Expermental And Numercal Investgaton Of The Flow Analyss Of The Water-Savng Safety Valve Muhammed Safa KAMER s PhD Student n Department of Mechancal Engneerng n Kahramanmaras Sutcu Imam Unversty, Turkey. E-mal:msafakamer@hotmal.com, msafakamer@ksu.edu.tr Ahmet KAYA s Assoc. Prof. n Department of Mechancal Engneerng n Kahramanmaras Sutcu Imam Unversty, Turkey. E-mal: kaya38@ksu.edu.tr Abdullah SISMAN s Assst. Prof. n Department of Mechancal Engneerng n Kahramanmaras Sutcu Imam Unversty, Turkey. E-mal: assman@ksu.edu.tr Muhammed Safa Kamer, Ahmet Kaya, Abdullah Ssman Abstract: In ths study, an auto-mechancal safety valve was desgned and manufactured n order to prevent possble wastage of water and water rad after nstantaneous water cuts durng water usage n places where water use s wdespread. Safety valve s actvated and t swtches off the lne when water s cut off (when mans pressure s equal to atmospherc pressure), and as t does not allow water to pass when t comes back, t saves water and prevents the formaton of rads. An experment set was conducted n order to measure the pressure drop between the nlet and outlet of the safety valve and t was found that wth the ncreased flow rate the pressure drop ncreases. The three-dmensonal flow analyss of the safety valve was carred out wth Ansys-Fluent software package and the results obtaned were compared wth expermental data, and a good harmony was acheved. Index Terms: Ansys-Fluent, Computatonal Flud Dynamcs, Expermental Study, Pressure Drop, Safety Valve. 1 INTRODUCTION WATER requrement s rapdly ncreasng together wth the growng populaton and boomng economy. Usng clean water sources wthout wastng s the bggest goal n managng water economcally. One of the key factors that lead to wasted water resources s water losses n the network, and ths s one of the mportant research topcs n our country as well as n other countres [1]. In cases of nterrupton of mans water, openforgotten valves cause water loss. To prevent water losses n the network and systems, to reduce water consumpton n nstruments where water s used, and to prevent water rads caused by varous water leaks, varous studes have been conducted from the past to the present. Kavurmacoglu and Karadogan [2] ntroduced pessure regulatng valves and ther characterstcs, and dentfed some regulator characterstcs of the pressure regulator valves n the laboratory settngs. By adustng pressure usng automatc control valves, they determned that t s possble to reduce water leakage from all szes of nstallatons. Celkag [3] determned the pressure loss coeffcent for ball valves expermentally and numercally. He used the Fluent program, a fnte volume method, n numercal methods. Amrante et al. [4] made the flow analyzes usng the Fluent software package n order to mprove the performance of hydraulc proportonal valve and make desgn mprovements. Chern et al. [5] studed the performance of the ball valve, the flow characterstcs and the cavtaton effect expermentally. To determne the performance of valve, they determned necessary coeffcents for dfferent volumetrc flow and dfferent pressures. Duymaz [6] calculated the local head loss coeffcent of a butterfly valve n the nomnal dameter of www.str.org DN 40 quanttatvely and expermentally. She used the Fluent software package, a fnte volume method, n numercal analyss. Koyunbaba [7] analyzed the flow characterstc curves of the ball and butterfly valves whch are valve types wdely used n ndustry wth the help of ANSYS program and compared wth catalog data of the valve producng companes. Prnccler [8] desgned a sngle body dstrbuton unt used n the dstrbuton of water n pressurzed rrgaton system and nvestgated flow analyss expermentally and numercally. Expermentally obtaned pressure losses were compared wth the results obtaned from numercal methods (FLUENT). Yuksel [9] calculated pressure loss coeffcent n gate valves dependng on the valve openngs expermentally and numercally. Kaya [10] nvestgated the performance of a centrfugal pump whch s horzontal shaft, sngle-staged, and end-suctoned numercally. He used the FLUENT program, a fnte volume method, n hs numercal