Research of performance prediction to energy on hydraulic turbine

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IOP Conference Series: Earth and Environmental Science Research of performance prediction to energy on hydraulic turbine To cite this article: H Quan et al 2012 IOP Conf. Ser.: Earth Environ. Sci. 15 032013 View the article online for updates and enhancements.

1 IOP Conference Series: Earth and Environmental Science Research of performance prediction to energy on hydraulic turbine To cite this article: H Quan et al 2012 IOP Conf. Ser.: Earth Environ. Sci View the article online for updates and enhancements. Related content - The impact of inlet angle and outlet angle of guide vane on pump in reversal based hydraulic turbine performance F X Shi, J H Yang, X H Wang et al. - Experimental and numerical study on inlet and outlet conditions of a bulb turbine with considering free surface Y P Zhao, W L Liao, H D Feng et al. - Numerical simulation of pressure pulsations in Francis turbines M V Magnoli and R Schilling This content was downloaded from IP address on 14/08/2018 at 20:23

2 Research of performance prediction to energy on hydraulic turbine H Quan 1, R N Li 1, Q F Li 1, W Han 1 and Q M Su 2 1. School of Energy and Power Engineering, Lanzhou Univ. of tech., Lanzhou , China 2. School of Petrochemical Technology, Lanzhou Univ. of tech., Lanzhou , China quanh2010@163.com Abstract. Refer to the low specific speed Francis turbine blade design principle and doublesuction pump structure. Then, design a horizontal double-channel hydraulic turbine Francis. Through adding different guide vane airfoil and and no guide vane airfoil on the hydraulic conductivity components to predict hydraulic turbine energy and using Fluent software to numerical simulation that the operating conditions and point. The results show that the blade pressure surface and suction surface pressure is low when the hydraulic turbine installation is added standard positive curvature of the guide vane and modified positive curvature of guide vane. Therefore, the efficiency of energy recovery is low. However, the pressure of negative curvature guide vane and symmetric guide vane added on hydraulic turbine installations is larger than that of the former ones, and it is conducive to working of runner. With the decreasing of guide vane opening, increasing of inlet angle, flow state gets significantly worse. Then, others obvious phenomena are that the reflux and horizontal flow appeared in blade pressure surface. At the same time, the vortex was formed in Leaf Road, leading to the loss of energy. Through analyzing the distribution of pressure, velocity, flow lines of overcurrent flow in the the back hydraulic conductivity components in above programs we can known that the hydraulic turbine installation added guide vane is more reasonable than without guide vanes, it is conducive to improve efficiency of energy conversion. 1. Introduction In the existing petroleum, chemical industry, sea water desalination and high energy consumption production enterprise, general there is a process phenomenon that many high pressure fluid through pressure reducing valve to the required must be low voltage or direct emissions. In the process of pressure and discharge, a large amount of fluid pressure can be changed into heat energy that lost in the environment, which caused this part of the energy of the waste directly. Hydraulic turbine energy recovery device put fluid pressure can be transformed into mechanical energy, or electric power, working process is in the role of high pressure fluid turbine wheels, produce the output power of shaft, to drive the other mechanical energy consumption. All places exist poor liquid pressure have energy to recycle. Excess pressure in industrial production is renewable energy, using hydraulic turbine to replace pressure reducing valve can avoid the waste of complementary energy. If the hydraulic turbine will recycle this part of energy, more complementary energy can be used for reproduction,. so in the long term of the production process, the profit to the enterprise is very considerable. Published under licence by Ltd 1

Therefore, basing on the design principles of low mix-flow turbine blades and the structural models of double suction pump in this paper, the full port of the Hydraulic turbine was used by hydraulic

field. The numerical simulation is conducted on the base of performance prediction and achieve structure optimization, which replace the traditional model test.

It also had a significant guidance to the energy recovery of hydraulic turbine machine. 2. The models description and calculation methods 2.1.

