JP3909179B2 - Suction pipe of water turbine or pump water turbine - Google Patents

Description

曲がり部で発生する損失ΔＨは、ΔＨ＝ζ×Ｖ²／２ｇで表される（Ｖは曲が り管入口の断面平均流速）。したがって、発生する損失の大小は、この表の全損失係数ζの大小に依存する。
【００１３】
さて、この表から最初にわかることは、どのような断面形状でも曲がりの半径比Ｒ／ａ（またはＲ／（ｂ／２））が大きくなる程、損失が小さくなることである。ただし、Ｒが大きくなると図７に示した吸出し管の深さ寸法Ｆが大きくなるため、吸出し管を埋設するための土木掘削量が増えるという欠点がある。なお、前述の図９の吸出し管の曲がり部５ｂの半径比Ｒ／ａは、ａ＝Ｄe／２なので２.０に相当する。
【００１４】
一方、曲がり管の断面形状の影響については、円形断面の曲がり管よりも正方形断面の曲がり管の方が損失が少なく、また、正方形断面の曲がり管よりもｈ／ｂ比が２の長方形断面の曲がり管の方が損失が少ないことがわかる。
【００１５】
以上の点を定量的に試算した結果を表２に示す。
【００１６】
【表２】

【００１７】
この試算では、３つの断面の曲がり管について、表１の値に基づき全損失係数ζを試算した。いずれの断面についても入口の断面積はπａ₀ ²とし、曲がり半径Ｒは円形断面の曲がり管の入口半径の２倍とした（すなわちＲ＝２×ａ₀）。そ の結果、円形断面のζは表１のＲ／ａ＝２からζ＝０.２４６と求められる。ま た、正方形断面は入口断面の面積をπａ₀ ²とすると一辺の長さは１.７７×ａ₀ ² （＝π^1/2ａ₀）となるので、
【数１】

となり、表１から損失係数を補間すると
【数２】

となる。この値は円形断面の曲がり管の損失係数より、約７％小さい値である。
【００１８】
損失係数が小さくなった場合の効果を定量的に述べると以下の様になる。すなわち、吸出し管入口の運動エネルギーの有効落差Ｈに対する割合を１５％とし、吸出し管入口から吸出し管上部において、その１／２が圧力エネルギーに変換され、曲がり部入口の運動エネルギーの有効落差に対する割合は７．５％とすると（すなわち、吸出し管上部で面積が１．４１倍大きくなり、流速が１／１．４１になり、運動エネルギーの有効落差に対する割合が、Ｖ²／（２ｇＨ）＝０．０ ７５となった）、円形断面の曲がり管の損失△Ｈは水車効率に対して、△Ｈ／Ｈ＝０．２４６×７．５％＝１．８５％の損失となる。一方、正方形断面の曲がり管は△Ｈ／Ｈ＝０．２２９×７．５％＝１．７２％の損失となり、正方形断面の曲がり管の方が、水車全体の効率では０．１３％向上することが期待できる。
【００１９】
一方、h／ｂ＝２の長方形の場合は、
【数３】