study. Deng et al. [11] determned the flow analyss and local temperature dstrbuton of ol whch flows at hgh speed, around the notches n a spool-valve by the Ansys-Fluent program based on the fnte volume method and ABAQUS program. Sandalc [12] determned pressure losses of two dfferent valves szed DN65 and DN80 at dfferent flow rates and dfferent openng angles (n dsk angels) expermentally. Yang et al. [13] nvestgated the flow analyss of a 3-D stop valve for dfferent volumetrc flows numercally. By applyng the RNG k-ε turbulence model, they solved the Naver-Stokes equatons by the Fluent software package. Chattopadhyay et al. [14] studed the flow through the pressure control valve usng computatonal flud dynamcs methods. For turbulence condtons, they solved the Naver-Stokes equatons usng the Fluent software packages. They used the standard k-ε and realzable k-ε models n numercal analyss. Lsowsk and Rada [15] studed the reducton of the pressure drop n a hydraulc system, usng drectonal control valve, expermentally and numercally. In the expermental study, an experment was set up and the pressure drop occurrng n dfferent volumetrc flows was determned. In the numercal study, on the other hand, usng the standard k-ε turbulence model n the Ansys-Fluent software package, analyss were made and they were compared wth expermental study results. Kamer [16] desgned a mechancal valve n order to save water. By dong flow analyss n ths desgned valve, he determned the pressure drop occurrng at varous flow rates, expermentally and numercally. In ths study, n order to prevent possble waste and water rad wth the arrval of the mans water from the taps forgotten open durng nstantaneous water cuts n publc water 189
consumpton areas (hosptals, schools, etc.), a mechancallyautomatcally operated securty valve was desgned and manufactured. The flow propertes (velocty and pressure dstrbuton and pressure drop-mass flow relaton) of ths desgned and manufactured safety valve were examned expermentally and numercally. 2 MATERYAL AND METHODS 2.1 Expermental Study In order to prevent possble waste and water rad wth the arrval of the mans water from the taps forgotten open durng nstantaneous water cuts by mechancally- automatcally operated mechansms, a new valve (Hand Operated Safety Valve) was desgned and manufactured. The Hand Operated Safety Valve conssts of, as shown n Fgure 1, the outer body (1), the swtchng slder (2), the closng sprng (3), the apertured sldng plug (4) and the openng knob (5). In the frst case, as the swtchng slder (2) s n the swtched poston due to the force of the closng sprng (3), even f there s tap water pressure n water supply nstallatons, the Hand Operated Safety Valve does not allow the water to pass to the 'Ext' lne. In cases when there s tap water pressure n water supply nstallatons, the release knob (5) s pulled by manpower n the drecton shown n Fgure 1a, and the swtchng slde (3) s swtched on and left as such. Thus, water passage s suppled to the outlet lne of the Hand Operated Safety Valve. The force of the swtchng slder (2) of the closng sprng (3) n the open poston s desgned n a way that t can not defeat the force formed by the mnmum supply pressure whch affects the swtchng slder (2) (the pressure affectng the swtchng slder (2) n cases when last user valve / valves are completely open). Therefore, n cases where there s mans pressure n the mans water nstallatons, once the Hand Operated Safety Valve s swtched on, t does not get nto the off poston untl the mans water s cut off. In addton, even f the mans water s cut off, n cases when any user valves are not open, the valve stll does not go off because n order for the valve to go off, n addton to the removal of the pressure affectng the swtchng slder (2), the water n the valve should be draned and t should not prevent the movement of the swtchng slde (2) towards the swtched poston. When mans water s cut off, as the mans pressure affectng swtchng slder (2) s removed, under the nfluence of forces of the closng sprng (3) the swtchng slde (2) automatcally goes off (For ths, t requres that any user valve s open or the water n