Relevant bibliographies by topics / Inlet Recirculation

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  1. Journal articles
  2. Dissertations / Theses
  3. Book chapters
  4. Conference papers

Academic literature on the topic 'Inlet Recirculation'

Author: Grafiati
Published: 4 June 2021
Last updated: 16 February 2022

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Journal articles on the topic "Inlet Recirculation"

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Elvery, D. G., and K. Bremhorst. "Wall Pressure and Effective Wall Shear Stresses in Heat Exchanger Tube Inlets With Application to Erosion-Corrosion." Journal of Fluids Engineering 119, no. 4 (1997): 948–53. http://dx.doi.org/10.1115/1.2819522.

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Inclined flow into tube inlets is studied in order to identify flow characteristics associated with enhanced erosion-corrosion rates at tube inlets. Measured wall pressures and shear stresses are presented for inlet flow with inclination angles up to 60 deg for a tube Reynolds number of 71,000. These show that the areas with most potential for wear are located near the reattachment point of the recirculation bubble as well as in regions at the downstream side of the tube inlet. The latter are located opposite the recirculation region but away from the symmetry plane due to strong swirl of the flow in that region. The results are related to erosion-corrosion patterns observed in practice.
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Alpan, K., and W. W. Peng. "Suction Reverse Flow in an Axial-Flow Pump." Journal of Fluids Engineering 113, no. 1 (1991): 90–97. http://dx.doi.org/10.1115/1.2926503.

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Experiments are carried out to determine the effects of different inlet geometries on the onset of suction recirculation and its associated power consumption in an axial-flow pump. The critical flow rate is determined by both the “string” visual technique and “pressure” method. The results are correlated with the inlet area and flow velocity distribution upstream of the impeller. Four different conical covers matching the impeller leading edge are employed to cover the impeller inlet completely or partially. Covering the inlet area reduces the critical flowrate corresponding to the onset of suction recirculation and eliminates all recirculation at higher flowrates. The power consumption associated with the suction recirculation flow for the uncovered impeller is determined by comparing the shaft powers with and without inlet covers. At the shut-off condition, the power is estimated from a comparison with the shaft power measured with the impeller inlet completely covered. Experimental studies conclude that the power consumption due to suction recirculation is mainly controlled by the impeller inlet area and is insensitive to the inlet pipe configuration. At shut-off condition, the power coefficient correlates well with the parameter based on the hydraulic radius of inlet area. At a finite through flowrate the analytical model recommended by Tuzson (1983) is adequate, except for a proportionality coefficient determined from the test data.
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Nithesh, N., and S. Prajwal. "Effect of Splitters in Recirculation Channels on Performance of Turbocharger Compressors Used in Gasoline Engines- A CFD Study." International Journal of Automotive and Mechanical Engineering 16, no. 1 (2019): 6214–29. http://dx.doi.org/10.15282/ijame.16.1.2019.10.0472.

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Turbochargers used in gasoline engines have their compressor outlet directly coupled to the engine inlet via the throttle valve. On sudden closing of the throttle, the compressor outlet is blocked, and the compressed air has no path to exit resulting in a compressor surge. Compressor recirculation valves are used to connect the outlet of the compressor to the inlet to recirculate excess air and thus reduce the compressor surge. Under normal operating conditions, when the valve is closed, the channel connecting the compressor inlet and the valve causes an inlet disturbance resulting in the reduction of compressor efficiency. Hence a steady state CFD analysis of a gasoline engine turbocharger compressor modelled with a recirculation channel at the inlet was conducted. The channel connecting the compressor inlet and the recirculation valve was observed to cause inlet aerodynamic disturbance resulting in a drop in compressor efficiency by 1%. To overcome this problem, splitters were used in recirculation channels and 80% recovery of loss was observed with the use of splitters.
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Liu, Yin Li, and Hao Tang. "Numerical Study on the Interaction Mechanism between Swirl and Reverse Flow Rate in a Twin Swirl Combustor." Advanced Materials Research 960-961 (June 2014): 341–48. http://dx.doi.org/10.4028/www.scientific.net/amr.960-961.341.

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An isothermal flow in a Twin Swirl Combustor (TSC) was simulated with the Renormalized Group (RNG) k-ε turbulence model. The swirling and recirculation intensity was studied under different structures and inlet conditions. The results confirmed that there was a significant negative correlation between the trend lines of the swirl number (S) and reversed flow rate (Xr). The gradient of reversed flow rate was larger in the front and middle parts of the combustor than that of swirl number. The end-surface-inlet structure had a better swirl and recirculation enhancement effect. With the end-surface-inlet structure, the internal swirl and reverse intensity could be flexibly adjusted by switching the swirl intensity of the primary air. Under the structure of staggered-inlet, there was a critical distance between primary and secondary air inlets. When exceeded, it would be more difficult to enhance the swirl and reverse flow effect by increasing the swirl intensity of the secondary air.
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Lipej, Andrej, and Dusko Mitrusevski. "Numerical Prediction of Inlet Recirculation in Pumps." International Journal of Fluid Machinery and Systems 9, no. 3 (2016): 277–86. http://dx.doi.org/10.5293/ijfms.2016.9.3.277.

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Zhou, Yu, Yuan Huang, and Zhongqiang Mu. "Large eddy simulation of the influence of synthetic inlet turbulence on a practical aeroengine combustor with counter-rotating swirler." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 3 (2017): 978–90. http://dx.doi.org/10.1177/0954410017745900.

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To study the influence of inlet turbulence on the prediction of flow structure in practical aeroengine combustor, large eddy simulation with dynamic Smagorinsky subgrid model is used to explore the complex unsteady flow field in a single burner of a typical aeroengine combustor with two-stage counter-rotating swirler. The complex geometric configuration including all film cooling holes is fully simulated without any conventional simplification in order to reduce the modeling errors. First, unsteady process that flow developing from static to statistically stationary state is fully simulated under laminar inlet condition to obtain a fundamental understanding of flow characteristics in the combustor. Afterwards, synthetic eddy method is utilized to generate a turbulent inlet condition so that a perturbation with about 5% turbulence intensity is superimposed to the inlet plane. Simulation result shows that for the laminar inflow case, flow separation occurs in the near-wall region of the diffusion section, inducing a boundary layer transition and consequently introducing turbulence with nonuniformity in space before the swirler. In contrast, synthesized inflow generated under turbulent inlet condition by synthetic eddy method is more spatially homogeneous. Time-averaged flow field inside the swirler cup reveals that turbulent inflow ultimately causes the swirling flow with higher rotating speed in central region and more uniform distribution along the circumferential direction. It also enhances the transverse jet flow from primary holes and reverse flow in the central recirculation zone, and makes streamlines corresponding to the recirculation vortices more symmetrical on central profile. Maximum recirculating velocity predicted in central recirculation zone is −27.65 m/s and −17.86 m/s in turbulent and laminar case respectively, and corresponding total pressure recovery coefficient is 96.03% and 96.81%.
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Ali, M., and T. Fujiwara. "A numerical study on the mixing of air and hydrogen in a scramjet combustor." Aeronautical Journal 109, no. 1097 (2005): 325–35. http://dx.doi.org/10.1017/s0001924000000774.

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Abstract A numerical study on mixing of air and hydrogen is performed by solving two-dimensional full Navier-Stokes equations. The main stream is air of Mach 5 entering through the configured inlet of the combustor and gaseous hydrogen is injected from the configured jet on the side wall. Supersonic mixing and diffusion mechanisms of a transverse hydrogen jet in two-dimensional finite air streams have been analyzed and discussed. The computed results are compared with the experimental data and show good agreement. For an otherwise fixed combustor geometry, the air inlet width and injection angle are varied to study the physics of mixing and flow field characteristics. On the effect of inlet width variation, two competing phenomena have been observed: (i) upstream of injector the strength of recirculation is higher for wider inlet and consequently the mixing increases, and (ii) downstream, the diffusion of hydrogen decreases with the increase of inlet width and eventually mixing decreases. As a result, in far downstream the mixing efficiency increases up to certain inlet width and then decreases for further increment of inlet width. For the variation of injection angle results show that upstream of injector the mixing is dominated by recirculation and downstream the mixing is dominated by mass concentration of hydrogen. Upstream recirculation is dominant for injecting angle 60° and 90°. Incorporating the various effects, perpendicular injection shows the maximum mixing efficiency and its large upstream recirculation region has a good flame holding capability.
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Claveau-Mallet, Dominique, Félix Lida, and Yves Comeau. "Improving phosphorus removal of conventional septic tanks by a recirculating steel slag filter." Water Quality Research Journal 50, no. 3 (2015): 211–18. http://dx.doi.org/10.2166/wqrjc.2015.045.