となり、表１から損失係数を補間すると
【数４】

となり、さらに損失係数が小さくなる。
【００２０】
この場合、水車効率に対しては、△Ｈ／Ｈ＝０．１６×７．５％＝１．２％の損失となり、円形の断面の曲がり管に場合より０．６５％も水車全体の効率が向上することが期待できる。
【００２１】
以上説明したように、（１）曲がり部の損失は曲がりの半径Ｒの影響を受け、損失低減の観点からは半径Ｒが大きい方が好ましいが、土木掘削量低減の観点からは半径Ｒが小さい方が好ましいこと、かつ（２）曲がり部入口の面積が一定の場合は、曲がり方向（縦方向）の断面の幅（＝前述のｂ）はなるべく小さくし、その分、それと直交する方向（横方向）の断面の幅を大きくすれば曲がり部で発生する損失を小さくできることがわかる。
【００２２】
本発明は、上記知見に基づき、水車又はポンプ水車の吸出し管の形状および構造を最適化するものであり、羽根車出口と放水路を連結するとともに、前記羽根車出口に接続された吸出し管上部と、前記吸出し管上部に接続されるととともに前記吸出し管内を通る流体の流れの方向を変化させる曲がり部とを有する水車又はポンプ水車の吸出し管において、前記吸出し管のある部位をその管路の軸線方向に垂直な面で切断して得られる断面をその部位における垂直方向断面と呼び、かつ、ある垂直方向断面を含む平面と前記曲がり部の軸線を含む平面とが交わる直線の方向をその垂直方向断面の縦方向、縦方向に直角な方向をその垂直方向断面の横方向と呼ぶこととした場合、前記吸出し管上部のうち少なくとも前記曲がり部との境界から上流側の所定の範囲における垂直方向断面の断面積が、前記羽根車出口からの距離が大きくなるに従って増加しており、かつ、前記所定の範囲における垂直方向断面の縦方向の幅の増加割合が横方向の幅の増加割合と比較して少なくなっていることを特徴としている。
【００２３】
本発明によれば、曲がり部の入口における断面の横方向の幅を縦方向の幅より大きくすることができ、吸出し管の深さの増大を抑えつつ吸出し管の損失を低減することができる。
【００２４】
前記吸出し管上部のうち前記所定の範囲の垂直方向断面の縦方向の幅は、前記羽根車出口からの距離に関わらず一定とすることができる。
【００２５】
前記吸出し管上部の前記羽根車出口側に、前記所定の範囲以外の領域が存在してもよく、この場合、前記所定の範囲以外の領域は、垂直方向断面の断面積が前記羽根車出口からの距離が大きくなるに従って増加しており、かつ、垂直方向断面の縦方向の幅の増加割合が横方向の幅の増加割合と等しい円錐台形状とすることができる。このようにすることにより、羽根車出口から流出する流体とのマッチングを良好にとることができる。
【００２６】
前記吸出し管上部と前記曲がり部との境界における垂直方向断面は、横方向を長軸とし縦方向を短軸とする楕円形とすることができる。また、前記吸出し管上部と前記曲がり部との境界における前記垂直方向断面は、横方向に延びる一対の直線と一対の半円とを組み合わせた輪郭を有する長円形状を有するように構成することもできる。なお、この場合、前記所定の範囲の最も上流側の部位における垂直方向断面を円形とすることができる。
【００２７】
また、前記吸出し管上部のうち前記所定の範囲の垂直方向断面の縦方向の幅は、前記羽根車出口からの距離に関わらず一定にすることができ、この場合、前記所定の範囲は、横方向に関して互いに対向する一対の側面を有し、この一対の側面は、断面が円形の直管を２分割した部材により形成することができる。このように構成することにより、吸出し管の製作を容易化することができる。
【００２８】
また、前記曲がり部の垂直方向断面の輪郭は、前記羽根車出口からの距離に関わらず、横方向に延びる一対の直線と一対の半円とを組み合わせた輪郭を有する長円形状を有するように構成することができ、かつ、前記曲がり部のうち前記一対の直線に対応する部位が縦方向に関して互いに対向する一対の第１の側面を構成しており、前記曲がり部のうち前記一対の半円に対応する部位が横方向に関して互いに対向する一対の第２の側面を構成し、前記一対の第１の側面同士の間隔は、前記羽根車出口からの距離に関わらず一定に構成することができる。このように構成することにより、土木掘削量を水平方向および垂直方向に関して適切にバランスさせることができる。
【００２９】
この場合、前記曲がり部の第２の側面は、円形断面を有する管をその軸線方向に沿って分割した部材から形成することができ、また、前記曲がり部の第１の側面は、平板を曲げ加工した部材により形成することができる。このように構成することにより、吸出し管の製造を容易化することができる。
【００３０】
また、前記曲がり部の前記垂直方向断面は、前記羽根車出口からの距離に関わらず横方向に延びる一対の直線と、前記一対の直線の両端をそれぞれ接続する一対の曲線とを組み合わせた輪郭を有し、かつ、前記曲がり部の前記垂直方向断面の横方向幅は縦方向幅より大きくなるように構成し、前記曲がり部のうち前記一対の直線に対応する部位が縦方向に関して互いに対向する一対の第１の側面を構成しており、前記曲がり部のうち前記一対の曲線に対応する部位が横方向に関して互いに対向する一対の第２の側面を構成するようにすることができる。
【００３１】
この場合、前記曲がり部の第２の側面は、円形断面を有する管をその軸線に交差する方向に沿って切断することにより得られた複数の部材を接合して形成することができ、また、前記曲がり部の第１の側面は、平板を複数の折り曲げ線に沿って折り曲げた部材により形成することができる。このように構成することにより、吸出し管の製造を容易化することができる。
【００３２】
また、この場合、前記一対の第１の側面間の距離は、前記羽根車出口からの距離に関わらず一定とすることができ、このように構成することにより、土木掘削量を水平方向および垂直方向に関して適切にバランスさせることができる。
【００３３】
なお、吸出し管の曲がり部の入口断面を正方形または矩形断面にすることは特開昭４２−３６４５号「水車又はポンプの吸出管」で示されているが、この提案の目的は製造コストの低減なので、曲がり部の損失低減は考慮されていない。前述した通り、曲がり部の入口断面を円形断面から正方形断面にしただけで、掘削深さまたは流動損失を低減できるが、断面の縦横比を変えれば、その効果は更に大きくなることを前述した。本発明の狙いは、曲がり部の入口断面の縦横寸法の比を変えて流動損失を低減することにあり、特公昭４２−３６４５号に開示されたものとは狙っている作用効果が異なる。
【００３４】
また、特開平２−１５７４８１号「曲り流路」では、曲がり部での流動損失を低減するため、曲がり部での断面積変化の方法と曲がり部の流路幅の決定方法を示しているが、前記した表２に示されている通り、曲がり流路の損失に大きな影響を与える因子は曲がり半径Ｒと流路の縦方向の幅ｂとの比と断面の横方向幅ｈとｂの比の２つであり、特開平２−１５７４８１号に開示された断面積変化と曲がり部の流路幅の影響は前記２つの因子の影響と比較すると小さい。いずれにしろ特開平２−１５７４８１号に係る方法と本発明の方法は曲がり部の流動損失を低減するという目的は同じであるが、作用効果が異なっている。
【００３５】
【発明の実施の形態】
以下に図面を参照して本発明の実施の形態について説明する。
【００３６】
［第１の実施形態］
まず、図１を参照して第１の実施形態について説明する。図１は本発明の第１の実施の形態の吸出し管の形状を示す図である。なお、図１において、図７と同様の構成要素については同じ符号を付けている。
【００３７】
吸出し管５は、垂直方向を向き羽根車出口（図１には図示せず）に接続された吸出し管上部５ａと、水平方向を向き下流側に向けて断面積が増大する水平拡大部５ｃと、両端が吸出し管上部５ａと水平拡大部５ｃとを接続する曲がり部５ｂとから構成されている。吸出し管５内を流れる流体（水）は、曲がり部５ｂにおいて、その流れ方向が垂直方向から水平方向に変換される。
【００３８】
以下、吸出し管５のある部位をその管路の軸線（中心線）方向に垂直な面で切断して得られる断面をその部位における「断面」と呼び（他の方法により得られた断面と混同するおそれがある場合には、特に「垂直方向断面」と呼ぶ）、かつ、ある断面を含む平面と前記曲がり部の軸線を含む平面（曲がり部の軸線は曲線であるためこの平面は一意的に定まる）とが交わる直線の方向をその断面の「縦方向」、縦方向に直角な方向をその断面の「横方向」と呼ぶこととする。
【００３９】
吸出し管上部５ａの断面は、入口すなわち羽根車出口からの距離が離れるに従い面積が大きくなるように形成している。しかも吸出し管上部５ａの断面の縦方向および横方向の幅の関係は、縦方向の幅の増加率の方が横方向の幅の増加率に比べて小さくしてある。
【００４０】
その結果、吸出し管上部５ａの入口、すなわち羽根車出口側の上端部の断面は円形であるのに対して、吸出し管上部５ａと曲がり部５ｂとの接続部すなわち曲がり部５ｂの入口における断面の形状は、縦方向を短軸、横方向を長軸とする楕円形となる。
【００４１】
なお、曲がり部５ｂの断面形状は、その入口から出口（水平拡大部５ｃと曲がり部５ｂとの接続部まで、変化することなく一定となっている。
【００４２】
次に、本実施形態による吸出し管の効果を、図９に示した吸出し管上部５ａが徐々に拡径する円形断面を有する従来の吸出し管と比較して説明する。なお、ここでは比較のため、両者の吸出し管上部５ａの入口の断面積および曲がり部５ｂの入口の断面積は同一とする。
【００４３】
本実施形態の吸出し管５において、曲がり部５ｂの入口面積を図９の吸出し管と同様にπ×Ｄe²／２とするならば、例えば曲がり部５ｂの入口の断面形状を、短軸の長さは１.１×Ｄe、長軸の長さは１.８×Ｄe（但しＤeは吸出し管上部５ ａの入口断面の直径）の楕円と設定することができる（図１参照）。
【００４４】
ここで、曲がり部５ｂの断面の縦方向幅ｂと曲がりの半径Ｒの比（以下、Ｒ／ｂ比ともいう）が同じであれば、曲がり部５ｂにおける損失係数はほぼ同等となる（前記の表１及び表２参照）。そして、図９に示す従来の吸出し管の曲がりの半径Ｒは１.４１×Ｄeであり、曲がり部５ｂの断面の縦方向幅ｂは１.４１×Ｄeであるため、Ｒ／ｂ比は１.０である。
【００４５】
従って、本実施形態における曲がり部５ｂにおけるＲ／ｂ比を図９に示す従来のものにおけるＲ／ｂ比と同一にするならば、第１の実施形態の吸出し管５の曲がり部５ｂの曲がりの半径Ｒ（曲がり部５ｂの軸線の半径）は１.１×Ｄeとなり、従来の吸出し管より曲がり部５ｂの曲がり半径Ｒは小さくなる。このため、図１に示した本実施形態の吸出し管では、吸出し管５の深さ寸法Ｆを（１．４１−１．１）×１．５×Ｄｅ＝０．４６５×Ｄe 小さくすることができ、吸出し管 ５を埋設するための土木掘削量を少なくすることができる。大形のフランシス水車ではＤｅが１０ｍ程度のものもある。この場合は掘削深さを５ｍ程度浅くできるため、その効果は大きい。
【００４６】
また、曲がり部５ｂの断面の形状が楕円であり、楕円はその縦横比が円形より長方形に近いため、楕円の長軸を横方向にとることにより全損失係数を低減することができ（前述の表１参照）、曲がり部５ｂにおける流動損失を低減することができる。
【００４７】
また、従来の吸出し管と同じ深さ寸法Ｆとする場合は、吸出し管上部５ａの長さが図１の状態より更に長くなり、これに伴い曲がり部５ｂの入口断面の縦方向幅が大きくなる。この縦方向幅が大きくなった分、曲がり部の曲がり半径Ｒは１.２〜１.３×Ｄe程度となり、曲がり部５ｂの入口の面積を図１のπ×Ｄe²／２ より大きくすることができる。このため、曲がり部入口の流速が小さくなり、曲がり部５ｂでの損失係数が同一としても、曲がり部で発生する流動損失を低減することができる。従って、土木掘削量は同一の場合でも、吸出し管全体としての損失を低減することができる。
【００４８】
このように、本実施形態によれば、従来の吸出し管と同じ程度の性能をより浅い土木掘削量で実現することができる。また土木掘削量を同一にするならば従来の吸出し管より流動損失を低減することができる。
【００４９】
［第２の実施形態］
