Experimental and Numerical Study on Hydraulic Performances of a Turbopump With and Without an Inducer

2018 ◽  
Author(s):  
Yanxia Fu ◽  
Meng Fan ◽  
Giovanni Pace ◽  
Dario Valentini ◽  
Angelo Pasini ◽  
...  
Keyword(s):  
Total Pressure ◽  
Pressure Rise ◽  
Hydraulic Performance ◽  
Numerical Results ◽  
Operating Conditions ◽  
Design Flow ◽  
Low Flow ◽  
Flow Rates ◽  
Lower Flow ◽  
Inlet Duct

The hydraulic performance of a centrifugal turbopump with and without a 3-bladed axial inducer has been studied both experimentally and numerically. A 3D numerical model has been used to simulate the flow through from the inlet to the outlet ducts of the turbopump with and without an inducer using the ANSYS CFX code. The sensitivity of the numerical results has been analyzed with reference to the adopted turbulent flow models, to the length of the input and output ducts included in the simulations, to the reference positions used for the evaluation of the total pressure rise and to the temperature of the operating fluid. The measured and predicted hydraulic performances of the turbopump with and without the inducer have been compared under different operating conditions. As expected, the predicted hydraulic performance of the turbopump is significantly influenced by the lengths of the inlet and outlet ducts, the turbulence models and, at low flow rates, the reference positions of the total pressure rise measurements. The pressure rise coefficients obtained from the simulations using an inlet duct with length of 3 rTi and 10 rTi were significantly lower than the experimental results, while at low flow rates those referring to the inlet duct with length greater than 10 rTi were significantly higher than those obtained for the shorter inlet duct. With reference to the effect of the pressure measurement locations, the difference between the numerical results of the pressure rise coefficient and the experimental values was much higher when the data were obtained at the locations where the transducers was mounted in the experimental tests at lower flow rates. Moreover, the hydraulic performance of the turbopump at lower flow rates can be significantly influenced by the use of the upstream inducer, with a pressure drop of 20% in particular at 60% of the design flow rate.

scholarly journals Investigation of the Flow Field in the Vicinity of an Axial Flow Fan During Low Flow Rates

2014 ◽  
Author(s):  
Francois G. Louw ◽  
Theodor W. von Backström ◽  
Sybrand J. van der Spuy
Keyword(s):  
Flow Field ◽  
Numerical Simulations ◽  
Flow Rate ◽  
Axial Flow ◽  
Operating Conditions ◽  
Design Flow ◽  
Low Flow ◽  
Axial Flow Fan ◽  
Free Vortex ◽  
Flow Rates

Large axial flow fans are used in forced draft air cooled heat exchangers (ACHEs). Previous studies have shown that adverse operating conditions cause certain sectors of the fan, or the fan as a whole to operate at very low flow rates, thereby reducing the cooling effectiveness of the ACHE. The present study is directed towards the experimental and numerical analyses of the flow in the vicinity of an axial flow fan during low flow rates. This is done to obtain the global flow structure up and downstream of the fan. A near-free-vortex fan, designed for specific application in ACHEs, is used for the investigation. Experimental fan testing was conducted in a British Standard 848, type A fan test facility, to obtain the fan characteristic. Both steady-state and time-dependent numerical simulations were performed, depending on the operating condition of the fan, using the Realizable k-ε turbulence model. Good agreement is found between the numerically and experimentally obtained fan characteristic data. Using data from the numerical simulations, the time and circumferentially averaged flow field is presented. At the design flow rate the downstream fan jet mainly moves in the axial and tangential direction, as expected for a free-vortex design criteria, with a small amount of radial flow that can be observed. As the flow rate through the fan is decreased, it is evident that the down-stream fan jet gradually shifts more diagonally outwards, and the region where reverse flow occur between the fan jet and the fan rotational axis increases. At very low flow rates the flow close to the tip reverses through the fan, producing a small recirculation zone as well as swirl at certain locations upstream of the fan.

An Artificial Intelligence Based Method for Performance Prediction and Inverse Design of Hydraulic Turbochargers

2020 ◽  
Author(s):  
Azam Thatte ◽  
Ganesh Vurimi ◽  
Prabhav Borate ◽  
Teymour Javaherchi
Keyword(s):  
Neural Network ◽  
Pressure Rise ◽  
Operating Conditions ◽  
Inverse Design ◽  
Geometrical Parameters ◽  
Total Efficiency ◽  
Design Algorithm ◽  
Flow Rates ◽  
Radial Turbine ◽  
Radial Pump

Abstract A neural network based method is developed that can learn the underlying physics of hydraulic turbocharger (a radial pump coupled with a radial turbine) from a set of sparse experimental data and can predict the performance of a new turbocharger design for any given set of previously unseen operating conditions and geometric parameters. The novelty of the algorithm is that it learns the underlying physical mechanisms from a very sparse data spanning a broad range of flow rates and geometrical size brackets and uses these deeper common features recognized through a “mass-learning process” to predict the full performance curves for any given single geometry. The deep learning algorithm is able to accurately predict the key performance parameters like total efficiency of the turbocharger, its operating speed, pressure rise provided by the radial pump of the turbocharger and the shaft power produced by the radial turbine of the turbocharger for any given input combination of pump and turbine flow rates, differential pressure across the turbine and a limited set of geometrical parameters of pump and turbine impellers and volutes. Lastly, a novel method for fast inverse design of turbomachinery using a physics trained neural network and a constrained optimization algorithms is developed. The algorithm uses Nelder-Mead and Interior Point methods to find the global minimum of turbocharger design objective function in multi-dimensional space. The newly developed method is found to be very efficient in optimizing turbomachinery design problems with both equality and inequality constraints. The inverse design algorithm is able to successfully recommend an optimal combination of geometrical parameters like pump blade exit angle, pump impeller diameter, blade width, eye diameter, turbine nozzle diameter and rotational speed for a given target efficiency and head rise requirements. The preliminary results from this study indicate that it has a great potential to minimize the need for expensive 3D CFD based methods for the design of turbomachinery.

Turbulence Measurements in a Centrifugal Pump With a Synchronously Orbiting Impeller

1991 ◽  
Author(s):  
Ronald D. Flack ◽  
Steven M. Miner ◽  
Ronald J. Beaudoin
Keyword(s):  
Centrifugal Pump ◽  
Reynolds Stress ◽  
Flow Rate ◽  
Cross Product ◽  
Design Flow ◽  
Low Flow ◽  
Rate Variation ◽  
Flow Rates ◽  
The Individual ◽  
Design Flow Rate

Turbulence profiles were measured in a centrifugal pump with an impeller with backswept blades using a two directional laser velocimeter. Data presented includes radial, tangential, and cross product Reynolds stresses. Blade to blade profiles were measured at four circumferential positions and four radii within and one radius outside the four bladed impeller. The pump was tested in two configurations; with the impeller running centered within the volute, and with the impeller orbiting with a synchronous motion (ε/r2 = 0.016). Flow rates ranged from 40% to 106% of the design flow rate. Variation in profiles among the individual passages in the orbiting impeller were found. For several regions the turbulence was isotropic so that the cross product Reynolds stress was low. At low flow rates the highest cross product Reynolds stress was near the exit. At near design conditions the lowest cross product stress was near the exit, where uniform flow was also observed. Also, near the exit of the impeller the highest turbulence levels were seen near the tongue. For the design flow rate, inlet turbulence intensities were typically 9% and exit turbulence intensities were 6%. For 40% flow capacity the values increased to 18% and 19%, respectively. Large local turbulence intensities correlated with separated regions. The synchronous orbit did not increase the random turbulence, but did affect the turbulence in the individual channels in a systematic pattern.

scholarly journals Optimal Design of Inlet Passage for Waterjet Propulsion System Based on Flow and Geometric Parameters