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The objective of this project was to increase the phosphorus (P) retention capacity of a conventional septic tank by adding a recirculating slag filter. Two recirculation modes and recirculation ratios from 5 to 50% were tested in the laboratory with reconstituted domestic wastewater. The best system was recirculation from the end to the inlet of the second compartment of a septic tank with a 50% recirculation ratio in the slag filter, achieving 4.2 and 1.9 mg P/L at the effluent for total phosphorus (TP) and orthophosphate (o-PO4), respectively, and a pH of 8.8. The calculated size of the slag filter for a two-bedroom house application was 1,875 kg for an expected lifetime of 2 years. The 1 mg P/L level goal was not reached, but P precipitation may be favoured by the relatively high effluent pH reaching the infiltration bed.
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Yang, Ce, Yingjun Wang, Dazhong Lao, Ding Tong, Longyu Wei, and Yixiong Liu. "Investigation on inlet recirculation characteristics of double suction centrifugal compressor with unsymmetrical inlet." Journal of Thermal Science 25, no. 4 (2016): 312–24. http://dx.doi.org/10.1007/s11630-016-0866-7.

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Yuan, Jian Ping, Wei Sun, Long Yan Wang, and Yun Liang. "Numerical Simulation Research on Vortex Characteristics of Centrifugal Pump Inlet Recirculation." Advanced Materials Research 468-471 (February 2012): 2235–40. http://dx.doi.org/10.4028/www.scientific.net/amr.468-471.2235.

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The 3-D steady turbulent flow in a centrifugal pump under different conditions was simulated by ANSYS CFX software. The intensity, location and the morphology of the inlet recirculation vortex were analyzed using standard k-ε turbulent model through steady simulation. Based on the results, the turbulent flow in the impeller inlet was simulated by Large Eddy Simulation. The dynamic characters and the whole changing process of the recirculation vortex during the rotation of the impeller were analyzed. The results indicate that the critical flow rate of the recirculation onset is 0.7Qd. As the flow rate decreases, the size and the intensity of the recirculation vortex increase and the vortex partially block the flow passage. The vortex first appears in the passage which passes by the outlet section of the volute. During one rotating, the vortex undergoes a whole process of onset, developing, decreasing and disappearing. As the relative speed and the pressure gradient change under different conditions, the vortices present different morphologies.
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Dissertations / Theses on the topic "Inlet Recirculation"

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Schreiber, Christoph. "Inlet recirculation in radial compressors." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/270611.

