Avalable onlne at www.scencedrect.com Physcs Proceda 19 (2011) 472 476 Internatonal Conference on Optcs n Precson Engneerng and Nanotechnology 2011 CAD and CAE Analyss for Sphon Jet Tolet Yuhua Wang a *, Guoj Xu a,b, Hashu Tan a a Department of Mechatroncs Engneerng, Foshan Unversty, Foshan 528000, Chna b School of Mechancal & Automoble Engneerng, South Chna Unversty of Technology, Guangzhou 510640, Chna Abstract The hgh precson 3D laser scanner wth the dual CCD technology was used to measure the orgnal desgn sample of a sphon jet tolet. The dgtal tolet model was constructed from the cloud data measured wth the curve and surface fttng technology and the CAD/CAE systems. The Realzable k double equaton model of the turbulence vscosty coeffcent method and the VOF multphase flow model were used to smulate the flushng flow n the tolet dgtal model. Through smulatng and analyzng the dstrbuton of the flushng flow s total pressure, the flow speed at the tolet-basn surface and the sphonng bent tube, the tolet performance can be evaluated effcently and convenently. The method of establshng dgtal model, flushng flow smulatng, performances evaluatng, functon shape modfyng would provde a hgh effcency approach to develop new water-savng tolets. 2011 Publshed by Elsever B.V. Open access under CC BY-NC-ND lcense. Selecton and/or peer-revew under responsblty of the Organsng Commttee of the ICOPEN 2011 conference Keywords: Sphon Tolet, 3D Laser Scannng, CCD, Numercal Smulaton, Structure Optmzaton 1. Introducton Tradtonally, the development process of the hgh performance tolet was manually operated by the master craftsman by the way of many trals. Ths method needed long development perod, rch expenses and more dffcultes for developng new water-savng products. Wth the advance of optcal measurng and dgtal manufacturng technologes, t has become possble to utlze ths advance effcency method to develop new type water-savng tolet. For nvestgatng the dgtal ntegrated manufacturng solutons, the smulaton of tolet flushng flow process play a very mportant part, whch can analyze and mprove the flushng performance of the tolet s dgtal prototype n the computer before the tral manufacture. Ths method can evaluate the tolet s performance quckly and make the new water-savng product developng convenently [1]. In ths paper, the cloud data of the tolet dgtal model were measured by scannng a tolet s developng sample wth the 3D scannng measurement technology usng the lne laser sources and dual CCD acqustons. The 3D tolet dgtal model was bult wth the CAD/CAE ncludng edge detecton, flterng, curve and surface reconstructon accordng the cloud data of t. The method to smulate the tolet s flushng flow processes and to evaluate the tolet s performance were proposed and * Correspondng author. Tel.: +86-0757-82985259; fax: +86-0757-83960006. E-mal address: wyh5537@sna.com 1875-3892 2011 Publshed by Elsever B.V. Open access under CC BY-NC-ND lcense. Selecton and/or peer-revew under responsblty of the Organsng Commttee of the ICOPEN 2011 conference do:10.1016/j.phpro.2011.06.194
Yuhua Wang et al. / Physcs Proceda 19 (2011) 472 476 473 researched. Wth ths establshng dgtal model, flushng flow smulatng, performances evaluatng, functon shape modfyng method, the best performance tolet type would be developed rapdly. 2. Tolet Dgtal Model Constructon The dgtal tolet model was constructed by the curve and surface fttng from the measured data. Measured by the 3D laser scanner wth the dual CCD technology, the cloud data (a large number of pont data) of the orgnal tolet sample were obtaned. The measured pont data were preprocessed by nose flterng, pont data smoothng, pont data flterng and so on. Then the curves and surfaces of the tolet have been bult and edted as well as the curve curvature and surface errors have been analyzed. After the preprocess, the curve and surface data of the tolet have been transferred to the CAD/CAE systems through the converson nterface such as IGES, and those data have been put together accordng the nter-relatonshp among the algnment of the coordnate system and the wreframe algnments to establsh tolet wreframe model wth the asssted analyss software. The completed dgtal model for the orgnal tolet sample was shown as Fg.1. 3. Prncple of Tolet s Flushng Flow Smulaton Fg. 1 Tolet dgtal model The smulaton of the tolet s flushng process has been mad wth the fnte element analyss software and the tolet dgtal model. The flushng process of the sphon jet tolet s a complcated multphase flow problem wth the three-dmensonal unsteady states and the free surface boundary condtons. Those problems can be smulated wth the pressure solver n the FLUENT software package based on the low speed and ncompressble flow. The flushng flow model, wall surface condtons and the calculatng models used n the smulaton were n what follows. The Realzable k double equaton model of the turbulence vscosty coeffcent method was used as the flush flow model for the numercal smulaton [2]. Realzable model s the complement of the standard k model and the RNG k model. The Realzable means that the model satsfes certan mathematcal constrants as same as the turbulence flow model. The transport equatons of the Realzable k double equaton model are as follows: k ku k (1) t x Gk Gb YM Sk x j k x j k ku t x k 2 C S C C C Gb S x 1 2 1 3 j k x j k k (2) C max0.43, k 1 S 5, Where k equaton s same as the k equaton n the standard k model and the RNG k model except the constants, but the equaton s qute dfferent as whch n the standard k model and the RNG k model. The standard k model s approprate to smulate the general turbulence. RNG k model s generally used to treat the flow whch has hgh stran rates and larger degree of bendng streamlne. Realzable k model has some advantages n smulatng the flows such as mxed jet stream flow, ppe flow, boundary layer flow and separaton flow. All of these models above are belong to the hgh Reynolds number model and sutable for the turbulence flows whch have developed very adequately n the regon havng some enough dstance to the wall surface. In the regon nearby the wall surface, the molecular vscosty n the flow could have some strong nfluence than the
