Effects of the Geometrical Conditions on Side Channel Pump

nucleusuate of the Geometrical Conditions on fount Channel nitty-grittyEffects of the Geometrical Conditions on the Performance of a Side Channel Pump A reviewAppiah Desmond, Zhang Fan, Yuan Shouqi and Osman Majeed KorantengNational Research Center of Pumps, Jiangsu University, Zhenjiang 212013, China scheme The post blood line nub is a type of regenerative ticker which plays a role in between the centrifugal affectionateness and the positive displacement warmness. This variety show of philia delivers a elevated bearing at relatively small adverts compared with other axial and centrifugal pumps even though it requires a low specialised speed. This paper firstly focuses on the physical principle behind the run for distinctions illustrating the complex break away in incline the slope comport pump. Further discussions disclosed that, the hydraulic performance of the pump amplely depends on the variations of the geometrical parameters. This review draws conclusion th at, enhancement of the computational simulationing techniques will repair the efficiency of this pump on that pointby broadening its applications.Keywords Side Channel Pump, Hydraulic Performance, head, geometrical parameters, computational modeling1.0 Introduction The side ancestry pump since its inception in 1920 by Siemen and Hinsch 1 has had great influence in the world of engineering. This pump plays a role in between the centrifugal pump and the positive displacement pump. The side channel pump is a kind of regenerative pump which has a low specific speed and requires minimal Net Suction Pump Head (NSPH). Due to its unique properties to self-prime and transports both(prenominal) liquids and bollocks, it has been used mainly in the fields of oil and gas industry, mining and other applicable fields. Most of these pumps concur the ability to handle liquid with gas or vapor inclusions up to ab come forth 50% and to a fault other media close to their boiling point 2. The sid e channel pumps base its operation on the momentum transfer principle moving from the impeller sword to the bland in the side channel of the pump 3, 4.The side channel pump delivers a with child(p) head performance at relatively small flows 5. The fluid gets into the pump and leaves afterward numerous impeller movements. The fluid velocity and its head increase ca utilise it to have the capability to produce a head ( instancy) compared to the axial and centrifugal pumps. Due to the smaller pressure difference, a fluid entering this type of pump scalelike to its vapor pressure is less susceptible to the pressure change that can bring about cavitation4. Over the years, the enhancement of the total efficiency of this pump relieve remains a challenge to engineers and scientist. The flow prise of fluid in the side channel pump is meaning(a)ly influenced by the impeller designs on this basis pressing attention needs to be given to the design and optimization of the impeller and si de channel 5, 6.2.0 Flow Mechanism The side channel pump mainly features a side channel in figure 1a. and an impeller usually with 18 to 26 weathervanes figure 1b, which delivers the fluid circumferentially. The assembly of the side channel and the impeller is shown in figure 1c. The fluid flows in a straight line from the deferral of the pump and leaves through the outlet in a helical form after numerous re-entries into the rotating impeller. This effect causes an up grow in the pump head (pressure) from about 510 times better than the impeller of a common pump rotating at the same speed 5, 6.side channel (b) radial impellerThe assembly of side channel and impeller strain 1 Typical side channel with radial impellerThis makes the flow of fluids in this kind of pump very complex as depicted in figure 2. The pump does not transport the same volume of fluid that enters out meanwhile nigh portion of the fluid moves back into interrupter gap and is conveyed by the pressure side of th e marque to the suction side 6. Shirinov and Oberbeck 3 explained the movement of gas in the side channel pump. They pointed out that the momentum acquired by the blades of the impeller is transferred to the gas. The velocity of the gas is then increased both in the axial and radial direction by the impeller blades in the side channel. regard 2. Flow pattern of liquids in the Side Channel Pump 5The upthrust and the circulation models are largely used to describe the performance of the pump and in addition the characteristic curve computation. The side channel pump efficiency is usually below 40% because it is a type of a regenerative pump 5, 6. Basically, the flow is very dependent on the orientation of the impeller, impeller blade and the side channel. There are many configurations of the impeller blade and shapes of the channel as depicted in figure 3 by Song et al. 7.Figure 