Axial pico turbine construction and experimental research

Transcription

1 IOP Conference Serie: Material Science and Engineering PAPER OPEN ACCESS Axial pico turbine contruction and experiental reearch To cite thi article: G. Peczki et al 017 IOP Conf. Ser.: Mater. Sci. Eng View the article online for update and enhanceent. Related content - Nuerical invetigation of the flow in axial water turbine and arine propeller with cale-reolving iulation Mitja Morgut, Dragica Jošt, Enrico Nobile et al. - Theoretical and experiental reearch of organic Rankine cycle tea turbine plant A A Kihkin, A V Delkov and M G Melkozerov - Experiental reearch on quality feature of etallurgical coke V Andrei and N Contantin Thi content wa downloaded fro IP addre on 05/1/017 at 08:53

2 (HERVICON+PUMPS-017) IOP Conf. Serie: Material Science and Engineering (017) doi: / x/33/1/01016 Axial pico turbine contruction and experiental reearch G. Peczki 1, Z Goryca, A Korczak 1 1 Politechnika Śląka, St. Konarki 18 Street, Gliwice, Poland Kielce Univerity of Technology, Aleja Tyiąclecia Pańtwa Polkiego 7, PL Kielce, Poland E-ail: peczki@wp.pl Abtract: The paper concern axial water turbine of power equal to 1 kw. The exaple of axial water turbine contructional calculation wa provided, a well a turbine rotor contruction with NACA profile blade. The laboratory tet rig deigned and built to perfor eaureent on pico turbine wa decribed. The turbine drove three-phae electrical generator. On the bai of highet efficiency paraeter, pico turbine baic characteritic were elaborated. The experiental reearch reult indicated that pico turbine can achieve axiu efficiency cloe to the value of larger water turbine. 1. Introduction The ot prevalent natural hydrological condition in the lowland, predoinating in Central Europe, are characterized by low head in all and ediu watercoure flow rate. Such condition favor ue of water head energy by ean of water wheel, Bank - Mitchell turbine and propeller turbine [3]. Rational location for thee turbine poible intallation are largely dipered, o that their power do not uually exceed everal to everal dozen kw. Claification of hydropower plant, according to capacity intalled: Large hydropower plant > 10 MW, Sall hydropower plant (MEW) < 10 MW, including: ini < 1 MW, icro < 100 kw, pico < 5 kw. The paper concern contruction, experiental reearch and aeent of pico turbine perforance, which i deigned to work in following condition: - water coure with low head and low dicharge, - regeneration, Moreover, the invetigated contruction can be concerned a the odel achine for the higher capacity turbine..water turbine efficiency The deciion concerning contructing and building a power achine reult, aong other, fro efficiency that it can achieve. In Figure 1. the chart how hydraulic loe, which for turbine with ipeller diaeter <0,46 grow progreively. Content fro thi work ay be ued under the ter of the Creative Coon Attribution 3.0 licence. Any further ditribution of thi work ut aintain attribution to the author() and the title of the work, journal citation and DOI. Publihed under licence by Ltd 1

3 (HERVICON+PUMPS-017) IOP Conf. Serie: Material Science and Engineering (017) doi: / x/33/1/01016 Figure 1. Hydraulic loe in axial turbine a function of Reynold nuber [A.M. Chrytjakov]. Reynold nuber for propeller turbine i a follow [1]: d gh Re 3 (1) where: d 3 propeller turbine outlet diaeter, H water head, v kineatic vicoity, g gravitational acceleration, According to Figure 1, the pico turbine are characterized by additional hydraulic loe, reulting fro low Reynold nuber. The epirical invetigation i jutified, a it ai to iniize the total lo during achine perforance. The eaureent on pico turbine can be carried out on the achine with caling factor 1. On the bai of dynaic iilarity the reult of the eaureent can be ued a the odel tet in deigning proce of geoetrical iilar, higher capacity achine. 3 For the pecific peed n b 0, 33 and dicharge Q 0,65 total efficiency C can be obtained fro: Q 0,07 5 C 0, 7 log nb 0, 814 () 0,048 where 0, for one tage turbine. The total efficiency obtained fro experient invetigation wa proved by reult of calculation conducted according to cited forula. The hydraulic efficiencie h of a turbine cannot be obtained fro experient reult, but they are neceary for contructional calculation. They are deterined according to following forula propoed by: Wilicenu 0,0 0,06 0,88 0, 84 (3) h C 0,4 Loakin h 1 0, 85 (4) 3 Q log4, ,17 60n