the valve should be draned somehow). At ths stage, f the swtchng slder (2) s desred to be turned on by pullng the release knob (5) by manpower n the drecton shown n Fgure 1a, snce there s no system pressure n water supply nstallatons, agan under the nfluence of forces of the closng sprng (3) the swtchng slder (2) automatcally goes off. In the event that mans pressure agan comes to the mans water systems, untl the swtchng slder (2) s swtched on by pullng the release knob (5) n the drecton shown n Fgure 1a by manpower, the Hand Operated Safety Valve does not allow the passage of water to the 'Ext' lne. Thus, n case of water supply nterrupton, even f the water valve / valves on the nstallatons after the Hand Operated Safety Valve are forgotten open, no water flows from ths valve / these valves f the tap water comes agan. Close poston of the valve (a) Open poston of the valve (b) Fgure 1. Cross-Sectonal Vews of Hand Operated Safety Valve When t s realzed that there s no flow of water from water valve / valves, the Hand Operated Safety Valve s set to open wth the help of manpower and so water passage s ensured to the last user valves. After water passage s ensured to the last user valves, t s notced that the water flows from the valves left open and these valves are swtched off. Ths valve whch s desgned and manufactured s shown n Fgure 2. An experment was desgned n order to test ths mproved handoperated safety valve and determne the pressure drop rates at dfferent flows (Fgure 3). The desgned expermental set prncpally conssts of 100 lter tank, crculaton pump, closed expanson tank, pressure regulator, ball valve, electromagnetc flowmeter, dgtal pressure gauge, safety valve, long faucets and electrcal panel elements. www.str.org 190
the flow transferred to the frst outlet s reduced through the ball valve, to prevent damage to the pump, clean water s drected to the second outlet wheren t opens the safety valve and reaches the warehouse. Fgure 2. The Desgned Hand Operated Safety Valve The clean water flled n the tank s sent to the system through the crculaton pump system. The clean water reaches the long tap tourng the nstallaton elements and s transferred to the tank from the tap agan. The system operaton contnues n closed cycle n ths manner. The clean water sucked from the tank wth the ad of the crculaton pump s dvded nto two paths at the pump outlet. In the frst one of these outlets, the clean water reaches the long faucet after tourng varous nstallaton elements. In the second outlet, on the other hand, the clean water s transferred to the warehouse after t tours the safety valve and a varety of nstallaton elements. The clean water followng the frst outlet, here, frst enters the pressure regulator. The clean water comng out of the the pressure regulator enters the ball valve n order to get the flow adustment. 2.2 Numercal Study Wthn the scope of numercal study, the three-dmensonal sold model of the analyss area was modeled n the computer envronment by takng measures on the experment set. The drawngs were performed consderng the open poston of the Hand Operated Safety Valve. In computer envronments, n three-dmensonal sold modelng operatons the SoldWorks commercal software was used and n the flow analyses the Ansys-Fluent commercal software was used.the assumptons made n the numercal calculatons; In the valve nlet-outlet, steel ppes and ron fttngs materals were used and the roughness values of these materals are taken as 1.6 µm as a fxed value for steel ppes and 5.12 μm for ron fttngs materals. Valve s, on the other hand, made of bronze and ts roughness value s taken as 3.2 μm as a fxed value [17]. Numercal calculatons, for turbulent, three-dmensonal, contnuous, forced convecton, are acheved by usng Ansys Fluent computer program whch s often used n CFD applcatons. In solutons, the segregated solver and the SIMPLE algorthm was used [18]. Contnuty and momentum conservaton equatons [11]; t u t u 0 uu p ( ) (1) (2) Fgure 3. The Schematc Dagram of The Experment Set Used n Pressure Drop Measurement The flow measurement of the clean water comng out of ball valves s made