Technical report describing that voids were measured in a ½-inch by 1-3/4-inch channel with the S-1 insert (B(0)/B(1) = 0.4, L(0) = 0.1 inch), at 2 inches ahead of the insert (position A), ½-inch past the insert (position B), 5 inches past (position C), and 12 inches past (position D). The conditions were: P – 1000 psia, G = 1.00 x 10(6) lb/h-ft(2), and x = 18.8 percent. Average void and void distribution at position A are the same as for flow in a straight channel. Void distribution at position B shows that the stagnation region downstream of the inserts contains a high fraction of voids. Average void and void distribution at positions C and d show that the two-phase mixture becomes strongly mixed (homogenized) as a result of passing through he contraction-expansion inserts. Distribution at position D approaches the distribution at position A; i.e., the straight channel distribution.

Technical report describing that the pressure drop along an annular channel with dimensions D(1) = 0.375 inch; D(2) = 0.875 inch, L = 70 inches. Flow was vertical and upward, and only the internal surface was heated. Subcooled conditions existed at the inlet, with two-phase conditions at the exit. Groups of three radial spacer pins on 18-inch centers along the channel, held the inner surface concentric with the outer surface. The single phase loss coefficient for each spacer group is K(8) = 0.21. The single phase friction factor for the annual channel is given by f = 0.16 N(R)(-0.16). The two phase pressure drop increases as the quality increases for G [over] 10(6) = 0.5 ;b/hr ft(2). The effect of heat flux on the pressure drop is very is very slight over the range of fluxes tested (0.55 less than or equal to Q over 10(6).\ less than or equal to 0.8). The two-phase pressure drop gradient in the same annulus, with no heat addition is qualitatively the same as for a 1/4-inch by 1-3/4 inches rectangular channel but is quantitatively greater than for the rectangular channel.