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渣漿泵葉片入口角的選擇
對于抽送均質(zhì)液體的菜，葉片入口角，厚度和入口邊的位置，根據(jù)保證很高吸入能力的條件來選取，因此，對于最佳工作狀態(tài)，采用沖角09=3°~10°。
對于抽送磨蝕性固液混合物的泵，葉片入口角，葉片厚度和入口位置，根據(jù)最小可能的磨損量并考慮所抽送固液混合物的磨蝕特性，主要考慮固體顆粒的粒度來確定。
在選取入角時可以分為兩種情況:
(1)泵抽送細(xì)顆粒固液混合物，這時入口邊磨損強度很小，入口角選取的主要條件是保證所需的吸入能力。對于一般用途泵，下列推薦值是正確的，Pu=18°~25"
(2) 抽送砂礫固液混合物的泵，入口邊磨損強度很大，即其磨損量可以預(yù)側(cè)葉輪壽命，選取葉片入口角的主要準(zhǔn)則是保證磨損量最小。因此，入口邊磨損量隨著入口角的增大而減小，采用入口角要大于根據(jù)據(jù)提高泵汽蝕特性條件所要求的角度，一般采用葉片入口角βBn=30°~40。
六、葉片入口邊位置的確定
入口邊位置對葉片磨損以及對葉輪后蓋板磨損均有重要影響。
顯然，在抽送均質(zhì)液體的泵上，在入口段葉片很薄，入口邊位置在很小的半徑上(入口邊拉向葉輪入口)，可以改善吸入能力。但是，對于抽送磨蝕性固液混合物的泵，由于入口處葉片增厚，使液流排擠增強并且由于相當(dāng)寬的過流斷面，不可能使入口邊處在很小的半徑上。通常，入口邊與葉輪蓋板具有一定角度;同時，前蓋板側(cè)入口邊位置半徑大致等于或者略大于葉輪入口半徑。
根據(jù)中間流束，采用下列方法檢查葉片入口角Pur選擇的正確性:
(1)計算圓周速度u1= Rwn式中半徑R1根據(jù)所選擇的入口邊位置由圖上求得。
(2)在不考慮排擠的情況下，確定液流在葉片入口的軸面分速Cim.
(3)在不考慮排擠的情況下，繪制入口三角形(圖3-9-1）。
(4) 根據(jù)公式ψ=1- n/確定液流在入口處的排擠系數(shù)。式中，o.為半徑R圓周方向上葉片厚度; 01=a/simB.n;t1為葉片入口節(jié)距；t1=2rR/z.
由于抽送磨蝕性固液混合物泵葉輪葉片進(jìn)行加厚(并且在入口段，葉片不但不變薄，如抽送清水的泵那樣。而且在一些情況下甚至要加厚)，對于這些泵，排擠系數(shù)變小，大致為0.65-0.75.在確定排擠系數(shù)時，根據(jù)本章上述推薦值選取入口角并且對于不同，使用條件，這些角度是不同的。
葉片較厚部分的厚度(除了入口段和出口段以外)，可以根據(jù)關(guān)系式δ= (0.1~0.13) Dx確定(式中，Dbc為吸入短管半徑），根據(jù)現(xiàn)有泵結(jié)構(gòu)葉片厚度分析得到上述關(guān)系.渣漿泵廠家
Selection of blade inlet angle of slurry pump
For vegetables pumping homogeneous liquid, the inlet angle, thickness and position of the inlet edge of the blade shall be selected according to the conditions ensuring a high suction capacity. Therefore, for the best working condition, the impact angle is 09 = 3 ° ~ 10 °.
For the pump pumping the abrasive solid-liquid mixture, the blade inlet angle, blade thickness and inlet position are determined according to the minimum possible wear amount and considering the abrasive characteristics of the pumped solid-liquid mixture, mainly considering the particle size of the solid particles.
There are two situations when selecting the angle of entry:
(1) Pump pumping fine solid-liquid mixture, when the wear strength of the inlet side is very small, the main condition for the selection of the inlet angle is to ensure the required inhalation capacity. For general purpose pumps, the following recommended values are correct, Pu = 18 ° ~ 25“
(2) For pumps pumping gravel solid-liquid mixtures, the wear intensity at the inlet side is very high, that is, the wear amount can predict the life of the impeller. The main criterion for selecting the inlet angle of the blade is to ensure the minimum wear amount. Therefore, the wear of the inlet side decreases with the increase of the inlet angle. The inlet angle is larger than the angle required according to the condition of improving the cavitation characteristics of the pump. Generally, the blade inlet angle β BN = 30 ° ~ 40.
Vi. determination of the position of the blade inlet edge
The position of the inlet side has an important influence on the wear of the blade and the back cover plate of the impeller.
Obviously, in the pump pumping homogeneous liquid, the blade in the inlet section is very thin, and the position of the inlet side is on a very small radius (the inlet side pulls toward the impeller entrance), which can improve the inhalation capacity. However, for the pump pumping the abrasive solid-liquid mixture, because the inlet blades are thickened, the liquid flow extrusion is enhanced, and because of the quite wide flow passage section, it is impossible to make the inlet edge at a very small radius. Generally, the inlet side has a certain angle with the impeller cover plate; at the same time, the position radius of the inlet side of the front cover plate is approximately equal to or slightly greater than the impeller inlet radius.
According to the intermediate flow beam, the following methods are used to check the correctness of the selection of the blade inlet angle pur:
(1) calculate the circumferential velocity U1 = rwn where the radius R1 is obtained from the figure according to the selected entrance edge position.
(2) determine the axial velocity of liquid flow at the blade inlet, CIM, without considering extrusion.
(3) draw the entrance triangle without considering crowding (Figure 3-9-1).
(4) according to the formula ψ = 1-N / determine the liquid flow at the entrance of the extrusion coefficient. In the formula, O. is the blade thickness in the circumferential direction of radius R; 01 = A / simb. N; T1 is the blade inlet pitch; T1 = 2rr / Z.
Because the impeller blades of the pump are thickened (and in the inlet section, the blades are not only the same thin, as the pump pumping clean water). And in some cases, it even needs to be thickened). For these pumps, the extrusion coefficient becomes smaller, about 0.65-0.75. When determining the extrusion coefficient, select the inlet angle according to the above recommended values in this chapter and for different conditions of use, these angles are different.
The thickness of the thicker part of the blade (except for the inlet section and the outlet section) can be determined according to the relationship δ = (0.1 ~ 0.13) DX (where DBC is the radius of the suction short pipe). The above results can be obtained according to the thickness analysis of the existing pump structure blade.
