【Daily Question】June 26: Concept of the proportional law for centrifugal pumps (First 80 participants + 3–8 points extra for those who get 2 answers correct)
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This post was last edited by A Le on 2015-6-28 00:34. The Machinery Section has introduced the \"Question of the Day\" feature, which not only helps to foster an active atmosphere for technical discussions and guide their direction but also provides users with financial rewards, enabling them to experience various cool features. 【Daily Question】In practical applications of variable-frequency speed control, the proportional law may be used to estimate the performance of a centrifugal pump after frequency conversion. According to the proportional law of centrifugal pumps, when the impeller diameter remains constant, its flow rate is proportional to the （） of the rotational speed; its head is proportional to the （） of the rotational speed; and its shaft power is proportional to the （） of the rotational speed. A. First power B. Second power C. Third power D. Fourth power Answer: A, B, C Requirements and hints for answering the question: Reply with the answers you think are correct; if you provide a detailed explanation or analysis of the question and answers, you will receive an additional reward. Extra rewards will be given if your answers are correct and your explanations are accurate and thorough. Feel free to answer the questions. Please note: We will close this post after 24 hours, and at that time we will announce the best reply (the best assistance), as well as the answer and explanation. Do not submit answers repeatedly. As a reward for your effort, if you post a topic in this section within two days that provides a detailed explanation of the knowledge points covered by this question, please reply or leave a comment in this post to let us know; we will then have a moderator award you + Charm. It is not allowed to simply copy and paste; original content is preferred, with at least some organization by the user along with personal insights. After registration, we will rank participants based on the content of their posts: the last-place contestant will receive +1 charm, the second-to-last +2 charm, and so on, with the highest score earning +5 charm. Other content: Call for weekly topics and daily questions (prizes for participation) [Mechanical Section] Collection of essential knowledge [Seeking manufacturer sponsors] (long-term campaign) [Rewards for recommending valuable content] Summary of daily questions and answers related to mechanical equipment for 2015
In practical use of variable-frequency speed control, the proportional law may be employed to estimate the performance of a centrifugal pump after frequency conversion. According to the proportional laws of centrifugal pumps, when the impeller diameter remains constant, its flow rate is proportional to the speed raised to the power of (A); its head is proportional to the speed raised to the power of (B); and its shaft power is proportional to the speed raised to the power of (C). A. First power B. Second power C. Third power D. Fourth power
In practical use of variable-frequency speed control, the proportional law may be employed to estimate the performance of a centrifugal pump after frequency conversion. According to the proportional law of centrifugal pumps, when the impeller diameter remains constant, its flow rate is proportional to the speed raised to the power of (A); its head is proportional to the speed raised to the power of (B); and its shaft power is proportional to the speed raised to the power of (C). A. First power B. Second power C. Third power D. Fourth power
In practical use of variable-frequency speed control, the proportional law may be employed to estimate the performance of a centrifugal pump after frequency conversion. According to the proportional laws of centrifugal pumps, when the impeller diameter remains constant, its flow rate is proportional to the speed raised to the power of (A. 1), its head is proportional to the speed raised to the power of (B. 2), and its shaft power is proportional to the speed raised to the power of (C. 3). For the same pump, when the impeller diameter remains constant, changing the rotational speed results in a direct proportional relationship with flow rate, while there is a direct proportional relationship between the square of the rotational speed and head. The cube of the rotational speed is directly proportional to the shaft power. That is: Q1/Q2=n1/n2 ； H1/H2=(n1/n2)^2 ； P1/p2=(n1/n2)^3 Where: Q1, H1, Pa1 represent the flow rate, head, and shaft power at a rotational speed of n1 ； Q2, H2, Pa2 —— represent the flow rate, head, and shaft power at a rotational speed of n2.
In practical use of variable-frequency speed control, the proportional law may be employed to estimate the performance of a centrifugal pump after frequency conversion. According to the proportional law of centrifugal pumps, when the impeller diameter remains constant, its flow rate is proportional to the ( ) of the rotational speed; its head is proportional to the ( ) of the rotational speed; and its shaft power is proportional to the (B) of the rotational speed. A. First power B. Second power C. Third power D. Fourth power
Its flow rate is proportional to the speed raised to the power of (A. 1), its head is proportional to the speed raised to the power of (B. 2), and its shaft power is proportional to the speed raised to the power of (C. 3).
ABC flow is proportional to, head is proportional to the square of, and power is proportional to the cube of
In practical use of variable-frequency speed control, the proportional law may be employed to estimate the performance of a centrifugal pump after frequency conversion. According to the proportional laws of centrifugal pumps, when the impeller diameter remains constant, its flow rate is directly proportional to the speed raised to the power of (A); its head is directly proportional to the speed raised to the power of (B); and its shaft power is directly proportional to the speed raised to the power of (C). A. First power B. Second power C. Third power D. Fourth power
When the impeller diameter remains constant, its flow rate is proportional to the cube of the rotational speed; I choose C