The effect of the rib angle orientation on local heat transfer distributions and pressure drop in a square channel with two opposite in-line ribbed walls was investigated for Reynolds numbers from 15,000 to 90,000. composed ten isolated copper sections has length-to-hydraulic diameter ratio 20; height-to-hydraulic is 0.0625; pitch-to-height equals 10. Nine configurations were studied: 90 deg rib, 60 45 parallel ribs, crossed ∨-shaped ∧-shaped ribs. results show that (or deg) performs better...

An experimental study of fully developed turbulent air flow in square ducts with two opposite rib-roughened walls was performed to determine the effects rib pitch-to-height and height-to-equivalent diameter ratios on friction factor heat transfer coefficients Reynolds number varied between 7000 90,000. Based four-sided, smooth-duct correlation ribbed-duct similarity law, a general prediction method for average Stanton rectangular smooth ribbed developed. There good agreement measurements....

The effect of the channel aspect ratio on distribution local heat transfer coefficient in rectangular channels with two opposite ribbed walls (to simulate turbine airfoil cooling passages) was determined for a Reynolds number range 10,000 to 60,000. width-to-height ratios (W/H, ribs side W) were 1/4, 1/2, 1, 2, and 4. test heated by passing current through thin, stainless steel foils instrumented thermocouples. coefficients wall smooth each from entrance fully developed regions measured rib...

Repeated rib roughness elements have been used in advanced turbine cooling designs to enhance the internal heat transfer. Often ribs are perpendicular main flow direction so that they an angle of attack 90 deg. The objective this investigation was determine effect on pressure drop and average transfer coefficients fully developed turbulent air a square duct with two opposite rib-roughened walls for Reynolds number varied from 7000 90,000. height-to-equivalent diameter ratio (e/D) kept at...

Evaporation and boiling heat transfer coefficients are presented for thin, distilled water films flowing over the outside of horizontal, electrically heated brass tubes. Tests were conducted with a thin-slot distribution system 2.54- 5.08-cm-dia smooth Both local average data obtained nonboiling conditions corresponding to feedwater temperatures ranging from 49 127°C heat-flux values 30 80 kW/m2. Feed-water flow rates ranged 0.135 0.366 kg/s per meter length side tube. correlations developed...

The effect of compound turbulators on friction factors and heat transfer coefficients in rectangular channels with two opposite ribbed-grooved walls was determined for a Reynolds number range 10,000 to 50,000. channel width-to-height ratio 10. fully developed the smooth side each test were measured six rib-groove spacings (p/e = 8, 10, 15, 20, 25, 30). similar aspect ribbed rib 8.5 11.5) also comparison. results show that performance roughened duct is much better than duct. wall enhances 3.4...

The influence of uneven wall temperature on the local heat transfer coefficient in a rotating, two-pass, square channel with smooth walls is investigated for rotation numbers from 0.0352 to 0.352 by varying Reynolds 25,000 2500. two-pass channel, composed 12 isolated copper sections, has length-to-hydraulic diameter ratio 12. mean rotating radius hydraulic kept at constant value 30. Three cases thermal boundary conditions are studied: (A) four same temperature, (B) flux, and (C) trailing...

The detailed mass transfer distributions around the sharp 180 deg turns in a two-pass, square, smooth channel and an identical with two rib-roughened opposite walls were determined via napthalene sublimation technique. top, bottom, inner (divider), outer of test napthalene-coated surfaces. For ribbed tests, transverse, brass ribs attached to top bottom alignment. rib height-to-hydraulic diameter ratios (e/D) 0.063 0.094; pitch-to-height (P/e) 10 20. Experiments conducted for three Reynolds...

The spoke-type interior permanent magnet synchronous motor (STIPMSM) is used in the drive systems of electric heavy-duty truck. motors are prone to overload operation when truck climbs a slope or operates under heavy load. reliability challenge. sustained capacity an important index STIPMSM performance. An improved multi-objective nonlinear coupled iterative calculation method for proposed, which can accurately calculate performance changes different conditions. nonlinearity magnetic circuit...