3 Different kinds of blade and channel shapes 7A study by Senoo 8 on the influence of the burgeon for thing surface domain of a function for assorted geometries of the entrance region of the regenerative pump observed the large channel region at the admittance port as capable of developing high pressure head leading to a better cavitation performance of the pump. Song et al. 7 developed a model for the flow theory in the regenerative pump to help care for the lapses in the influences of Senoo8 and Wilson et al. 9 which mainly concentrated on the exchange of momentum of the flow. There were inaccuracies of some of the models suggested by 8, 9 to reduce the losses and slip factor links. This make the accurate prediction of the off-design flow conditions very incapable. Song and his colleagues 7 concentrated on introducing vibrant mathematical algorithms demonstrating the true behavior of the flow in the developing area of the inlet region. They establish their research on assumptions which guided them in arriving at some meaningful conclusions. The velocity tri locomote relatio n between absolute velocity, V relative velocity, W and the impeller velocity, U was define based on the velocity tri burthen in figure 4 at blade inlet, R1 and blade outlet, R2.Figure 4 Velocity triangle at locations R1 and R2 7From figure 5, there is no tangential velocity in the front and rear faces of the blade region. Thereby, the continuity was defined in equation 1 based on their first assumption that the flow should be steady and incompressible.(1)Figure 5 Elements of one side channel and blade 7They developed the first-order nonlinear Ordinary Differential Equation (ODE) for predicting the circulatory velocity which showed a good agreement when its results were compared with that of experimental results.A new differentiate of fluid mechanics developed in the last decades called Computational Fluid Dynamics (CFD) has been employed lately in the modern engineering science to probe the flow of fluids in turbo machines. The study of the fluid flow in the side channel pump us ing the CFD tool and an analytical method was the centered of Bhle and Mullers 10 research. They developed an analytical model for the flow taking into condition some assumptions. A momentum balance was expressed for the control volume of the flow in a circumferential course.(2)Where Cin = uniform velocity in circumferential courseCsc = uniform velocity in the side channelexch = mass exchange flowp = static pressureA =Side channel cross-section areaA1 = surface control volume = mean snip stressFigure 6 momentum balance 7The efficiency of the impeller and side channel was defined as(3)Where imp = impeller efficiencyPexch = Exchange feat PowerP dig = Power of shaftPhydr = Hydraulic power losses(4)Where sc= side channel efficiencyPeff = effective power = side channel pump mass flowg = acceleration due to gravityH = head of side channel pumpCin = uniform velocity in circumferential course= flow rate volumeA =Side channel cross-section areaBased on the efficiencies of the impeller an d the side channel, the efficiency of the side channel pump, was computed to be(5)Later, Kristof and his colleagues 11 also utilize the CFD to model the flow course in the side channel pump as displayed in figure 6. A technique was modeled to optimize the orientation of the blade and the shape of the side channel to control the flow losses. They carried out simulations with the k- turbulent conditions based on a 40100 cell tetrahedral mesh.Figure 6(a) and (b) Typical flow course with the side channel pump 11In 2005, Engeda and Raheel 12 presented mathematical tools capable of examining the complex flow inside the regenerative pumps. These mathematical tools were used also used to develop the prediction performance code for regenerative pumps3.0 Effects of the Geometrical design of the parameters of the Side Channel Pump The performance of the regenerative pump was examined by Iverson 13 with his focus on the shear stress generated by the impeller on the fluids. He then confirmed o n his resulting expressions (two shear coefficients and an average impeller velocity) through experimentations. A mathematical tool was proposed by Wilson et al. 9 to investigate the performance of regenerative pumps which used radial blades. Equal pressure head rise and circulatory velocity through the channel region was anticipated by Wilson and his team. frequently attention was given to the spiral flow to achieve many ways of curtailing the losses. Their results provided experimental verification after comparing the numerical and experimental performance curves. Yoo et al. 14 also tried to develop advanced mathematical equations to calculate the geometry of the rotating flows. They offered enhanced models to examine the flow rate, the average radii of the inlet and outlet impeller and the slip factor based on