Regenerative blowers for higher pressure ratios

Up to now regenerative blowers are built and used only for low pressure ratios in the working range of pi = 1.10 to 1.30 despite of their high pressure coefficients. The small outer dimensions are their essential advantage compared to other flow machines but they are mostly used with low peripheral speed. The reachable stage pressure ratio can be increased by rising the peripheral speed but the expansion flow on the block has to be considered. With regard to the expansion flow on the block two pressure ranges on the block result. The undercritical and the supercritical range of the expansion flow on the block have to be taken into consideration when designing such machines. With a multistage realization of regenerative blowers higher pressure ratios up to pi > 2.0 are within reach.