29 Aug 2019
The article presents research which numerically simulates the unsteady water flow and silt-laden flow in a dredge pump and comparatively analyses the unsteady characteristics of the pump performance and the flow field in three typical conditions to expound the influence of sands and the relationship between head and flow field. Results show that high-concentration sands enhance the flow fluctuation and change the head curve slope at part-load conditions which is adverse to operation stability of the pump-pipe combined system.
In the condition of 0.5 times of the design flow rate, the uneven distributed sands induce rotating stall in the impeller and makes the dominant frequency of head fluctuation decrease from three times of rotational frequency to the rotational frequency. In the design condition, the dominant frequency of head fluctuation maintains at three times of rotational frequency, but the turbulence enhancement of sands enrich the frequency components. In the condition of 1.3 times of the design flow rate, sands exacerbate the complexity and random of the flow state near the downstream of the tongue and the diffused section of the volute casing, causing the dominant frequency of head fluctuation increase to 3.89 times of rotational frequency and there are more frequency components and larger amplitude. Therefore, in engineering, considering the safety and stability of the dredge pump system, an accurate performance curve should first be obtained and then the pump should be controlled to work in a reasonable range of flow rate.
DOWNLOAD THE ARTICLE
Read the article: