International Journal of Modern Trends in Engineering and Research www.ijmter.com e-ISSN No.:2349-9745, Date: 28-30 April, 2016 CONTROL OF HYDRAULIC JUMP USING ABRUPT RISE INBED Pradnya Dixit1, Raj Shet2,Kishan Kansagara3,PrajwalitWanjari4, Snehal Jadhav5,Atharva Karkhanis6 1 Assistant Professor, Civil Engineering,Vishwakarma Institute of Information Technology, Pune 2-6 prdxt11@gmail.com, Students, Civil Engineering,Vishwakarma Institute of Information Technology, Pune Abstract - Hydraulic jump is a phenomenon caused by change in flow from super-critical to subcritical flow with considerable energy dissipation and rise in depth of flow. This paper presents the results of experimental investigations to control the hydraulic jump by providing the abrupt rise (hump) at the bed of rectangular open channel. Various types of humps were designed and fabricated based on the critical velocity analysis for the maximum discharge in the flume. These humps were placed in flume at different positions from the upstream gate to control the hydraulic jump at the downstream. From the experimental results a new relationship is proposed to control the hydraulic jump at a specified location using the hump in the bed. This gives the economical solution in agricultural field which is one of the major contributions towards the society as well as it also gives technical inputs to the researchers in the field of same research. Keywords -hydraulic jump, open channel, hump, energy dissipation, laboratory flume, etc. I. INTRODUCTION A hydraulic jump is a phenomenon which has extensively been studied in the field of hydraulic engineering due to its frequent occurrence in open channel flow such as rivers and spillways. When the rapid change in the depth of flow from a low stage to high stage, the result is usually in the form of an abrupt rise at water surface, this local phenomenon is known as Hydraulic jump. By utilizing characteristics, hydraulic jump is immensely used as an energy dissipater to dissipate the excess energy of flowing water at the downstream of hydraulic structures such as spillways and sluice gates, to recover head or rise the in water level on the downstream side and thus maintain high water level in the channel for irrigation or other water distribution purposes. It is useful for increasing weight on an apron to reduce the uplift pressure under a masonry structure by raising the water depth on the apron, to increase the discharge of a sluice by holding back the tail water, to indicate special conditions of supercritical flow and of control section to decide the perfect location of gauging station, for mixing of chemicals, to remove air pockets from water supply line and to prevent water locking etc. Due to these many practical applications, hydraulic jump is an interesting topic that has caught the imagination of many researchersin 18th century who had done the first experimental investigation of jump to till date. But the control of the jump and its location to serve all these above mentioned uses is the foremost important task for the investigators. The hydraulic jump can be controlled or affected by the number of appurtenances as baffle blocks, sills, weirs, abrupt rise and drop in the channels. As the flow in the vicinity of these appurtenances is rapidly varied, the velocity distribution is not uniform. And it is difficult to apply the momentum equation to analyze accurately the formation of jump only by means of theoretical basis; therefore for useful design information one has to rely on the experimental investigations [1]. The researchers had done laboratory experiments to develop empirical relations for universal applications and model studies were conducted for specific projects. In the 20 thcentury,many researchershave done experiments on hydraulic jump, amongst them one has done model study with dual spillway [2], one of them had thrown a light on the impact of hydraulic jump [3] and few from the current era; in 2005 one had studied the jump on rough bed [4], in 2011 researcher noticed @IJMTER-2016, All rights Reserved International Journal of Modern Trends in Engineering and Research (IJMTER) Volume 3, Issue 4, [April 2016] Special Issue of ICRTET’2016 put forwarded that the forced hydraulic jump[5], and many researchers had recently worked on characteristics of jump ,location of jump and control of jump using weir [6][7][8]. To the author’s best knowledge all the work mentioned above had not given any concluding remark to control the jump using abrupt rise in the bed of the open channel. This is the main reason for such a continued interest in this topic and its enormous practical utility in the hydraulic engineering and allied fields is the motivation of the present research work. II. EXPERIMENTAL SET UP AND METHODOLOGY In the present study experiments were performed on a horizontal rectangular channel of dimensions 5m X 0.25m X 0.076m in Fluid Mechanics Laboratory of Civil Department of Vishwakarma Institutes of Information Technology, Pune. Initially flume was set to carry the maximum discharge ( =0.00195 /sec) for which critical velocity is calculated ( =0.385 /sec). On the basis of these values dimensional limits were decided for the humps and humps of different dimensions were designed and fabricated (Table no. 1) considering the specific energy graph [9]. A series of experiments performed at different values of discharge and hydraulic jump was formed by using various humps at different locations. For each experiment initial depth, middle depth, final depth, length of hydraulic jump, location of hump and location of hydraulic jump were measured. The above steps were performed sequentially at different discharge. The discharge in the channel is measured using discharge measuring water tank. The depths were measured using point gauge and length by using measuring scale. From the above measured quantities, velocity before and after the jump, energy dissipation after the jump and Froude number were calculated. The statistical analysis of position of hump with respect to the location of jump is done as the main aim of the present study. Along with this the characteristics behavior of the jump with respect to the position of humps is also studied from the experimental observations. Table No. 1 Different dimensions of hump Figure No. 1 Multipurpose tilting flume III. EXPERIMENTAL OBSERVATIONS The experiments were carried out in flume of rectangular cross-section with zero slope level i.e. horizontal position. Hump was placed at desired location and water allowed from inlet valve in channel. The jump had occurred in channel due to hump and flow changes from supercritical to subcritical flow. Various depths of flow were measured at different locations along the length of channel. Discharge was measured in the measuring tank and velocity and energy calculation were done for each specific run. Similar procedure was followed with different locations and different humps. The variations observed during the experimental investigations in energy loss, Froude Number, location of jump and the depth of flow with respect to different humps along with their dimensions are presented in 3.1 to 3.4 sections respectively and the concerned results of which are presented in the next section 3.1 Variation in Energy Loss with respect to Location and Dimensions of Hump: @IJMTER-2016, All rights Reserved 438 International Journal of Modern Trends in Engineering and Research (IJMTER) Volume 3, Issue 4, [April 2016] Special Issue of ICRTET’2016 Energy loss in percent 40 Distance of hump from upstream Energy loss in percent for various cases 30 20 10 0 10*226*76 12*226*76 25*226*76 30*226*76 12*113*76 25*113*76 1710 2.57 7.49 6.24 26.02 6.49 5.07 2600 3.60 10.41 17.13 30.86 8.66 15.70 3100 4.82 8.05 15.23 18.81 8.11 15.70 Figure no. 2. Variation in Energy Loss w.r.t location and dimension of hump Froude number 3.2 Variation in Froude number with respect to Location and Dimension of Hump: Distance of hump from upstream 3.00 2.50 2.00 1.50 1.00 0.50 0.00 Froude number for different hump 10*226*76 12*226*76 25*226*76 30*226*76 12*113*76 25*113*76 1710 0.65 0.68 1.68 2.57 0.65 1.59 2600 0.67 0.81 2.23 2.72 0.76 1.86 3100 0.74 0.83 2.09 2.22 0.79 1.97 Figure no. 3. Variation in Froude number w.r.t. location and dimensions of hump 3.3 Variation in location of jump related to location and dimensions of hump: Figure no 4. Variation in location of jump w.r.t location and dimensions of hump @IJMTER-2016, All rights Reserved 439 International Journal of Modern Trends in Engineering and Research (IJMTER) Volume 3, Issue 4, [April 2016] Special Issue of ICRTET’2016 3.4 Variation in final depth with respect to location and dimensions of hump: Final flow depth for various hump 60.00 58.00 Depth 56.00 54.00 52.00 50.00 Distance of hump from upstream 10*226*76 12*226*76 25*226*76 30*226*76 12*113*76 25*113*76 1710 57.40 57.70 57.90 58.20 57.90 58.10 2600 54.43 56.29 56.39 55.07 56.40 56.56 3100 53.00 53.72 54.00 54.00 54.30 54.69 Figure no.5. Final flow depth related to location and dimensions of hump IV. RESULTS AND DISCUSSIONS In fig no.2, it is observed that for hump (113*12*76mm) that energy dissipation maximum when the hump is placed closed to the center of the channel. For hump (25*113*76mm) placed at 2075 mm from the upstream gate, the energy dissipation is 6.18%. Similarly, for hump (25*226*76mm) placed at 2075 mm from the upstream gate, the energy dissipation is 70.71%. Therefore, it can be said that as the length of the hump is increased at the first position, the energy dissipation is larger. For hump (12*113*76mm) placed at 2075 mm from the upstream gate, the energy dissipation is 13.28%. For hump (30*113*76mm) placed at 2075 mm from the upstream gate, the energy dissipation is 19.62%. It is evident from these results that keeping length of the hump constant and only the depth is increased then the energy dissipation is greater. From fig no.3, it is observed that as the location of the hump from the upstream gate increases, Froude number also increases.As the thickness of the hump increases, the Froude number decreases as the location of the hump from upstream gate increase. From fig no.5, we additionally observed that as the location of the hump from the upstream gate increases, the downstream depth decreases. As the thickness of the hump increases, the downstream depth decreases. As the thickness of the hump