the exchange of momentum proposal by Wilson et al 9. The models required an experimental boost to evaluate an empirical upshot in the proposed experimental model. The ef fect of the blade angle was not considered thus limiting the applicability as a design tool.The variation of the radial blade numbers, the clearance and the channel region of regenerative pumps were conducted by Shimosaka and Yamazaki 15. Investigations conducted by varying the dimension of flow channels, impellers and clearances on a regenerative pump concluded that, the characteristic dimension of the flow channel is related to the clearances effects, which in turn influences the pump efficiency. The characteristic dimension of the flow channel was introduced as a special dimension which was given as(6)Where Rmis the characteristic dimension of flowA is the cross-sectional area of the flow channel is the circumferential length of the blade(vane)Figure 7 Flow channel and blade penThey reported that a suitable Rm would yield a high efficiency of the pump. Therefore, the value of the Rm determines the permissible clearance. The pump efficiency was also strongly influenced by the num ber of blades (vanes) which is dependent on the characteristic dimension of the flow channel, the thickness and length of the blade and the breadth ratio as shown in figure 7. It was established that the efficiency of the pump varies with different width ratios of the vane groove which aids in the determination of the blade number.Width ratio,(7)Defining Z = Number of bladesD = Diameter of impellert1 = Peripheral width of blade groove t2 = Peripheral length of blade grooveAdditionally, Yamazak et al. 16 also carried out works to investigate the efficiency of the regenerative pump. Unlike Shimosaka and Yamazaki 15, they used the non-radial blades and concluded that the blade angle and the cross-sectional area of the flow channel play a vital role in the determination of the head (pressure) loss in the flow channel.h = Hs Hmin(8)Where h = the magnitude of head loss Hs = the suction head Hmin = the minimum pressure head in flowIt was noted that the magnitude of h reduces to almost h alf that of water with the same velocity in the event of high viscous liquid. Motivated especially by the observations made by 15, 16, Grabow 17 also took into consideration the effects of the impeller, the number of blades and the role of the radii and thickness of the blades during his research study. The blade angles were varied to define a very satisfactory exchange of naught and pressure head levels, which in effect helps to evaluate cavitation performance better. Bartolini and Romani 18 also affirm that, the flow rate of the regenerative pumps depends on the optimization of the impeller flow. A new theory was proposed by Badami 19 on the calculation of the circulation flow rate of the regenerative pumps. This model took into account the field of the centrifugal force in both the side channel and the blade orientation. Also, his work also considered the influences of the geometry of the blades (number and angles) and the area of the side channel. Earlier it had been discussed by Sachs and Shirinov 20 that the best number of blades depends directly on the diameter of the impeller and inversely proportional to the side channels size. by and by that work, Shirinov and Oberbeck3 then focused their investigations on the transportation of gas in the side channel pump by using different blade profiles. They compared C, V, and Y blade profiles with the radial (T) blade profile as shown in figure 8.Figure 8 goblineller with different blade profilesAfter comprehensive comparisons, it was established that blade profile C gave an optimal performance at pressures exceeding 20kPa meanwhile at pressures from 100Pa to 20kPa, the impeller with blade profile V (Chevron) recorded an optimal performance because there was a high transfer of momentum from the impeller to the gas inside the side channel within such pressure range. An extensive experimental research was also conducted by Choi et al. 21.Their work was mainly focused on the limitations of 14, 15, 17. They exami ned the effects of the geometry on the blade on the efficiency of regenerative pumps. Ten different configurations of blades which comprised straight inclined blades with angles of 0, 15, 30 and 45 and chevron impeller blade with chevron angles of 15, 30, and 45 were used in conducting the experiments. The measured performance of the pump were measured based on the dimensionless flow , head coefficient, , efficiency, and power coefficient, .