2019 ◽  
Vol 2019 ◽  
pp. 1-21 ◽  
Author(s):  
Weixuan Jiao ◽  
Li Cheng ◽  
Di Zhang ◽  
Bowen Zhang ◽  
Yeping Su ◽  
...  
Keyword(s):  
Velocity Ratio ◽  
Optimization Method ◽  
Hydraulic Performance ◽  
Numerical Results ◽  
Propulsion System ◽  
Operating Conditions ◽  
Geometric Parameters ◽  
Hydraulic Characteristics ◽  
Design And Optimization ◽  
Ship Speed

As an important overcurrent component in a waterjet propulsion system, the inlet passage is used to connect the propulsion pump and the bottom of the propulsion ship. The anticavitation, vibration, and noise performance of the waterjet propulsion pump are significantly affected by the hydraulic performance of the inlet passage. The hydraulic performance of the inlet passage directly affects the overall performance of the waterjet propulsion system, thus the design and optimization method of the inlet passage is an important part of the hydraulic optimization of the waterjet propulsion system. In this study, the hydraulic characteristics of the inlet passage in the waterjet propulsion system with different flow parameters and geometric parameters were studied by a combination of numerical simulation and experimental verification. The model test was used to verify the hydraulic characteristics of the waterjet propulsion system, and the results show that the numerical results are in good agreement with the test results. The numerical results are reliable. The hydraulic performance of the inlet passage is significantly affected by the inlet velocity ratio. There is a certain correlation between the hydraulic performance of the inlet passage and ship speed, and the hydraulic performance of the inlet passage is limited by ship speed. The geometric parameters of the best optimization case are as follows: the inflow dip angle α is 35°, the length L is 6.38D0, and the upper lip angle is 4°. The optimal operating conditions are the conditions of IVR 0.69–0.87.

Under-Expanded Gaseous Flow at a Straight Micro-Tube Exit

2014 ◽  
Vol 136 (8) ◽  
Author(s):  
Takahiro Yoshimaru ◽  
Yutaka Asako ◽  
Toru Yamada
Keyword(s):  
Total Pressure ◽  
Gas Flow ◽  
Numerical Results ◽  
Pitot Tube ◽  
Outer Diameter ◽  
Flow Rates ◽  
Gaseous Flow ◽  
Mass Flow Rates ◽  
Tube Exit ◽  
Slight Discrepancy

This paper focuses on under-expanded gaseous flow at a straight micro-tube exit. The pitot total pressure of gas flow (jet) in the downstream region from a straight micro-tube exit was measured by a total pressure pitot tube to accumulate data for validation of numerical results. A micro-tube of 495μm in diameter and 56.3 mm in length and a total pressure pitot tube of 100 μm in outer diameter were used. The pitot total pressure was measured at intervals of 0.1 mm in both the flow and radial directions. The measurement was done for the mass flow rates of 9.71 × 10−5 kg/s and 1.46 × 10−4 kg/s. The data were accumulated for validation of the numerical results to reveal the characteristics of the under-expanded gas flow at the exit of a micro-tube. Comparisons were conducted for numerical results of corresponding cases and a slight discrepancy can be seen between numerical and experimentally measured pitot total pressures.

Turbulence Measurements in a Centrifugal Pump With a Synchronously Orbiting Impeller

1992 ◽  
Vol 114 (2) ◽  
pp. 350-358 ◽  
Author(s):  
R. D. Flack ◽  
S. M. Miner ◽  
R. J. Beaudoin
Keyword(s):  
Centrifugal Pump ◽  
Reynolds Stress ◽  
Flow Rate ◽  
Cross Product ◽  
Design Flow ◽  
Low Flow ◽  
Rate Variation ◽  
Flow Rates ◽  
The Individual ◽  
Design Flow Rate

