An Experimental Study on the Elbow Pressure Drop and Conveying Stability of Pneumatic Conveying for Stiff Shotcrete Based on Response Surface Methodology

Abstract

The pressure drop and conveying stability caused by the bend significantly affect the pneumatic conveying process of stiff shotcrete, which is the key to solving the problem of long-distance transportation. In this paper, the effects of different air velocities (32 m/s, 36 m/s, 40 m/s), water-cement ratios (0.1, 0.2, and 0.3), and bending-diameter ratios (4, 12, and 20) on the pressure drop of the elbow R1 and conveying stability R2 are studied using the response surface method. The conveying stability is characterized by the pressure variation coefficient (C.V). The response surface graph aids in the intuitive analysis of the effects of these variables. The results show that the impact of air velocity on R1 and R2 is exceptionally significant, and the interaction of each factor on the response value is analyzed. The response value and the quadratic polynomial regression equation between the various factors are obtained in addition to the flow characteristics of stiff shotcrete under different working conditions. The relationship established by the statistical processing of the experimental results can provide some reference for specifying the pressure loss model of stiff shotcrete.

Optimal Design of a Closed Rectangular Aerostatic Guideway

“…The accuracy test of fitting equation is shown in Table 7. In engineering application, when the correlation coefficient R 2 of the model is greater than 0.95, the test error is small and the reliability is very high; The closer the correction fitting degree R 2 (Adj) and the prediction fitting degree R 2 (Pred), the Signal-to-Noise Ratio (Adeq Precision) greater than 4 can be considered a good fit [22]. The coefficient of variation CV is 0.8136% and 4.87% respectively, less than 10%, which indicates that the model has a good stability.…”