Study On The Flow Resistance Characteristic Of Key Parts In Ventilation Network Of The Underground Cavern Group Of Hydropower Station

Since the end of last century, the construction of hydropower stations has beenbooming in China. Three Gorges hydropower station, Xiaowan hydropower station,Longtan hydropower station and Shuibuya hydropower station built in China, as well asBaihetan hydropower station in the constraction are the first in the world in differentaspects. In recent years, the construction of underground hydropower station isparticularly prominent. In spite of this, thermal and humid environment control theoriesand technology applications in the plants of hydropower station are relatively lag, andhvac system design methods of giant underground hydropower station have manylimitations. The values of airflow movement characteristics and resistancecharacteristics in the key channels are not accurate, causing that the equipmentselections don’t match with the actual demands, which is one of hvac technicallimitations in the underground hydropower station. As an important part of thehydropower station construction, plant ventilation directly affects thermal environmentand air distribution of cavities. Therefore, it is necessary for us to study the parametersof air flow resistance characteristics in the key channels. In this way can we select theequipment types accurately and avoid thermal and humid environment imbalance andenergy dissipation. This paper is one of the study content about the National NaturalScience Foundation surface project (51178482)"deep underground hydropower stationthermal environment formation mechanism and energy regulation".In this paper, takes BHT hydropower station for example and finds out keychannels of the underground cavern group by analyzing the process of ventilationnetwork system of underground cavern group. Key channels include the air inletchannel, the exhaust channel, clip wall air channel (embedded duct), main voltageswitchyard room and main electrical wire hall. And then an experiment was conductedon nine key parts of the air inlet channel of BHT hydropower station through the similarmodel test method. From the experiment, gets the local resistance coefficients ofcomponent forms such as elbow, tee and stone(two in and two out), and obtains thechange of local resistance coefficients in various forms. Besides, the fitting relationshipbetween the local resistance coefficients of several tees or stone and flow ratioQ2:Q3(Stone flow ratio is Q3:Q4) is acquired. Studies the flow characteristics of some key channel in model test research by themethod of CFD numerical simulation in this paper. Verifies the method of CFDnumerical simulation feasible and reliable to study ventilation air flow characteristics ofthe key parts of hydropower station underground cavern group through the comparativeanalysis is between the simulation results and the experimental results. And then adoptsthe method of CFD numerical simulation to study characteristics of flow resistance forother types of key parts.①Obtains local resistance coefficients of two elbows in clipwall duct (embedded duct) with several typical sizes by the method of CFD numericalsimulation and analyzes the pressure distribution and velocity distribution in theembedded duct.②Due to the lack of time, only studies single main voltage switchyardroom of BHT hydropower station by the method of CFD numerical simulation. Andgets the equation between its impedance value S and the outlet area A2. It provides thereference value for the design of the similar single main voltage switchyard roomventilation system of other underground hydropower stations.③Simulates theventilation flow resistance characteristics of main electrical wire hall of BHThydropower station using CFD method, finds out the main parts of air flow resistancegenerated, and analyzes the reason that impedance value S is small and can be ignored.By the simulation for main electrical wire hall of XW hydropower station, concludesthe change rule of impedance value S with different outlet areas of A2, and fits out theequation. With the main electrical wire hall exhaust system of JP hydropower station asan example, studies that dynamic pressure loss of the draught fan in the location of theair outlet influences on the main electrical wire hall resistance. Finally, it is concludedthat when we calculate the ventilation resistance of monolayer main electrical wire hallwithout fire tuyere under unheated condition, we can ignore the resistance of air flowingthrough the internal device segment completely in main electrical wire hall andcalculate air flow resistance in the exhaust channel using the calculation method of airduct. And the reduction methods of resistance loss of main electrical wire hall are putforward.