Turbulence profiles were measured in a centrifugal pump with an impeller with backswept blades using a two-directional laser velocimeter. Data presented include radial, tangential, and cross product Reynolds stresses. Blade-to-blade profiles were measured at four circumferential positions and four radii within and one radius outside the four-bladed impeller. The pump was tested in two configurations: with the impeller running centered within the volute, and with the impeller orbiting with a synchronous motion (ε/r2 = 0.016). Flow rates ranged from 40 to 106 percent of the design flow rate. Variation in profiles among the individual passages in the oribiting impeller were found. For several regions the turbulence was isotropic so that the cross product Reynolds stress was low. At low flow rates the highest cross product Reynolds stress was near the exit. At near-design conditions the lowest cross product stress was near the exit, where uniform flow was also observed. Also, near the exit of the impeller the highest turbulence levels were seen near the tongue. For the design flow rate, inlet turbulence intensities were typically 9 percent and exit turbulence intensities were 6 percent. For 40 percent flow capacity the values increased to 18 and 19 percent, respectively. Large local turbulence intensities correlated with separated regions. The synchronous orbit did not increase the random turbulence, but did affect the turbulence in the individual channels in a systematic pattern.

Unsteady Flow Pattern Characteristics Downstream of a Forward-Curved Blades Centrifugal Fan

2000 ◽  
Vol 123 (2) ◽  
pp. 265-270 ◽  
Author(s):  
Sandra Velarde-Sua´rez ◽  
Rafael Ballesteros-Tajadura ◽  
Carlos Santolaria-Morros ◽  
Jose´ Gonza´lez-Pe´rez
Keyword(s):  
Operating Conditions ◽  
The Other ◽  
Low Flow ◽  
Centrifugal Fan ◽  
Hot Wire ◽  
Measured Velocity ◽  
Flow Rates ◽  
Velocity Fluctuations ◽  
Flow Asymmetry ◽  
Steady Velocity

The results of an experimental investigation of the flow at two exit radial locations of a forward-curved blades centrifugal fan are presented. Hot wire techniques were used to obtain steady velocity components and velocity unsteadiness levels (rms value of the components of velocity fluctuation) for different operating conditions. Globally speaking, the data reveal a strong flow asymmetry, with considerable changes in both magnitude and direction along the different circumferential positions. Particularly, big differences appear between the circumferential positions closer to the volute tongue and the other ones. The periodic character of the velocity signals due to the passing of the blades, clearly observed around the impeller, is missed in the vicinity of the volute tongue, where the main contribution to the velocity fluctuations appears to be random. Based on the measured velocity signals, velocity unsteadiness of the flow is determined analyzing the main contributions as a function of the flow rate and the measurement position. High levels of velocity unsteadiness were observed near the volute tongue, mainly at low flow rates.

scholarly journals РЕЗУЛЬТАТЫ УСОВЕРШЕНСТВОВАНИЯ СТУПЕНИ ВЫСОКОНАГРУЖЕННОЙ ТУРБИНЫ НИЗКОГО ДАВЛЕНИЯ

2019 ◽  
pp. 30-37
Author(s):  
Игорь Федорович Кравченко ◽  
Сергей Александрович Хомылев
Keyword(s):  
Flow Separation ◽  
Wedge Angle ◽  
Operating Conditions ◽  
Design Flow ◽  
Flow Coefficient ◽  
Low Flow ◽  
Energy Losses ◽  
Suction Surface ◽  
Experimental Development ◽  
Leading Edges

One of the characteristic features of high loaded low-pressure turbine (LPT) with a low flow coefficient is the high-level flow deflection in the blade rows, which have sufficiently thin and strongly curved cross-section profiles. Such profiles are very sensitive to off-design flow angles, especially to positive incidence. Therefore, the effectiveness of a high loaded LPT strongly depends on the working conditions. At the same time, for various reasons, in the process of research tests or operating the engine, the operating conditions may differ greatly from the design ones. Therefore, the creation of a robust LPT design is an actual task. The article considers the computational approbation of the method of increasing the resistance to large off-design angles of attack of vane and blade rows of the intermediate stage of a high loaded LPT of an experimental engine by changing the shape of the leading edges. The turbine was previously tested as part of a full-scale engine, where it was determined that the operating conditions of the LPT and its efficiency are significantly different from the calculated ones. Numerical (CFD) analysis of the flow showed that one of the reasons for the low efficiency is the large angles of attack on the vane and blade rows of the second stage, which lead to the flow separation and an increase of the energy losses coefficients at final. The modernization of the profiles was carried out by reducing the radius and a local increase of the leading edges wedge angle without changing the basic profiles. According to the calculation results, it was allowed to significantly improve the stream. The intensity of the flow deceleration behind the shock wave at the point of transition from the circumference of the edge to the suction surface was reduced, this made it possible to eliminate or reduce the intensity of the flow separation in the vane row and significantly reduce the energy losses coefficient. A more favorable flow was also achieved in the blade row, where a slight decrease in the losses coefficient was also obtained. As a result, the efficiency of the stage and the whole LPT was increased at the off-design operating conditions. This approach can be recommended both to increase the efficiency of the turbine at the experimental development, and when designing new turbines to increase their robustness.

