離心泵平衡孔泄漏量對軸向力特性影響的研究
發(fā)布時間：2018-09-07 12:11
【摘要】：開平衡孔雙密封環(huán)葉輪具有平衡大部分軸向力的特性,目前仍普遍應(yīng)用在離心泵中。平衡孔液體的泄漏量對這種葉輪平衡軸向力的能力有著決定性的作用,這不僅影響離心泵的容積效率、輪阻損失和泵腔內(nèi)的液體壓力分布,而且對軸向力的計算都有較大的影響,因此研究平衡孔液體的泄漏量的測量及計算方法就顯得格外必要。本文設(shè)計了通過調(diào)節(jié)平衡腔液體壓力來測量平衡孔液體泄漏量的試驗裝置,利用試驗測量和數(shù)值分析的方法,測試不同平衡孔孔徑的試驗泵的平衡孔液體泄漏量、泵性能、泵腔和平衡腔液體壓力,深入研究了平衡孔液體泄漏量及泄漏量系數(shù)的特性及其對泵性能、泵腔壓力分布以及平衡腔區(qū)域軸向力影響規(guī)律。本文主要研究內(nèi)容如下:1.針對平衡孔孔徑對泵性能影響的問題,以IS80-50-315型離心泵為研究對象,通過設(shè)計的平衡孔套可以實現(xiàn)在同一個葉輪上改變平衡孔孔徑,在不同平衡孔孔徑條件下,測量了不同運行工況的試驗泵的流量,進口壓力、出口壓力、轉(zhuǎn)速和輸入功率,得到了不同平衡孔孔徑和運行工況下試驗泵的性能曲線,試驗結(jié)果表明,不同孔徑的平衡孔條件下,試驗泵的性能曲線變化規(guī)律都相似,且增大平衡孔孔徑會影響泵的性能,使其揚程減小,輸入功率增大,效率降低,在平衡孔的孔徑小于6 mm時,改變平衡孔孔徑對離心泵性能影響較小,當(dāng)平衡孔的孔徑大于6 mm時,改變平衡孔孔徑對泵性能影響較大。在相同泵揚程下,泵進口液體壓力最大差值僅為2.12 kPa,說明平衡孔孔徑對泵進口液體壓力影響很小。2.針對測量平衡孔實際泄漏量的難題,設(shè)計了通過調(diào)節(jié)平衡腔液體壓力來測量平衡孔液體泄漏量裝置,測量了在不同運行流量條件下,不同平衡孔孔徑的泄漏量,得到了對應(yīng)的平衡孔泄漏量系數(shù),并引入無量綱的比面積和揚程系數(shù)。試驗結(jié)果表明,平衡孔液體的泄漏量及泄漏量系數(shù)與比面積的關(guān)系曲線變化具有明顯的規(guī)律性,平衡孔孔徑和比面積增加,平衡孔液體的泄漏量隨之增加,其流量系數(shù)隨之減小;在相同比面積條件下,離心泵的揚程系數(shù)越大,通過平衡孔的液體的泄漏量越大,而平衡孔泄漏量系數(shù)越小。分析得到的不同揚程系數(shù)下,平衡孔流量系數(shù)與比面積的關(guān)系曲線為計算相似泵的平衡孔泄漏量提供了新的方式。3.試驗測量了試驗泵在不同工況下平衡腔的液體壓力,得到了不同工況下平衡腔區(qū)域的軸向力以及軸向力系數(shù)。試驗結(jié)果表明,在相同平衡孔孔徑條件下,平衡腔區(qū)域的軸向力隨離心泵揚程增加而增加;在相同的揚程條件下,平衡孔孔徑增大,平衡腔區(qū)域軸向力明顯降低,但平衡腔區(qū)域軸向力的降幅收窄。平衡腔區(qū)域的軸向力系數(shù)與比面積的關(guān)系曲線是非線性曲線,在比面積小于2.5時,其軸向力系數(shù)隨比面積增大而迅速減小;比面積位于2.5至4.5之間時,軸向力系數(shù)曲線趨于平坦,比面積大于4.5時,軸向力系數(shù)曲線幾乎平行于橫坐標(biāo)。4.建立了試驗泵在不同平衡孔孔徑條件下的不同運行流量的45個計算模型,通過對試驗泵的全流道模型進行了數(shù)值計算,得到了試驗泵在不同工況下的平衡孔泄漏量和平衡腔軸向力的模擬值,以及平衡孔附近區(qū)域和平衡腔的液體速度和壓力分布,并與試驗結(jié)果進行了對比分析。分析得到,試驗泵在同一平衡孔孔徑的條件下,其平衡孔液體泄漏量的試驗值與模擬值都隨泵運行流量的增加而逐漸減小;同一運行流量的條件下,隨著葉輪平衡孔孔徑增大,平衡腔軸向力逐漸減小;平衡孔的存在使平衡腔壓力相較于無平衡孔時有數(shù)量級的降低,但平衡孔的使用使葉片進口處壓力分布變得混亂,葉片背面低壓區(qū)增大,且平衡孔孔徑越小,通過平衡孔液體的流動速度越大。
[Abstract]:The double-ring impeller with balanced holes has the characteristic of balancing most of the axial forces, and is still widely used in centrifugal pumps. The leakage of the balanced holes plays a decisive role in the ability of the impeller to balance the axial forces, which not only affects the volumetric efficiency of the centrifugal pump, the loss of wheel resistance and the distribution of liquid pressure in the pump chamber, but also affects the axial direction. It is necessary to study the measurement and calculation method of the liquid leakage in the balance hole because the calculation of force has great influence. In this paper, a test device is designed to measure the liquid leakage in the balance hole by adjusting the liquid pressure in the balance cavity. The test pump with different balance aperture is tested by means of experimental measurement and numerical analysis. The characteristics of the liquid leakage rate and leakage coefficient of the balanced orifice and their effects on the pump performance, the pressure distribution in the pump cavity and the axial force in the balanced chamber area are studied in detail. Taking IS80-50-315 centrifugal pump as the research object, the balance aperture can be changed on the same impeller by designing the balance aperture sleeve. Under the condition of different balance aperture, the flow rate, inlet pressure, outlet pressure, rotational speed and input power of the test pump under different operation conditions are measured. The different balance aperture and operation worker are obtained. The experimental results show that the performance curves of the test pump are similar under the condition of balanced holes with different apertures, and the performance of the pump will be affected by the increase of balanced