4 (HERVICON+PUMPS-017) IOP Conf. Serie: Material Science and Engineering (017) doi: / x/33/1/01016 Jekat 0,8 h 1 0,86 (5) 0, ,3Q 3 Q Michajlow 0 7, 0,0835log h 0, 84 (6) 60n The reearch decribed in thi article ai to verify the accuracy of thee forula on the bai of epirical invetigation of achine perforance. Due to the diaeter of pico turbine d<0,5 for contruction calculation the auption of h 0, 75 wa done. 3. Deterination of principle dienion of axial turbine rotor During contruction proce the highet efficiency operating condition were aued, what wa proved in epirical invetigation: 3 flow rate Q 4, head H,, rotational peed in The dynaic pecific peed n fro forula: n obr n 850 in Q 3,65n 476 (7) 0, 75 H The pecific peed n b, ued in following calculation [3]: n nb 0,39 (8) 113,9 The value of pecific peed indicate that the invetigated turbine i an axial one. The power on turbine haft i defined a: Meridional velocity: c gpqh P (9) h K YN,07 (10) Figure. The relation between the pecific peed and K coefficient. 3

5 (HERVICON+PUMPS-017) IOP Conf. Serie: Material Science and Engineering (017) doi: / x/33/1/01016 The coefficient K for the average eridional velocity can be obtained fro the chart (Figure ) or by the forula: Turbine rotor diaeter ratio can be calculated fro: Meridional velocity: D D The diaeter D A can be deterined: K n A c D 1,1 b 0,0688 0, 733n 0,331 (11) n 0,5 0, 584 0,630,346 (1) A D D b Q Qz,11 (13) 4 n A 4 Q Qz Dn c 1 D A 0,8 (13a) Figure 3. The diaeter of deigned turbine rotor. With the auption of contant eridional velocity and dividing the flow between the diaeter D A, C, S, D, B hown in Figure 3 equally, thee diaeter can be calculated fro: D S DA Dn DS DA DB DS 0,187 DC 0,08 DD 0,16 ( 14 a,b,c) Figure 4. Velocity triangle of axial rotor. The change of tangential coponent of rotor velocity on diaeter D i equal to: cu1 cu r,19 (15) 4

6 (HERVICON+PUMPS-017) IOP Conf. Serie: Material Science and Engineering (017) doi: / x/33/1/01016 Where - circulation around rotor blade foil, which i defined a: hgh r 1,8 (16) u The average tangential coponent of relative velocity (Figure 4) i: The change of tangential coponent of relative velocity: Auing c = c it can be tated: The theoretical angle wu1 wu gh wu u (17) u u u u1 h w w w (18) c arctg (19) w u, ha to be increaed by an additional angle Δβ = Δδ and a a reult, the angle of attack e 157, i obtained for rotor outer diaeter. The angle e for other trealine i calculated in the ae way. Figure 5. The hape of NACA 41 profile, ued to deign the blade. 4. Axial turbine blade deign proce The hape of turbine blade were deigned on bai of NACA 41 foil (Figure 5). The foil i decribed by characteritic dienion ratio. The profile ketch wa drawn on XY plane. Next, the profile chord wa increaed, with proportion kept. Then it wa decided to change the proportion, o that the thickne of blade wa reduced to technologically poible iniu. The obtained blade profile no longer kept the proportion of original NACA 41 profile, particularly the ratio between the axiu thickne and chord length wa interrupted. In Figure 6 the different rotor diaeter profile obtained fro thi ethod are hown. Figure 6. NACA profile for different rotor diaeter. 5