by electromagnetc flowmetre. The clean water whch goes through electromagnetc flowmeter enters the Hand Operated Safety Valve (Fgure 2). The clean water comng out of the Hand Operated Safety Valve frst enters the long tap and the water comng out of t flows back to the tank. A dgtal pressure gauge s placed to the nlet and outlet of the Hand Operated Safety Valve to measure pressure n these parts. In the event that the long tap on the system s closed or www.str.org Here, p s statc pressure; s expanson tensor. u u T 2 ui 3 (3) Here, µ s the molecular vscosty and s used as the effectve vscosty n the turbulent flow ( eff t, here t s the turbulent vscosty). For three-dmensonal numercal analyss, the followng boundary condtons have been dentfed;. Inlet boundary condton: "mass-flow-nlet defntons are made, and mass flow rates are taken n the range from 0.2149 kg/s to 0.2915 kg/s.. Outlet boundary condton: defned as "pressure-outlet". The expermentally determned numercal value of the valve outlet pressure s entered.. Ppe and valve walls are defned as "wall". In numercal analyss, Standard k-ε and realzable k-ε turbulence models are used. In k-ε models, for the turbulent knetc energy (k) and the rate of loss "dsspaton" (ε), two transport equatons are solved n addton to the Naver-Stokes equatons. In standard k-ε turbulence model; the turbulence knetc energy (k) and loss rate (ε) are solved usng the followng equatons [11; 15; 19]. k ku t x x t k G k x k (4) 191
u 2 t C1 Gk C2e t x x (5) x k k In these equatons, G k s the turbulence knetc energy producton caused by the average rate gradent. s the vscosty of turbulence and s determned by the equaton of 2 t C k. Constants n turbulence model are gven below [11; 15; 20]. The coeffcent C whch s fxed n the "Standard k-ε" model takes a dynamc form n the realzable k- ε turbulence model and s obtaned by the equaton of C 1 / A A k S [19]. 0 Here; 0 4. 04 s A S and 1 cos 6W A, 6cos are 3 constants. The deformaton tensor S s calculated as follows: S 1 u 2 x u x The relaton between the term W and S s as [14]; SS W (7) S S In the realzable k-ε turbulence model, to determne the turbulent knetc energy (k) and loss rate (ε) the followng equatons are used. k ku t x u t x x t k G k x t C S x 1 x k C 2 t (6) (8) 2 (9) k v The constants of the "Realzable k-ε" turbulence model have the followng values [20]. C, 1. 0, 1. 2 2 1.9 k 2.3 Mesh Structure In the quanttatve soluton of the Hand-operated safety valve, the network structure shown n Fgure 4 was used. A heavy network was used to get a better vew of the speed and pressure changes at the corner ponts. For the valve soluton area, the network structure numbered 1.25x10 6 was used. 2.4 Error Analyss In expermental studes, t s mportant to determne the number of errors whch affect the accuracy of the results. In experments carred out n an experment settng establshed n accordance wth the standards specfed n the lterature, when the data obtaned are evaluated, errors arse n two dfferent ways. They are the nevtable errors arsng from the structure of the expermental set and measurement nstruments and errors caused by the neglgence of the person makng the experment. The error analyss made for the evaluaton of these errors are very mportant for nterpretaton of results [21]. After a certan number of experments, to determne the error rates of these experments several methods have been developed n practce. One of the most wdely used of these s the "ratonal approach" method. In ths type of error analyss, t s accepted that all nstruments n measurng system make maxmum errors at the same tme [22]. Consderng ths method, the analyss of the error between the expermentally and quanttatvely calculated pressure drop (ΔP) results can be performed. Wthn the scope of expermental study, the pressure drop values (ΔP) were calculated by subtractng the pressure values measured n the output lne (P O ) from the pressure values separately measured n the Hand Operated Safety Valve nlet lne (P ) for each experment. The measurement precsons (w B ) of dgtal pressure gauges used n the measurement of these pressures s ±%0.5, and these pressure gauges can measure only as the bar unt. Assumng that the pressure gauges make the maxmum and mnmum errors at the nlet and outlet at the same tme, for each experment the maxmum pressure drop (ΔP max ) and the mnmum pressure drop (ΔP mn ) values were calculated takng nto account the senstvty of the measurng nstruments. In calculatons (11) and (12) numbered equatons were used. P P P o (10) P max P P w P P w (11) B o o B P P w P P w P mn (12) B o (a) (b) Fgure 4. Network Structure Used n Numercal Analyss o B www.str.org 192
