Blade Trailing Edge Research Articles

The effect of working fluid and compressibility on the optimal solidity of axial turbine cascades

The blade solidity, namely the blade chord-to-pitch ratio, largely affects the fluid-dynamic performance of turbomachinery and its cost. For turbo-machines operating with air or steam, the optimal value of the solidity which maximizes the efficiency is estimated with empirical correlations such as the ones proposed by <xref ref-type="bibr" rid="fn19">Zweifel (1945)</xref> and <xref ref-type="bibr" rid="fn17">Traupel (1966)</xref>. However, if the turbomachine operates with unconventional fluids, the accuracy of these correlations is questionable. Examples of such fluids are the organic compounds (e.g., hydrocarbons, siloxanes) used in organic Rankine cycle (ORC) power systems. This study concerns an investigation on how the working fluid, its thermodynamic state, and flow compressibility influence the optimum pitch-to-chord ratio of turbine stages. A first principle reduced-order model (ROM) for the computation of profile losses was developed for this purpose. The ROM results are compared with those obtained from numerical simulations of the flow over two axial turbine cascade geometries. The influence of both the working fluid, the flow compressibility, and the solidity value on both the boundary layer state at the blade trailing edge and the base pressure are evaluated. Models to compute mixing and passage losses in the compressible regime as a function of the axial solidity are proposed and discussed. Results show that the value of the optimal solidity of turbine cascades significantly increases with the flow compressibility, and mildly increases if the fluid is in the dense vapor state. Moreover, the optimal solidity value is strongly affected by the mixing process occurring downstream of the blade trailing edge. Therefore, currently available models for its estimation, which are solely based on the minimization of the profile losses, are inaccurate.

Optimizing Flow and Heat Transfer With Guiding Pin Fins in a Wedge-Shaped Cooling Channel for Gas Turbine Blade Trailing Edge

Abstract In this study, an innovative guiding pin-fin array optimization has been developed through three-dimensional numerical simulations to enhance the cooling efficiency of gas turbine blade trailing edge. The guiding pin-fin array is optimized using the Kriging surrogate model and Genetic Algorithm (GA), aiming to significantly improve the heat transfer rates and uniformity within the wedge-shaped channel. The design parameter chosen for optimization is the deflection angle of each guiding pin fin, and the optimization process is conducted in two rounds. The first-round optimization yields a first-optimized guiding pin-fin array, which exhibits superior overall heat transfer performance and reasonable pressure loss compared to conventional circular, oblong, and parallel pin-fin arrays. For the first-optimized guiding pin-fin (1st-OGP) channel at the Reynolds number of Re = 50,000, the total Nusselt number and pressure loss are 44.1% higher and 9.9% lower than those of the baseline circular pin-fin array (CP), respectively. An experimental validation using the transient liquid crystal (TLC) thermography method is carried out and proves the effectiveness of the optimization process. However, it is noted that the first-optimized guiding pin-fin exhibits even lower heat transfer at a low Reynolds number of Re = 10,000, particularly in the channel middle region, which is mainly due to the incapable turning flow control in the root region of the wedged channel. To address this issue and further improve the heat transfer performance at low Reynolds numbers, a second-round optimization is performed by specifically adjusting the deflection angle of the selected guiding pin fins near the root region of the wedged channel. This secondary optimization demonstrates significant heat transfer improvements over the whole studied Reynolds number range with a reasonably reduced consumption of computational resources. The total Nusselt number and pressure loss are 69.3% higher and 11.9% lower than those of the baseline circular pin-fin array, respectively, at Re = 50,000. The optimization process proposed in this paper produces a high-performance cooling structure design with elaborate guiding pin-fin arrangements in the wedge-shaped channel, which indicates high heat transfer enhancement and relatively lower pressure loss in the wedged channel for the turbine blade trailing edge.