3 Therefore, basing on the design principles of low mix-flow turbine blades and the structural models of double suction pump in this paper, the full port of the Hydraulic turbine was used by hydraulic design and 3d model, using Computational Fluid Dynamics (here in after referred to as CFD) to analyse the numerical simulation of software hydraulic turbine's full port complex turbulent in flow field. The numerical simulation is conducted on the base of performance prediction and achieve structure optimization, which replace the traditional model test. And the wheel was the core part of energy conversion, successfully carry on the forecast of hydraulic turbine runner energy performance. It also had a significant guidance to the energy recovery of hydraulic turbine machine. 2. The models description and calculation methods 2.1. The basic parameters and the models of the double passages hydraulic turbine machine model. Table 1. The basic technical parameters parameters Numerical value Design discharge Q/ m 3 /h 600 Design head H/m 70 Rotating speed n/r/min 2980 The guide vane numbers z o /n 16 Guide vane height b/m 44 Guide vane distribution cirle diameter D 0 /mm 215 Runner reel nominal D 0 /mm 180 Runner reel blade number z o /n 16 In this paper numerical simulation of the area of horizontal hydraulic turbine machine after combine actual situation Francis spiral case was imported to the half spiral pipe of the whole flow the export, mainly including the diffuser area, lead water agencies, wheel area and the area conduit export area. In Pro/E software platform, base the hydraulic turbine with CAD machine flow components of hydraulic turbine 2d graphics to complete the whole 3d model of the machine. Among them, the 3d model runner diagram and the hydraulic turbine machine 3d model and its whole cutting graph respectively as shown in figure 1 and figure 2 shows. Figure 1. The 3d model runner figure Figure 2. Hydraulic turbine machine 3d model and its whole cutting figure 2

4 2.2. Basic assumption The flow of the mix-flow turbine runner hydraulic machine actually is very complicated. But, in order to a variety of engineering problems, the researchers had to make some simplified and assumptions to the actual flow to the real fluid. At present, in the hydraulic design, the mix-flow turbine runner of hydraulic machine is still hypothesizing like this: First, the liquid is ideal. Second, the relative motion of the fluid in wheel is a constant movement. Third, the number of leaf number is infinite and the thickness the leaf is infinitely thin. Forth the flow in the runner is fluid in the axial symmetry The numerical method The import boundary conditions. The hydraulic turbine machine imported has a stable differential pressure, small flow characteristic, so use the pressure import boundary conditions in this paper The outlet boundary conditions. When the choose of the imported boundary conditions of the hydraulic turbine machine is pressure conditions, it cannot be used the assumption that flow in the diffusion fluxes of all variables for 0 the full development of the conditions (outflow), which will lead to the fluent out of work, so use the pressure outlet boundary The solid wall conditions. In the near wall flow near the area, take standard wall function, wheel and upstream and downstream flow components of the connection by setting up action coupling face realized. 3. The selection of the research scheme In order to discuss the influence of the structure of the hydraulic turbine machine to hydraulic performance, according to the analysis, hydraulic turbine in the water of the machine parts has no guide blade (scheme Ⅰ), add standard curvature guide blade (scheme Ⅱ), the retrofit of the curvature guide vane (scheme Ⅲ), negative curvature guide blade (scheme Ⅳ) and symmetric type guide blade (scheme Ⅴ) to study its properties. The airfoil profile is shown in figure 3 below. Figure 3. The airfoil profile 4. Performance prediction to energy on hydraulic turbine runner Under different conditions to complete the numerical simulation on complex turbulence flow through the full passage of a hydraulic turbine, the following formula can be applied to predict the runner s efficiency and power and then provided abundant reference for structural optimization of the installations. The runner efficiency is calculated by: η ( Γ Γ ) ω 2π gh 1 2 = (1) where η is hydraulic turbine runner efficiency, Г 1 and Г 2 are respectively the velocity circulation of the inlet and outlet, ω the angular velocity of the hydraulic turbine runner, g the acceleration of gravity, H the working head of hydraulic turbine. 3