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Deficient performances of turbocharger compressors inside turbo-charged engines limit the behaviour of the drive train. This problem has shifted the design space for compressors towards their performance at part-speed and low-flow conditions. The most dominant feature of these flow conditions is inlet recirculation. It causes a large portion of flow to be expelled through the rotor inlet, creating a blockage ring on the casing. While on the one hand, inlet recirculation is the main loss-source at low-speed and low-flow within centrifugal compressors, on the other hand, it also keeps the compressors functioning because it reduces incidence. This thesis aimed towards increasing the understanding of inlet recirculation, with the scope on improving the part-speed, low-flow performance of automotive turbocharger compressors. The phenomenon was investigated regarding its key features, the conditions at which it occurs and its impact on performance. Furthermore, a reduced order model was derived and the influence of the tip gap size as a design parameter was analysed. The research was carried out on an automotive turbocharger compressor which was investigated experimentally and numerically. Inlet recirculation is a phenomenon which takes place in the tip region of the rotor, extending far downstream and far upstream of the leading edge. The flow within the recirculation bubble features a strong positive swirl component, affecting the work input into the machine. The phenomenon is non-periodic in a time-averaged sense. An investigation of the rotor flow-field regarding inlet recirculation, carried out for the first time, revealed that the starting point of inlet recirculation is located far inside the rotor passage. An analysis based on mass, momentum and energy allowed the derivation of a low-order model to account for inlet recirculation in preliminary design. In the compressor map, inlet recirculation was present over 40% of the map width at low speeds. It maintained its presence with increasing rotor speed beyond the point where the inlet flow became transonic. The losses in the inlet recirculation zone were shown to be up to 35% of the total compressor loss at low speed. A loss analysis showed that inlet recirculation was the main loss source at low-flow conditions. The tip clearance study showed that the size and intensity of inlet recirculation was independent of the tip gap size. Efficiency gains due to reduced tip leakage were marginalised by the presence of inlet recirculation but the rotor maintained enhanced pressure rise capabilities for reduced tip gap sizes.
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Heinz, Pavel. "Vstupní recirkulace u odstředivého čerpadla." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-416449.

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This diploma thesis deals with the phenomenon appearing in hydrodynamic pumps at the sub-optimal flow rate. This phenomenon is inlet recirculation, which is an undesirable phenomenon in the suction of the pump. This recirculation causes cavitation, pressure pulsations and may cause clogging of the suction line. The main goal of the diploma thesis is CFD simulation for the recirculation mode, identification of the flow phenomena, and designs of possible measures to suppress inlet recirculation.
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Page, Vivian J. "Development of a validated computational procedure for the analysis of diesel engine inlet manifold flows with exhaust gas recirculation : predicaments, perceptions and policy-responses." Thesis, Loughborough University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251001.

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Li, Wenyin. "Airflow and contaminants in a swine barn with recirculation assisted slot inlets." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq23999.pdf.

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Book chapters on the topic "Inlet Recirculation"

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Harley, P. X. L., S. W. T. Spence, J. Early, D. Filsinger, and M. Dietrich. "Inlet recirculation in automotive turbocharger centrifugal compressors." In 11th International Conference on Turbochargers and Turbocharging. Elsevier, 2014. http://dx.doi.org/10.1533/978081000342.89.

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Vishnu, S. B., and Biju T. Kuzhiveli. "Effect of Roughness Elements on the Evolution of Thermal Stratification in a Cryogenic Propellant Tank." In Low-Temperature Technologies [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98404.

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The cryogenic propulsion era started with the use of liquid rockets. These rocket engines use propellants in liquid form with reasonably high density, allowing reduced tank size with a high mass ratio. Cryogenic engines are designed for liquid fuels that have to be held in liquid form at cryogenic temperature and gas at normal temperatures. Since propellants are stored at their boiling temperature or subcooled condition, minimal heat infiltration itself causes thermal stratification and self-pressurization. Due to stratification, the state of propellant inside the tank varies, and it is essential to keep the propellant properties in a predefined state for restarting the cryogenic engine after the coast phase. The propellant’s condition at the inlet of the propellant feed system or turbo pump must fall within a narrow range. If the inlet temperature is above the cavitation value, cavitation will likely to happen to result in the probable destruction of the flight vehicle. The present work aims to find an effective method to reduce the stratification phenomenon in a cryogenic storage tank. From previous studies, it is observed that the shape of the inner wall surface of the storage tank plays an essential role in the development of the stratified layer. A CFD model is established to predict the rate of self-pressurization in a liquid hydrogen container. The Volume of Fluid (VOF) method is used to predict the liquid–vapor interface movement, and the Lee phase change model is adopted for evaporation and condensation calculations. A detailed study has been conducted on a cylindrical storage tank with an iso grid and rib structure. The development of the stratified layer in the presence of iso grid and ribs are entirely different. The buoyancy-driven free convection flow over iso grid structure result in velocity and temperature profile that differs significantly from a smooth wall case. The thermal boundary layer was always more significant for iso grid type obstruction, and these obstructions induces streamline deflection and recirculation zones, which enhances heat transfer to bulk liquid. A larger self-pressurization rate is observed for tanks with an iso grid structure. The presence of ribs results in the reduction of upward buoyancy flow near the tank surface, whereas streamline deflection and recirculation zones were also perceptible. As the number of ribs increases, it nullifies the effect of the formation of recirculation zones. Finally, a maximum reduction of 32.89% in the self-pressurization rate is achieved with the incorporation of the rib structure in the tank wall.
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Conference papers on the topic "Inlet Recirculation"