aperture, the head will be reduced, the input power will be increased, and the efficiency will be reduced. When the aperture of the balanced aperture is less than 6 mm, the change of the balance aperture will affect the performance of the centrifugal pump. When the hole diameter of the balance hole is larger than 6 mm, the change of the balance hole diameter has a great influence on the pump performance. At the same pump head, the maximum difference of the liquid pressure at the pump inlet is only 2.12 kPa, indicating that the balance hole diameter has little influence on the pump inlet liquid pressure. 2. Aiming at the difficult problem of measuring the actual leakage of the balance hole, the adjustment level is designed. The device for measuring the liquid leakage of the balance hole by the pressure of the liquid in the balance chamber is used to measure the leakage of the balance hole. The leakage coefficient of the balance hole is obtained by measuring the leakage of the liquid in the balance hole with different balanced aperture under different operating flow conditions. The relationship curve has obvious regularity, the balance hole diameter and specific area increase, the balance hole liquid leakage increases, its flow coefficient decreases; under the same area condition, the centrifugal pump head coefficient is bigger, the liquid leakage through the balance hole is bigger, and the balance hole leakage coefficient is smaller. The relationship between the balance hole flow coefficient and specific area provides a new way to calculate the balance hole leakage of similar pumps under different lift coefficients. Under the same balancing aperture, the axial force in the balancing chamber increases with the increase of the head of the centrifugal pump; under the same head condition, the axial force in the balancing chamber decreases obviously with the increase of the balancing aperture, but the decrease amplitude of the axial force in the balancing chamber area narrows. When the specific area is less than 2.5, the axial force coefficient decreases rapidly with the increase of specific area; when the specific area is between 2.5 and 4.5, the curve of axial force coefficient tends to be flat; when the specific area is larger than 4.5, the curve of axial force coefficient is almost parallel to abscissa. 4. A set of 45 meters of test pump under different balanced aperture conditions are established. Computational model, through the numerical calculation of the full-channel model of the test pump, the simulation values of the balance hole leakage and the axial force of the balance chamber under different working conditions, the liquid velocity and pressure distribution near the balance hole and the balance chamber are obtained, and compared with the experimental results. Under the condition of balanced aperture, the experimental and simulated values of liquid leakage in balanced aperture decrease with the increase of pump operating flow rate; under the condition of the same operating flow rate, the axial force of balanced chamber decreases with the increase of balanced aperture of impeller; the existence of balanced aperture makes the pressure of balanced chamber have an order of magnitude compared with that without balanced aperture. However, the pressure distribution at the inlet of the blade becomes confused and the low pressure area on the back of the blade increases with the use of the balancing orifice. The smaller the balancing orifice, the greater the liquid flow velocity through the balancing orifice.
