest that advective heat transport by fluid flow causes relatively minor thermal effects. Pervasive upward fluid flow results in thermal effects analogous to regional uplift rates on the order of 0.2 mm/yr. Fluid flow channelized along the subduction shear zone translates the local thermal structure of the shear zone updip at ∼1 mm/yr. A more important thermal effect results from exothermic retrograde reactions in the hanging wall that release ∼30 kJ/mol of H 2 O consumed. Retrograde reactions significantly retard cooling of the hanging wall just as prograde reactions retard warming of the subducting slab.

Analysis of Single- and Two-Phase Flows in Turbopump Inducers

A model is developed for analytically determining pump inducer performance in both the single-phase and cavitating flow regimes. An equation of state for vaporizing flow is used in an approximate, three-dimensional analysis of the flow field. The method accounts for losses and yields internal distributions of fluid pressure, velocity, and density together with the resulting overall efficiency and pressure rise. The results of calculated performance of two sample inducers are presented. Comparison with recent theory for fluid thermal effects on suction head requirements is made with the aid of a resulting dimensionless vaporization parameter.

Regnault's Experiments on the Joule-Thomson Effect

THAT Regnault made a number of experiments similar to some of those described by Joule and Kelvin in their papers on the thermal effects of fluids in motion does not seem to be commonly known; at all events, the numerical results of his work on this subject are not often mentioned. After experimenting on the flow of gases through small holes in thin plates, and through long capillary tubes, he followed the example of Joule and Kelvin in using porous bodies, especially discs and tubes of soft; unglazed porcelain. He found great difficulty in getting definite results, especially in the regard that the temperature observed in the stream of gas issuing from the porous wall depended on the position of the thermometer. He concludes the account of his experiments in the following words:—“Après ces tentatives infructueuses et beaucoup d'autres dont je ne parlerai pas, j'ai renoncé à l'espoir d'obtenir quelque chose de précis, d'expériences fondées sur la mesure de températures dans les courants gazeux, et il ne m'est resté que le regret d'avoir consacré beaucoup de temps à des recherches stédies” (Regnault, “Relation des Experiences,” vol. iv., p. 707, 1870).

Concerning the Thermodynamic Correction for an Air Thermometer

IT seems noteworthy not only that the theoretical investigation on this subject, given in Maxwell's “Theory of Heat” and Tait's “Heat,” is fallacious, as has been pointed out by Mr. Rose-Innes in his letter which appeared in your issue of May 26, but that there is no indication in either of these text-books that the result given is not in accordance with the experimental facts. The investigation in question, which is practically the same as that first given by Lord Kelvin before the experiments were performed, leads to the result that the cooling effect should be proportional to the difference of the logarithms of the pressures before and after passing the plug, instead of proportional to the difference of the pressures themselves, as was actually found to be the case; the discrepancy was, of course, noted'by the experimenters. The methods used in all the theoretical discussions in Lord Kelvin's papers on this subject prior to the final one in Part iv. of the papers “On the Thermal Effects of Fluids in Motion,” seem equally open to objection. The numerical results derived by the-last method, which seems perfectly sound, were given apparently for the first time in the article “Heat” in the “Encyclopaedia Britannica”; the investigation and results are reproduced in Preston's “Theory of Heat,” and substantially in Parker's “Thermodynamics.” The correction obtained to the number representing the temperature of melting ice on the absolute scale by this method was + ˙70, the previous methods giving in succession + ˙83, –˙3 and + .87; the uncorrected estimate finally used was also different from that taken at first.

XXIII. On the thermal effects of fluids in motion. —Part IV

A brief notice of some of the experiments contained in this paper has already appeared in the ‘Proceedings.’ Their object was to ascertain with accuracy the lowering of temperature, in atmospheric air and other gases, which takes place on passing them through a porous plug from a state of high to one of low pressure. Various pressures were employed, with the result (indicated by the authors in their Part II.) that the thermal effect is approximately proportional to the difference of pressure .on the two sides of the plug.