(9)Where Q = volumetric flow rateQs= rigid- proboscis rotational volume displacement rate (10)H = headUg = rigid body rotation velocityg = acceleration due to gravity(11)The experimental results showed that the pressure head and the pump efficiency is greatly related to the geometry (shape and angle) of the blade as revealed in figure 9(a) and 9(b).Figure 9(a). Pump curve characteristics for the different blade orientation 21Figure 9(b). Efficiency curve characteristics for the blade orientations 21The chevron blade(V-shaped) with chevron angle of 30 recorded the highest head performance with a better pump efficiency as revealed in figure 8(a) and 8(b) after a comparative rise of all the ten blades masking that there was an optimum chevron angle of around 30. This report showed good agreement with the work of 3 because of the high energy transfer at high pressures. The variation of the Reynolds number plays an important role in the performance of the regenerative pump computationally and experimentally. It was established by Horiguchi et al. 22 that, as the Reynolds number declines the pressure head of the regenerative pump rises at low flow rate and reduces at high flow rate. This effect of the Reynolds number is greatly affected by the degree of the shear force applied the impeller and the shear stress exerted by the fluid on the casing wall. Meakhail and Park 23 with the help of the CFD put forward an ameliorate model to enhance the efficiency of the regenerative pump. They based their arguments on the experimental w orks conducted by Meakhail et al. 24, Abdou et al. 25 and Abd El-Messih et al. 26 on the same kind of pump. They then confirmed their numerical model with the experimental results which were in good correlation.Figure 10a Spiral flow course 23 Figure 10b Impeller and Side channel dimensions 23The improved model considered the tip (2), side (2s) and inlet (1) angles since a part of the fluid flowing leaves at the tip of the impeller and the other part of the fluid leaves at the side as indicated in figure 10. The CFX software program was used to compare the efficiency of the pump with radial blades of different 2s at the tip of the blade and 1 for the same 2. They confirmed that the side-blade angle has a significant effect on the performance of the side channel pump. The FLUENT software was applied in the examination of the flow of the fluid in this kind of pump by 27, 28. The experimental results corroborated the CFD analysis. They also used a one-dimensional method to describe th e energy transfer inside the regenerative pump and estimate the influence of the geometry of the blade on the efficiency of the pump.The performance of the regenerative pump was examined by Karanth et al. 29 numerically with the help of CFD. They studied the complex nature of the flow of fluid inside the regenerative pump. It was discussed that the number of impeller blades had a great significant on the performance of the pump. The head performance of the pump appreciates with the increase in the number of blades. Following the works of 29 the CFD was also applied by Maity et al. 30 to simulate the flow of fluids in regenerative pumps. It was established from their work that the pressure head loss can be minimized by curving the outlet flow domain as indicated in figure 11.Figure 11 Regenerative Pump model displaying the curvature in the outlet domain 30It was indicated that there is a high rotating stalling flow at the outlet of the pump because of the reduction of the area. This effect enhances the static and total pressure across the pump. Hence, the curvature in turn increases the moolah pressure head by reducing the vortex flow as in shown in figure 12.Figure 12 Bar diagram showing the total pressure for the Pump model with outlet domain curvature 30They also ended that, the net pressure is significantly enhanced by locate the blades on either side of the impeller by offsetting. Moreover, the net pressure is also affected by varying the number of blades on either side of the impeller. Fleder 31 numerically and experimentally examined the effects of the geometry of the blade on industrial side channel pumps in 2012. Two different impeller blade profiles were developed using ANSYS CFX 13.0 and subjected to investigations as shown in figures 13 and 14.Figure 13 Design of the Side Channel Pump 31Figure 14 Impeller Blade Profiles 31He concluded his work after comparison of the computational and experimental results. The experimental validation was done with a rotational speed of 750 rpm. The Imp 1 depicted good accordance both numerically and experimentally. Meanwhile, Imp 2 recorded a faster head rise because of the higher circulation frequency. This, in turn produces a greater multi-stage influence as depicted in figure 15.Figure 15 Assessment of the pressure head performance of the simulated and experimental results for Imp 1 and Imp 231In addition, Fleder again with Bohle 32 carried out advanced studies to improve the performance of the side channel pump. In this paper, they extended their scope not only to cover the blade profile. The impeller diameter, the size of the gap, interrupter size, side channel height and