Front Angle Research Articles

A Dual-Layer Control System for Steering Stability of Distributed-Drive Electric Vehicle

In addressing the limitations of traditional steering stability control strategies applied to distributed-drive electric vehicles (DDEVs)—which primarily focus on measuring yaw rate and sideslip angle and may result in loss of control during steering maneuvers—this study conducts a more comprehensive analysis of DDEVs’ steering control stability. It specifically investigates the relationships among the lateral positions of both the front and rear wheels, the slip ratios, and the angular orientation of the vehicle’s body during steering processes. Furthermore, a dual-layer steering stability control system aimed at enhancing the steering stability performance of DDEVs is introduced. This control system consists of two components: a lateral controller and a longitudinal controller. The lateral controller aims to establish clear linkages among four key variables, the front and rear wheel sideslip angles, yaw rate, and sideslip angle, and then to compute the necessary active front wheel steering angle and corresponding yaw moment based on the current vehicle body attitude. The findings indicate that, in comparison to the conventional DDEV controller, the proposed two-layer controller achieves substantially closer alignment to the reference curve during steering, with the accuracy increased by a factor of approximately 5 to 20. These results unequivocally affirm the efficacy and viability of the proposed approach.

Investigation of a piezoelectric ultrasonic surface wave transducer that minimizes structural scattering

Abstract The Structural of ultrasonic surface wave transducers affects structural scattering. A numerical model of an ultrasonic surface wave transducer was established. Numerical simulations and dynamic acoustic analysis were performed to systematically assess, the effects of the transducer parameters, such as the front and back angles, matching layer, and front wedge shape on structural scattering. The results show that the acoustic amplitude of the transducer structure scattered waves is basically stable when the back angle of the wedge is 64° -68 °and the front angle is 65°-85°. The amplitude obtained from a transducer with orthogonal slots and a front uniform matching layer is 61% lower for the primary structure scattering, 56% lower for the secondary structure scattering.
When equipped with the upper matching layer, the amplitude of the secondary structural scattering echo is reduced by 78.2%. The experimental results show that the transducer with orthogonal slots on the wedge and a matching layer at the front and upper edges has a signal-to-noise ratio of 19.6dB when detecting the echo signal of a ϕ8 through-hole in a welded steel plate, indicating good detection capability. The experiment validates the numerical simulation results. The proposed transducer can be used for structural monitoring of welded structures and detecting flaws.

Robust integrated control of autonomous vehicles path following with response performance improvement considering lateral stability

In this paper, a robust integrated control scheme is developed for autonomous vehicles path following considering both yaw stability and roll stability. First, a controller with H∞ and optimal guaranteed cost performances is presented, and the poles of the closed-loop system are configured in a given disk region to improve the state response performance. The controller outputs front and rear wheel angles for path following, as well as an external yaw moment and an external roll moment for lateral stability control. Secondly, the braking forces acted on four wheels are optimally distributed by means of quadratic programing. Besides, the steering angles of the four wheels conform to the Ackermann geometry relation. Finally, the proposed control scheme is verified by CarSim/Simulink co-simulation, the results show that the scheme has better performance on path following accuracy and stability of yaw and roll. Meanwhile, constraining the poles in a given disk region can improve the state response performance of the vehicle during operation.

Minimum cutting thickness prediction model for micro-milling machining and experimental Study of FeCoNiCrMn high-entropy alloy machining

FeCoNiCrMn high entropy alloy has excellent properties such as high hardness, high strength and high wear resistance, which has a broad application prospect in aerospace, military and other fields. As an emerging difficult-to-machine material, the minimum cutting thickness determines the highest machining accuracy of micro-milling. In order to improve the micro-milling quality of FeCoNiCrMn high-entropy alloy, a minimum cutting thickness prediction model based on the effective front angle of the tool is established according to the analysis of micro-milling force model. Through the FeCoNiCrMn high-entropy alloy micro-milling processing experiments, the milling force parameters are calculated by substituting them into the prediction model, and the minimum cutting thickness value of FeCoNiCrMn high-entropy alloy is 1.367 μm when the flank radius of the milling cutter is 5 μm.When the feed rate of each tooth is in the range of 1 μm–1.5 μm, the severe size effect and the ploughing effect lead to the specific cutting energy nonlinearly increase, and the cutting force and surface roughness increase sharply with large fluctuations. From this, the range of the minimum cutting thickness of the high-entropy alloy was judged to be between 1 μm and 1.5 μm, and the accuracy of this prediction model was verified.