Design and analysis of hundred-meter wind turbine blade trailing edge based on finite element method (FEM)

Abstract The trailing edge region of composite wind turbine blades usually has a large deformation under wind load and the accidents caused by the damage of blade trailing edge accounts for a large proportion among blade accidents. With the development of large blade size, higher requirements are put forward for the stability of wind turbine blade trailing edge. Therefore, the trailing edge region is critical in the design of blade. A detailed study of the design and analysis for wind turbine blade trailing edge region was carried out in which the structure stability was regarded as the key. The influence of auxiliary spar cap and auxiliary spar web on the stiffness distribution and stability of the trailing edge were studied based on focus and finite element method (FEM). The respiratory effect of different structures due to deformation were analyzed and compared. The results showed that the structure of the auxiliary spar cap and auxiliary spar web can significantly increase stiffness, stability and decrease respiratory deformation at the trailing edge of blade compared to the traditional three webs structure. The structure of auxiliary spar and auxiliary spar web is the best design scheme for hundred-meter composite blade trailing edge.

Stability impact on wind turbine blades trailing edge from bonding zone modelling methods

Abstract The trailing edge of wind turbine blade will undergo a large deformation under the action of load, resulting in a higher risk of damage and failure. The finite element analysis modeling method directly affects the simulation result, furthermore impacts the result of blade structure design. Therefore, it is necessary to find out a modeling method, which is capable to reflect the stability of bonding regions more accurately. This paper aims to discuss the influences of different finite element modeling methods on the buckling stability of blade trailing edge. The influences of shell element, tetrahedron element and hexahedron element on the blade stiffness are considered. The bonding region were simulated separately by combining shell element with bonding web, shell element with tetrahedron element and shell element with hexahedron. The influences of different bonding region modeling methods on the trailing edge buckling factor were analyzed by using the eigenvalue buckling analysis method of finite element. The simulation results provided data support for the future validation of the blade trailing edge bonding area modeling method. The results show that, the tetrahedral mesh provides a higher stiffness, followed by the hexahedral mesh, and the adhesive web form has the smallest stiffness. In order to simulate the more realistic stiffness of the adhesive area at the trailing edge of the blade, adhesive web plates can be built in the flange area of the blade root and the core material area of the trial adhesive mold; The direct bonding area can be simulated employing the hexahedron mesh; The tetrahedral mesh has high stiffness and is not suitable for modeling the adhesive area at the trailing edge. Blade simulation modeling can flexibly use different adhesive forms according to actual situations, ensuring the reliability of the simulation model.

Temporal-spatial and energy dissipation characteristics of vortex evolutions in Francis turbine during load reduction

This study numerically investigates the load reduction effects, on a model Francis turbine, combining cavitation model and structured dynamic grid technique. The results indicate that the vapor volume in the draft tube undergoes two rapid increases and decreases until cavitation ceases. The precessing vortex rope transitions from a strong helical structure to axial contraction as ellipticity increases, ultimately forming a discrete band before disappearing. Initially, vapor volume in the runner increases gradually and linearly, followed by continued growth with a consistent pulsation amplitude. The inter-blade vortex (IBV) first appears at the blade trailing edge and then develops into a complete structure extending from the runner crown to the blade trailing edge, driven by pulsating vapor volume growth. Axial force extracted by the runner changes significantly and correlates closely with variations in the vapor volume in the runner. Flow separation in the runner occurs near the runner crown, forming dual separation lines that enhance IBV formation, which highlights the significant influence of crown-proximal flow separation on IBV development. Regarding energy loss, initial decreases followed by increases are observed in both the draft tube and runner, with draft tube losses consistently exceeding 57.4% and runner losses exceeding 27.1%. Turbulent kinetic energy generation and Reynolds stress are the primary forms of energy dissipation, with high-value regions corresponding to vortex locations, underscoring the substantial role of vortices in energy dissipation. This study provides new insights into the evolution of vortices and energy dissipation characteristics during load reduction in Francis turbines.