次に、図２を参照して第２の実施形態について説明する。図２は本発明の第２の実施の形態の吸出し管の形状を示す図である。第２の実施形態は、第１の実施形態に対して、吸出し管上部５ａが、羽根車出口側の第１の拡大部５ａ１と、第１の拡大部５ａ１に接続された曲がり部５ｂにつながる第２の拡大部５ａ２との２つの部分から構成されている点が異なり、他の構成は第１の実施形態と略同一である。
【００５０】
第１の拡大部５ａ１は、テーパー状に拡開する円錐台形状を有している。すなわち第１の拡大部５ａ１の断面は円形であり、その円の半径が羽根車から離れるに従って大きくなっている。
【００５１】
第２の拡大部５ａ２の断面は、拡大部５ａ２入口においてのみ円形であり、拡大部５ａ２入口から下流側に行くに従って、横方向幅のみが大きくなってゆく（断面の縦方向幅は一定）。従って、第２の拡大部５ａ２の入口以外の断面は、横方向幅が縦方向幅より大きい楕円となっている。
【００５２】
本実施形態の吸出し管５において、曲がり部５ｂの入口面積を図８の吸出し管と同様にπ×Ｄe²／２とするならば、第１の拡大部５ａ１および第２の拡大部５ａ２の形状寸法は、例えば図２に示すように、第１の拡大部５ａ１を入口の断面が直径がＤeの円形、出口が直径１.１×Ｄeの円形とし、第２の拡大部５ａ２を 入口の断面が直径１.１×Ｄeの円形、出口の断面が短軸長さ１.１×Ｄe、長軸長さ１.８×Ｄeの楕円とするように設定することができる。
【００５３】
本実施形態においても、第１の実施形態で説明したのと同様の理由により、従来の吸出し管と比較して、同一の流動損失で従来の吸出し管より曲がり部の半径が小さくなり、吸出し管の深さ寸法Ｆが小さくなり、吸出し管を埋設するための土木掘削量を少なくすることができる。
【００５４】
また、特に本実施形態においては、吸出し管上部５ａの入口近傍がテーパー状の円管となっており同芯の円形断面が続くため、羽根車から流出してきた流れとのマッチングは第１の実施形態の吸出し管より良好であり、吸出し管上部内の流動損失を更に低減することができる。また同芯のため吸出し管上部５ｂの製造も第１の実施形態の場合より容易である。
【００５５】
［第３の実施形態］
次に、図３を参照して第３の実施形態について説明する。図３は本発明の第３の実施の形態の吸出し管の形状を示す図である。第３の実施形態は、第２の実施形態に対して、吸出し管上部５ａの第２の拡大部５ａ２の形状が異なる点と、第２の拡大部５ａ２の形状変更に伴い曲がり部５ｂの形状が変更されている点が異なり、他は第２の実施形態と略同一である。
【００５６】
図３に示すように、第２の拡大部５ａ２の入口の断面は円形であり、第２の拡大部５ａ２の出口すなわち曲がり部５ｂの入口の断面は、その輪郭が、横方向に延びる互いに平行な一対の直線と、各直線の端部を結ぶ一対の半円とから構成された長円となっている。
【００５７】
また、曲がり部５ｂの垂直方向断面の形状および寸法は、羽根車出口からの距離に関わらず一定となっている。従って、曲がり部５ｂの縦方向両側の側面（各垂直方向断面の輪郭の直線部分の集合で表される）は、それぞれ２次曲面となり、かつ２次曲面間の距離は、羽根車出口からの距離に関わらず常に一定である。
【００５８】
本実施形態では、曲がり部５ｂの入口の垂直方向断面を楕円ではなく長円形状としているため、吸出し管上部との断面形状のつながりの滑らかさ、製造の容易性という点においては、第１及び第２の実施形態より優れている。
【００５９】
また、本実施形態の吸出し管５において、曲がり部５ｂの入口面積を図９の吸出し管と同様にπ×Ｄe²／２とするならば、図３に示すように、第２の拡大部５ａ２の入口の断面を直径１.１×Ｄeの円とし、第２の拡大部５ａ２の出口すなわち曲がり部５ｂの入口の断面を、縦方向幅１.１×Ｄe、横方向幅１.６６×Ｄe、半円の半径を０.５５×Ｄeの長円とすることができる。
【００６０】
したがって、吸出し管は羽根車方向から見た場合の曲がり部の横方向の幅が１．６６×Ｄeとなり、第１及び第２の実施形態の吸出し管の幅（＝１．８×Ｄe）と比較して小さくなる。このため、深さ方向の掘削量は第１及び第２の実施形態と同等であるが、水平方向の掘削量も含めると本実施形態の吸出し管が最も少なくなる。
【００６１】
本実施形態においても、第１の実施形態で説明したのと同様の理由により、従来の吸出し管と比較して、同一の流動損失で従来の吸出し管より曲がり部の半径が小さくなり、吸出し管の深さ寸法Ｆが小さくなり、吸出し管を埋設するための土木掘削量を少なくすることができる。
【００６２】
［第４の実施形態］
次に、図４を参照して第４の実施形態について説明する。図４は本発明の第４の実施の形態の吸出し管を示す図である。本実施形態における吸出し管５の形状は本発明の第２の実施形態のものと基本的に同一である。ただし、本実施形態の吸出し管の曲がり部５は下記の様な特徴をもつ部品で構成されている。
【００６３】
まず、曲がり部５ｂのうち横方向に関して互いに対向する両側面を構成している部材５ｆ、５ｇは、曲がり半径Ｒ（Ｒは円形エルボの軸線の曲がりの半径）の円形エルボを２分割した部材によりそれぞれ形成されている。また曲がり部５ｂのうち縦方向に関して互いに対向する両側面を構成している部材５ｄ、５ｅは、円筒の周面の一部をなす形状の板材により構成されている。部材５ｄ、５ｅはそれぞれ、半径Ｒ＋ｒ、半径Ｒ−ｒ（Ｒは円形エルボの軸線の曲がりの半径、ｒは円形エルボの円形断面の半径）の円筒の周面の一部をなす。
【００６４】
図４に示すように、部材５ｄ、５ｅは横方向に関して所定の間隔をおいて配置される。そして、部材５ｄ、５ｅは縦方向両側から部材５ｆ、５ｇに挟まれ、部材５ｆ、５ｇに溶接により接合される。部材（曲面）５ｄ、５ｅの距離は曲がり部５ｂの入口から出口まで変化せず一定である。
【００６５】
本実施形態によれば、部材５ｆ、５ｇは円形エルボを２分割して形成できるためされ、その製作は容易である。また部材５ｄ、５ｅは、円筒の周面の一部をなす単純な形状のため、平板を曲げ加工して容易に成形することができる。このため、曲がり部５ｂを容易に製作することができる。
【００６６】
また、本実施形態によれば、図８に示した従来の吸出し管のように流れと直交する溶接線が存在しないため、溶接のビードが突出したことに起因する損失を無くすことができ、低流動損失の吸出し管を提供することができる。
【００６７】
また曲がり部５ｂの曲がりが単純な曲がり半径Ｒが一定の場合は、部材５ｆ、５ｇを市販のエルボ管を加工することにより製作することができるため、製作コストを低減することができる。
【００６８】
なお、曲がり部５ｂの曲がり半径Ｒが一定でない場合にも、本実施形態の手法に準じた手法で曲がり部５ｂを製作することができる。すなわちこのような場合には、上記の市販のエルボ管を用いることはできなくなるが、断面の半径が一定であれば、市販の直管を曲げ加工した後これを２分割することにより部材５ｆ、５ｇを製作することができ、部材５ｄ、５ｅは部材５ｆ、５ｇの曲がりに対応させて平板を曲げ加工して容易に成形することができる。従って、この場合も製作コストを低減することができる。
【００６９】
このように本実施形態によれば、損失が少なく、製作コストも少ない吸出し管を提供することができる。
【００７０】
［第５の実施形態］
次に、図５を参照して第５の実施形態について説明する。図５は本発明の第５の実施形態の吸出し管を示す図である。ここで吸出し管５の曲がり部５ｂの構成は、図４に示した第４の実施形態のものと同一である。また、本実施形態における吸出し管上部５ａの構成は、図３に示した第３の実施形態の吸出し管上部５ａと同一であり、円形断面を有するテーパー状の第１の拡大部５ａ１と、第２の拡大部５ａ２との２つの部分から構成されている。
【００７１】
ここで、図５に示すように、第２の拡大部５ａ２の横方向の側面は、円管を２分することにより得られた部材５ａ２−１と部材５ａ２−２で構成され、その間は三角形の平板状の部材５ａ２−３と部材５ａ２−４とにより構成されている。
【００７２】
第２の拡大部５ａ２を上記のように分割された複数の部材により構成することにより、第２の拡大部５ａ２の製作が容易となり製作コストを低減することができる。
【００７３】
また、第２の拡大部５ａ２の円断面の半径と曲がり部５ｂの側面の円断面の半径が必然的に同一となるため、吸出し管内の流れに沿って著しい断面形状の変化が無いため流動損失を低減することができる。
【００７４】
［第６の実施形態］
次に、図６を参照して第６の実施形態について説明する。図６は本発明の第６の実施の形態による吸出し管の製作方法を示す図である。
【００７５】
本実施形態の吸出し管５の吸出し管上部５ａおよび曲がり部５ｂの形状寸法は、曲がり部５ｂの垂直方向断面の横方向幅が一定ではなく下流側に行くに従って増大するように若干変化している点を除いて、図４に示した第４の実施形態と同一である。
【００７６】
曲がり部５ｂの両側面は円形断面の直管を２分割した部材を複数組み合わせて形成されている。図６において符号５ｂ１、５ｂ２、５ｂ３、…、５ｂ１２で示す部材は、円形断面の直管を２分割することにより得られた部材である。
【００７７】
また、曲がり部５ｂの内側面および外側面は、それぞれ単一の部材５ｂＵおよび部材５ｂＬにより形成されている。部材５ｂＵおよび部材５ｂＬは、互いに隣接する部材５ｂ１、５ｂ２、５ｂ３、…、５ｂ１２間の継ぎ目に対応する部位で折れ曲がっており、複数の平面から構成されている。
【００７８】
これらの部材５ｂ１、５ｂ２、５ｂ３、…、５ｂ１２および５ｂＵ、５ｂＬは、溶接により互いに接合される。従って、部材５ｂ１、５ｂ２、５ｂ３、…、５ｂ１２は、海老の外殻のように、流れ方向に相互に連結されている。なお、部材５ｂ１〜５ｂ１２の部材の接断面は、もとの円形断面の直管の管軸と垂直でなく、傾いている。
【００７９】
本実施形態の吸い出し管において、曲がり部５ｂの入口断面形状は本発明の第３の実施形態と同様な形状で、曲がり部の内側面および外側面（横方向に互いに対向する面）の間の距離は、第４の実施形態と同様に一定なので、第３及び第４の実施形態と同様に、従来の吸出し管より流動損失を低減できる。また発生する損失を同程度にするために必要な吸出し管の深さ寸法Ｆも従来の吸出し管より浅くなり、土木掘削量の低減が可能となる。
【００８０】
図９に示すような従来の吸出し管の製作方法では、個々の部材５ｂ１、５ｂ２、…を形成するために、平面に展開した形状を求め、平板からそれらを切り出し、更に曲げ加工を実施することが必要であったが、本実施形態においては、円管をを切断した部材と、平板を折り曲げ加工した部材とを準備するだけでよいので、製造が容易で、コストの低減および納期の短縮を実現できる。特に、部材５ｂＬと５ｂＵには流れ方向と直交する折れ線はあるが溶接ビードのような流れと直交する突起はないため、図８の従来の吸出し管より流動損失は小さくなる。また、必要となる円管の寸法次第では、市販の直管を使用することも可能となるため、さらに製造の容易化、コストの低減および納期の短縮が可能となる。
【００８１】
また本実施形態による構造をとることにより、曲がり部５ｂの流路の幅を変化させることができ、設計の自由度が大きくなるため、第４の実施形態で説明した構造に比べて適用範囲は広くなる。
【００８２】
【発明の効果】
以上説明したように、本発明によれば、吸出し管の損失低減、製造コストの低減、土木掘削量の低減等を図ることができ、ひいては低コストで効率の高い水力機械を提供することができる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態の水力機械の吸出し管を示す図。
【図２】本発明の第２の実施の形態の水力機械の吸出し管を示す図。
【図３】本発明の第３の実施の形態の水力機械の吸出し管を示す図。
【図４】本発明の第４の実施の形態の水力機械の吸出し管を示す図。
【図５】本発明の第５の実施の形態の水力機械の吸出し管を示す図。
【図６】本発明の第６の実施の形態の水力機械の吸出し管を示す図。
【図７】従来の水力機械の構成と吸出し管を示す図。
【図８】従来の吸出し管の製作方法を示す図。
【図９】従来の吸出し管の形状を示す図。
【符号の説明】
１ ケーシング
２ 羽根車
５ 吸出し管
５ａ 吸出し管上部
５ｂ 曲がり部
５ａ１ 吸出し管上部の第１の拡大部（所定領域以外の領域）
５ａ２ 吸出し管上部の第２の拡大部（所定領域）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a suction pipe of a water turbine or a pump turbine, and more particularly to an improvement in the shape and structure of a suction pipe having a bent portion.
[0002]
[Prior art]
FIG. 7 shows the configuration of a Francis turbine, which is a type of conventional hydraulic machine. In this water wheel, high-pressure water flows from the upper pond (not shown) into the casing 1 to rotate the impeller 2, and the impeller 2 drives the generator 4 by the main shaft 3. Then, the water flowing out from the impeller 2 flows out into the lower pond 6 through the suction pipe 5.
[0003]
The suction pipe 5 includes a suction pipe upper part 5a, a bent part 5b, and a horizontal enlarged part 5c, and the suction pipe upper part 5a is generally circular in both an inlet cross section and an outlet cross section. For this reason, the cross section of the entrance of the bent portion 5b is often circular. On the other hand, the cross-sectional shape of the horizontal expansion tube 5c is often rectangular.
[0004]
The fluid is Ve at the inlet of the suction pipe.²/ 2g kinetic energy. In a low head turbine, the kinetic energy mentioned above reaches 10-20% of the effective head He. Therefore, it is an important role of the suction pipe to efficiently convert this kinetic energy into pressure energy. If only half of the kinetic energy is converted to pressure energy, a loss of 5 to 10% of the effective head is generated in the suction pipe. For this reason, in order to increase the efficiency of a low-head water turbine, it is important to make a suction pipe with low loss.
[0005]
In the vertical turbine as shown in FIG. 7, the suction pipe 5 has a bent portion 5 b that converts the direction of the downward flowing water into the horizontal direction, and the loss generated in the bent portion 5 b is large in the loss in the suction pipe 5. Occupy part. Therefore, in order to make a suction pipe with a small loss, how to suppress the loss of the bent portion 5b is an important issue.
[0006]
On the other hand, in the water turbine with the vertical axis as shown in FIG. 7, when the vertical distance F between the lowermost portion of the suction pipe 5 and the center of the water turbine (hereinafter referred to as “suction pipe depth dimension”) increases, The amount of civil engineering excavation to bury the plant will increase, and the increase in the amount of civil engineering excavation will lead to a rise in power plant construction costs. Therefore, it is desirable that the suction pipe not only has a small loss but also has a small suction pipe depth dimension F.
[0007]
FIG. 8 is a view showing a conventional method for manufacturing a suction pipe. As shown in FIG. 8, the suction pipe upper portion 5a and the bent portion 5b have a plurality of portions 5b1, 5b2, 5b3 with respect to the flow direction. It is divided into ... Each of the portions 5b1, 5b2, 5b3,... Is individually cut out from the flat plate, then bent so as to have a predetermined R shape, and then assembled by welding. That is, since the conventional suction pipe has a structure like a shrimp shell, the number of welding stages is large and the manufacturing cost is high.
[0008]
In the suction pipe having such a structure, as shown in FIG. 8, there is a weld line perpendicular to the flow in the flow path, so that if the weld bead protrudes from the flow wall surface, the flow is disturbed and the loss increases. There's a problem. For this reason, after welding, the process of smoothing a bead part etc. is needed, and a manufacturing cost increase is promoted.
Therefore, it is better that the number of welding lines orthogonal to the direction of flow is as small as possible, which also reduces the manufacturing cost.
[0009]
[Problems to be solved by the invention]
The present invention has been made in view of the above points, and reduces the flow loss of the suction pipe without increasing the amount of civil engineering excavation, and also reduces the production cost of the suction pipe. The purpose is to provide equipment.
[0010]
[Means for Solving the Problems]
First, what kind of suction pipe is desirable to suppress the loss at the bent portion will be discussed below. Here, as a representative example of a conventional suction pipe, a simplified suction pipe as shown in FIG. 9 is considered. In this simplified suction pipe, the suction pipe upper part 5a is a simple circular cross-section enlarged pipe (a truncated cone-shaped pipe that expands toward the lower side), and its inlet cross section is a circle with a diameter De and an outlet. The cross section is a circle with a diameter of 1.41 × De. In order to reduce the loss of the bent portion 5b, the bent portion 5b is a bent tube having a circular cross section with a constant cross section. The radius R of the bend is 1.41 × De. Further, the cross section of the horizontal expansion tube 5c gradually changes from a circular cross section having a diameter of 1.41 × De to a rectangular cross section.
[0011]
Here, Table 1 shows the total loss coefficient ζ of the loss generated in the bent pipes of various cross sections (referenced from Table 4.18 of the flow resistance / pipe fluid resistance P74 edited by the Japan Society of Mechanical Engineers).
[0012]
[Table 1]