Study on cutting temperatures of SiCp ∕ Al composites for ultrasonic vibration-assisted cutting

Abstract. In order to deeply understand the cutting mechanism of SiCp / Al in ultrasonic vibration-assisted turning, a prediction model of a cutting temperature field of SiCp / Al composites in UVAC (ultrasonic vibration-assisted cutting) was established. A theoretical model of instantaneous cutting depth and transient shear angle was established considering the real-time changing cutting depth, tool front angle and shear angle characteristics of UVAC. The relationship between cutting speed, shear speed and chip flow speed in UVAC processes is revealed, as well as the shear force and the front cutter friction force. Finally, the influence of heat generated by the heat source zone and shear heat source zone on the temperature rise was calculated, and the temperature field model was established. The experiment of processing SiCp / Al composites by UVAC was carried out. SiCp / Al composites with 25 % volume fraction were turned, and the cutting temperature data were measured and recorded by an infrared thermal imaging device. The cutting speed, cutting depth and feed rate were tested by a single factor, and the changes in cutting temperature under different parameters were compared. Finally, the experimental data were compared with the theoretical values to verify the validity of the theoretical model.

Fluoroscopically calibrated 3D-printed patient-specific instruments improve the accuracy of osteotomy during bone tumor resection adjacent to joints

BackgroundInadequate surface matching, variation in the guide design, and soft tissue on the skeletal surface may make it difficult to accurately place the 3D-printed patient-specific instrument (PSI) exactly to the designated site, leading to decreased accuracy, or even errors. Consequently, we developed a novel 3D-printed PSI with fluoroscopy-guided positioning markers to enhance the accuracy of osteotomies in joint-preserving surgery. The current study was to compare whether the fluoroscopically calibrated PSI (FCPSI) can achieve better accuracy compared with freehand resection and conventional PSI (CPSI) resection.MethodsSimulated joint-preserving surgery was conducted using nine synthetic left knee bone models. Osteotomies adjacent to the knee joint were designed to evaluate the accuracy at the epiphysis side. The experiment was divided into three groups: free-hand, conventional PSI (CPSI), and fluoroscopically Calibrated PSI (FCPSI). Post-resection CT scans were quantitatively analyzed. Analysis of variance (ANOVA) was used.ResultFCPSI improved the resection accuracy significantly. The mean location accuracy is 2.66 mm for FCPSI compared to 6.36 mm (P < 0.001) for freehand resection and 4.58 mm (P = 0.012) for CPSI. The mean average distance is 1.27 mm compared to 2.99 mm (p < 0.001) and 2.11 mm (p = 0.049). The mean absolute angle is 2.16° compared to 8.50° (p < 0.001) and 5.54° (p = 0.021). The mean depth angle is 1.41° compared to 8.10° (p < 0.001) and 5.32° (p = 0.012). However, there were no significant differences in the front angle compared to the freehand resection group (P = 0.055) and CPSI (P = 0.599) group. The location accuracy observed with FCPSI was maintained at 4 mm, while CPSI and freehand resection exhibited a maximum deviation of 8 mm.ConclusionThe fluoroscopically calibrated 3D-printed patient-specific instruments improve the accuracy of osteotomy during bone tumor resection adjacent to joint joints compared to conventional PSI and freehand resection. In conclusion, this novel 3D-printed PSI offers significant accuracy improvement in joint preserving surgery with a minimal increase in time and design costs.

Does presenting perpetrator and innocent suspect faces from different facial angles influence the susceptibility of eyewitness memory? An investigation into the misinformation effect and eyewitness misidentification.

This study investigated the effects of face angle congruency across stages of a misinformation paradigm on lineup discrimination accuracy. In a between-subjects design, participants viewed a mock crime with the perpetrator's face from the front or profile angle. They then read a news report featuring an innocent suspect's image from the same or different angle as the perpetrator had been shown. A subsequent lineup manipulated perpetrator presence and viewing angle of the lineup members, who were all shown either from the front or in profile. No significant difference emerged in identification errors based on angle congruency between stages. However, accuracy was higher when faces were shown from the front angle, both during the initial event and the lineup, compared to the profile angle. The results of this research underscore the importance of considering viewing angles in the construction of lineups.