Evolution of large-scale flow structures in an axial-flow pump during performance breakdown

This paper presents a very large eddy simulation analysis of the unsteady flow in the pre-stall to stall transition process of an axial-flow pump, with the aim to elucidate the spatiotemporal evolution of large-scale flow structures during the performance breakdown of the pump. The transient flow is investigated utilizing a time-dependent flow rate computation scheme. The results demonstrate that, as the flow rate is dynamically reduced, the reduction in pump head is found lags behind the reduction in flow rate by approximately 15 impeller revolutions. The leading edge separation on the blade suction side (SS) evolves into a leading edge separation vortex (LSV) in conjunction with the dynamic reduction in flow rate. The attached flow on the SS in the vicinity of the hub and blade trailing edge squeezes the mainstream outwards, resulting in the formation of a cross passage vortex (CPV) on the tip side of the passage. The combined effect of the LSV, CPV, and tip-clearance flow induces a penetrating upstream flow in the tip region of the impeller, which gives rise to a swirling backflow within the inlet pipe. At stall, the CPV is stably attached to the SS and extends upstream of the leading edge of the neighboring blade. Furthermore, a trailing edge backflow is observed near the junction of the blade trailing edge and the hub, and it collides with the inflow near the hub, resulting in the formation of a hub-attached vortex.

Bioinspired swept-curved blade design for performance enhancement of Darrieus wind turbine

The present research proposes novel swept-curved bioinspired blades for Darrieus wind turbine. The design was influenced by the curved flippers of the bottle-nose dolphin. The proposed model was designed using the Solidworks software, empirically tested for power improvement, later fine-tuned adopting high fidelity numerical modeling. An in-depth analysis comparing the traditional H-bladed turbine with the new-bladed design was performed using OpenFOAM. Further, an elaborate experimental observations on the proposed design suggest that the model with 0.6c forward sweep outperformed the rest. The efficiency of the curved blade was notably enhanced by 14.41%, in contrast to the conventional model, and the numerical analysis endorses this observation. The modified turbine blades have the maximum wind streamlines that converge toward the center of the blade's trailing edge due to the lateral shift, and the resulting convergence reduces blade tip losses. The modified blade models demonstrated improved angular acceleration at a given wind speed, indicating enhanced efficiency and superior self-starting capabilities. Notably, these improvements were evident even at a lower wind speed of 4.2 m/s compared to the traditional H-model.

Information transfer between tip leakage vortex and blade aerodynamic force of a compressor cascade

The compressor blade exhibits intricate flow patterns near stall conditions, with the tip leakage vortex and the main flow shedding vortex from the blade's trailing edge identified as factors influencing the blade's aerodynamic force oscillation. The tip leakage vortex is recognized as the primary contributor to flow structures during non-synchronous vibration (NSV), although existing compressor NSV reduced order models often attribute the fluid oscillation to the passage flow shedding vortex. A tool capable of distinguishing between flow structures and blade aerodynamic force is crucial for resolving this discrepancy. Detached eddy simulations (DES) in a compressor cascade form the basis for gathering data on vortex structures and blade aerodynamic force. This study employs an information thesis method to elucidate the cause-and-effect relationship between the tip leakage vortex and blade aerodynamic force. Through a series of unsteady single passage simulations and experimental validation, the mechanisms leading to variations in blade aerodynamic force are demonstrated. Notably, this research utilizes Proper Orthogonal Decomposition (POD) mode time coefficients in span and axial directions to represent dynamic information on vortex structures. Additionally, transfer entropy is introduced as a metric to evaluate the causal interaction between turbulent flow of the tip leakage and the blade's aerodynamic force, marking a significant advancement. The analysis of information transfer entropy aids in identifying the vortex structure with a stronger relationship to aerodynamic force, a critical finding. By applying this approach, the study examines tip leakage vortex structures in various tip clearance sizes concerning aerodynamic force. The Tip3C and Tip5C tip geometries exhibit tip leakage vortex features with radial vortex characteristics and backflow, akin to structures associated with non-synchronous vibration. These tip vortex structures in the Tip3C and Tip5C tip geometry cascades demonstrate substantial correlations with aerodynamic force oscillation on the blade surface. Conversely, the Tip1C tip geometry cascade displays distinct tip leakage vortex features compared to Tip3C and Tip5C, with weaker ties to blade aerodynamic force oscillation. As simulation models progress, consideration of vortex structures in the passage and leakage vortex at the leading edge is imperative for accurate predictions of aerodynamic force oscillation response.