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Harley, Peter, Stephen Spence, Dietmar Filsinger, Michael Dietrich, and Juliana Early. "Meanline Modelling of Inlet Recirculation in Automotive Turbocharger Centrifugal Compressors." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25853.

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This study provides a novel meanline modelling approach for centrifugal compressors. All compressors analysed are of the automotive turbocharger variety and have typical upstream geometry with no casing treatments or pre-swirl vanes. Past experience dictates that inducer recirculation is prevalent toward surge in designs with high inlet shroud to outlet radius ratios; such designs are found in turbocharger compressors due to the demand for operating range. The aim of the paper is to provide further understanding of impeller inducer flow paths when operating with significant inducer recirculation. Using 3D Computational Fluid Dynamics (CFD) and a single-passage model, the flow coefficient at which the recirculating flow begins to develop and the rate at which it grows are used to assess and correlate work and angular momentum delivered to the incoming flow. All numerical modelling has been fully validated using measurements taken from hot gas stand tests for all compressor stages. The new modelling approach links the inlet recirculating flow and the pressure ratio characteristic of the compressor. Typically for a fixed rotational speed, between choke and the onset of impeller inlet recirculation the pressure ratio rises gradually at a rate dominated by the aerodynamic losses. However, in modern automotive turbocharger compressors where operating range is paramount, the pressure ratio no longer changes significantly between the onset of recirculation and surge. Instead the pressure ratio remains relatively constant for reducing mass flow rates until surge occurs. Existing meanline modelling techniques predict that the pressure ratio continues to gradually rise toward surge, which when compared to test data is not accurate. A new meanline method is presented here which tackles this issue by modelling the direct effects of the recirculation. The result is a meanline model that better represents the actual fluid flow seen in the CFD results and more accurately predicts the pressure ratio and efficiency characteristics in the region of the compressor map affected by inlet recirculation.
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Tamaki, Hideaki, Masaru Unno, Ryuuta Tanaka, Satoshi Yamaguchi, and Yohei Ishizu. "Enhancement of Centrifugal Compressor Operating Range by Control of Inlet Recirculation With Inlet Fins." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-42154.

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The operating points of a turbocharger compressor tend to approach or cross its surge line while an engine is accelerating, particularly under low-engine speed conditions, hence the need for an acceptable surge margin under low compressor-speed conditions. A method shifting the stability limit on a compressor low-speed line toward a lower flow rate is expected and inlet recirculation is often observed in a centrifugal compressor with a vaneless diffuser near a surge and under a low compressor-speed condition. First, examples of inlet recirculation were introduced in this paper, whereupon the effect of inlet recirculation on compressor characteristic was discussed by 1-D consideration and the potential shown for growth of inlet recirculation to destabilize compressor operations. Accordingly, this study focused on suppressing the effect of inlet recirculation on compressor characteristics using small fins mounted in a compressor-inlet pipe, and examining whether they enhance the compressor operating range under low-speed conditions. Small fins are known as inlet fins in this paper. According to test results, they showed great promise in enhancing the compressor operating range during inlet recirculation. Besides, attempts were also made to investigate the qualitative effect of inlet fins on flow fields using CFD and the disadvantages of inlet fins were also discussed.
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Yedidiah, S. "An Updated Study of Recirculation at the Inlet of a Rotodynamic Impeller." In ASME 2005 Fluids Engineering Division Summer Meeting. ASMEDC, 2005. http://dx.doi.org/10.1115/fedsm2005-77048.