This paper presents detailed film effectiveness distributions over a flat surface with one row of injection holes inclined streamwise at 35 deg for three blowing ratios (M = 0.5, 1.0, 2.0). Three compound angles 0, 45, and 90 air (D.R. 0.98) CO2 (D. R. 1.46) as coolants are tested an elevated free-stream turbulence condition (Tu ≈ 8.5 percent). A transient liquid crystal technique is used to measure local heat transfer coefficients effectiveness. Detailed results presented near around holes....

This paper presents experimental heat transfer results in a two-pass square channel with smooth and ribbed surfaces. The ribs are placed staggered half-V fashion the rotation orthogonal to axis. orientation varies respect plane. A change about rotating frame causes secondary flow structure associated turbulence distribution. Consequently, coefficient from individual surfaces of changes. effects number on local Nusselt ratio distributions presented. Heat coefficients show different...

Experiments study the turbulent heat transfer and friction for fully developed flow of air in a square channel with discrete rib turbulators. The ribs are staggered on two opposite walls alternate rows three ribs. Nine configurations examined: transverse an angle attack (α) 90 deg, α = parallel arrays 45 deg −45 rows, crossed 60, 45, 30 deg. height-to-hydraulic diameter ratio pitch-to-height 0.0625 10, respectively. Reynolds number ranges from 10,000 to 80,000. Results show that average...

The effect of wall heat flux ratio on the local transfer augmentation in a square channel with two opposite in-line ribbed walls was investigated for Reynolds numbers from 15,000 to 80,000. composed ten isolated copper sections has length-to-hydraulic diameter (L/D) 20. rib height-to-hydraulic (e/D) is 0.0625 and pitch-to-height (P/e) equals 10. Six side smooth ratios (Case 1—q″r1/q″s = q″r2/q″s 1; Case 2—q″r1/q″s 3; 3—q″r1/q″s 6; 4—q″r1/q″s 6 4; 5—q″r1/q″s ∞; 6—q″r1/q″s ∞ 0) were studied...

The effect of unsteady wake flow and air (D.R. = 0.97) or CO2 1.48) film injection on blade effectiveness heat transfer distributions was experimentally determined. A spoked wheel type generator produced the wake. Experiments were performed a five-airfoil linear cascade in low-speed wind tunnel at chord Reynolds number 3 × 105 for no case Strouhal numbers 0.1 0.3. model turbine with several rows holes its leading edge, pressure suction surfaces ( −0.2<X/C< 0.4) used. Results show that...

The heat transfer characteristics of turbulent air flow in a two-pass channel were studied via the naphthalene sublimation technique. test section, which consisted two straight, square channels joined by sharp 180 deg turn, resembled internal cooling passages gas turbine airfoils. top and bottom surfaces roughened rib turbulators. height-to-hydraulic diameter ratio (e/D) was 0.063 pitch-to-height (P/e) 10. local heat/mass coefficients on wall, smooth divider side walls channel, determined...

Experiments were conducted to study the effects of lateral flow ejection on overall heat transfer and pressure drops for turbulent through pin fin channels. The two test sections investigation rectangular channels with staggered arrays six eight streamwise rows pins, respectively. length-to-diameter ratio was one both spanwise spacings 2.5 times diameter. Heat friction data obtained various exit geometries, ratios between 0 1, Reynolds numbers 6000 60,000. results show that, any given ratio,...

Detailed heat transfer coefficient and film effectiveness distributions are presented on a cylindrical leading edge model using transient liquid crystal technique. Tests were done in low-speed wind tunnel crossflow with two rows of injection holes. Mainstream Reynolds number based the cylinder diameter was 100,900. The holes located at ±15 deg from stagnation. spaced four hole diameters apart angled 30 90 to surface spanwise streamwise directions, respectively. Heat only one side front half...