Transient vortical structure evolution under part-load condition in a high-power double-suction centrifugal pump based on Liutex method

Abstract In order to investigate the evolution of vortical structures inside a high-power double-suction centrifugal pump, the flow fields were solved numerically by the SST k-ω turbulence mode. After experimental validation, the Liutex/Rortex method was adopted for identifying vortices for each step from the numerical results, and the enstrophy was adopted to present the kinetic energy that vortical structures contained. The vortical structures at different seconds were obtained, and the vortices evolution was figured out. The results indicate that: the wake vortex was the dominant type inside the volute. Vortical structures at the impeller inlet evolve periodically. The interactions between the impeller leading edge with suction ribs and the blade trailing edge and volute tongues were critical factors for vortex evolution. Vortical structures mainly formed at the impeller inlet near the blade suction side. The suction rib would decrease the absolute rotational intensity around it, but the relative local rigid vortex would keep a high intensity. Due to the suction rib and volute tongues, the vortices variated with a period of 1/2T.

Analysis of pressure pulsation in a multi-stage double suction centrifugal pump

Abstract Pressure pulsation is a common phenomenon, which results from different causes. The intenser pressure pulsation occurs in the pump, the severer the damage to the pump. In the paper, with the assistance of detached eddy simulation method, the characteristic of pressure pulsation in the multi-stage double suction centrifugal pump is studied to understanding the internal flow circumstance. The results reveal that the pressure pulsation intensity reaches the maximum at blade trailing edge, which propagates to the tongue region of forward flow channel and double-volute under the low rates. Furthermore, it can be concluded that the pressure pulsation of region with obvious rotor–stator interaction between rotating impeller and stationary volute is generally larger at low flow rates. The pressure pulsation near the suction side of blade trailing edge shows the feature of broadband frequency and with increasing flow rate the bandwidth of broadband decreases drops rapidly except BP1. Due to the influence of the number of impeller blades, the dominant frequency of monitoring points in the inter-stage flow channel and the volute is basically located at a frequency that is twice the blade frequency. Meanwhile, because of the symmetry of the geometric structure of the reverse flow channel, the pressure pulsation curve changes of its internal monitoring points are similar under the same flow rate.

Influence of blade trailing edge profile on pressure pulsation in high-speed centrifugal pump

High-speed centrifugal pump can easily lead to severe pressure pulsation due to complex flow, seriously influencing the stable operation. The slant-cutting suction surface to the blade trailing edge midpoint is proposed to improve the fluid flow and dynamic–static interference at the blade outlet for the high-speed pump. Based on large eddy simulation method, the pressure pulsations in a high-speed centrifugal pump were comparatively analyzed under different blade edge profiles with slant-cutting angles of 15°, 30°, and 45°. The numerical performance curves for an OB high-speed centrifugal pump are basically consistent with the experimental ones. In addition, the heads and efficiencies for MB15, MB30, and MB45 pumps are all higher than those of the OB high-speed centrifugal pump under all working conditions, and the head increases to the maximum of 1.24% when the slant-cutting angle is 15°. The high-intensity pressure pulsation at the blade outlet is closely related to the shedding periodic vortex from the blade pressure surface and flow separation under high-speed conditions. Compared with the OB high-speed centrifugal pump, the pressure intensity is decreased by 3.92% and 4.07% at tongue area for MB15 and MB30 pumps, respectively.