474 Yuhua Wang et al. / Physcs Proceda 19 (2011) 472 476 turbulence fluctuaton nfluence and would produce the turbulence developed nsuffcently, whch would lead to make the flow beng n a lamnar flow state n ths regon. So the sem-emprcal formula was used drectly to lnk the physcal soluton varables on the wall surface wth the varables where n the core area of the turbulence. Therefore the core regon of the flushng flow should be smulated wth the Realzable k model and the flow n the edge range nearby the wall surface should be treated wth the sem-emprcal formula whch drectly lnks the physcal soluton varables n the wall surface wth the varables n the core area of turbulence. That s the value of the varable nodes n the wall nearby range could be drectly equal to the adjacent control volume of the wall surface, and the frst nner node n the wall nearby range had been put on the logarthmc regon and confgured to enough developed turbulent regon. Flushng flow of the sphon jet tolet belongs to the flud flow problem wth free surface whose shape and locaton would vary ntrcately and contnually. Such problems could be smulated wth the VOF multphase flow model very well. In the VOF model, the fxed Euleran s grds were used to track the multphase flow surfaces and the dfferent flud components sharng a set of momentum equatons, and the volume rato occuped by every flud composton of each grd unt could be calculated [3]. All varables and ther property domans were shared by each phase flow unt and represented the volume-averaged values. The volume rato of each phase at whatever locaton has been calculated. Each flow unt s varables and ther attrbutes were smply belongng to a phase or a phase mxture, absolutely dependng on the volume rato value. Thus f the q-phase flud volume rato was denoted by q n an unt, and the three followng condtons were possble (1) q = 0, When the q-phase flud n the unt was empty (2) q = 1, When the q-phase flud n the unt was flled (3) 0 < q < 1, When the unt contaned the q-phase flud and another phase or multphase flud nterface Accordng to the local values of q, the approprate propertes and varables were assgned to each control volume n a certan range. Through solvng a phase or mult-phase wth the volume rato of the contnuty equaton, the nterface of trackng phase could be obtaned. The model of three-dmenson non-steady flud was used for numercal calculatng; the flushng flow speed was looked as the absolute speed; the unt pressure gradent was used for the dervatve tem of control equaton. The tme-related tems were calculated usng one-order mplct expresson. The reference pont was adopted on the top of water tank where was full of ar. The dmensonal coordnate was (356, 574, -170) and the acceleraton of gravty was -9.81m/s 2. The lghtest ar phase densty was selected for work densty, whch would elmnate the accumulaton effect of water statc pressure. The PISO algorthm for the non-steady flow has fast calculatng speed and relatvely hgh overall effcency, whch has been used for pressure-velocty couplng calculatng. The method of body force weght was adopted for the pressure nterpolaton calculaton. The two-order dscrete was used to dscretzaton the momentum equaton and knetc energy equaton of the flow, whle the one-order dscrete was used to dscretzaton the flow dsspaton rate equaton. The under-relaxaton factor of the PISO algorthm was very mportant for the calculatng convergence, whch has been adjusted accordng to the convergence resduals n the calculatng process. In the teratve calculatng process, the calculatng convergence could be stablzed when the values of pressure, densty, body force, momentum, turbulence knetc energy, turbulence dsspaton rate and turbulent vscosty were 0.6, 1, 1, 0.1, 0.8, 0.5 and 0.7. 4. Tolet Flushng Process Smulaton Durng the flushng, the water flowng out from the tank washes the nner wall surface of the tolet-basn through the crcle arranged nozzles whch at same tme can spn up the water n the water package to promote the sewage dschargng. The pressure of the flow drectly lnks wth the flow effectve mechancal energy. The total pressure dstrbuton of the flushng flow ndcates the flow resstance at each stes of the tolet. If the local total pressure of some ste vared by a bg margn, the resstance of the flow could be estmated and the shape of ths ste would be adjust. The total pressure dstrbutons of the flushng flow at the dfferent tme were shown as Fg.2. Accordng to the Fg.2, the water pressure at the bottom of water tank ncreased sharply at the tme of 0.6s. Ths revealed that the knetc energy of the flow couldn t ncrease mmedately at the flushng ntal stage. Durng the tme of 1.4s to 2.5s, the total pressure of tolet-basn flow was ncreasng to about 200~400 Pascal, but ths pressure was not hgh enough for washng the tolet-basn surface well. Durng the tme of 2.5s to 3.5s, the dynamc pressure was bg enough to push the pollutants out.