7 (HERVICON+PUMPS-017) IOP Conf. Serie: Material Science and Engineering (017) doi: / x/33/1/01016 Next contructional work, perfored in XYZ coordination yte, included connecting different diaeter profile with one urface and blade root, which enable proper, explicit connection with the rotor hub. The hape of blade in hown in Figure 7. In the invetigated contruction, the blade i placed on cylinder hub, o that the angle of attack change are not poible. The blade placing on a hub reult in one configuration, hown in Figure 8. The change of blade angle i poible only in cae of at leat partial pherical hub. Preented turbine rotor blade wa ued in experiental reearch. It wa ade of PA6 aluinu alloy, with ue of ulti axi illing technique. Figure 7. The blade obtained fro profile connection. The blade root ebedded on conical fitting. The proceing of thee type of eleent eet the proble of deflection and vibration of proceed aterial under the cutter preure (due to the low tiffne). During the erial production it hould not be a proble, a the blade would be a cating or a forging, but it wa a difficulty during prototype eleent production. Figure 8. The view of the hub with 4 blade. 5. The water turbine prototype For invetigation purpoe it wa decided to build an axial turbine connected to generator with a clutch (ee Figure 9). The ceraic buhing with water paing through the turbine a a lubricating fluid wa ued. Thi olution provide very low echanical loe in bearing. However, thi type of bearing ha low reitance to reilience. The lack of axial bearing in a chee hown in Figure 9 i a reult of axial force tranfer by ean of generator bearing. In thi ituation, it i neceary to ue an untypical clutch, that rotating part of the turbine i hung on. At the inlet to the turbine rotor the tator with profiled blade wa intalled. The tator blade have the regulated angle. The geoetry of tator blade i not included in the paper. 6

8 (HERVICON+PUMPS-017) IOP Conf. Serie: Material Science and Engineering (017) doi: / x/33/1/01016 Figure 9. The chee of the turbine. Four blade rotor verion. 6. The turbine tet rig The chee of pico turbine tet rig i hown in Figure 10. Taking into conideration pecific peed of the turbine and after literature reearch, it wa decided to build yetrical inflow channel with one crowie rib, that prevent water circulation at the turbine inlet. The lack of rib reulted in cyclic vortex appearance, which caued air inflow to the turbine. The water turbine tet rig wa deigned for only one ize of the turbine. The propoed hape of inflow channel can be intalled under target condition (e.g. a river etuary). Water wa delivered to the circuit by ean of a centrifugal pop. A draft tube of contant diaeter wa anufactured for eaureent purpoe. In future work, it i planned to apply a diffuer with appropriate angle. 7

9 (HERVICON+PUMPS-017) IOP Conf. Serie: Material Science and Engineering (017) doi: / x/33/1/01016 Figure 10. The chee of water turbine and three phae generator tet rig. 1- turbine, - generator, 3-upplying pup, 4- pup otor, 5- valve, 6 inflow channel, 7- buffer, 8 uction pipe, 9 load-bearing contruction 10, - draft tube 11 underfloor tank, 1 dicharge pipe, 13 electrical eter, 14 electrical reitor. 6.1 Perforing the experient To obtain turbine perforance curve it i neceary to perfor the eaureent at contant rotational peed. During the eaureent erie of point with different operating condition were deterined. The further analyi included highet efficiency operating point. The view of the tet rig i hown in Figure 11. Water wa puped fro a tank located under the floor by ean of the pup with ooth rotational peed regulation. It flowed evenly to the turbine through the inflow channel. To reduce the flow rate of the water (to lower water velocity), the flow wa directed to a tank and then it overflowed to the inflow channel. After paing the turbine water wa flowing through the draft tube back to the underfloor tank. Regulation of water flow rate wa perfored by changing the rotational peed of upplying pup. Regulation of water head wa done by changing the water level in the underfloor tank. Electricity produced by three - phae turbine generator upplie et of lightbulb connected in a wye yte. The eaureent of electrical paraeter were alo carried out. To increae the load of each phae the additional lightbulb were added erially and alo in parallel. Figure 11. View of the eaureent yte during the experient. 8

