Experimental Study on the Distribution Trends of Fouling on a Compressor Blade

The formation of a scale on a compressor blade surface is inevitable, and the study of the distribution of the scale can provide effective guidance for the cleaning of a wing engine. Using the waste liquid collected from the engine during the wing water washing process as a data sample, the main components of compressor blade surface fouling were analysed, which included 49.9% SiO2, 14.5% FeO, 11.5% Al2O3, 9.4% CaO, etc. Based on JKR contact theory, a model for calculating the total thickness of the fouling layer on the blade surface was established. Through a simulation experiment on the fouling of a blade surface, the number of particulates deposited on the pressure surface was lower than the amount of the secondary deposition mass on the suction surface. From contrastive analysis of the results of perforation, the fouling is divided into three types: loose, dense, and transitional. The surface of a single blade can be divided into four different fouling areas. The parameters of the engine cleaning process can be designed according to the characteristics of the fourth area.

Scale Invariance of Cell Size Fluctuations in Starving Bacteria

In stable environments, cell size fluctuations are thought to be governed by simple physical principles, as suggested by recent findings of scaling properties. Here, by developing a novel microfluidic device and using E. coli, we investigate the response of cell size fluctuations against starvation. By abruptly switching to non-nutritious medium, we find that the cell size distribution changes but satisfies scale invariance: the rescaled distribution is kept unchanged and determined by the growth condition before starvation. These findings are underpinned by a model based on cell growth and cell cycle. Further, we numerically determine the range of validity of the scale invariance over various characteristic times of the starvation process. Combining theory and simulations, we reveal the number of multifork replications is crucial for the scale invariance. Our results emphasize the importance of intrinsic cellular cycle processes in this problem, suggesting different distribution trends for bacteria and eukaryotes.