the shape of the side channel were the main parameters considered. Variation of the height of the side channel, h, the width of the blade, w and the length of the blade, l, were applied to two different pump models in figure 15.Pump Model A Pump Model AImpeller Diameter = 150 mm Impeller Diameter = 160 mm jailbreak Siz e s, = 0.2 mmGap Size s, = 0.4 mmInterrupter size = 300Interrupter size = 460Side Channel height, h = 35 mmSide Channel height, h = 40 mmShape of Side Channel = semi-circleShape of Side Channel = StraightFigure 16 Variations in the pump models A and B 32Figure 17 Parameters of the Side Channel Pump 32The ICEM software was applied to develop the computational models which were meshed using the structured hexahedral multi-blocks grids. They chose k-w-SST profile to assess the flow fluctuations. It was gathered that the efficiency of the pump is dependent on the ratio of the side channel height, h to the blade length, l. Furthermore, sharper pressure head features and meaningfully greater efficiencies are achieved with a gap reduction of the pump.The work done by 21, 31, 32 on the influence of the blade angle motivated Nejadrajabali et al.4 in 2016 also to analyze the pattern of the flow and the improvement of the efficiency of the pump by modifying the geometry of the blades. Their fo cus was on the effect of the variations of the angle of the blade, numerically on the efficiency of the regenerative pump such as the side channel pump. The investigations were carried out using two sets of impellers i.e. (the symmetric blade angles and asymmetric blades angles). The symmetric blade angles were designed with the same inlet and outlet angles of 10o, 30o and 50o whiles the asymmetric blade angles were also designed with the inlet set to 0o and different outlet angles ranging from 10o to 50o as illustrated in figure 18.Forward/backward 1,2 = 10o Forward/backward 1,2 = 30o Forward/backward 1,2 = 50oSymmetric blades with equal inlet 1 and outlet 2 anglesForward/backward 2 = 10o Forward/backward 2 = 30o Forward/backward 2 = 50oAsymmetric blades with inlet 1 = 0oFigure 18 Geometrical designs of impellers 4These geometrical designs were well enhanced with the application of the CFX software using the Reynolds decomposition to evaluate the complete 3D Reynolds-averaged Na vier-Stokes equations. It was pointed out after the numerical simulations that, the forward symmetric blade angles compared with the other models recorded higher coefficients of heads and displayed a better performance. Recently, Zhang together with his colleagues 33 improved the head pressure performance of the side channel pump by varying the suction side blade angles from 00 to 300 as indicated in figures 19 and 20.Figure 19 Cross-sectional area of the blade 33 Figure 20 The impeller with motley suction side blade profileangles indicating = 100, = 200 and = 300 33The CFX 14.5 commercial software was used to simulate the turbulence based on the k-w SST model. After experimentally comparing the results with the numerical simulations, it was recognized that the head performance appreciates with increasing suction side blade angles within a certain range. Even though the impeller blade profile with suction angle 300 recorded the optimal head performance, there was no significant promotional material in the efficiency of the side channel pump. The regenerative pump (side channel pump) records efficiencies lesser than other types of pumps like the axial and centrifugal pumps. Bhle et al. 34 lately attempted to improve the efficiency of the side channel pump by using the direct method in the context of the CFD simulations to calculate the massive losses which are associated with the various kinds of internal flow patterns of the fluid. The second law of thermodynamics was main physical principle applied in the estimation of the internal losses due to the flow patterns. gibe to Spurk and Aksels 35 proposal expressed in equation 10, the specific entropy s is a state variable agreeing with the second law of thermodynamics appreciates in all material and irreversible mechanical process in the case of turbomachinery.(12)Where = density of the fluids = specific entropyu = velocity component in x directionv = velocity component in y direction w = velocity compone nt in z directionx = x coordinatey = y coordinatez = z coordinate= heat flux density vector= Dissipation= local dissipation by heat transferAfter the applications of three different models ( i.e. k- model, k- model and the k- -SST model) to calculate and locate the coefficient of the losses, they remarked that the k- model and k- model predicts estimates regions of higher coefficient of losses matched to the k--SST model.4.0 ConclusionThough there have been several investigations into the theory of the flow principle of the fluid and variation of the geometry of the impeller and side channel, t