scholarly journals Effect of Two- and Three-Dimensionally Designed Guide Vanes with Different Camber Length on Static Pressure Recovery of a Wall-Mounted Axial Fan

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1595
Author(s):  
Yong-In Kim ◽  
Yong-Uk Choi ◽  
Cherl-Young Jeong ◽  
Kyoung-Yong Lee ◽  
Young-Seok Choi
Keyword(s):  
Flow Rate ◽  
Guide Vane ◽  
Dynamic Pressure ◽  
Pressure Rise ◽  
Design Flow ◽  
Low Flow ◽  
Axial Fan ◽  
Flow Angle ◽  
Numerical Effort ◽  
Vane Angle

This study was based on a numerical effort to use the motor support (prop) as a guide vane when the motor of a wall-mounted axial fan was located at the fan outlet while maintaining the structural and spatial advantage. The design for the guide vane followed two- and three-dimensional methods. The inlet vane angle, meridional length (total), and meridional length with a vane angle of zero (0) degrees (linear) were considered as design variables. At the design and some low flow rate points, the 2D design offered the most favorable performance when the meridional length with a vane angle of zero (0) degrees (linear) was 30% based on total length, and was the worst for 70%. The 3D design method applied in this study did not outperform the 2D design. In the 2D design concept, averaging the flow angle for the entire span at the design flow rate could ensure a better pressure rise over a more comprehensive flow rate range than weighting the flow angle for a specific span. In addition, the numerical results were validated through an experimental test, with an important discussion of the swirl (dynamic pressure) component. The influence of the inlet motor and turbulence model are presented as a previous confirmation.

Compressible Simulation of Flow and Sound Around a Small Axial-Flow Fan With Flow Through Casing Slits

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Hiroshi Yokoyama ◽  
Katsutake Minowa ◽  
Kohei Orito ◽  
Masahito Nishikawara ◽  
Hideki Yanada
Keyword(s):  
Flow Field ◽  
Flow Rate ◽  
Aerodynamic Performance ◽  
Design Flow ◽  
Low Flow ◽  
Axial Fan ◽  
Flow Rates ◽  
Blade Tip ◽  
Flow Through ◽  
Design Flow Rate

Abstract Small axial fans are used for cooling electronic equipment and are often installed in a casing with various slits. Direct aeroacoustic simulations and experiments were performed with different casing opening ratios to clarify the effects of the flow through the casing slits on the flow field and acoustic radiation around a small axial fan. Both the predicted and measured results show that aerodynamic performance deteriorates at and near the design flow rate and is higher at low flow rates by completely closing the casing slits compared with the fan in the casing with slits. The predicted flow field shows that the vortical structures in the tip vortices are spread by the suppression of flow through the slits at the design flow rate, leading to the intensification of turbulence in the blade wake. Moreover, the pressure fluctuations on the blade surface are intensified, which increases the aerodynamic sound pressure level. The suppression of the outflow of pressurized air through the downstream part of the slits enhances the aerodynamic performance at low flow rates. Also, the predicted surface streamline at the design flow rate shows that air flows along the blade tip for the fan with slits, whereas the flow toward the blade tip appears for the fan without slits. As a result, the pressure distributions on the blade and the torque exerted on the fan blade are affected by the opening ratio of slits.

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