Spreading angle

The minimum case is when rhe diameter of vena contracta of the plume is about 80% of the upper surface diameter and is located approximately one-third of a diameter above the source. I he spreading angle of rhe plume is set ro 25". For low-temperature sources, Skistad - recommends the maximum case, whereas rhe minimum case best fits the measure ments for larger, high-temperature sources. 

Recess stabilization appears to have two major disadvantages. The first is due to the large increase in heat transfer in the step area, and the second to flame spread angles smaller than those obtained with bluff bodies. Smaller flame spread angles demand longer combustion chambers. 

Analyzing Fig. 12.3, it is noticed that the flame width in the bluff-body stabilized flame increases almost linearly with the distance from the baffle with the spreading angle of about 3° to 5°. Since the flame spreading angle directly affects the ramjet combustion efficiency, it is important to check the performance of the ABC by applying it to combustors with different tailpipes. 

The ahgmnent of SWNTs can be determined in macroscopic quantities using a low 6 X-ray diffraction pattern. A detailed study of the low 6 X-ray diffraction on pellets of SWNTs (prepared by applying pressure of 10 k bars) shows that the tubes axis are ahgned in the plane of the pellets within an out-of-plane spread angle of The orientation and... 

Assuming that atomization is caused by aerodynamic surface wave growth, Ranz (37) predicted the spreading angle, 0, of the atomizing jet by relating the radial velocity of the unstable surface waves to the axial injection velocity... 

Much of the available research agrees that supercritical jets typically behave similar to turbulent gas jets, specifically variable-density gas injection. Chehroudi et al. [6] first found favorable comparison between measured transcritical (Type II or IV) jet spreading angles and those of variable-density gas jets. Barata et al. [7] used numerical variable-density gas jet models to predict experimental results, and found good agreement. 

Oschwald and Micci [12] found spreading angles similar to those of Chehroudi et al. [10], but centerline densities differed from variable-density gas jet data in then-study. 

Recent research has also investigated which independent variables (e.g., density ratio, temperature, mass flow rate) significantly affect jet structure and mixing. The quantities measured include penetration length, concentration or density profiles, spreading angles, velocity, and core lengths. 

Chen [16] found that the penetration length of a supercritical jet was affected by injection temperature and chamber pressure. Doungthip et al. [17] observed that changing flow rate and/or temperature affected both penetration length and spreading angle. 

Oschwald, M. Micci, M. (2002). Spreading angle and centerline variation of density of supercritical nitrogen jets. Atom. Sprays, 11, 91-106. 

M. Ahmed, N. Ashgriz, H. N. Tran Break-up length and spreading angle of liquid sheets formed by splash plate nozzles. Journal of Fluid Engineering, 131, 1-9. 

This is analogous to the spreading angle of a main lobe of a diffracted plane wave from a circular aperture, given by... 

Table XXXIII indicates that temperature of com, degree of consistency, time of spreading, angle of cone, and surface of cone have highly significant effects on consistency readings. Interaction between temperature and consistency and between angle and surface of cone were also shown to be significant. In the present case the experiment achieved a very high degree of sensitivity because of the large number of observations.

Spreading angle a. (From Krum, A., Course Notes, UCLA Extension, Engineering 881.152, Power Hybrids Design and Processing, April 3-6, 1995, Los Angeles, CA. 

An approximation for the spreading angle, based on the ratio of thermal conductivities of the layers, is given by N.B. Nguyen [12],... 

When = K2, the spreading angle will be 45°. As the ratio of K /K2 increases, the spreading angle asymptotically approaches 90°. 

For the configuration shown in Figure 3.6 [11], which depicts a silicon chip on a direct-bond-copper metallized substrate, the spreading angle in the... 

A good approximation in first-order thermal calculations is to use a 45° spreading angle. 

A more exact spreading angle model uses 26.6° for cases when the ratio of heat-spreader thickness to heat-dissipating-element side is less than 2 [13]. 

Spreading-angle definition. (From Krum, A., Thermal Management Handbook, Electronic Packaging and Interconnection Series, Eds., Krum, A. and Sergent, ]., New York McGraw-FHU, 1998. chap. 5. With permission.)... 

Because of the high thermal conductivity of copper (401 W/m-K), it is an excellent heat spreader. As defined in Chapter 3, the spreading angle (a) of two materials bonded together as shown in Figure 8.1 is... 

For a copper sheet direct-bonded to a 96% alumina substrate, the spreading angle is calculated as follows ... 

As the maximum spreading angle in any configuration is 90°, the spreading angle in this example can be considered extremely high. 

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