水輪機(jī)蝸殼的計(jì)算設(shè)計(jì)案例綜述對(duì)于大中型水輪機(jī)的蝸殼，混凝土蝸殼的選用范圍為最大水頭小于40米，鋼板焊接蝸殼的選用范圍為最大水頭大于40米。昌波水電站最大工作水頭為67.61米，選用金屬蝸殼。1.1斷面形狀及包角選擇為改善受力條件，金屬蝸殼的斷面形狀為圓形，且金屬蝸殼的包角一般采用345°REF_Ref17913\r\h[3]。1.2蝸殼尺寸設(shè)計(jì)（1）蝸殼進(jìn)口斷面平均流速由設(shè)計(jì)水頭，查得蝸殼進(jìn)口斷面平均流速，本水電站的設(shè)計(jì)水頭=68m，查得Vc=7m/s。（2）蝸殼座環(huán)尺寸水輪機(jī)轉(zhuǎn)輪直徑為6m，設(shè)計(jì)水頭68m,查《水力機(jī)械》表2-16，得導(dǎo)葉內(nèi)徑Db=8200mm,座環(huán)固定導(dǎo)葉外徑Da=9350mm。（3）蝸殼各斷面尺寸設(shè)計(jì)根據(jù)蝸殼任一斷面上的圓周速度vu斷面半徑：斷面中心距：斷面外半徑：式中φi——從蝸殼鼻端至斷面i的包角，°Qmax——水輪機(jī)最大引用流量，m3/sVcra根據(jù)ra=Da/2=4675mm，Qmax=267.90m3/s，Vc=7m/s，現(xiàn)從0~345°表SEQ表\*ARABIC2.1蝸殼尺寸計(jì)算斷面包角（°）流量（m3/s）斷面半徑m斷面中心距m斷面外半徑m00.0000.0004.6754.6751511.1630.7135.3886.1003021.3251.0085.6836.6914533.4881.2345.9097.1446044.6501.4256.1007.5267555.8131.5936.2687.8629066.9751.7466.4218.16610578.1381.8856.5608.44612089.3001.0166.6918.706135100.4631.1386.8138.951150111.6251.2546.9299.182165121.7881.3647.0399.402180133.9501.4697.1449.612195145.1131.5697.2449.814210156.2751.6667.34110.008225167.4381.7607.43510.195240178.6001.8517.52610.376255189.7631.9387.61310.552270200.9253.0237.69810.722285211.0883.1067.78110.888300223.2503.1877.86211.049315234.4133.2667.94111.206330245.5753.3438.01811.360345256.7383.4188.09311.510當(dāng)取Vc=7m/s時(shí)，蝸殼的進(jìn)水口斷面直徑較大，后續(xù)的進(jìn)水閥的選型時(shí)，無(wú)法選用合適的進(jìn)水閥；在咨詢老師后，建議將Vc表1.2蝸殼尺寸計(jì)算斷面包角流量斷面半徑斷面中心距斷面外半徑°m^3/smmm00.0000.0004.6754.6751511.1630.6285.3035.9323021.3250.8895.5646.4534533.4881.0895.7646.8526044.6501.2575.9327.1897555.8131.4056.0807.4869066.9751.5396.2147.75410578.1381.6636.3388.00112089.3001.7786.4538.230135100.4631.8856.5608.446150111.6251.9876.6628.650165121.7881.0846.7598.844180133.9501.1776.8529.029195145.1131.2666.9419.207210156.2751.3527.0279.378225167.4381.4347.1099.543240178.6001.5147.1899.703255189.7631.5917.2669.858270200.9251.6667.34110.008285211.0881.7407.41510.154300223.2501.8117.48610.296315234.4131.8807.55510.435330245.5751.948