Effects of nozzle angles of a double-row jet collector on harvesting performance

Owing to its high collection efficiency, the double-row jet collector is an important application in industrial operations. Presently, few studies on its collection efficiency and impact from its front and rear nozzle angles are available. In this paper, the computational fluid dynamics–discrete element method is employed to numerically study the jet parameters of a typical double-row jet collector from three aspects: flow characteristics, particle movement and collection efficiency. Defining α as the front nozzle and β as the rear nozzle, five different combinations of jet angles were first selected and an optimal configuration of the front nozzle at 30°and the rear nozzle at 55° was last obtained, the simulation results were confirmed via the performance experiment. The influence of the change in the front and rear jet angles on the flow field of the collection is shown, and the results indicate that of the angle α and β, α plays a dominant role, while β has relatively little influence on the whole collecting process, which guides for the optimal design.

Improvement of labyrinth seal performance using the partial honeycomb lands

In this study, a partial honeycomb land was proposed for improving the sealing performance of a labyrinth seal which has been widely applied to the low-pressure section of a gas turbine. The partial honeycomb land in this experiment is distinguished by a solid strip under the fin of the honeycomb land labyrinth seal. The tested fin front angle of the labyrinth seal was 60°, and the clearance size ranged from 1.15 to 2.82 times the fin tip thickness. The honeycomb cell diameter was 4 times the fin tip thickness, and the honeycomb cell depth was 10.58 times the fin tip thickness. The experiments were conducted under pressure ratios ranging from 1.1 to 2.5, and it was confirmed that the application of the partial honeycomb land resulted in a maximum 39.4 % reduction in the discharge coefficient. Computational Fluid Dynamics (CFD) analysis revealed that the application of the partial honeycomb land altered the flow of leakage, leading to a decrease in the effective clearance. It was confirmed that, for the honeycomb labyrinth seal with smaller clearance, the sealing performance degradation for the conventional honeycomb land case due to the weakened vortex inside the fin cavity was not observed for the case with partial honeycomb land. Therefore, the improvement in sealing performance of the labyrinth seal with partial honeycomb land was attributed not only to the reduction in the effective leakage flow area, but also to the maintained vortex size, which induced resistance to the leakage flow even in smaller clearance conditions.

Full-field solution from an oblique shock to estimate ground motion from blasting

The full-field solution (FFS) of the seismic radiation from a blasthole is refined with the use of a source function consistent with the shock physics on the detonation shock/rock interface. This source function accounts for the directionality of the flow in the detonation front, that is curved under the influence of the confining rock, inducing on it an oblique shock mostly on axial direction, contrary to current models that consider a radial source. The interaction of the explosive/confiner system is solved with the oblique shock local polar theory. From this analysis, pressure (p) versus deflection angle (Θ) polar curves are constructed and plotted in the p-Θ plane. The intersection of the explosive and confiner polar curves corresponds to the possible shock matching solution across the explosive/rock interface, which leads to a shock incident angle. A code has been written in MATLAB to perform the shock polar analysis. The resulting detonation front angle of the explosive with the confiner is considered to build a combined radial/axial source. For this, the displacement potentials for the axial component of the source are formulated and incorporated to the solution. Experimental data from quarry blasting are used to illustrate the application of the FFS model and the calibration of results in terms of attenuation coefficients. The effect of introducing the radial/axial combined source is also discussed.

Long-term results of orbicularis oris muscle reconstruction in primary cleft lip repair using the "basket-weave method".

The basket-weave method is an orbicularis oris muscle reconstruction method used in primary unilateral cleft lip repair. We compared the long-term results of the basket-weave method with those of a conventional method. For primary unilateral cleft lip repair, we compared the long-term results of 7 cases in which the orbicularis oris muscle was reconstructed by use of the basket-weave method, and of 7 cases in which the reconstruction was performed by use of the conventional method. The average postoperative follow-up period was 12 years and 7 months for the basket-weave method, and 11 years and 9 months for the conventional method. Using photographs of the front and elevation angle views, we evaluated the results as good if the philtrum ridge was formed on the fissure side and was almost symmetrical in height; as fair if the philtrum ridge was lower than the normal side; and as poor if the philtrum ridge had disappeared. For the basket-weave method, the results were good in 6 cases (85.7%), fair in 1 case (14.3%), and poor in 0 cases. For the conventional method, the results were good in 2 cases (28.6%), fair in 4 cases (57.1%), and poor in 1 case (14.3%). A significant difference was found between the 2 groups (Mann-Whitney U test, P = 0.0417). The philtrum ridge shape could be reconstructed by use of the basket-weave method, which gave better results in the long-term than did the conventional method for orbicularis oris muscle reconstruction in primary unilateral cleft lip repair.