XIX. On the thermal effects of fluids in motion.—Part III. On the changes of tem­perature experienced by bodies moving through air

This interesting branch of our researches has been prosecuted by us from time to time since 1856. In the spring of that year we commenced our experiments by trying the effect of whirling thermometers in the air. This process had been confidently recom­mended as a means of obtaining the temperature of the atmosphere, but we were sure that the plan was not absolutely correct, and one of us had, as early as 1847, explained the phenomena of “shooting stars” by the heat developed by bodies rushing into our atmosphere. In our early experiments we whirled a thermometer by means of a string, alternately quickly and slowly, and it was found that the thermometer was invariably higher after quick than after slow whirling, in some cases the difference amounting to as much as a degree Fahrenheit. We also succeeded in exhibiting the same phenomenon by whirling a thermo-electric junction. In 1857 we resumed the subject, using an apparatus consisting of a wheel worked by hand, communicating rapid rotation to an axle, at the extremity of which an arm carrying a thermometer, with its bulb out­wards, was fixed. The distance between the centre of the axle and the thermometer bulb was 39 inches. The thermometers made use of were filled with ether or chloro-form, and had, the smaller 275, and the larger 330 divisions to the degree C. The lengths of the cylindrical bulbs were 9/10 and 1 4/10 inch, their diameters .26 and .48 of an inch respectively. The method of experimenting was to revolve the thermometer bulb at a certain velocity until we knew by experience that it had obtained the full thermal effect, then to stop it as suddenly as possible and observe the temperature. Alternately with these observations others were made to ascertain the temperature after a slow velocity, the effect due to which was calculated from the other observations, on the hypothesis that it varied with the square of the velocity. In all cases the results in the Tables are means of several experiments.

V. On the thermal effects of fluids in motion—temperature of bodies moving in air

An abstract of a great part of the present paper has appeared in the ‘Proceedings,’ vol. viii. p. 556. To the experiments then adduced a large number have since been added, which have been made by whirling thermometers and thermo-electric junctions in the air. The result shows that at high velocities the thermal effect is proportional to the square of the velocity, the rise of temperature of the whirled body being evidently that due to the communication of the velocity to a constantly renewed film of air. With very small velocities of bodies of large surface, the thermal effect was very greatly increased by that kind of fluid friction the effect of which on the motion of pendulums has been investigated by Professor Stokes.

On the thermal effects of fluids in motion

"On the thermal effects of fluids in motion." The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, 20(136), pp. 552–553

XXI. On the thermal effects of fluids in motion:—Temperature of a body moving slowly through air

The motion of air in the neighbourhood of a body moving very slowly through it, may be approximately determined by treating the problem as if air were an incompressible fluid. The ordinary hydro-dynamical equations, so applied, give the velocity and the pressure of the fluid at any point; and the variations of density and temperature actually experienced by the air are approximately determined by using the approximate evaluation of the pressure thus obtained.

I. On the thermal effects of fluids in motion

A very great depression of temperature has been remarked by some observers when steam of high pressure issues from a small orifice into the open air. After the experiments we have made on the rush of air in similar circumstances, it could not he doubted that a great elevation of temperature of the issuing steam might be observed as well as the great depression usually supposed to be the only result. The method to obtain the entire thermal effect is obviously that which we have already employed in our experiments on permanently elastic fluids, viz. to transmit the steam through a porous material and to ascertain its temperature as it enters into and issues from the resisting medium. We have made a preliminary experiment of this kind which may be sufficiently interesting to place on record before proceeding to obtain more exact numerical results.

XI. On the thermal effects of fluids in motion. — No. II

The first experiments described in this paper show that the anomalies exhibited in the last table of experiments, in the paper preceding it, are due to fluctuations of temperature in the issuing steam consequent on a change of the pressure with which the entering air is forced into the plug.