The loss ΔH generated at the bend is ΔH = ζ × V²/ 2 g (V is the average cross-sectional flow velocity at the bent pipe inlet). Therefore, the magnitude of the generated loss depends on the magnitude of the total loss coefficient ζ in this table.
[0013]
The first thing to know from this table is that the loss decreases as the radius ratio R / a (or R / (b / 2)) of the bending increases in any cross-sectional shape. However, since the depth dimension F of the suction pipe shown in FIG. 7 increases as R increases, there is a disadvantage that the amount of civil engineering excavation for embedding the suction pipe increases. The radius ratio R / a of the bent portion 5b of the suction pipe in FIG. 9 corresponds to 2.0 because a = De / 2.
[0014]
On the other hand, regarding the influence of the cross-sectional shape of the bent tube, the bent tube having the square cross section has less loss than the bent tube having the circular cross section, and the rectangular cross section having an h / b ratio of 2 is compared to the bent tube having the square cross section. It can be seen that the bent pipe has less loss.
[0015]
Table 2 shows the results of quantitative estimation of the above points.
[0016]
[Table 2]

[0017]
In this trial calculation, the total loss coefficient ζ was calculated based on the values in Table 1 for three cross-section bent pipes. For any cross section, the cross-sectional area of the inlet is πa₀ ²And the bend radius R is twice the entrance radius of the bend pipe having a circular cross section (ie, R = 2 × a₀). As a result, ζ of the circular cross section is obtained from R / a = 2 in Table 1 as ζ = 0.246. In addition, the square cross section indicates the area of the inlet cross section by πa.₀ ²Then, the length of one side is 1.77 × a₀ ² (= Π^1/2a₀)
[Expression 1]

When the loss factor is interpolated from Table 1,
[Expression 2]

It becomes. This value is about 7% smaller than the loss factor of the curved pipe having a circular cross section.
[0018]
The following is a quantitative description of the effect when the loss factor is small. That is, the ratio of the kinetic energy at the suction pipe inlet to the effective head H is 15%, and half of the kinetic energy from the suction pipe inlet to the top of the suction pipe is converted into pressure energy, and the ratio to the effective head of the kinetic energy at the bent section inlet. Is 7.5% (that is, the area at the top of the suction pipe is 1.41 times larger, the flow velocity is 1 / 1.41, and the ratio of the kinetic energy to the effective drop is V²/(2gH)=0.075), the loss ΔH of the curved pipe with the circular cross section is the loss of ΔH / H = 0.246 × 7.5% = 1.85% with respect to the turbine efficiency. It becomes. On the other hand, a curved pipe with a square cross section has a loss of ΔH / H = 0.229 × 7.5% = 1.72%, and a curved pipe with a square cross section improves the efficiency of the entire turbine by 0.13%. I can expect that.
[0019]
On the other hand, in the case of a rectangle with h / b = 2,
[Equation 3]

When the loss factor is interpolated from Table 1,
[Expression 4]