Path Tracking Control with Constraint on Tire Slip Angles under Low-Friction Road Conditions

This paper presents a method to design a path tracking controller with a constraint on tire slip angles under low-friction road conditions. On a low-friction road surface, a lateral tire force is easily saturated and decreases as a tire slip angle increases by a large steering angle. Under this situation, a path tracking controller cannot achieve its maximum performance. To cope with this problem, it is necessary to limit tire slip angles to a value where the maximum lateral tire force is achieved. The most commonly used controllers for path tracking, linear quadratic regulator (LQR) and model predictive control (MPC), are adopted as a controller design methodology. The control inputs of LQR and MPC are front and rear steering angles and control yaw moment, which have been widely used for path tracking. The constraint derived from tire slip angles is imposed on the steering angles of LQR and MPC. To fully verify the performance of the path tracking controller with the constraint on tire slip angles, a simulation is conducted on vehicle simulation software. From the simulation results, it is shown that the path tracking controller with the constraint on tire slip angles presented in this paper is quite effective for path tracking on low-friction road surface.

The Impact of Temperature on the Electromagnet and Structural Optimization of a Solenoid Valve

The mathematical model of the solenoid valve under varying temperatures is constructed to investigate itsperformance and enhance heat dissipation balance. The relationship between temperature and electromagnetic force isdetermined. Electrothermal coupling simulation using COMSOL is conducted, optimizing the outer diameter and lengthstructure parameters of the coil. It is established that the heat dissipation of the coil is influenced by its outer diameter.Subsequently, based on optimized coil structure parameters, an orthogonal experimental design method combinedwith Ansys Maxwell is employed for simulation solution analysis to study the impact of structural parameters such aslength, position, front and rear angles of the magnetic barrier ring in the iron core, armature length, and through-holesize on electromagnetic force. Optimal structural parameters are identified. Results indicate a decrease in steady-stateelectromagnet temperature by 3–4℃, an increase in the initial electromagnetic force by 32.63%, and a rise in the maximumelectromagnetic force by 27.10%.

ОДИН ИЗ МЕХАНИЗМОВ ВОЗНИКНОВЕНИЯ ВЫСОКОЧАСТОТНЫХ КОЛЕБАНИЙ ПРИ ТОЧЕНИИ

The article presents the results of theoretical studies of the mechanism of high-frequency oscillations in the cutting zone based on wave processes accompanying the change in the elastic deforming state of the material during its destruction along the shear plane. Based on the studies carried out, it was confirmed that the source of high-frequency self-oscillations generated in the cutting zone is the dynamics of deformation of the material during its destruction along the shear plane. This plane represents the interface of the two media initiating wave processes propagating into the body of the workpiece and chips. Their character and parameters largely depend on the properties of the material being treated (modulus of elasticity and density), the haracteristics of the tool (material, front angle and quality of the front surface) and such operating parameters as the supply to the revolution and the width of the cut. It is noted that the cutting speed affects them indirectly, through the shear angle and the main component of the cutting force. Analytical dependence is proposed, establishing their relationship. It will allow a priori assessment of frequency ranges of possible self-oscillations in order to exclude modes that lead to deterioration of the quality of the treated surfaces.

Influence of carbide tooth grinding parameters on shaping efficiency of high steel grade tubing

Complex oil and gas well service conditions very easily trigger downhole casing deformation and failure, resulting in most of the oil and gas field casing shaping and repairing the difficulty of rising, casing micro-plasticity and micro-expansion technology can effectively solve the problem of casing local shrinkage and bending and deformation, in order to study the grinding shoe alloy teeth cloth angle, grinding speed and grinding depth on the grinding force change rule, according to the grinding theory to establish a single tooth and casing microelement section plane numerical model Model, the use of Johnson-Cook damage isomorphism model to characterize the material dynamic cutting failure, through the numerical simulation results fitted to the grinding force as the dependent variable, alloy tooth angle, speed, depth of grinding for the independent variables of the evaluation formula. The analysis results show that the grinding force decreases with the change of alloy tooth front angle from 0° to 60°; the grinding force does not change significantly in the range of milling speed from 40r/min to 80r/min; and the grinding force increases gradually when the milling depth increases. It is concluded that the angle and depth of the alloy tooth front are the main controlling factors for controlling the grinding and milling capacity, and this understanding provides technical references for the design and optimization of casing repair and is of great significance for accurately predicting the shaping capacity of the deformed casing and ensuring the integrity of the wellbore.

