【Q&A Question 116】2016.08.14
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【Q&A Question 116】2016.08.14 How to change the characteristic curve of a pump? The answer key will be available after responding; scoring is based on answering the key points. 1. Change the rotational speed. 2. Change the impeller diameter.
First, increase the impeller size. Increase the number of impeller stages.
Change the pump’s speed or the diameter of the impeller
Change the rotation speed and water pump impeller diameter
Methods to modify the pump performance curve include variable speed control and cutting the outer circumference of the impeller. 1. Variable speed regulation: This involves using a variable rotation speed to alter the performance curve of the pump, thereby changing its operating point, while keeping the pipeline characteristic curve unchanged. When the speed changes, both the head and flow rate change; as the speed increases, both qv and H increase. Using this method to adjust the flow rate and head results in no additional energy losses, making it the most economical approach. However, new requirements were placed on the prime mover: it should be capable of adjusting its speed, such as steam engines or internal combustion engines, or a speed-changing device should be installed. Due to the high cost of such devices, they are rarely used in small and medium-sized pumps. 2. Cutting the outer circumference of the impeller: After the impeller is cut, its diameter decreases, which allows the qv-H curve of the pump to be altered; as a result, the operating point of the pump also changes. By using this method to regulate flow, a basic model of centrifugal pump can be equipped with impellers of several different diameters, which are selected as needed when the flow rate needs to be changed periodically. Using this method is more economical.
Change the number of stages of the pump, adjust the size of the impeller, change the opening degree of the pump’s outlet valve, and vary the diameter of the pipelines. If I don’t say too much, it seems like I’m on the wrong track
1. Reducing the diameter of the impeller can lower the head and flow rate； 2. Change the speed
1. Reducing the diameter of the impeller can lower the head and flow rate. 2. Changing the speed also works. 3. The minimum flow line can be activated to adjust the pump’s outlet flow rate.
①Speed adjustment； ②Adjustment of the outer diameter of the cutting impeller ； ③Adjustment of the angle of the upstream guide vane blades ； ④Adjustment of the end-clearance of semi-open impeller blades ； ⑤Adjustment of pump parallel and series connection.