3 RESULTS AND DISCUSSION The purpose of ths study s to desgn and manufacture a mechancally- automatcally operated securty valve n order to prevent possble waste and water rad wth the arrval of the mans water from the taps forgotten open durng nstantaneous water cuts n publc water consumpton areas (hosptals, schools, etc.). The flow propertes (velocty and pressure dstrbuton and pressure drop-mass flow relaton) of ths safety valve whch s desgned and manufactured were examned expermentally and numercally. 3.1 Analyss of Expermental Data Wthn the scope of expermental study, before takng the expermental data, for the system to reach equlbrum, the electromagnetc flow meter, dgtal pressure gauges and crculaton pump were run, and the Hand Operated Safety Valve and the long tap were set open. All experments were performed whle the system was n ths way. After flow adustment, by watng at least 20 mnutes for each experment t s ensured that the system reaches the regme. Each experment was repeated three tmes and the average values were taken. In the expermental study, pressure drop changes were determned n sx dfferent flow rates. Usng the expermental results, the valve pressure drop (ΔP) and the rato (%ΔP 0 ) of the pressure drop (ΔP) to the nlet pressure (P ) were calculated for 6 dfferent flow rates and the results obtaned are gven n Table 1. % P 0 P P (13) 100 As the mass flow of flud passng through the valve ncreases, the pressure drop that occurs between the nlet and outlet also ncreases. It s known that ths ncrease s caused by cases, such as ppe surface roughness, frcton, and sudden contracton-expanson. When Table 1 s analyzed, t s seen that the pressure drop rates (%ΔP 0 ) of all experments appear to be very close to each other. That these rates are close to each other shows that mass flow ( m ) change and pressure drop (ΔP) change are almost lnear. By applyng error analyss to expermental results, t s determned that measured values can vary at whch ntervals and they are shown n Table 2. 3.2 Analyss of Numercal Results Wthn the scope of numercal study, the flow analyss of the valve whose three- dmensonal sold model was created was carred out by the Ansys-Fluent software package. To be used n numercal analyss, some features of the flud (water) were dentfed. The thermodynamc propertes of water crculatng n the expermental set were presented n Table 3 accordng to the the temperature values durng the experments and these features were used n numercal studes. Reynolds number was calculated accordng to the maxmum cross secton (d p gven n Fgure 1.b) and the mnmum cross sectons (d G gven n Fgure 1.b) of the flow area and t was determned that the flow s turbulent n all crcumstances. In the numercal study conducted, the used volume element szes (the dstance between two nodes) have a consderable effect on the results. Therefore, elements network nfrastructure must be small enough to gve accurate results. In ths study, for both used turbulence models the effect of the number of cells n the network structure on the expermental results were examned and gven n Table 4. Accordng to the examnaton conducted, n the event that the cell number n network structure s 1.250.000, t was observed that the results obtaned are very close to the results of the expermental results and n the realzable k-ε turbulence model, the error rate s much lower (0.6%) and ths turbulence model was used n the studes. Table 1. Mass Flow Change of The Pressure Drop that Occurs n The Valve Input-Output Experment No Temperature Mass Flow Inlet Pressure Outlet Pressure Pressure Drop T [K] m [kg/s] P [Pa] P o [Pa] ΔP [Pa] %ΔP 0 [%] 1 301.15 0.2915 185000 174000 11000 5.946 2 303.15 0.2816 173000 163000 10000 5.780 3 304.15 0.2663 156000 147000 9000 5.769 4 305.15 0.2483 136000 128000 8000 5.882 5 306.15 0.2315 118000 111000 7000 5.932 6 307.15 0.2149 102000 96000 6000 5.882 Experment No Mass Flow Inlet Pressure Table 2. Error Analyss-Appled Expermental Results Outlet Pressure Maxmum Pressure Drop Measured Pressure Drop Mnmum Pressure Drop m [kg/s] P G [Pa] P Ç [Pa] ΔP max [Pa] ΔP [Pa] ΔP mn [Pa] 1 0.2915 185000 174000 12795 11000 9205 2 0.2816 173000 163000 11680 10000 8320 3 0.2663 156000 147000 10515 9000 7485 4 0.2483 136000 128000 9320 8000 6680 5 0.2315 118000 111000 8145 7000 5855 6 0.2149 102000 96000 6990 6000 5010 Numercal studes were conducted usng sx dfferent expermental data, and the solutons obtaned by two dfferent turbulence models were compared wth expermental data and www.str.org 193
Experment No INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 4, ISSUE 10, OCTOBER 2015 ISSN 2277-8616 shown n Table 5. It was found that the results obtaned usng realzable k-ε turbulence model are n good agreement wth expermental data. Therefore, by usng the results of the numercal analyss conducted by the realzable k-ε turbulence model, pressure drops (ΔP) and the pressure drop rates (%ΔP 0 ) were calculated. Pressure drops (ΔP) varyng accordng to dfferent mass flow ( m ) are obtaned numercally and they are shown n Fgure 5 by comparng them to the expermental results. Obtaned expermental and numercal results, the change n mass flow rate-pressure drop was found to be qute compatble. It was determned that the numercally obtaned results are among the data obtaned by applyng. Table 3. Propertes of Saturated Water [24] error analyss to the expermental data. Wth the ncrease n mass flow, t was determned that the pressure drop occurrng between the nlet and outlet of the safety valve ncreases, and ths ncrease was found to be almost lnear. Smlar changes were also found n the studes conducted for dfferent valve mechansms n lterature [6; 12; 14; 15; 23]. That the expermental and numercal results are compatble showed that when expermental system was establshed n ths and other smlar studes, complex problems that may create hgh costs can be solved by Ansys-Fluent software package at a mnmal cost and n a short tme Temperature Densty Specfc Heat T [K] ρ [kg/m³] C P [J/kg.K] Heat Conducton Coeffcent K [W/m.K] Dynamc Vscosty µ [kg/m.s] Knematc Vscosty υ x 10-7 [m²/s] Reynolds Number Mnmum Dameter, d G Maxmum Dameter, d p 1 301.15 996.400 4178.800 0.612 0.000835 8.38218 44460.917 14820.306 2 303.15 996.000 4178.000 0.615 0.000798 8.01205 44953.147 14984.382 3 304.15 995.600 4178.000 0.617 0.000782 7.85858 43358.342 14452.781 4 305.15 995.200 4178.000 0.618 0.000767 7.70498 41250.096 13750.032 5 306.15 994.800 4178.000 0.620 0.000751 7.55127 39257.782 13085.927 6 307.15 994.400 4178.000 0.621 0.000736 7.39743 37215.601 12405.200 Table 4. The Impact of The Number of Cell Elements on The Soluton Inlet Pressure, P Mass Error Rate Numercal Number of Flow m Expermental Standart k- elements Standart k-ε Realzable k-ε ε kg/s Pa Pa Pa % % 1 600,000 190227 190084 2.748 2.675 2 700,000 186681 186398 0.900 0.750 3 800,000 0.2915 185000 186878 186425 1.005 0.764 4 1,000,000 187054 186518 1.098 0.814 5 1,250,000 186374 185258 0.737 0.600 Analyss No Table 5. Analyss of The Quanttatve Results wth Dfferent Turbulence Models Realzable k- ε Experment Analyss No Inlet Pressure, P Sayısal Error Rate Standart k - ε Realzable k - ε Standart k - ε Realzable k - ε Pa Pa Pa % % Expermental 1 185000 186702 186116 0.912 0.600 2 173000 175081 174155 1.189 0.663 3 156000 157803 156779 1.143 0.497 4 136000 137262 136600 0.919 0.439 5 118000 118699 118448 0.589 0.378 6 102000 102714 102472 0.695 0.461 The flud n the system s pressurzed wth the help of crculaton pump. As the flud moves forward n the system, t wll be subected to pressure drop due to losses, such as frcton, valves and fttngs and so on. Therefore, t s expected that the pressure at the nlet valve (P ) s more than the pressure at the outlet valve (P O ). Pressure dstrbuton n the flow s shown n Fgure 6, and that the pressure n the nlet regon s hgher s dentfed. It s expected that there s a sudden contracton and the pressure s expected to ncrease www.str.org n the regons where the flow splashes (Fgure 6). Velocty dstrbuton was obtaned n the flow area and t was dentfed that the speed ncreases n the narrowest sectons (Fgure 7). 194