Experimental study on the influences of cutter geometry and material on scraper wear during shield TBM tunnelling in abrasive sandy ground

When shield TBM tunnelling in abrasive sandy ground, the rational design of cutter parameters is critical to reduce tool wear and improve tunnelling efficiency. However, the influence mechanism of cutter parameters on scraper wear remains unclear due to the lack of a reliable test method. Geometry and material optimisation are often based on subjective experience, which is unfavourable for improving scraper geological adaptability. In the present study, the newly developed WHU-SAT soil abrasion test was used to evaluate the variation in scraper wear with cutter geometry, material and hardness. The influence mechanism of cutter parameters on scraper wear has been revealed according to the scratch characteristics of the scraper surface. Cutter geometry and material parameters have been optimised to reduce scraper wear. The results indicate that the variation in scraper wear with cutter geometry is related to the cutting resistance, frictional resistance and stress distribution. An appropriate increase in the front angle (or back angle) reduces the cutting resistance (or frictional resistance), while an excessive increase in the front angle (or back angle) reduces the edge angle and causes stress concentration. The optimal front angle, back angle and edge angle for quartz sand samples are α = 25°, β = 10° and γ = 55°, respectively. The wear resistance of the modelled scrapers made of different metal materials is related to the chemical elements and microstructure. The wear resistances of the modelled scrapers made of 45#, 06Cr19Ni10, 42CrMo4 and 40CrNiMoA are 0.569, 0.661, 0.691 and 0.728 times those made of WC-Co, respectively. When the alloy hardness is less than 47 HRC (or greater than 58 HRC), scraper wear decreases slowly with increasing alloy hardness as the scratch depth of the particle asperity on the metal surface stabilizes at a high (or low) level. However, when the alloy hardness is between 47 HRC and 58 HRC, scraper wear decreases rapidly with increasing alloy hardness as the scratch depth transitions from high to low levels. The sensitive hardness interval and recommended hardness interval for quartz sand are [47, 58] and [58, 62], respectively. The present study provides a reference for optimising scraper parameters and improving cutterhead adaptability in abrasive sandy ground tunnelling.

Structure of rotating detonation in mixtures of natural gas and oxygen

The rotating detonation combustor is investigated as a potential implementation of pressure-gain combustion. Achieving net pressure-gain has proven to be extremely challenging in most combustors reported in the literature, regardless of their operating parameters. The performance losses observed in rotating detonation, compared to ideal predictions, can be attributed to mechanisms such as vitiation by residual burnt gases, partial detonation, and pre-combustion of reactants. The literature frequently discusses the impact of these mechanisms on measurable properties such as thrust and wave speed, but their effects on the front structure have not been fully understood. This study proposes using the rotating detonation structure for the first time to evaluate the vitiation quantitatively. The front structure of a compressed natural gas — oxygen-fueled rotating detonation is characterized using broadband chemiluminescence, and properties such as oblique shock angle, expansion angle, and front height are reported. The experimental values are then compared to the ideal predictions derived based on mass flow rates. The experimental front heights are found to be much higher than their ideal predicted counterparts. Analytical calculations that include pre-burning and vitiation show an increase in front height and a reduction in expansion angle, consistent with the chemiluminescence levels observed. The vitiated mass fraction is then deduced from the experimental front height, and the remaining velocity deficit is then used to evaluate the partial detonation mass fraction. Vitiated front angles compare favorably to the predicted values.Novelty and SignificanceThis study reports high-quality chemiluminescence imaging of natural gas/oxygen rotating detonation front enabling the measurement of critical geometrical front features such as the front height, oblique shock angle, and expansion angle. The conventional front mass flow rate balance is extended to account for the re-circulation of burnt gases effects and is used to estimate the experimental vitiation. Most notably, vitiation of the fresh mixture, which was already known to reduce front speed and pressure rise, is also shown to strongly decrease the expansion angle resulting in further losses of axial thrust.