Thus, the loss factor is further reduced.
[0020]
In this case, ΔH / H = 0.16 × 7.5% = 1.2% loss with respect to the turbine efficiency, which is 0.65% of the efficiency of the entire turbine as compared with the case of a curved pipe having a circular cross section. Can be expected to improve.
[0021]
As described above, (1) the loss of the bent portion is affected by the radius R of the bend, and the radius R is preferably larger from the viewpoint of reducing the loss, but the radius R is small from the viewpoint of reducing the amount of civil engineering excavation. (2) When the area of the bent portion entrance is constant, the width of the cross section in the bending direction (longitudinal direction) (= b described above) should be made as small as possible, and the direction perpendicular to it (lateral) It can be seen that the loss generated at the bent portion can be reduced by increasing the width of the cross section in the direction.
[0022]
  Based on the above knowledge, the present invention optimizes the shape and structure of the suction pipe of the water turbine or pump water turbine, and connects the impeller outlet and the water discharge passage and connects the upper portion of the suction pipe connected to the impeller outlet. And a suction pipe of a water turbine or a pump water turbine that is connected to the upper part of the suction pipe and has a bent portion that changes the flow direction of the fluid passing through the suction pipe. A cross section obtained by cutting along a plane perpendicular to the axial direction is referred to as a vertical cross section at that portion, and the direction of a straight line intersecting a plane including a certain vertical cross section and a plane including the axis of the bent portion is the vertical direction. When the longitudinal direction of the directional section and the direction perpendicular to the longitudinal direction are referred to as the transverse direction of the vertical section, it is upstream from the boundary with at least the bent portion of the upper portion of the suction pipe. Of the cross-sectional area of the vertical cross section in a predetermined range, said has increased as the distance from the impeller exit is increased, and, in the vertical cross section in the predetermined rangeOf vertical widthIncrease rateLateral widthIt is characterized by a decrease compared to the rate of increase.
[0023]
According to the present invention, the width in the horizontal direction of the cross section at the entrance of the bent portion can be made larger than the width in the vertical direction, and the loss of the suction pipe can be reduced while suppressing an increase in the depth of the suction pipe.
[0024]
  Of the upper part of the suction pipe,Predetermined rangeThe vertical width of the vertical cross section can be constant regardless of the distance from the impeller exit.
[0025]
  On the outlet side of the impeller above the suction pipe,Predetermined rangeThere may be regions other thanPredetermined rangeIn other areas, the cross-sectional area of the vertical cross section increases as the distance from the impeller exit increases, and the vertical cross sectionOf vertical widthIncrease rateLateral widthA frustoconical shape equal to the increase rate can be obtained. By doing in this way, matching with the fluid which flows out from an impeller exit can be taken favorably.
[0026]
  The vertical cross section at the boundary between the upper portion of the suction pipe and the bent portion may be an ellipse having a major axis in the horizontal direction and a minor axis in the vertical direction. In addition, the vertical cross section at the boundary between the upper portion of the suction pipe and the bent portion may be configured to have an oval shape having a contour combining a pair of straight lines extending in the lateral direction and a pair of semicircles. it can. In this case, the aboveOf a given rangeThe vertical cross section at the most upstream site can be circular.
[0027]
  Also, the upper part of the suction pipePredetermined rangeThe vertical width of the vertical cross section can be constant regardless of the distance from the impeller exit,Predetermined rangeHas a pair of side surfaces facing each other in the lateral direction, and the pair of side surfaces can be formed by a member obtained by dividing a straight pipe having a circular cross section into two parts. By configuring in this way, it is possible to facilitate the production of the suction pipe.
[0028]
Further, the contour of the vertical section of the bent portion has an oval shape having a contour combining a pair of straight lines and a pair of semicircles extending in the lateral direction regardless of the distance from the impeller exit. The portions corresponding to the pair of straight lines of the bent portions constitute a pair of first side surfaces facing each other in the vertical direction, and the pair of semicircles of the bent portions The portions corresponding to the above form a pair of second side surfaces facing each other in the lateral direction, and the distance between the pair of first side surfaces can be constant regardless of the distance from the impeller outlet. . By comprising in this way, the amount of civil engineering excavation can be appropriately balanced regarding a horizontal direction and a perpendicular direction.
[0029]
In this case, the second side surface of the bent portion can be formed from a member obtained by dividing a tube having a circular cross section along the axial direction thereof, and the first side surface of the bent portion is formed by bending a flat plate. It can be formed by a processed member. By comprising in this way, manufacture of a suction pipe can be made easy.
[0030]
Further, the vertical cross section of the bent portion has a contour combining a pair of straight lines extending in the lateral direction regardless of the distance from the impeller outlet and a pair of curves connecting both ends of the pair of straight lines. And a pair of the bent portions that are configured such that a lateral width of the vertical cross section of the bent portion is larger than a vertical width, and portions corresponding to the pair of straight lines of the bent portions are opposed to each other in the vertical direction. The portion corresponding to the pair of curves in the bent portion may constitute a pair of second side surfaces facing each other in the lateral direction.
[0031]
In this case, the second side surface of the bent portion can be formed by joining a plurality of members obtained by cutting a tube having a circular cross section along a direction intersecting its axis, and The first side surface of the bent portion can be formed by a member obtained by bending a flat plate along a plurality of bending lines. By comprising in this way, manufacture of a suction pipe can be made easy.
[0032]
Further, in this case, the distance between the pair of first side surfaces can be constant regardless of the distance from the impeller exit. With this configuration, the amount of civil engineering excavation can be set horizontally and vertically. Proper balance can be achieved with respect to direction.
[0033]
In addition, it is shown in Japanese Patent Application Laid-Open No. 42-3645 “Suction pipe of water turbine or pump” that the inlet cross section of the bent portion of the suction pipe is made into a square or rectangular cross section. The purpose of this proposal is to reduce the manufacturing cost. Therefore, the loss reduction of the bent portion is not considered. As described above, it is possible to reduce the excavation depth or the flow loss only by changing the entrance cross section of the bent portion from the circular cross section to the square cross section, but it has been described above that the effect is further increased by changing the aspect ratio of the cross section. The aim of the present invention is to reduce the flow loss by changing the ratio of the vertical and horizontal dimensions of the inlet cross section of the bent portion, and the intended effect is different from that disclosed in Japanese Patent Publication No. 42-3645.
[0034]
Japanese Patent Application Laid-Open No. 2-157482 “Bent channel” shows a method of changing the cross-sectional area at the bent part and a method of determining the channel width of the bent part in order to reduce the flow loss at the bent part. As shown in Table 2 above, the factor that greatly affects the loss of the bent flow path is the ratio of the bend radius R and the vertical width b of the flow path and the ratio of the horizontal width h and b of the cross section. The effects of the change in cross-sectional area and the flow path width of the bent portion disclosed in Japanese Patent Laid-Open No. 2-157482 are small compared to the effects of the two factors. In any case, the method according to Japanese Patent Laid-Open No. 2-154781 and the method of the present invention have the same purpose of reducing the flow loss at the bend, but the effects are different.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0036]
[First Embodiment]
First, a first embodiment will be described with reference to FIG. FIG. 1 is a diagram showing the shape of a suction pipe according to a first embodiment of the present invention. In FIG. 1, the same components as those in FIG.
[0037]
The suction pipe 5 has a suction pipe upper part 5a connected in the vertical direction and connected to an impeller outlet (not shown in FIG. 1), and a horizontal enlarged part 5c in which the cross-sectional area increases in the horizontal direction toward the downstream side. Both ends are constituted by a bent portion 5b connecting the suction pipe upper portion 5a and the horizontal enlarged portion 5c. The flow direction of the fluid (water) flowing through the suction pipe 5 is changed from the vertical direction to the horizontal direction at the bent portion 5b.
[0038]
Hereinafter, a cross section obtained by cutting a part of the suction pipe 5 along a plane perpendicular to the axis (center line) direction of the pipe line is referred to as a “cross section” at that part (confused with a cross section obtained by another method). In particular, it is called a “vertical section”, and a plane including a certain section and a plane including the axis of the bent portion (the axis of the bent portion is a curved line, so this plane is uniquely The direction of the straight line intersecting with the vertical direction is called the “vertical direction” of the cross section, and the direction perpendicular to the vertical direction is called the “lateral direction” of the cross section.
[0039]
The cross section of the suction pipe upper part 5a is formed so that the area increases as the distance from the inlet, that is, the impeller outlet, increases. Moreover, the relationship between the vertical and horizontal widths of the cross section of the suction pipe upper portion 5a is such that the increase rate of the vertical width is smaller than the increase rate of the horizontal width.
[0040]
As a result, the cross section of the inlet of the suction pipe upper portion 5a, that is, the upper end portion on the impeller outlet side is circular, whereas the cross section at the connection portion of the suction pipe upper portion 5a and the bent portion 5b, that is, the inlet of the bent portion 5b. The shape is an ellipse with the short axis in the vertical direction and the long axis in the horizontal direction.
[0041]
In addition, the cross-sectional shape of the bent portion 5b is constant without changing from the inlet to the outlet (the connection portion between the horizontal enlarged portion 5c and the bent portion 5b).
[0042]
Next, the effect of the suction pipe according to the present embodiment will be described in comparison with a conventional suction pipe having a circular cross section in which the suction pipe upper portion 5a shown in FIG. Here, for comparison, the cross-sectional area of the inlet of both the suction pipe upper portions 5a and the cross-sectional area of the inlet of the bent portion 5b are the same.
[0043]
In the suction pipe 5 of the present embodiment, the entrance area of the bent portion 5b is π × De as in the suction pipe of FIG.²/ 2, for example, the sectional shape of the inlet of the bent portion 5b is 1.1 × De for the minor axis and 1.8 × De for the major axis (where De is the upper portion of the suction pipe 5a). Can be set as an ellipse (see FIG. 1).
[0044]
Here, if the ratio of the longitudinal width b of the cross section of the bent portion 5b and the radius R of the bend (hereinafter also referred to as R / b ratio) is the same, the loss coefficient in the bent portion 5b is substantially equal (described above) Table 1 and Table 2). The radius R of the bending of the conventional suction pipe shown in FIG. 9 is 1.41 × De, and the longitudinal width b of the cross section of the bent portion 5b is 1.41 × De, so the R / b ratio is 1 0.0.
[0045]
Therefore, if the R / b ratio in the bent portion 5b in the present embodiment is made the same as the R / b ratio in the conventional one shown in FIG. 9, the bent portion 5b of the suction pipe 5 in the first embodiment is bent. The radius R (radius of the axis of the bent portion 5b) is 1.1 × De, and the bent radius R of the bent portion 5b is smaller than that of the conventional suction pipe. Therefore, in the suction pipe of this embodiment shown in FIG. 1, the depth dimension F of the suction pipe 5 can be reduced by (1.41-1.1) × 1.5 × De = 0.465 × De. The amount of civil engineering excavation for burying the suction pipe 5 can be reduced. Some large Francis turbines have a De of about 10 m. In this case, since the excavation depth can be reduced by about 5 m, the effect is great.
[0046]
Further, since the cross-sectional shape of the bent portion 5b is an ellipse, and the aspect ratio of the ellipse is closer to a rectangle than a circle, the total loss factor can be reduced by taking the major axis of the ellipse in the horizontal direction (described above). The flow loss in the bent portion 5b can be reduced.
[0047]
Further, when the depth F is the same as that of the conventional suction pipe, the length of the suction pipe upper portion 5a is longer than that in the state shown in FIG. 1, and accordingly, the longitudinal width of the inlet section of the bent portion 5b is increased. . As the vertical width increases, the bending radius R of the bent portion becomes about 1.2 to 1.3 × De, and the area of the entrance of the bent portion 5b is π × De in FIG.²Can be greater than / 2. For this reason, even if the flow velocity at the bent portion entrance becomes small and the loss coefficient at the bent portion 5b is the same, the flow loss generated at the bent portion can be reduced. Therefore, even if the civil engineering excavation amount is the same, the loss of the entire suction pipe can be reduced.
[0048]
Thus, according to the present embodiment, the same level of performance as that of the conventional suction pipe can be realized with a shallower amount of civil engineering excavation. Moreover, if the civil engineering excavation amount is the same, the flow loss can be reduced as compared with the conventional suction pipe.
[0049]
[Second Embodiment]
Next, a second embodiment will be described with reference to FIG. FIG. 2 is a diagram showing the shape of the suction pipe according to the second embodiment of the present invention. In the second embodiment, the suction pipe upper portion 5a is connected to the first enlarged portion 5a1 on the impeller outlet side and the bent portion 5b connected to the first enlarged portion 5a1 with respect to the first embodiment. The difference is that the second enlarged portion 5a2 is composed of two parts, and the other configurations are substantially the same as those of the first embodiment.