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This paper presents an updated report of certain causes and effects of recirculation at the inlet of a rotodynamic impeller. It demonstrates how certain geometrical features of the inlet parts of the blades are affecting the pattern of the inlet-recirculation, and how this pattern is affected by the flow-rate. It demonstrates the effects of recirculation on the steepness of the QH-curve at reduced flow-rates, and the occasionally observed hysteresis within a certain range of partial flow-rates. Also, it discusses the manner in which recirculation is producing very intense instabilities at reduced NPSH, in axial-flow impellers and inducers. The conclusions arrived at are supported by results of test, reported in different papers. In addition of the above, it lists some of the uses of our present knowledge of the causes and effects of inlet-recirculation, which have been successfully applied in practice.
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Qiu, Xuwen, David Japikse, and Mark Anderson. "A Meanline Model for Impeller Flow Recirculation." In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-51349.

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Flow recirculation at the impeller inlet and outlet is an important feature that affects impeller performance, especially the power consumption at a very low flow rate. Although the mechanisms for this flow phenomenon have been studied, a practical model is needed for meanline modeling of impeller off-design performance. In this paper, a meanline recirculation model is proposed. At the inlet, the recirculation zone acts as area blockage to relieve the large incidence of the active flow at a low flow rate. The size of the blockage is estimated through a critical area ratio of an artificial “inlet diffuser” from the inlet to throat. The intensity of the reverse flow can then be calculated by assuming a linear velocity profile of meridional velocity in the recirculation zone. At the impeller outlet, a recirculation zone near the suction surface is established to balance the velocity difference on the pressure and suction sides of the blade. The size and the intensity of the outlet recirculation zone is assumed related to blade loading, which can be evaluated based on flow turning and Coriolis force. A few validation cases are presented showing a good comparison between test data and prediction by the model.
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Ribaud, Y. "Experimental Aerodynamic Analysis Relative to Three High Pressure Ratio Centrifugal Compressors." In ASME 1987 International Gas Turbine Conference and Exhibition. American Society of Mechanical Engineers, 1987. http://dx.doi.org/10.1115/87-gt-153.

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The test results of three high pressure ratio centrifugal compressors are analyzed. Two of them show one or two discontinuities in the surge line. A careful study of the different experimental parameters indicates the existence of three different operating zones for the rotor. For the low inlet flow coefficients, two recirculations take place in the rotor: one at the inlet and the other at the outlet. For moderate flow coefficients, the outlet recirculation disappears. In these regions, the occurrence of these recirculations is explained and a simple model is given. The inlet recirculation can stabilize the flow if a 2D blade stall occurs but it is not possible in the third zone where the inlet flow coefficient is higher than the critical value.
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Hermez, Munther Y., Badih A. Jawad, Liping Liu, Vernon Fernandez, Kingman Yee, and Eli Oklejas. "Comparison of Inlet Curved Disk Arrangements for Suppression of Recirculation in Centrifugal Pump Impellers." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-65448.

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The present work aims to numerically study the inlet flow recirculation and modified impeller interaction in a centrifugal pump. An optimization of modified shrouded impeller with curved disk arrangement to suppress the unsteady flow recirculation is pursued. This modification will enhance the impeller characteristics with a wider operation range at both low and high flow rates in a high speed centrifugal pump type. The unstable flow in the centrifugal pumps is a common problem that leads to damage in the pump’s internal parts, consequently increases the operating cost. At certain flow rates, generally below the Best Efficiency Point (BEP), all centrifugal pumps are subject to internal recirculation occurs at the suction and discharge areas of the impeller. For decades, experimental work has been done to investigate the complex three-dimensional flow within centrifugal pumps impellers, before computational work gains momentum due to advancement of computing power and improved numerical codes. In this study the impeller with a curved disk arrangement has been investigated by using a three-dimensional Navier-Stokes code with a standard k-ε turbulence model. The purpose is to evaluate and select the optimum impeller modification that would increase the pump suction flow rate range. Three-dimensional numerical Computational Fluid Dynamics (CFD) tools are used to simulate flow field characteristics inside the centrifugal pump and provide critical hydraulic design information. In the present work, ANSYS v.16.1 Fluent solver is used to analyze the pressure and velocity distributions inside impeller suction and discharge passages. The ultimate goal of this study is to manufacture and validate the most optimized and efficient centrifugal pump impeller with a curved disk. The best case curve identifies the highest increase of total pressure difference by 22.1%, and highest efficiency by 92.3% at low flowrates.
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Gancedo, Matthieu, Ephraim Gutmark, E. Guillou, and Ashraf Mohamed. "PIV Measurements of Flow in Recirculation Cavities at the Inlet of a Centrifugal Compressor." In 50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition. American Institute of Aeronautics and Astronautics, 2012. http://dx.doi.org/10.2514/6.2012-454.

