پديد آورندگان :
آﻗﺎﯾﯽ، ﺳﻤﺎﻧﻪ داﻧﺸﮕﺎه ﺻﻨﻌﺘﯽ ﻧﻮﺷﯿﺮواﻧﯽ ﺑﺎﺑﻞ، ﺑﺎﺑﻞ، اﯾﺮان , ﺣﻤﯿﺪي، ﻣﻬﺪي داﻧﺸﮕﺎه ﺻﻨﻌﺘﯽ ﻧﻮﺷﯿﺮواﻧﯽ ﺑﺎﺑﻞ - داﻧﺸﮑﺪه ﻣﻬﻨﺪﺳﯽ ﻋﻤﺮان، ﺑﺎﺑﻞ، اﯾﺮان , ﻣﻠﮏ ﭘﻮر، اﺣﻤﺪ ﮔﺮوه ﻫﯿﺪروﻟﯿﮑﯽ ﻧﻮآور، ﺗﻮرﻧﺘﻮ، ﮐﺎﻧﺎدا
كليدواژه :
ﭘﺮﮐﺮدن ﺧﻄﻮط ﻟﻮﻟﻪ , ﺑﺴﺘﻪ ﻫﻮاي ﻣﺤﺒﻮس , ﮐﻨﺎرﮔﺬر و ﺟﺮﯾﺎن ﮔﺬرا , ﺟﺪاﯾﯽ ﺳﺘﻮن
چكيده فارسي :
ﺗﻌﻤﯿﺮات در ﺧﻄﻮط ﻟﻮﻟﻪ اﻣﺮي اﺟﺘﻨﺎب ﻧﺎﭘﺬﯾﺮ اﺳﺖ. ﺟﻬﺖ اﻧﺠﺎم ﺗﻌﻤﯿﺮات در ﺑﺨﺸﯽ از ﺧﻄﻮط ﻟﻮﻟﻪ، ﻧﯿﺎز ﺑﻪ ﻗﻄﻊ ﺟﺮﯾــﺎن و ﺳــﭙﺲ ﭘﺮﮐﺮدن ﻣﺠﺪد آن اﺳﺖ. ﻧﺤﻮه ﭘﺮﮐﺮدن ﻟﻮﻟﻪ ﺑﺴﯿﺎر ﻣﻬﻢ ﺑﻮده و ﻋﺪم وﺟﻮد ﯾﮏ دﺳﺘﻮراﻟﻌﻤﻞ ﺑﻬﺮهﺑﺮداري ﻣﻨﺎﺳﺐ ﻣﯽﺗﻮاﻧﺪ ﻣﻨﺠﺮ ﺑﻪ ﺗﺨﺮﯾﺐ ﺧﻂ ﻟﻮﻟﻪ ﮔﺮدد. ﺗﺎﮐﻨﻮن اﺛﺮات اﺳﺘﻔﺎده از ﮐﻨﺎرﮔﺬر در ﺣﯿﻦ ﭘﺮﮐﺮدن ﺧﻂ ﻟﻮﻟﻪ ﻣﻮرد ﻣﻄﺎﻟﻌﻪ ﺳﯿﺴﺘﻤﺎﺗﯿﮏ ﻗﺮارﻧﮕﺮﻓﺘﻪ اﺳﺖ. در اﯾﻦ ﻣﻘﺎﻟﻪ ﯾﮏ ﻣــﺪل رﯾﺎﺿﯽ ﯾﮏ ﺑﻌﺪي اﻻﺳﺘﯿﮏ ﺟﻬﺖ ﻣﺪلﺳﺎزي ﻓﺮآﯾﻨﺪ ﭘﺮﮐﺮدن ﺧﻄﻮط ﻟﻮﻟﻪ ﻣﻌﺮﻓﯽ ﺷﺪه اﺳﺖ. ﭘﺲ از ﺻﺤﺖﺳﻨﺠﯽ، اﯾﻦ ﻣﺪل ﺑﻪﻋﻨﻮان اﺑﺰاري ﺟﻬﺖ ﺷﻨﺎﺳﺎﯾﯽ ﻋﻮاﻣﻞ ﻣﻮﺛﺮ ﺑﺮ ﻓﺮآﯾﻨﺪ ﭘﺮﮐﺮدن ﻟﻮﻟﻪ اﺳﺘﻔﺎده ﺷﺪهاﺳﺖ. ﺑﺎ اﺳﺘﻔﺎده از ﻣﺪل ﻣﻌﺮﻓﯽ ﺷﺪه، اﺛﺮات ﻫﯿﺪروﻟﯿﮑﯽ ﮐﻨﺎرﮔــﺬر در ﺣــ ﯿﻦ ﭘﺮﮐﺮدن ﯾﮏ ﺧﻂ ﻟﻮﻟﻪ ﻃﻮﯾﻞ داراي ﻓﺮاز و ﻧﺸﯿﺐ ﻓﺮﺿﯽ، ﻗﺎﺑﻞ ﺗﻌﻤﯿﻢ ﺑــﻪ ﺧﻄــﻮط ﻟﻮﻟــﻪ واﻗﻌــﯽ، ﺑﺮرﺳــﯽ ﺷــﺪه اﺳــﺖ. ﻣــﺪل ﻣــﺬﮐﻮر ﻗﺎﺑﻠﯿــﺖ ﺷﺒﯿﻪﺳﺎزي ﺟﺮﯾﺎن ﮔﺬراي اﯾﺠﺎد ﺷﺪه در زﻣﺎن ﭘﺮﮐﺮدن ﻟﻮﻟﻪ را داﺷﺘﻪ و ﻗﺎدر اﺳﺖ ﮐﻪ ﺟﺪاﯾﯽ ﺳــﺘﻮن آب را ﻣﺪلﺳــﺎزي ﻧﻤﺎﯾــﺪ. ﺣــﻞ ﻋــﺪدي ﻣﻌﺎدﻻت ﺗﻮﺳﻂ روش ﻣﺸﺨﺼﻪ و ﺟﺪاﯾﯽ ﺳﺘﻮن آب ﺗﻮﺳﻂ روش ﺣﻔﺮه ﮔﺎز ﻣﻨﻘﻄــﻊ اﻧﺠــﺎم ﺷــﺪه اﺳــﺖ. ﻧﺘــﺎﯾﺞ ﺣﺎﺻــﻞ از ﻣﺪلﺳــﺎزي ﻧﺸــﺎن ﻣﯽدﻫﻨﺪ ﮐﻪ ﻧﺒﻮد ﯾﮏ ﺑﺮﻧﺎﻣﻪ ﺑﻬﺮهﺑﺮداري دﻗﯿﻖ و ﻋﺪم وﺟﻮد ﺗﺠﻬﯿﺰات ﻫﯿﺪروﻣﮑﺎﻧﯿﮑﺎل ﺑﺎ اﺑﻌﺎد ﻣﻨﺎﺳﺐ ﻣﯽﺗﻮاﻧــﺪ ﻣﻨﺠــﺮ ﺑــﻪ اﯾﺠــﺎد ﻓﺸــﺎرﻫﺎي ﻣﺜﺒﺖ و ﻣﻨﻔﯽ ﻣﺨﺮب در ﺧﻂ ﻟﻮﻟﻪ ﮔﺮدد. ﻧﺘﺎﯾﺞ ﺣﺎﺻﻞ از اﯾﻦ ﻣﻘﺎﻟﻪ ﻧﺸﺎن ﻣﯽدﻫﺪ ﮐﻪ ﻃﺮاﺣﯽ ﻣﻨﺎﺳﺐ ﻗﻄﺮ روزﻧﻪ ﺧﺮوج ﻫــﻮا ﺑــﻪ ﻫﻤــﺮاه ﯾــﮏ ﮐﻨﺎرﮔﺬر ﺑﺎ اﺑﻌﺎد ﻣﻨﺎﺳﺐ و ﻫﻤﭽﻨﯿﻦ ﺑﺎزﮐﺮدن ﺷﯿﺮ ﮐﻨﺘﺮل در زﻣﺎن ﻣﻨﺎﺳﺐ ﺑﺎﻋﺚ ﻣﯽﺷﻮد ﮐﻪ ﺣﺪاﮐﺜﺮ و ﺣﺪاﻗﻞ ﻓﺸــﺎرﻫﺎي ﮔــﺬرا در ﻣﺤــﺪوده ﻗﺎﺑﻞ ﻗﺒﻮﻟﯽ ﺑﺎﻗﯽ ﺑﻤﺎﻧﺪ و ﭘﺮﮐﺮدن در ﺳﺮﯾﻊﺗﺮﯾﻦ زﻣﺎن ﻣﻤﮑﻦ اﻧﺠﺎم ﺷﻮد.