5 The hydraulic turbine runner power can be expressed as: N = M ω =ΔP Q η (2) The working head of hydraulic turbine can be expressed as: 2 2 P1 P2 V1 V2 H = ( Z1 Z2) + + (3) ρg 2g where Z 1,Z 2 are respectively the inlet and outlet position height which relative to a datum. P 1,P 2 are respectively the pressure of the inlet and outlet. V 1,V 2 are respectively the average absolute velocity of the flow cross sections at the inlet and outlet The performance prediction calculation conditions table According to the hydraulic turbine design parameters and possible range of operation, and in the case of maintaining unit velocity unchanged, the paper s numerical analysis of interior flow field of hydraulic turbine is in the hydraulic turbine without guide vanes and adds four different airfoil guide vanes under the 70m-head, and select five operating points respectively which under the different gate openings, then the detailed numerical simulation of internal flow in hydraulic turbine under all conditions was carried out which obtained flow characteristics of the flow passage components. The operating point parameters showed in Table 2. Table 2. Numerical analysis of hydraulic turbine calculation conditions table scheme working head H/m number Ⅰ 70 guide vane a0/mm Ⅱ Ⅲ Ⅳ Ⅴ Performance prediction results and working characteristic curve According to the performance prediction results in different operating points of the design scheme from table2,the flow and efficiency working characteristics curve of the hydraulic turbine which in different programs can be drawn, and as shown in figure 4. As can be seen from the figure, optimum operating point flow of the design scheme is basically the design flow which meets the design requirements. In the large flow conditions, the relation curve distribution between flow and efficiency is almost in line which during the scheme Ⅲ Ⅳ Ⅴ, only the efficiency of the schemeⅠis more than a percentage point lower which compared to other programs, but when the deviation from the optimum operating point flow about 30%, the efficiency of the schemeⅡis higher than other programs, which indicates that the standard form of the positive curvature vane is more suitable for the large flow conditions; In the small flow conditions, the degrade gradient in the efficiency of the schemeⅡis large, while in other design schemes, especially the scheme Ⅱ, with the flow reduction, the decreased amplitude of efficiency is very small, and which indicates that the section of highest hydraulic efficiency of hydraulic turbine is wide under this design and suitable for the practical application of hydraulic turbine. The highest efficiency of the hydraulic turbine in the scheme Ⅳ is 88% when H=70 m, Q= m 3 /s, and the efficiency of the main operating point are above 80%, basically meet the design requirements of the hydraulic turbine. 4

6 Figure 4. The Flow Working Characteristics Curve of the Hydraulic Turbine 4.3. Analysis of the hydraulic loss Since this paper makes a multi-program design comparison about the guide components of the hydraulic turbine to search for the most appropriate design program, and then analyzes the hydraulic loss of the diversion components and the guide components of the hydraulic turbine under the design scheme, which is defined as: e loss ein eout = 100% (4) ρgh where e in is total energy at the spiral case inlet, e out is total energy at runner blade inlet and also the total energy at guide apparatus outlet, H is specified calculation head. For the diversion components and the guide components of the hydraulic turbine, the hydraulic losses basically from eddy loss, impact loss generated when the flow around the guide vane, skin friction loss and wake loss etc. Especially in non-optimum operating point, impingement loss of the guide vane head occupies the dominant position in the hydraulic losses of the diversion components and the guide components. For the convenience of computing, the gross energy at import and export was substituted by the total pressure at import and export.the follows show the hydraulic losses of the diversion components and the guide components in the optimum working conditions of the design scheme, as shown in Table 3. Table 3. The hydraulic loss of the diversion components and the guide components comparison scheme number total pressure of volute inlet (Pa) total pressure of runner blade (Pa) hydraulic losses eloss(%) Ⅰ Ⅱ Ⅲ Ⅳ Ⅴ As can be seen from the table, the hydraulic losses of the diversion components and the guide components of the hydraulic turbine without guide vanes are very small, while in several programs of adding guide vanes, the loss of scheme Ⅱ higher than the other three programs 0.7%~1.13% by adding head thicker guide vanes, and the hydraulic loss of scheme Ⅳ is the minimum which contribute to achieving the purpose of maximizing energy recovery. 5

4.4. The numerical simulation results and analysis In order to explore the effects of presence or absence of the guide vane on the

of without guide vane (scheme I) and adding the standard form of the positive curvature vane(scheme II)were explored on pressure

Figure 5 are the numerical simulation results of both schemes.

Figure 5. Pressure Surface and Suction Surface Velocity Vector Figure 6.

of designs in respective optimum operating conditions as shown in figure 5 See from Table 3 that in the case of identical or similar

energy recovery is 82.78% which higher than the latter 8.57%, and vastly improved the efficiency of hydraulic turbine energy recovery.

tangential velocity reflects the velocity circulation distribution and it is an important index of energy conversion performance.

greatly, overall import surfaces tangential velocity cloud chart becomes clearer, the tangential velocity circulation Г=2π v u r along