[0050]
The first enlarged portion 5a1 has a truncated cone shape that expands in a tapered shape. That is, the cross section of the first enlarged portion 5a1 is circular, and the radius of the circle increases as the distance from the impeller increases.
[0051]
The cross section of the second enlarged portion 5a2 is circular only at the inlet of the enlarged portion 5a2, and only the lateral width increases from the inlet of the enlarged portion 5a2 toward the downstream side (the vertical width of the cross section is constant). Therefore, the cross section other than the entrance of the second enlarged portion 5a2 is an ellipse whose lateral width is larger than the longitudinal width.
[0052]
In the suction pipe 5 of the present embodiment, the entrance area of the bent portion 5b is π × De as in the suction pipe of FIG.²/ 2, the first enlarged portion 5a1 and the second enlarged portion 5a2 are shaped so that, for example, as shown in FIG. 2, the first enlarged portion 5a1 has a circular shape with a cross section of the entrance having a diameter De. The outlet has a circular shape with a diameter of 1.1 × De, the second enlarged portion 5a2 has a circular shape with an inlet cross section of a diameter of 1.1 × De, and the cross section of the outlet has a short axis length of 1.1 × De, a long axis length. It can be set to be an ellipse of 1.8 × De.
[0053]
Also in this embodiment, for the same reason as described in the first embodiment, the radius of the bent portion is smaller than that of the conventional suction pipe with the same flow loss as that of the conventional suction pipe. Therefore, the depth F of the construction can be reduced and the amount of civil engineering excavation for burying the suction pipe can be reduced.
[0054]
Particularly in the present embodiment, the vicinity of the inlet of the suction pipe upper part 5a is a tapered circular pipe, and the concentric circular cross section continues, so matching with the flow flowing out from the impeller is the first implementation. It is better than the shape of the suction pipe, and the flow loss in the upper part of the suction pipe can be further reduced. Further, because of the concentricity, the suction pipe upper part 5b can be manufactured more easily than in the first embodiment.
[0055]
[Third Embodiment]
Next, a third embodiment will be described with reference to FIG. FIG. 3 is a diagram showing the shape of a suction pipe according to the third embodiment of the present invention. The third embodiment differs from the second embodiment in the shape of the second enlarged portion 5a2 of the suction pipe upper portion 5a and the shape of the bent portion 5b in accordance with the shape change of the second enlarged portion 5a2. Is different, and the others are substantially the same as in the second embodiment.
[0056]
As shown in FIG. 3, the cross section of the inlet of the second enlarged portion 5a2 is circular, and the cross section of the outlet of the second enlarged portion 5a2, that is, the inlet of the bent portion 5b, is parallel to each other. It is an ellipse composed of a pair of straight lines and a pair of semicircles connecting the ends of the straight lines.
[0057]
Further, the shape and size of the vertical cross section of the bent portion 5b are constant regardless of the distance from the impeller exit. Therefore, the side surfaces on both sides in the vertical direction of the bent portion 5b (represented by a set of straight portions of the contour of each vertical section) are each a quadratic curved surface, and the distance between the quadric curved surfaces is from the impeller exit. It is always constant regardless of the distance.
[0058]
In the present embodiment, the vertical cross section of the inlet of the bent portion 5b is not an ellipse, but an oval shape. Therefore, in terms of the smooth connection of the cross section with the upper portion of the suction pipe and the ease of manufacture, It is superior to the second embodiment.
[0059]
Further, in the suction pipe 5 of the present embodiment, the entrance area of the bent portion 5b is π × De as in the suction pipe of FIG.²As shown in FIG. 3, as shown in FIG. 3, the cross section of the inlet of the second enlarged portion 5a2 is a circle having a diameter of 1.1 × De, and the outlet of the second enlarged portion 5a2, that is, the inlet of the bent portion 5b. The cross section may be an ellipse having a longitudinal width of 1.1 × De, a lateral width of 1.66 × De, and a semicircular radius of 0.55 × De.
[0060]
Therefore, the suction pipe has a width in the lateral direction of the bent portion when viewed from the impeller direction of 1.66 × De, and the width of the suction pipe of the first and second embodiments (= 1.8 × De) and It becomes small compared. For this reason, the amount of excavation in the depth direction is the same as that in the first and second embodiments, but if the amount of excavation in the horizontal direction is also included, the suction pipe of this embodiment is the smallest.
[0061]
Also in this embodiment, for the same reason as described in the first embodiment, the radius of the bent portion is smaller than that of the conventional suction pipe with the same flow loss as that of the conventional suction pipe. Therefore, the depth F of the construction can be reduced and the amount of civil engineering excavation for burying the suction pipe can be reduced.
[0062]
[Fourth Embodiment]
Next, a fourth embodiment will be described with reference to FIG. FIG. 4 is a view showing a suction pipe according to a fourth embodiment of the present invention. The shape of the suction pipe 5 in the present embodiment is basically the same as that of the second embodiment of the present invention. However, the bent portion 5 of the suction pipe of the present embodiment is composed of parts having the following characteristics.
[0063]
First, members 5f and 5g constituting both side surfaces facing each other in the lateral direction of the bent portion 5b are formed by dividing a circular elbow having a bending radius R (R is a radius of bending of the axis of the circular elbow) into two parts. Each is formed. Further, the members 5d and 5e constituting both side surfaces facing each other in the longitudinal direction in the bent portion 5b are constituted by a plate material having a shape forming a part of the circumferential surface of the cylinder. Each of the members 5d and 5e forms a part of a peripheral surface of a cylinder having a radius R + r and a radius Rr (where R is a radius of bending of the axis of the circular elbow and r is a radius of the circular cross section of the circular elbow).
[0064]
As shown in FIG. 4, the members 5d and 5e are arranged at a predetermined interval in the lateral direction. The members 5d and 5e are sandwiched between the members 5f and 5g from both sides in the vertical direction, and are joined to the members 5f and 5g by welding. The distance between the members (curved surfaces) 5d and 5e does not change from the entrance to the exit of the bent portion 5b and is constant.
[0065]
According to the present embodiment, the members 5f and 5g can be formed by dividing the circular elbow into two parts, and the manufacture thereof is easy. Further, since the members 5d and 5e have a simple shape forming a part of the circumferential surface of the cylinder, they can be easily formed by bending a flat plate. For this reason, the bending part 5b can be manufactured easily.
[0066]
Further, according to the present embodiment, since there is no weld line orthogonal to the flow as in the conventional suction pipe shown in FIG. 8, loss due to the protruding weld bead can be eliminated, and low A flow loss suction pipe can be provided.
[0067]
In addition, when the bending radius R is simple and the bending portion 5b is bent, the members 5f and 5g can be manufactured by processing a commercially available elbow tube, so that the manufacturing cost can be reduced.
[0068]
Even when the bending radius R of the bent portion 5b is not constant, the bent portion 5b can be manufactured by a method according to the method of the present embodiment. That is, in such a case, the above-mentioned commercially available elbow pipe cannot be used. However, if the radius of the cross section is constant, the member 5f is obtained by bending the commercially available straight pipe and then dividing it into two. 5g can be manufactured, and the members 5d and 5e can be easily formed by bending a flat plate corresponding to the bending of the members 5f and 5g. Therefore, the manufacturing cost can be reduced also in this case.
[0069]
As described above, according to the present embodiment, it is possible to provide a suction pipe with low loss and low manufacturing cost.
[0070]
[Fifth Embodiment]
Next, a fifth embodiment will be described with reference to FIG. FIG. 5 is a view showing a suction pipe according to a fifth embodiment of the present invention. Here, the configuration of the bent portion 5b of the suction pipe 5 is the same as that of the fourth embodiment shown in FIG. Further, the configuration of the suction pipe upper portion 5a in the present embodiment is the same as the suction pipe upper portion 5a of the third embodiment shown in FIG. 3, and a tapered first enlarged portion 5a1 having a circular cross section, It consists of two parts with two enlarged parts 5a2.
[0071]
Here, as shown in FIG. 5, the lateral side surface of the second enlarged portion 5 a 2 is composed of a member 5 a 2-1 and a member 5 a 2-2 obtained by dividing the circular tube into two, and a triangle is formed between them. The plate-shaped member 5a2-3 and the member 5a2-4 are configured.
[0072]
By configuring the second enlarged portion 5a2 with a plurality of members divided as described above, the second enlarged portion 5a2 can be easily manufactured and the manufacturing cost can be reduced.
[0073]
Further, since the radius of the circular cross section of the second enlarged portion 5a2 and the radius of the circular cross section of the side surface of the bent portion 5b are inevitably the same, there is no significant change in the cross sectional shape along the flow in the suction pipe. Can be reduced.
[0074]
[Sixth Embodiment]
Next, a sixth embodiment will be described with reference to FIG. FIG. 6 is a view showing a method of manufacturing a suction pipe according to the sixth embodiment of the present invention.
[0075]
The shape dimensions of the suction pipe upper part 5a and the bent part 5b of the suction pipe 5 of the present embodiment are slightly changed so that the lateral width of the vertical section of the bent part 5b is not constant but increases toward the downstream side. Except for this point, this embodiment is the same as the fourth embodiment shown in FIG.
[0076]
Both side surfaces of the bent portion 5b are formed by combining a plurality of members obtained by dividing a straight pipe having a circular cross section into two parts. In FIG. 6, members denoted by reference numerals 5b1, 5b2, 5b3,..., 5b12 are members obtained by dividing a straight pipe having a circular cross section into two parts.
[0077]
Further, the inner surface and the outer surface of the bent portion 5b are formed by a single member 5bU and a member 5bL, respectively. The member 5bU and the member 5bL are bent at a portion corresponding to the joint between the members 5b1, 5b2, 5b3,..., 5b12 adjacent to each other, and are configured by a plurality of planes.
[0078]
These members 5b1, 5b2, 5b3,..., 5b12 and 5bU, 5bL are joined to each other by welding. Therefore, the members 5b1, 5b2, 5b3,..., 5b12 are connected to each other in the flow direction like a shrimp outer shell. In addition, the contact section of the members 5b1 to 5b12 is not perpendicular to the tube axis of the straight tube having the original circular cross section, but is inclined.
[0079]
In the suction pipe of this embodiment, the inlet cross-sectional shape of the bent portion 5b is the same shape as that of the third embodiment of the present invention, and is between the inner side surface and the outer side surface (surfaces facing each other in the lateral direction) of the bent portion. Since the distance is constant as in the fourth embodiment, the flow loss can be reduced as compared with the conventional suction pipe as in the third and fourth embodiments. In addition, the depth F of the suction pipe necessary for making the generated loss comparable is also shallower than that of the conventional suction pipe, and the amount of civil engineering excavation can be reduced.
[0080]
In the conventional method for manufacturing the suction pipe as shown in FIG. 9, in order to form the individual members 5b1, 5b2,..., The shape developed on the plane is obtained, cut out from the flat plate, and further bent. However, in this embodiment, it is only necessary to prepare a member obtained by cutting a circular tube and a member obtained by bending a flat plate, so that manufacturing is easy, and cost reduction and delivery time are shortened. realizable. In particular, since the members 5bL and 5bU have a broken line perpendicular to the flow direction but no projection perpendicular to the flow like a weld bead, the flow loss is smaller than that of the conventional suction pipe of FIG. Moreover, since it becomes possible to use a commercially available straight pipe depending on the required size of the circular pipe, it becomes possible to further facilitate manufacturing, reduce costs, and shorten delivery time.
[0081]
Further, by adopting the structure according to the present embodiment, the width of the flow path of the bent portion 5b can be changed and the degree of design freedom is increased. Therefore, the application range is larger than the structure described in the fourth embodiment. Become wider.
[0082]
【The invention's effect】
As described above, according to the present invention, it is possible to reduce the loss of the suction pipe, reduce the manufacturing cost, reduce the amount of civil engineering excavation, and thus provide a low-cost and highly efficient hydraulic machine. .
[Brief description of the drawings]
FIG. 1 is a view showing a suction pipe of a hydraulic machine according to a first embodiment of the present invention.
FIG. 2 is a view showing a suction pipe of a hydraulic machine according to a second embodiment of the present invention.
FIG. 3 is a view showing a suction pipe of a hydraulic machine according to a third embodiment of the present invention.
FIG. 4 is a view showing a suction pipe of a hydraulic machine according to a fourth embodiment of the present invention.
FIG. 5 is a view showing a suction pipe of a hydraulic machine according to a fifth embodiment of the present invention.
FIG. 6 is a view showing a suction pipe of a hydraulic machine according to a sixth embodiment of the present invention.
FIG. 7 is a diagram showing a configuration of a conventional hydraulic machine and a suction pipe.
FIG. 8 is a view showing a conventional method for manufacturing a suction pipe.
FIG. 9 is a view showing the shape of a conventional suction pipe.
[Explanation of symbols]
1 casing
2 impeller
5 Suction pipe
5a Top of the suction pipe
5b Bent part
5a1 1st expansion part of upper part of suction pipe (area other than predetermined area)
5a2 Second enlarged portion (predetermined area) at the top of the suction pipe