Investigation on hydraulic loss characteristic of Kaplan turbines based on entropy generation theory

Abstract In this paper, the hydraulic losses of a Kaplan turbine under optimal and rated operating conditions are investigated through the theory of entropy generation. The results show that hydraulic loss values calculated using pressure drop and entropy generation theory are similar. The hydraulic losses are mainly concentrated in runner and draft tube. However, when the operation condition of Kaplan turbines deviates from the optimal condition, the proportion of hydraulic loss in draft tube increases. The hydraulic loss in draft tube is mainly composed of entropy generation caused by turbulence fluctuation, which is the result of unstable flow induced by vortex rope. The hydraulic losses of other parts are mainly composed of entropy production caused by wall shear. The high entropy production of the runner concentrated on the shroud, hub, blade surface, and blade trailing edge, while entropy production caused by wall shear is concentrated on blade pressure surface and shroud near blades when the turbine strays from optimal operating condition.

Energy loss analysis of a double-suction centrifugal pump using in pump mode and turbine mode

As an economical energy recovery device, pump as turbine (PAT) is widely used in micro-hydropower stations and the chemical industry. The inlet and outlet pipelines connected to the double-suction pump are on the same horizontal line. As the pipeline layout is very convenient, in some chemical industries, the way of residual pressure energy utilization is increasing using the double-suction pump as a turbine. Based on numerical simulation, experimental verification, and entropy generation theory, the energy loss rule of each flow component in the pump mode and turbine mode under different flow rates is compared and analyzed. The results show that when the double-suction pump is used as a turbine, the flow rate at the best efficiency point (BEP) in the turbine mode shifts to a large flow rate by 30.89% and the BEP efficiency decreases by 1.30%. In the pump mode and turbine mode, the main energy loss component is the impeller, and the turbulent entropy generation power and the wall entropy generation power are the main sources of energy loss. The energy loss in the suction chamber and impeller increases sharply, and the energy loss is primarily enhanced in the blade trailing edge and the tongue near due to the unsteady flow in the turbine mode. Due to the complex structure, the spiral suction chamber is not suitable for the flow direction of the fluid flow out of the impeller, and the flow state inside the impeller is negatively affected by the suction chamber in the turbine mode. This paper provides a theoretical basis for the design and application of double-suction centrifugal PAT.

Effect of airfoil trailing edge up on the performance of gas-liquid multiphase pumps

Abstract In this study, the impact of blade trailing edge structure on the performance of multiphase pumps was investigated. The modification parameters of the impeller blade airfoil were characterized by defining and adjusting the chord length ratio l/l 0 and deflection k, based on the design methodology employed for wing flap lifting devices. The impeller blade airfoil was modified using the trailing edge up design approach. Comparative analysis was conducted to evaluate the effectiveness of elevating the trailing edge of the airfoil in improving flow channel blockage, reducing turbulent energy at the impeller outlet, minimizing energy dissipation, and ultimately enhancing the efficiency of multiphase pumps. Remarkably, a maximum efficiency improvement of up to 3.04% was observed when the inlet gas content reached 70%.

Experimental investigations on cooling characteristics of different trailing-edge cutback geometries