Yuhua Wang et al. / Physcs Proceda 19 (2011) 472 476 475 (a) Pressure at 0.6s (b) Pressure at 1.4s (c) Pressure at 2.5s (d) Pressure at 3.5s Fg. 2 Total pressure dstrbutons of the flushng flow of the orgnal tolet Accordng to the Fg.2, the water pressure at the bottom of water tank ncreased sharply at the tme of 0.6s. Ths revealed that the knetc energy of the flow couldn t ncrease mmedately at the flushng ntal stage. Durng the tme of 1.4s to 2.5s, the total pressure of tolet-basn flow was ncreasng to about 200~400 Pascal, but ths pressure was not hgh enough for washng the tolet-basn surface well. Durng the tme of 2.5s to 3.5s, the dynamc pressure was bg enough to push the pollutants out. The bg enough flow velocty at the tolet-basn surface was mportant for cleanng the surface. The dstrbuton of the tolet-basn surface flow speed could dsplay the effect of the surface beng cleaned. The flushng flow speed at the tolet-basn surface pont A was shown as Fg.3(b), whch ndcated that the bg enough flow velocty greater than 1.5m/s sustaned only for about one second, and ths hgh speed flow duraton was not long enough for cleanng the surface well. The sphonng process at the sphon tube s top bent determned the capablty of the muck been sucked thoroughly. The sphonng speed and ts sustaned tme at the sphon tube s top bent pont B were shown n Fg.3(c). Ths pont s sphonng speed, whch was bg enough greater than 1.0m/s, appeared at the tme from 3s to 4s and sustaned only about 1s. Sphon ppe pont B Surface pont A (a) Poston of A and B (b) Flushng flow speed at A (c) Sphonng speed at B Fg. 3 Flushng flow speed and sphonng speed of the orgnal tolet The smulatons for the orgnal tolet revealed ts performances were not satsfed desgn requres well, and ts structure needed to be modfed for mprovng ts performances.. 5. Structure Adjust and ts Performances Accordng the smulatng results above, some stes shape and structure of the tolet were adjusted lke as the connecton slope between sttng rng and the water tank ppe, the tolet-basn shape and the sphon tube bent fgure etc. The smulatons for the modfed tolet were shown as Fg.4 and Fg.5. The total pressure dstrbuton of the modfed model showed that the bg enough speed flow duraton had been lasted and the sphonng speed and ts sustaned tme had been enhanced. That means that the smulaton method s very effcency and convenence for developng the hgh performance new-type tolet.
476 Yuhua Wang et al. / Physcs Proceda 19 (2011) 472 476 (a) Pressure at 0.6s (b) Pressure at 1.4s (c) Pressure at 2.5s (d) Pressure at 3.5s Fg. 4 Total pressure dstrbutons of the flushng flow of the modfed tolet (a) Flushng flow speed at A (b) Sphonng speed at B Fg. 5 Flushng flow speed and sphonng speed of the modfed tolet Accordng the smulatng results above, some stes shape and structure of the tolet were adjusted lke as the connecton slope between sttng rng and the water tank ppe, the tolet-basn shape and the sphon tube bent fgure etc. The smulatons for the modfed tolet were shown as Fg.4 and Fg.5. The total pressure dstrbuton of the modfed model showed that the bg enough speed flow duraton had been lasted and the sphonng speed and ts sustaned tme had been enhanced. That means that the smulaton method s very effcency and convenence for developng the hgh performance new-type tolet. 6. Concluson The Realzable k double equaton model and VOF method for multphase flow wth free surface are sutable for smulatng and analyzng the flushng flow of sphon tolet based on the dgtal wre frame technology. The performance of the tolet can be evaluated wth the three-dmenson flushng flow smulatng method through the dstrbuton of the two-phase flow feld, the total flow pressure, the flow speed at the tolet-basn surface and the sphonng bent tube. Those have provded a hgh effcency approach to develop new water-savng tolets. Acknowledgement Ths work was supported by the Natonal Natural Scence Foundaton of Chna under Grant No. 61072134. References [1] Zhang Zhengrong, Sun Yousong, Pan Xaotao and Xu Yanhua, Rapd manufacturng technology of complcated ceramcs based on CAD/CAE/CAM/RP, Chna Ceramcs, vol. 41, no. 5, pp. 35-38, 2005 [2] Wang Fujun, Computatonal Flud Dynamcs-Prncple and Applcaton of CFD Software, Tsnghua Unversty Press, Chna, 2004 [3] Zhao Shy, Lu Zjan and Peng Zhwe, Optmzed desgn of tolet sphon ppelne based on fluent and ts valdated test, Journal of System Smulaton, vol. 40, no.16, pp. 4412-4416, 2008