将下面两段话进行学术翻译：为了进一步对比变径提升管中颗粒密度对颗粒浓度变化的影响图5展示了FCC和玻璃珠颗粒浓度标准差在颗粒循环通量为14kgm2 · s时随表观风速的变化情况。随风速的增加两种颗粒的浓度标准差均降低这在之前文献中的结论一致。风速增加时扩径管内颗粒浓度降低气相主导下的流动使得颗粒分布趋于稳定。而且沿轴向高度风速对浓度标准差的影响减弱暗示了气固流动在扩径段内的发展。同循环通量一样风速

To further compare the influence of particle density on particle concentration variation in a variable diameter riser, Figure 5 shows the standard deviation of FCC and glass bead particle concentration with respect to superficial gas velocity at a particle circulation flux of 14 kg/m2·s. With the increase of superficial gas velocity, the standard deviation of particle concentration of both types of particles decreases, which is consistent with previous literature. The decrease in particle concentration in the expanding section with increasing gas velocity leads to a more stable particle distribution under gas-phase dominated flow. Additionally, the influence of superficial gas velocity on standard deviation of particle concentration weakens along the axial direction, indicating the development of gas-solid flow in the expanding section. Similar to the circulation flux, the impact of superficial gas velocity on standard deviation of particle concentration in the wall area of the expanding section is greater than that in the central and transition zones, demonstrating that the sensitivity of particle concentration variation in the wall area of the expanding section to operating parameters is higher. In Figure a, the standard deviation of FCC particle concentration at low superficial gas velocity shows a decreasing-then-increasing trend along the radial position, which is most obvious at the bottom of the expanding section. This indicates that under the current operating conditions, the flow of particles in the central area becomes unstable in all axial directions. In the transition zone, the standard deviation reaches the minimum value, indicating that the gas-solid fluctuation is the lowest in this area, and the flow process tends to be stable. From Figure b, it can be observed that the fluctuation of glass bead particle concentration increases overall from the center to the wall as the radial position moves. At the H3 position, the standard deviation of radial position does not vary much at various superficial gas velocities, indicating that the distribution of particle concentration in the top of the expanding section changes very little with the development of flow. Finally, comparing the radial distribution of particle concentration standard deviation of the two materials, it can be found that except for a few points, the value of particle concentration standard deviation at the same superficial gas velocity decreases with the increase of material density. This may be because the glass beads with larger density experience less gas drag at the same superficial gas velocity, leading to a weaker movement intensity and a decrease in the fluctuation degree of particle concentration.