چكيده لاتين :
Introduction: It is common practice to partially drain pipelines for inspection and repair. If not adequately controlled, refilling the pipeline can expose them to significant transient pressures that can compromise the integrity of the pipeline and associated connections. So far, the effects of using bypasses in pipelines during pipeline filling have not been systematically studied. This research has investigated the key factors affecting filling hydraulics using a numerical investigation. For this purpose, a numerical model for calculating the filling hydraulics is proposed. The model uses the method of characteristics to solve the water hammer equations and utilizes the discrete gas cavity model (DGCM) to handle column separation. The model is validated with the experiment and the numerical model presented in the literature. Extensive numerical exploration shows that the lack of a safe filling protocol and the absence or inadequate sizing of the required hydro-mechanical equipment can result in significant water hammer pressures. The results also conclude that it is impossible to control transient pressures during filling without a properly sized bypass and air valve.
Methodology: Extensive numerical exploration with a hypothetical water pipe system is performed to analyze the key factors affecting the transient pressures induced during filling. The pipeline has an undulating profile with a diameter, length, and acoustic wave speed of 0.9 m, 15900 m, and 1000 m/s, respectively. The pipeline is supplied by a reservoir with a constant water depth of 5m located at the upstream end of the pipeline. The last 1600m of the pipeline is assumed to be empty, and an air valve at the end of this section allows for air management during filling. A bypass line at the upstream end of the empty zone is equipped with a flow control valve to control the filling flow rate. Several numerical analyses are conducted with different sizes of the air valve, bypass line, and opening times of the flow control valve, and the maximum and minimum pressure heads induced during filling are recorded.
Results and Discussion: The analysis of the numerical results shows that when the flow control valve opens, the empty pipeline fills with a flow rate that depends on the size of the bypass and the opening time of the valve. The rapid opening of a large bypass results in significant positive and negative water hammer pressures in the system. The water column front in the empty pipe acts as a piston and pushes the air out of the system through the air valve. If the outlet opening of the air valve is large enough, the air pressure in the empty pipe does not increase significantly; otherwise, higher air pressures will build up, which can slow down the filling water column. When the last air escapes from the system, the water column is arrested, and significant water hammer pressures develop. The magnitude of the resulting water hammer pressure depends on the speed at which the water column hits the end of the pipe and the pipe acoustic wave speed. Numerical investigations show that the intensity of the induced water hammer pressures rests on the diameters of the air valve outlet orifice and the bypass, and the opening time of the flow control valve. For this particular case study, the bypass line diameter = 0.2 m, the orifice diameter of the air valve = 1.5 cm, and the opening time of the control valve = 40 s can control the maximum and minimum pressures within the acceptable range without unduly prolonging the filling time.
Conclusion: The proposed model can be successfully used to analyze the filling hydraulics and design a safe filling protocol. The main findings of this study are as follow:
• Without a proper filling protocol, the resulting transient pressures can be severe enough to rupture the pipeline
• Without a bypass, it is impossible to control negative pressures
• The opening rate of the flow control valve could play an essential role in controlling negative pressures
• Reducing the diameter of the air valve's outlet orifice reduces the resulting transient pressures and prolongs the filling
• An optimal filling protocol can be obtained by an iterative procedure in which the bypass and air valve diameters and the opening time of the flow control valve are determined.