10 (HERVICON+PUMPS-017) IOP Conf. Serie: Material Science and Engineering (017) doi: / x/33/1/ Meaureent reult The efficiency of water turbine and it generator i derived fro flow rate Q, head H and electrical power P e eaureent reult. Meaureent of flow rate were provided by ean of electroagnetic floweter. The value of head wa defined a a ditance between water level in the inflow channel and water level in the underfloor tank. To eaure the electrical power an univeral eter wa ued. It indicated voltage, current and phae angle (three-phae yte) Mechanical paraeter eaureent The Bet Efficiency Point for the invetigated pico turbine, at pecific head H, wa characterized by following paraeter: Head H =,18, Flow rate: Q = 4, 3 /in, Rotational peed: n = 859 rev/in, The average water axial velocity at turbine outlet: V r 1, 73 The eaured work paraeter indicate the hydraulic power of water flow: They alo indicate the pecific peed of the turbine [4]: P h = Q ρ g H = 1504 W (0) where: n [rev/in], P h [kw], H []. n Ph 1,167n 464,1 (1) 5 4 H 6.. Meaureent of generator electrical paraeter The eaureent were taken at electrical ide of the generator driven by the turbine. The generator wa loaded by electrical reitor. The three phae generator, at rotational peed n = 859 rev/in produced electrical current of following paraeter: Voltage U = 458 V, Current I = 1,65 A, Electrical power: Shaft power : P e 3UI co 1050W () Pe 1050 P 113,53W (3) 0,85 e The efficiency of turbine - generator yte wa derived fro water hydraulic power and generator electrical power: The efficiency of pico turbine i defined a: Pe a TG 0,698 (4) P h a 0,81 (5) T G where G generator efficiency wa deterined on bai of it characteritic hown in Figure 1. 9

11 (HERVICON+PUMPS-017) IOP Conf. Serie: Material Science and Engineering (017) doi: / x/33/1/ Figure 1. Generator efficiency G a a function of load P el. 6.3 The baic perforance curve for pico turbine On the bai of Bet Efficiency Point paraeter for the invetigated turbine and typical perforance curve for water turbine the characteritic for pico turbine were elaborated. They are depicted in Figure 13.,5,3,1 H(Q) 1,9 1,7 P h (Q) 1,5 1,3 P(Q) 1,1 0,9 0,7 h(q) 0,5 0,3 0,1-0,1 Q [ 3 /in] 0 0,5 1 1,5,5 3 3,5 4 4,5 5 Figure 13. The invetigated pico turbine characteritic, elaborated fro Bet Efficiency Point paraeter. 7. Concluion 1. The experiental reearch howed that efficiency of a pico turbine of rotor diaeter d = 8 can be a high a it i indicated in Equation (with no additional loe hown in Figure 1) under following condition: precie eleent production and pico turbine aebly and application of appropriate bearing.. The algorith decribed in [] wa ued in hydraulic and contructional calculation. The calculation reult were in good agreeent with turbine paraeter obtained during the experient. 3. The application of NACA 41 a rotor blade profile wa a good choice, which prove the concluion The ue of ceraic bearing, lubricated and cooled by water paing through the turbine wa alo a good choice. Moreover, they had low rolling reitance. 5. The application of an inflow channel with one crowie rib (with dienion recoended in [1]) enable to provide table flow rate through the turbine. 6. A it wa entioned in Introduction, pico turbine invetigation reult can be applied during production of thi type of turbine and a odel achine invetigation for higher capacity turbine. 10

12 (HERVICON+PUMPS-017) IOP Conf. Serie: Material Science and Engineering (017) doi: / x/33/1/ Stabilization of paraeter after generator load change (and turbine load conequently) wa quite tie conuing. It wa decided to build a different regulation yte in further reearch, o that the turbine load can be changed oothly, with iultaneou haft power eaureent. Reference [1] W Krzyżanowki 1971 Turbiny wodne, kontrukcja i zaady regulacji (Warzawa: WNT) [] Varchola M, Hlbočan P 016 Hydraulický návrh axiálneho troja (Bratilava: SUT) [3] Korczak A, Rduch J 009 Energetyka wodna w Polce, tan i perpektywy rozwoju Monografia Koitetu Inżynierii Środowika PAN, III Kongre Inżynierii Środowika (Lublin) 3 pp [4] Kowaliew N N 1971 Gidroturbiny (Leningrad: Mazinotrojenije) p