One important method for enhancing the performance of modern engines is to increase the turbine inlet temperature. Due to the high velocity near the throat, the heat transfer to the blade trailing edge is high, particularly on the pressure side near the trailing edge. Therefore, the design methodology for cooling structures becomes critical for the thinner trailing edge compared to other parts of the blade. Trailing-edge cutback is a common cooling structure that guides cold air to form an effective film near the blade pressure side. However, the cutback lip induces strong and unsteady shedding vortexes, which significantly reduce the downstream coolant effectiveness.Previous studies have explored the film cooling performances of cutback structures and the interaction between coolant and mainstream using experimental and numerical methods. Experimental results were obtained using Pressure-Sensitive Paint (PSP) and Particle Image Velocimetry (PIV) in a large-scale wind tunnel, while the Delayed Detached Eddy Simulation (DDES) with the Shear Stress Transport (SST) turbulence model was employed for capturing the unsteady flow field.In this paper, further investigation will be conducted on the lip profiles of the fillet structure to improve the effectiveness of the film coolant. The rounded lip design delays boundary layer separation, thereby reducing the scale and intensity of shedding vortices. This improvement in the effectiveness of the rounded lip nozzle model is observed across all blowing ratios. Furthermore, at low or medium blowing ratios, the rounded lip design significantly reduces momentum exchange, inhibiting the mixing between the mainstream flow and cooling air. This leads to a more pronounced enhancement in cooling effectiveness.

Rotating Flow and Heat Transfer Characteristics of a Novel Cooling Channel for Gas Turbine Blade Trailing Edge With Diamond-Type TPMS Structures

Abstract This work designs a Diamond-type triply periodic minimal surface (TPMS) structure that exhibits excellent thermomechanical properties in a gas turbine blade trailing edge to enhance thermal performance and improve heat transfer uniformity. Since the velocity and temperature distributions are altered in the rotating trailing edge channel, the flow and heat transfer characteristics of the baseline pin fin and Diamond TPMS models are numerically investigated at the Reynolds number of 10,000 and the rotation numbers of 0.0–0.28. Compared to the baseline model, the Diamond TPMS network significantly decreases recirculation flow at the inner wall, improving heat transfer, especially at the tip and outlet regions. Although the Diamond TPMS model incurs substantial pressure losses from 191% to 234%, it yields significantly higher overall heat transfer than the pin fins by 179%. Consequently, the thermal performance increased by 93.4%. The flow fluctuations due to the rotating effects are minor in the Diamond TPMS architecture, considerably reducing the differences in heat transfer between the leading and trailing walls. The differences in the wetted-area averaged Nusselt number of the baseline and Diamond TPMS models within the studied rotation numbers are 8.5–14.4% and about 8.5%, respectively. Moreover, the Diamond TPMS structure reduces the differences in heat transfer between the root and tip regions at the outlet by up to 80% compared to the pin fins. This improvement helps protect the trailing edge from thermal failure, thereby potentially prolonging the gas turbine blade's lifetime.

Investigation of control effects of end-wall self-adaptive jet on three-dimensional corner separation of a highly loaded compressor cascade

To overcome the limitations posed by three-dimensional corner separation, this paper proposes a novel flow control technology known as passive End-Wall (EW) self-adaptive jet. Two single EW slotted schemes (EWS1 and EWS2), alongside a combined (COM) scheme featuring double EW slots, were investigated. The results reveal that the EW slot, driven by pressure differentials between the pressure and suction sides, can generate an adaptive jet with escalating velocity as the operational load increases. This high-speed jet effectively re-excites the local low-energy fluid, thereby mitigating the corner separation. Notably, the EWS1 slot, positioned near the blade leading edge, exhibits relatively low jet velocities at negative incidence angles, causing jet separation and exacerbating the corner separation. Besides, the EWS2 slot is close to the blade trailing edge, resulting in massive low-energy fluid accumulating and separating before the slot outlet at positive incidence angles. In contrast, the COM scheme emerges as the most effective solution for comprehensive corner separation control. It can significantly reduce the total pressure loss and improve the static pressure coefficient for the ORI blade at 0°-4° incidence angles, while causing minimal negative impact on the aerodynamic performance at negative incidence angles. Therefore, the corner stall is delayed, and the available incidence angle range is broadened from −10°–−2° to −10°–4°.This holds substantial promise for advancing the aerodynamic performance, operational stability, and load capacity of future highly loaded compressors.

