Experimental Study on the Efficiency of Multiple Nozzle Oil Jet Pump for Lubrication System of Steam Turbine

The efficiency of the multiple nozzle oil jet pump was systematically investigated using the Mobile DTE Light Oil based on the similarity theory in experiment. The experimental condition is the same as that for the multiple nozzle oil jet pump in lubrication system of steam turbine in the power plant. Thus, the influence of the area ratio and the pressure ratio on the efficiency and the pressure ratio interval of variable conditions with stable efficiency was studied in the area ratio range of 4∼9. Results show that there is a fixed relationship between the area ratio and the pressure ratio, which leads to the high efficiency of multiple nozzle oil jet pump. However, the high efficiency value and the pressure ratio interval of variable conditions with stable efficiency show different tendencies with the changing area ratio of multiple nozzle oil jet pump. In the area ratio range of 4∼9, the pressure ratio with the high efficiency value increases by 0.03 with the decrement of 1 for the area ratio. When the area ratio is larger than 6.3, the high efficiency value increases by 1% absolutely with the area ratio decreasing by 1, but remains almost unchanged for the area ratio less than 6.3. Furthermore, the increasing area ratio widens the pressure ratio interval of variable conditions with stable efficiency. The increase of the area ratio by 1 leads to the increment of 9.7% relatively for the pressure ratio interval of variable conditions with stable efficiency. This study provides the quantitative criteria for the determination of the area ratio and the pressure ratio of multiple nozzle oil jet pump, which keeps the high and stable efficiency simultaneously. Apparently, this study has significant engineering contribution.