7 4.4. The numerical simulation results and analysis In order to explore the effects of presence or absence of the guide vane on the hydraulic performance of hydraulic turbine, following in respective optimum operating conditions, the feasibility of hydraulic turbine of without guide vane (scheme I) and adding the standard form of the positive curvature vane(scheme II)were explored on pressure distribution, velocity distribution, current line and other aspects in some computational domain. Figure 5 are the numerical simulation results of both schemes. The pressure and suction surface velocity vector of scheme Ⅰand Ⅱ The pressure and suction surface pressure contours of scheme Ⅰand Ⅱ Figure 5. Pressure Surface and Suction Surface Velocity Vector Figure 6. Scheme I and II Pressure Surface and Suction Surface Pressure Distribution In the same boundary condition, the efficiency of a variety of designs in respective optimum operating conditions as shown in figure 5 See from Table 3 that in the case of identical or similar flow, with guide vanes and without guide vanes of hydraulic turbine efficiency are not alike, the former maximum efficiency of the energy recovery is 82.78% which higher than the latter 8.57%, and vastly improved the efficiency of hydraulic turbine energy recovery. The reasons as following: (1) In hydraulic turbine runner blade imported torus, whose radius is a constant, so the distribution of tangential velocity reflects the velocity circulation distribution and it is an important index of energy conversion performance. Because the diversion of guide vanes, the runner blade import flows along the circumferential circulation distribution improved greatly, overall import surfaces tangential velocity cloud chart becomes clearer, the tangential velocity circulation Г=2π v u r along the blade imported torus, whose extreme value disparities have eased into uniform. It shows that guide vane can improve the circumferential heterogeneity of the flow, plays the partial amendment to circulation role, and is conducive to flow evenly into the runner blades, so as to achieve the efficient and stable running. 6

8 (2) Hydraulic turbine runner is the work parts. Energy conversion was carried out between the runner with blade and the medium of continuous flow around the blade, the advantages and disadvantages of velocity and pressure distribution on the surface of runner blade is related to the level of energy conversion index of the hydraulic turbine, the fail-safe operation of the unit and its service life. In scheme I, Since there is no drainage of guide vanes to the water current which out from the volute case, leading to impingement on the pressure surface inlet produced by water current, thus giving rise to uneven distribution of pressure surface velocity, forming vortex, increasing the hydraulic losses, resulting in reduced efficiency. As shown in Figure 3;In scheme II, whether it is pressure or suction surface the velocity distribution is relatively uniform, which from the inlet edge of blade flows evenly to the outlet have no clear separation, back flow, lateral flow etc. other secondary flow phenomenon, overall flows smoothly, as shown in Figure 5,6 shows: Without the guide vane, the pressure distributes unevenly on the pressure surface and suction surface, the high-pressure region as shown formed in the cutwater of the pressure surface, while at the inlet edge of blade, the pressure surface pressure is less than the suction surface pressure and is not conducive to energy conversion; In scheme II, the pressure are gradually reduced from the pressure surface to suction surface, which also presented a regular downward trend from the inlet to the outlet, consistent with principles of hydraulic turbine accomplish work and conducive to the efficient conversion of energy. 5. Conclusions Through the numerical analysis for the running operating points of several programs of adding different airfoil guide vanes on the guide components and without guide vanes concludes that the hydraulic losses of the diversion components and the guide components of the hydraulic turbine without guide vanes are very small, and that in the case of identical or similar flow, with guide vanes and without guide vanes of hydraulic turbine efficiency are not alike, the former maximum efficiency of the energy recovery is higher than the latter, which vastly improved the efficiency of hydraulic turbine energy recovery and contribute to achieving the purpose of maximizing energy recovery. References [1] Thompson J F, Warsi Z V A and Mastin C W 1982 Journal of Computational Physics 47(1) [2] Hakan N and Lars D 2001 A validation of Parallel multiblock CFD against the GAMM Francis water turbine runner at best efficiency and off-design operating conditions (Goteborg,Sweden,2001) [3] Jacoben O, et al Three-Dimensional turbulent flow simulation in hydraulic machinery Proc.of 15th IAHR Symp. Paper C [4] Hellstroem J G I, Marjavaara B D and Lundstroem T S 2007 Advances in Engineering Software 38(5) [5] Liu S H, Wu Y L, Zhang L, Xu Y and Tsujimoto Y 2009 International Journal of Nonlinear Sciences and Numerical Simulation

The impact of inlet angle and outlet angle of guide vane on pump in reversal based hydraulic turbine performance

IOP Conference Series: Earth and Environmental Science The impact of inlet angle and outlet angle of guide vane on pump in reversal based hydraulic turbine performance To cite this article: F X Shi et