【學(xué)位授予單位】：蘭州理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TH311
本文編號：2228228
[Abstract]:The double-ring impeller with balanced holes has the characteristic of balancing most of the axial forces, and is still widely used in centrifugal pumps. The leakage of the balanced holes plays a decisive role in the ability of the impeller to balance the axial forces, which not only affects the volumetric efficiency of the centrifugal pump, the loss of wheel resistance and the distribution of liquid pressure in the pump chamber, but also affects the axial direction. It is necessary to study the measurement and calculation method of the liquid leakage in the balance hole because the calculation of force has great influence. In this paper, a test device is designed to measure the liquid leakage in the balance hole by adjusting the liquid pressure in the balance cavity. The test pump with different balance aperture is tested by means of experimental measurement and numerical analysis. The characteristics of the liquid leakage rate and leakage coefficient of the balanced orifice and their effects on the pump performance, the pressure distribution in the pump cavity and the axial force in the balanced chamber area are studied in detail. Taking IS80-50-315 centrifugal pump as the research object, the balance aperture can be changed on the same impeller by designing the balance aperture sleeve. Under the condition of different balance aperture, the flow rate, inlet pressure, outlet pressure, rotational speed and input power of the test pump under different operation conditions are measured. The different balance aperture and operation worker are obtained. The experimental results show that the performance curves of the test pump are similar under the condition of balanced holes with different apertures, and the performance of the pump will be affected by the increase of balanced aperture, the head will be reduced, the input power will be increased, and the efficiency will be reduced. When the aperture of the balanced aperture is less than 6 mm, the change of the balance aperture will affect the performance of the centrifugal pump. When the hole diameter of the balance hole is larger than 6 mm, the change of the balance hole diameter has a great influence on the pump performance. At the same pump head, the maximum difference of the liquid pressure at the pump inlet is only 2.12 kPa, indicating that the balance hole diameter has little influence on the pump inlet liquid pressure. 2. Aiming at the difficult problem of measuring the actual leakage of the balance hole, the adjustment level is designed. The device for measuring the liquid leakage of the balance hole by the pressure of the liquid in the balance chamber is used to measure the leakage of the balance hole. The leakage coefficient of the balance hole is obtained by measuring the leakage of the liquid in the balance hole with different balanced aperture under different operating flow conditions. The relationship curve has obvious regularity, the balance hole diameter and specific area increase, the balance hole liquid leakage increases, its flow coefficient decreases; under the same area condition, the centrifugal pump head coefficient is bigger, the liquid leakage through the balance hole is bigger, and the balance hole leakage coefficient is smaller. The relationship between the balance hole flow coefficient and specific area provides a new way to calculate the balance hole leakage of similar pumps under different lift coefficients. Under the same balancing aperture, the axial force in the balancing chamber increases with the increase of the head of the centrifugal pump; under the same head condition, the axial force in the balancing chamber decreases obviously with the increase of the balancing aperture, but the decrease amplitude of the axial force in the balancing chamber area narrows. When the specific area is less than 2.5, the axial force coefficient decreases rapidly with the increase of specific area; when the specific area is between 2.5 and 4.5, the curve of axial force coefficient tends to be flat; when the specific area is larger than 4.5, the curve of axial force coefficient is almost parallel to abscissa. 4. A set of 45 meters of test pump under different balanced aperture conditions are established. Computational model, through the numerical calculation of the full-channel model of the test pump, the simulation values of the balance hole leakage and the axial force of the balance chamber under different working conditions, the liquid velocity and pressure distribution near the balance hole and the balance chamber are obtained, and compared with the experimental results. Under the condition of balanced aperture, the experimental and simulated values of liquid leakage in balanced aperture decrease with the increase of pump operating flow rate; under the condition of the same operating flow rate, the axial force of balanced chamber decreases with the increase of balanced aperture of impeller; the existence of balanced aperture makes the pressure of balanced chamber have an order of magnitude compared with that without balanced aperture. However, the pressure distribution at the inlet of the blade becomes confused and the low pressure area on the back of the blade increases with the use of the balancing orifice. The smaller the balancing orifice, the greater the liquid flow velocity through the balancing orifice.
【學(xué)位授予單位】：蘭州理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TH311
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，本文編號：2228228
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