increases, the downstream depth decreases for the same position of the humps. Similarly, from fig no.4 represents the occurrence of hydraulic jump w.r.t. upstream gate on X-axis and location of hump w.r.t. the upstream gate (rise in bed level) on Y- axis for different location of hump. It is observed in fig.4, as the hump’s distance from the upstream gate increase, the location of jump increases w.r.t. the upstream gate, i.e. the hydraulic jump moves towards the downstream gate. Also, when the hump (25*113*76mm) is positioned at 2075 mm from the upstream gate, the jump occurs at 2850 mm away from the upstream gate. Similarly, when the hump (25*226*76mm) is positioned at 2075 mm from the upstream gate, the jump occurs at 3635 mm away from the upstream gate. Therefore, it can be concluded that when the length of the hump placed in the channel is doubled, hydraulic jump moves towards the downstream side (i.e. distance from the upstream gate increases. It is also observed that when hump (25*113*76mm) is placed at 2075 mm from the upstream gate, the hydraulic jump occurs at 2850 mm from the upstream gate. Also, when hump (12*113*76mm) is placed at 2075 mm from the upstream gate, the hydraulic jump occurs at 3595 mm from the upstream gate. Thus, it can be concluded that, as the depth of the hump is decreased, the hydraulic jump moves towards the downstream side of the channel. Following mathematical relation is observed with due consideration of relation between depth and location of hump with location of jump. ∆Z * X = K* Y Where ∆Z = Depth of hump. @IJMTER-2016, All rights Reserved 440 International Journal of Modern Trends in Engineering and Research (IJMTER) Volume 3, Issue 4, [April 2016] Special Issue of ICRTET’2016 X = distance of hump from upstream gate. Y = distance of jump from upstream gate. And K is proportionality constant which depends on depth of hump given in table no.2 Table no. 2. K values fordifferent depth of hump V. CONCLUSIONS In this study, the effect of abrupt rise on the characteristics of hydraulic jump, consisting of energy loss, Froude number, depth of flow and location of jump has been experimentally investigated in open channel. It is apparent from results that Froude number increases as the location, depth, length of the hump increases from the upstream gate. Jump goes downstream side as the distance of hump increases from upstream gate and hence control of jump at the required position can be made possible. With this it can be stated that location of jump from the upstream gate has a linear relationship with the depth of the hump alongwith its distance from the upstream gate. When length of the hump is kept constant and only the depth is increased then the energy dissipation is greater.The derived expression (∆Z * X = K* Y) can be readily used at the field level for agricultural as well as irrigational purposes which is major contribution of this research towards the society. Also the required size of humpcan very easily be used by any farmer can very easily use with very low budget appliances. Water can safely be transfer from one channel to another with reduced velocity without constructing any additional structure or without operating any gate etc.In navigation channels flow can be changed from supercritical to subcritical as and when and where it is required without much expense, less laborious and with ease in function. At the end this can be further studied in depth for in the area of same research filed for case specific problems. Acknowledgement The authors would like to thank BCUD (Board of College and University Development, Pune.) for funding the project research work. VI. REFERENCES [1] [2] [3] [4] [5] [6] [7] [8] [9] Ven Te Chow, Open channel hyraulics , Tata McGraw- Hill book company inc, 1959. Mrs. V. V. Bhosekar m.ish, Mrs. M. I. Sridevi m.ish and P. B. Deolalikar f.ish, Hydraulic model studies for a dual purpose spillway with 21 m depth of overflow-a case study ISH journal of hydraulic engineering, 2005, Volume 11, Issue 3, p. 32-46 Willi H. Hager and Robert Wanoschek, Hydraulic jump in trapezoidal channel, Journal of Hydraulic Research,1989, Volume 27, Issue 3, pages 429-446. Carollo F., Ferro V., and Pampalone, V., Hydraulic Jumps on Rough Beds., J. Hydraul. Eng.,2007, 133(9), p. 989– 999. Zare, H. and Doering, J., Forced Hydraulic Jumps below Abrupt Expansions., J. Hydraul. Eng., 2011, 137(8), p. 825–835. A. Nassar Mohamed, Modeling of free jumps downstream symmetric and asymmetric expansions: theoritical analysis and method of stochastic gradient boosting, original research article journal of hydrodynamics, Feb 2010, ser. B, volume 22, issue 1, p. 110-120. M. Ben Meftah, M. Mossa and A. Pollio, Considerations on shock wave/boundary layer interaction in undular hydraulic jumps in horizontal channels with a very high aspect ratio Original Research Article European Journal of Mechanics - B/Fluids, November–December 2010, , Volume 29, Issue 6, p. 415-429 Madadi M R. and Dalir A H., Control of undular weir flow by changing of weir geometry, Flow measurement and instrumentation, Volume 34. Subramanya K., Flow in open channel, Tata McGraw Hill Publishing company Ltd. 2011. @IJMTER-2016, All rights Reserved 441