Solute imbibition in paper strip: Pore-scale insights into the concentration-dependent permeability

Capillary wicking in a thicker gel blot microfluidics paper has been investigated through a combination of an analytical framework, experiments, and numerical simulations. The primary objectives of this work are to investigate the concentration-dependent wicking process inside thicker microfluidic paper and to estimate the concentration-dependent permeability using both theoretical models and experimental data. An additional goal is to estimate the parameters for saturation-dependent flow modeling in thicker microfluidic paper. To comprehend the wicking phenomenon on thicker gel blot paper, a series of experiments employing aqueous food dye solutions at varying concentrations has been conducted. In order to calculate the temporal wicking length analytically, the Brinkman-extended Darcy equation is implemented. By modifying the permeability expression for a simple rectangular unidirectional fiber cell and pure liquid, the expression of effective permeability for the analytical framework has also been introduced. The concentrations of the food dye solutions appear to have a substantial influence on the wicking phenomenon. Effective permeability and wicking length have been found to follow a decreasing pattern at lower concentrations while both increase at higher values. Intriguingly, employing a microfluidics paper with a relatively greater thickness facilitates the visualization of the fluid front. This phenomenon is identified by the formation of an acute angle at intermediate time instants, while the fluid front angle assumes an angle nearly ∼90° during smaller and higher time instants. In order to evaluate the saturation-dependent capillary pressure and permeability, the empirical correlation of concentration-dependent Brooks and Corey parameters is additionally determined experimentally. These parameters are subsequently employed in numerical simulations to illustrate the saturation-dependent flow field using Richards’ equation. Furthermore, numerical simulations based on these estimated model parameters have been conducted, and it turns out that the saturation field has an excellent agreement with the experimental results. The results of the current study can be used to design low-cost paper-based diagnostic devices for usage in healthcare and environmental applications.

Numerical study on weakening vortex-induced vibration of semi-ring diversion type component

Conventional spoiler components are commonly employed to mitigate vortex-induced vibration (VIV), but their effectiveness varies significantly. Therefore, detailed comparative studies should be made between different components and a more comprehensive suppression method will be proposed. In this paper, numerical simulations are conducted to explore the weakening effect of hydrodynamic shapes on VIV of structures. Different spoiler components, including rectangular spoiler, fairing, and fin plate are investigated, and for further optimization, a novel concept of semi-ring diversion type component is proposed. The attenuation effects of different components on vibration are compared. In addition, sensitivity analyses of the diversion component, including slit width (XW), front angle (α), and nozzle size (BL), are conducted at various reduced velocities to determine the optimal sizes. Results indicate that traditional spoiler components have inherent shortcomings in terms of weakening efficiency, which can only reduce the maximum resonance value (Ay(max)) to 50%–77%, extend the dimensionless critical velocity (Ucr) by −0.5–1.5, and shorten the length of frequency lock-in interval to 2.5–3, compared to the bare cylinder. The diversion component effectively reduces the frequency of vortex shedding around the cylinder. The optimal vibration damping effect is achieved when XW = 0.03, α = 60°, and BL = 0.11. Compared to the bare cylinder, the structure shows a substantial reduction in resonant frequency by 69%, a threefold decrease in the length of the frequency lock-in interval, a 68.2% reduction in Ay(max) and a delay in Ucr of 2.65, demonstrating a potential mitigation device for VIV.

Effects of Reynolds Number and Tooth Front Angle on Leakage Loss and Heat Transfer Characteristics in a Rotating Labyrinth Seal

Abstract The labyrinth seal is effective in reducing leakage losses at the rotor blade top in the turbine. This study investigates the variation in labyrinth seal performance at different rotational speeds, different Reynolds numbers, and different tooth front angles. Three Reynolds numbers (Re = 6000, 10,000, 15,000), five rotational speeds (Ta/Re = 0, 0.01, 0.04, 0.08, and 0.1), and three tooth front angles(75 deg, 90 deg, and 102.4 deg) have been introduced. The variation of leakage losses and heat transfer under different conditions is compared and a detailed analysis of the flow field and energy losses is performed. The discharge coefficient is increased slightly with increased rotational speed for the same Reynolds number. This is caused by the high rotational speed reducing the throttling loss and vortex loss. The high rotational speed enhances the heat transfer at the tip wall of the passage, and also weakens the heat transfer at the tooth cavity bottom. Additionally, the sealing capacity of the labyrinth is better at large tooth front angles, which is caused by the reduction of frictional losses on the stator and eddy current losses in the tooth cavity. The change in local pressure loss also affects the velocity distribution along the channel, which is the reason for the change in the local Nusselt number.