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Ismail, B. I., R. Zhang, D. Ewing, J. S. Cotton, and J. S. Chang. "The Heat Transfer Characteristics of Exhaust Gas Recirculation (EGR) Cooling Devices." In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-39559.

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A one-dimensional steady state model was developed to predict the heat transfer performance of a shell (liquid)-and-tube (gas) heat exchanger used as a cooling device for exhaust gas recirculation (EGR) application where there is a significant temperature drop across the device. The predictions of the model results were compared with experimental measurements and the trends were found to be in good agreement for most of the transitional and turbulent regimes. The results showed that the exit gas temperature increases with increasing gas mass flow rate at fixed gas inlet temperature and coolant flow rate. It was also found that the exit gas temperature was essentially independent of the coolant flow rate for the typical operating range but did depend on the coolant inlet temperature. It was observed that the pressure drop across the cooling device was not a strong function of the gas inlet temperature. The heat-transfer effectiveness of the cooling device was found to slightly depend on the gas mass flow rate and inlet gas temperature. A preliminary analysis showed that fouling in the EGR cooling device can have a significant effect on both the thermal and hydraulic performance of the cooling device.
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Halpin, John L. "Swirl Generation and Recirculation Using Radial Swirl Vanes." In ASME 1993 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1993. http://dx.doi.org/10.1115/93-gt-169.

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The concept of the Swirl Number and its effect on recirculation is reviewed and problems with it are identified. Swirl generation through the use of radial inlet swirl vanes is then studied. The effect of vane and swirl cup design on recirculation is then evaluated using finite element computer modeling and verified using tufting tests. Vane geometry, combustor dome geometry, co- vs. counter-rotation and mass flow effects are all evaluated. It is shown that co- and counter-rotation generate very similar flow fields and recirculated mass flows. An approach for calculating swirl numbers in multiple swirler designs is proposed.
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Gancedo, Matthieu, Erwann Guillou, and Ephraim Gutmark. "Experimental Investigation of Flow Instability in a Turbocharger Ported Shroud Compressor." In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-95134.

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Turbocharger centrifugal compressors are equipped with a “ported shroud” to reduce flow instabilities at low mass flow rate. This passive stability control device using flow recirculation has been demonstrated to extend the surge margin of a compressor, without substantially sacrificing performance. However, the actual working mechanisms of the system remain not well understood. In this paper, the relationship between inlet flow recirculation and instability control is studied using stereoscopic particle image velocimetry (PIV) in conjunction with dynamic pressure transducers at the inlet of a turbocharger compressor with and without a ported shroud. Both stable and unstable operational points are analyzed with use of phase-locked PIV measurements in surge. Detailed description of unstable flow in a centrifugal compressor is presented with the reconstruction of the complex flow structure evolution at the compressor inlet during surge. Rather than one-dimensional, the surge flow is described by a three-dimensional axisymmetric structure of combined entering and exiting swirling flows, alternating in magnitude during the self-excited pressure cycle. The correlation between pressure and velocity measurements shows that the development of compressor unsteadiness is accompanied with swirling reversed flow at the impeller tip. The influence of the ported shroud on the inlet velocity flowfield is seen with the presence of localized flow recirculation. Stability improvement with a ported shroud is thus explained by removing swirling backflow at the impeller inducer tip and recirculating it to the impeller inlet to increase the near shroud inlet blade loading and incidence angle.
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