Fgure 6. Pressure Dstrbuton of Flow Volume Fgure 7. Velocty Vectors of Flow Volume 4 CONCLUSION In ths study, n order to prevent possble waste and water rad wth the arrval of the mans water from the taps forgotten open durng nstantaneous water cuts n publc water consumpton areas (hosptals, schools, etc.), a mechancally- automatcally operated securty valve was desgned and manufactured. The flow propertes (velocty and pressure dstrbuton and pressure drop-mass flow relaton) of ths safety valve whch s desgned and manufactured were examned expermentally and numercally. In order to determne the pressure drop n the safety valve, an experment set was desgned and pressure changes occurrng n dfferent mass flows were determned. Wthn the scope of the quanttatve study, on the other hand, the safety valve was modeled as three-dmensonal and the pressure drop between the nlet and outlet was determned by the Ansys Fluent program for each flow value. Expermental and numercal results obtaned were found to be compatble wth each other. The ncrease n the mass flow ncreased pressure drop whch occurs n the safety valve, and ths ncrease was determned to behave close to lnear. Also, the fact that the results obtaned from the numercal analyss program are compatble wth the expermental data has shown that the numercal analyss can be used effectvely n ths type of studes. NOMENCLATURE A 0, A s : turbulence model constants C p : specfc heat C 1, C 2, C 1ε, C 2ε, C µ : turbulence model constants D : characterstc length of the geometry, dameter for crcular ppes (m) d G : cross-sectonal dameter of the valve nlet lne (mnmum cross-sectonal) (m) d p : nner dameter of the pston (maxmum crosssectonal) (m) G k : turbulent knetc energy producton (kg/m s 3 ) K : heat conducton coeffcent (W/m K) k : turbulent knetc energy (m²/s²) m : mass flow rate (kg/s) P o : outlet pressure (Pa) P : nlet pressure (Pa) Re : Reynolds number S ε : source term for ε (m 2 /s 4 ) T : temperature (K) t : tme (s) u : velocty component n the horzontal drecton (m/s) υ : knematc vscosty of the flud (m²/s) V ort : average flow velocty (m/s) w B : precson dgtal pressure gauge (%) x : horzontal coordnate (m) ΔP : pressure drop (Pa) ΔP max : maxmum pressure drop (Pa) ΔP mn : mnmum pressure drop (Pa) % ΔP 0 : pressure drop rate (%) ε : turbulence dsspaton (loss) rate (m²/s³) µ : dynamc vscosty (kg/m s) µt : turbulence vscosty (kg/m s) ρ : densty (kg/m³) : turbulent Prandtl number for k k : turbulent Prandtl number for ε ACKNOWLEDGMENT The patent applcaton related to the valve whch s the subect of ths study was supported by TUBITAK as ARDEB proect No. 2013/1813 wthn the scope of TUBITAK 1008 - Patent Applcaton Promoton and Support Programme. REFERENCES [1] Pala, B., Latfoglu, A., Water Losses Occurrng n Water Dstrbuton Networks - Case of Kayser Provnce, V. Natonal Envronmental Engneerng Congress (n Turksh), Ankara, pp.1-7, 2003. [2] Kavurmacoglu, L., Karadogan, H., Water Leakage Reducton of the Installatons Usng Automatc Control Valves, VI. Natonal Installaton Engneerng Congress and Exhbton, Izmr, pp.635-644, 2003. [3] Celkag, B., Determnng Valve Loss Factor n Ball Valves Expermentally and by Fnte Volume Method, Master s Thess (n Turksh), Insttute of Scence, Ege Unversty, Izmr, p. 119, 2004. [4] Amrante, R., Moscatell, P.G., Catalano, L.A., Evaluaton Of The Flow Forces On A Drect (Sngle Stage) Proportonal Valve By Means Of A Computatonal Flud Dynamc Analyss, Energy Converson and Management 48, pp. 942-953, 2007. [5] Chern, M.J., Wang, C.C., Ma, C.H., Performance Test And Flow Vsualzaton Of Ball Valve, Expermental Thermal and Flud Scence 31, pp. 505-512, 2007. www.str.org 195
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