Claims (11)

A suction pipe upper part connected to the impeller outlet and a discharge pipe upper part connected to the impeller outlet; a bent part connected to the suction pipe upper part and changing a flow direction of the fluid passing through the suction pipe; In a suction pipe of a water turbine or a pump water turbine having
A cross section obtained by cutting a portion of the suction pipe with a plane perpendicular to the axial direction of the pipe line is called a vertical cross section in the portion, and a plane including the vertical cross section and an axis of the bent portion are When the direction of the straight line intersecting with the plane including the vertical direction of the vertical cross section, and the direction perpendicular to the vertical direction is called the horizontal direction of the vertical cross section,
A cross-sectional area of a vertical cross section in a predetermined range upstream from at least a boundary with the bent portion of the upper portion of the suction pipe increases as the distance from the impeller outlet increases, and the predetermined pipe A suction pipe of a water turbine or a pump water turbine, characterized in that the increasing ratio of the vertical width of the vertical section in the range is smaller than the increasing ratio of the horizontal width . 2. The turbine or pump turbine according to claim 1, wherein a vertical width of a vertical section of the predetermined range in the upper portion of the suction pipe is constant regardless of a distance from the outlet of the impeller. suction tube. The water wheel according to claim 1 or 2, wherein a vertical section at a boundary between the upper portion of the suction pipe and the bent portion is an ellipse having a major axis in the horizontal direction and a minor axis in the vertical direction. Pump water turbine suction pipe. The vertical cross section at the boundary between the upper portion of the suction pipe and the bent portion has an oval shape having an outline combining a pair of straight lines extending in a lateral direction and a pair of semicircles. The suction pipe of the water wheel or pump water wheel according to 1 or 2. Of the upper portion of the suction pipe, the vertical width of the vertical section of the predetermined region is constant regardless of the distance from the impeller outlet,
5. The predetermined range includes a pair of side surfaces facing each other in the lateral direction, and the pair of side surfaces is formed by a member obtained by dividing a straight pipe having a circular cross section into two parts. The suction pipe of the water wheel or pump water wheel described in 1. The contour of the vertical cross section of the bent portion has an oval shape having a contour combining a pair of straight lines and a pair of semicircles extending in the lateral direction regardless of the distance from the exit of the impeller, The portions corresponding to the pair of straight lines in the bent portion constitute a pair of first side surfaces facing each other in the vertical direction, and the portions corresponding to the pair of semicircles in the bent portion are related to the horizontal direction. A pair of second side surfaces facing each other,
The suction pipe of the water turbine or the pump turbine according to claim 1 or 2, wherein a distance between the pair of first side surfaces is constant regardless of a distance from the impeller outlet. The suction pipe of a water turbine or a pump turbine according to claim 6, wherein the second side surface of the bent portion is formed of a member obtained by dividing a pipe having a circular cross section along the axial direction thereof. The suction pipe of a water turbine or a pump turbine according to claim 6, wherein the first side surface of the bent portion is formed by a member obtained by bending a flat plate. The vertical section of the bent portion has a contour combining a pair of straight lines extending in the lateral direction regardless of the distance from the impeller outlet and a pair of curves connecting both ends of the pair of straight lines. And the lateral width of the vertical cross section of the bent portion is larger than the vertical width,
The portions corresponding to the pair of straight lines in the bent portion constitute a pair of first side surfaces facing each other in the vertical direction, and the portions corresponding to the pair of curves in the bent portion are mutually in the horizontal direction. The suction pipe of the water turbine or the pump water turbine according to claim 1 or 2, wherein a pair of opposing second side surfaces are formed. The second side surface of the bent portion is formed by joining a plurality of members obtained by cutting a tube having a circular cross section along a direction intersecting its axis. Item 10. A suction pipe of a water turbine or a pump water turbine according to Item 9. The suction pipe of a water turbine or a pump turbine according to claim 9, wherein the first side surface of the bent portion is formed by a member obtained by bending a flat plate along a plurality of bending lines.

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