Modeling and analyzing parametric sensitivity of annular flow between car and hoistway of ultra-high-speed elevator

Abstract

The annular flow field between the car and the hoistway of an elevator is an important part of the piston effect. It is, thus, important to study the law of airflow in the annular space to reduce the piston effect. The study establishes a theoretical model of annular flow between the car and the hoistway of an ultra-high-speed elevator based on the semi-empirical theory of turbulence and the Bernoulli principle to obtain the law of distribution and the characteristic position of annular flow velocity. The correctness of the theoretical model was verified by comparing its calculations with the results of experimental measurements and numerical simulations. The effects of the speed of the car and its length as well as the blocking ratio and length of the hoistway on the distribution of annular flow velocity are analyzed, and the general law of influence of parametric changes on annular flow is summarized. The results show that the distribution of flow velocity in the annulus was positive, then became negative, and finally tended to zero with increasing distance from the wall. The characteristic velocity in the annular flow field was reliant on many factors, and its distribution was most significantly affected by the velocity of the car, followed by the blocking ratio and height of the hoistway.