Trailing edge

Since it was required by LM Glasfiber that the scanner should be able to inspect joints between the shells and the iimer beams on each side and also the joints between the shells on the leading and trailing edge of the rotor blades, the X-Unit module was designed with three different set-ups for the Y-modules, which perform the movement of the probes transverse the length of the blade. The three different set-ups of the Y-modules are ... 

Inspection of joints between the shells on the trailing edge. 

When the scanning of the adhesive bonded joint between the shells on the leading edge is complete, the rotor blade is rotated 180° and another special designed Y-module is applied for inspection of the trailing edge of the rotor blade in set-up 3, illustrated on figure 5. 

Fig. 5 Y-module positioned for set-up 3, for inspection of bonded areas on the trailing edge...

Most flow injection analyses use peak height as the analytical signal. When there is insufficient time for reagents to merge with the sample, the result is a split-peak, or doublet, due to reaction at the sample s leading and trailing edges. This experiment describes how the difference between the peak times can be used for quantitative work. 

Determine the duration of time between the leading (or trailing) edges of successive pulses. 

When the adsorption equihbrium is nonlinear, skewed peaks are obtained, even when N is large. For a constant separation-factor isotherm with R < 1 (favorable), the leading edge of the chromatographic peak is steeper than the trailing edge. Wmen R > 1 (unfavorable), the opposite is true. 

It should be noted that in a blade the highest temperatures are encountered at the trailing edge and the highest stress points at about J/3 the height from the base at the trailing edge. 

The temperature distributions for film and convection cooling design are shown in Fig. 29-32. From the coohng distribution diagram, the hottest section can be seen to be the trailing edge. The web, which is the most highly stressed blade pai t, is also the coolest part of the blade. 

Figure 4-138 is a plot of die number of impacts per unit area and time versus die fraction of padi lengdi for die mean section of inter-mediate-size particles. It can be seen dial some of die particles impact die blade surface at least once, and dial first impacts occur over die entire surface. The density of second impacts is significant over only a diird of die surface, and is prominent only near die trailing edge. The density of diird impacts is relatively insignificant compared to die first impact density. 

Fig ure 5-25. Rotor disk shown from the exhaust end. Blade trailing edges are coated with chromium carbide. 

Inspeetion during shutdown showed evidenee of blade erosion and pits loeated on the leading edge and the eoneave side of the trailing edge. For expanders operating at a eonstant speed, the veloeity diagram depends on the absolute speed of the mass earrier. The absolute speed, Cj, may be ealeulated from the nozzle formula ... 

When mass flow is on the inerease, an exeessive eoneentration of fine dust (smaller than 10 p), eould oeeur and eatalyst deposits may be deteeted. Beeause of the highly sophistieate dust-plugging meeh-anism, there has been no unanimous explanation for this malfunetion. However, field experienee indieates that eatalyst fines settle in lower veloeity areas sueh as stator paths, the trailing edges of rotor blades, and between the rotor disks after dust ingestion events. 

The stresses in the strut insert are higher than those in the shell, and the stresses on the pressure side of the shell are higher than those on the suction side. Considerably more creep strain takes place toward the trailing edge than the leading edge. The creep strain distribution at the hub section is unbalanced. This unbalance can be improved by a more uniform wall temperature distribution. 

The trailing edge of the strut develops the highest creep strain. This strain occurs despite the sharp stress relaxation at the trailing edge projection. The creep strain in the strut is well balanced. Transpiration cooling requires a material of porous mesh resistant to oxidation at a temperature of 1600°F (871.1 °C) or more. Otherwise, the superior creep properties of this design... 

This design has the highest creep life next to a transpiration-cooled design, and it has the best strain distribution between leading and trailing edges. It is the closest to optimum. 

Total pressure surveys were made downstream of the stators in both the radial and circumferential directions to determine the effect of coolant on stator losses. The wake traces for the stator with discrete holes and the stator with trailing edge slots show that there is a considerable difference in total... 

The primary cause of efficiency losses in an axial-flow turbine is the buildup of boundary layer on the blade and end walls. The losses associated with a boundary layer are viscous losses, mixing losses, and trailing edge losses. To calculate these losses, the growth of the boundary layer on a blade must be known so that the displacement thickness and momentum thickness can be computed. A typical distribution of the displacement and momentum thickness is shown in Figure 9-26. The profile loss from this type of bound-ary-layer build-up is due to a loss of stagnation pressure, which in turn is... 

Prust, H.W. Jr., Behning, F.P., and Bider, B., Cold-Air Investigation of a Turbine with Stator Blade Trailing Edge Coolant Ejection, II—Detailed Stator Perfoimance, NASA, TM X-1963, 1970. 

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