Investigation on the unstable flow characteristic and its alleviation methods by modifying the impeller blade tailing edge in a centrifugal pump

In the field of the pumped storage plants, the unstable flow is universally caused by the rotating stall in the hydro-energy machinery, which further deteriorates the performance curves. To explore the alleviation method of the unstable flow, flow characteristic in a centrifugal pump with different impeller blade geometries is numerically investigated using a modified SST k-ω partially averaged Navier-Stokes model in this study. Numerical validation on the characteristic curves is carried out, which appears in accord with the experimental data of the test pump. Four types of available modification methods are attempted based on theoretical analysis, i.e., trimming the section side of the blade at trailing edge (TE) (named model A), decreasing the blade angle at TE (named model B), trimming the blade TE in spanwise direction with 45 degree (named model C) and adopting large lean angle blades (named model D). Results on the characteristic curves are first compared. In the test pump and model B, one positive slope region is observed under the same operation condition, while it is brought forward in the model A. On the contrary, the positive slope region is completely alleviated in model C and model D. Further exploration on the flow pattern in the impeller is conducted to give a comprehensive explanation. Due to the sudden increment of the energy loss, the flow pattern tends to be deteriorated, which further has impact on the characteristic curves. At last, unstable flow analysis in the impeller of the model D is carried out with emphasis on the evolution of the rotating stall. By using large lean angle blades, the rotating stall in the blade-to-blade passage of impeller is alleviated significantly with lower pressure fluctuation intensity.

Impeller optimization using a machine learning-based algorithm with dynamic sampling method and flow analysis for an axial flow pump

Design optimization for widely used axial flow pumps presents a formidable challenge due to the significant impact of numerous parameters associated with impeller geometry on hydraulic performance. The expansive design space raises concerns about the cost and time implications of the optimization process. This paper introduces a machine learning-based algorithm with a dynamic sampling approach to enhance the hydraulic performance of axial flow pumps. The focus is on an axial flow pump designed for China’s South-to-North Water Diversion Project. Optimization involves selecting 15 design variables governing impeller geometry, considering meridional shape and mean blade profiles. The optimization process predicts hydraulic performance using CFD methods, with a primary objective of maximizing efficiency at the axial flow pump’s design point while maintaining pump head around the design value. The results indicate that the proposed machine learning-based algorithm exhibits commendable convergence, delivering a notable improvement in performance. For instance, the optimized axial flow pump displays 2% efficiency increase compared to the initial design. Further analysis employing concepts like entropy generation rate and boundary vorticity flux reveals that the optimized pump has more uniform flow near the pressure side of the impeller blade. Additionally, design optimization effectively suppresses flow separation at the blade trailing edge near the impeller hub. This study offers valuable insights and a practical tool for the design optimization of axial flow pumps.

Investigation of radial force in a high-speed miniature pump

A high-speed miniature pump design is put forth for utilization in the aerospace sector, where the pump’s reliability holds critical importance under microgravity operational conditions. This study focuses on a dynamic bearing-equipped miniature centrifugal pump, chosen for its suitability in investigating radial forces. The prototype of the miniature pump is manufactured and tested by experiments at the rotational speed of 10,000r/min. A good agreement is observed between the numerical predictions and the experimental results. The radial force acting on different blade part has been analyzed for several flow rate conditions using the steady state CFD calculation. It has been found that the radial force exerted on the blade trailing edge exit is the main cause of the total radial force for the impeller. Moreover, using the unsteady CFD simulation, the evolution process of the radial force changing for both the direction and the magnitude with respect to the annular position due to the shaft rotation is discussed in details. The pressure pulsation is also monitored in impeller and volute casing. The results show that the amplitude of the unsteady radial force has a strong relationship with the time it takes for the blade trailing edge exit passing the volute tongue region, while the direction of the radial force hardly changes. The findings of this study contribute to facilitating the broader implementation of the high-speed miniature pump across diverse sectors of society.