To understand the effects of particle coincidence errors on the CDP cloud measurement in the large-scale icing wind tunnel, an icing cloud measurement test was conducted in the CARDC icing wind tunnel. Based on the test, the variation characteristics of CDP-measured cloud microphysical parameters, including total cloud number concentration, medium volume diameter, and liquid water content, were investigated for different nozzle number ratio and test section velocity conditions. Subsequently, the effects of the particle coincidence errors on CDP measurement results were analyzed. Finally, an assessment method of the particle coincidence intensity was presented based on the average transit distance. Results showed that either increasing nozzle number ratio or decreasing test section velocity could extend the average transit time, thereby enhancing the particle coincidence intensity. Under high concentration cloud conditions, significant particle coincidence errors not only changed the time-resolved characteristics of the measured cloud microphysical parameters, but also altered the cloud particle size distribution patterns, drastically reducing the total cloud number concentration, and greatly increasing the medium volume diameter and liquid water content. Consequently, the CDP’s ability to accurately capture the variation characteristics of real cloud microphysical parameters was compromised. The average transit distance can better characterize the particle coincidence intensity of the CDP in comparison with the average transit time.

To accurately evaluate the comprehensive cooling efficiency of turbine vane under high-temperature and high-pressure conditions, numerical simulations were performed to investigate the influence of thermal radiation on the extrapolation accuracy from low operating condition experiments. The results showed that without considering thermal radiation, the deviation between the extrapolated average comprehensive cooling efficiency and the real value was 3.14%. However, when radiation effects were included, the deviation increased significantly to 6.48%, indicating that thermal radiation was a primary factor causing modeling inaccuracy. To address this issue, a correction model in the form of a power function was constructed based on key dimensionless parameters: mainstream Reynolds number ratio, temperature ratio, and pressure ratio. The specific form of the correlation was determined using non-linear regression on multi-condition simulation data. Validation results demonstrated that after applying the proposed correction correlation, the maximum deviation of cooling efficiency between high and low operating conditions was controlled within 1.21%. The proposed method can significantly improve the accuracy of modeling prediction.

To enhance the quality of the exit temperature distribution from advanced combustors, it is necessary to investigate the flow and dilution characteristics of non-isothermal jets in strong swirling crossflow. In this study, two-color 1-methylnaphthalene planar laser-induced fluorescence (1-MN PLIF) thermometer technology was used to investigate the temperature distributions of single and multiple jets in strong swirling crossflow with high temperature difference. Meanwhile, large eddy simulation (LES) was employed to obtain the three-dimensional temperature and velocity fields, thereby revealing the flow and dilution mechanisms of jet in swirling crossflow. The results indicated that the low temperature jet inclined in swirling crossflow and generated a secondary low temperature zone downstream of the mainstream; the fluctuations of the swirling mainstream also intensified the jet's unsteady characteristics with distinct mode due to the jet/mainstream velocity ratio and the hole diameter. A single jet showed a nearly straight inclination in the streamwise cross-sections, whereas the multiple jets tended to be twisted to the swirl leeward side of the jets, with a lower degree of dilution than the single jet. The LES results showed that the multiple jets significantly impeded the tangential velocity of the swirling mainstream, leading to a reduction in the tangential force and tangential shear layer of the multiple transverse jets. This phenomenon was mainly attributed to the weaker dilution performance of multiple jets.

The complex heat transfer and cracking characteristics of supercritical hydrocarbon fuels in scramjet engine regenerative cooling channels pose a significant challenge. To address this, this study investigated the flow and pyrolysis of supercritical-pressure n-decane in an asymmetrically heated rectangular channel under an external convective boundary condition. Results were compared with those under constant heat flux and constant wall temperature conditions. Numerical simulations revealed that under external convection, the variation of thermal resistance and reduced temperature difference between inner/outer walls led to non-monotonic changes in heating surface heat flux and wall temperature. The cracking conversion rate and heat transfer proportion through the lower wall increased with elevated external gas temperature and convection coefficient. Heating surface heat flux, wall temperature, cracking characteristics, and inner wall heat transfer distribution varied with thermal boundary conditions. Under the conditions of external convective heat transfer and constant wall temperature, the average heat flux of the heated surface outside the channel increased by 116.7 kW/m² and 202.7 kW/m², respectively.

The inherent geometric complexity of triply periodic minimal surface (TPMS) significantly increases the computational consumption of numerical simulations, which has become a critical constraint on their engineering design and application. This study conducted full three-dimensional numerical simulations on TPMS structures with porosities ranging from 60% to 80%, systematically revealing the thermal-hydraulic performance of different porosity configurations under extreme operating conditions, and proposed a performance evaluation criterion coupling the power-to-weight ratio (WPEC). The results demonstrated that the TPMS structures with 75% porosity exhibited the optimal comprehensive performance under this criterion, achieving a WPEC value of 2.5. Furthermore, based on the overlapping mesh method and particle trajectory tracking method, a rapid prediction model for TPMS structures that coupled macroscopic performance with microscopic flow fields was constructed, achieving accurate performance evaluation with high computational efficiency. The computational time was reduced by over 90%, while the average prediction errors for total heat transfer, cold-side pressure drop, and hot-side pressure drop were 3.91%, 4.62%, and 5.42%, respectively.

This study experimentally investigated the effects of positive and negative velocity gradients in crossflows on the breakup modes and dynamic characteristics of water jets. Experiments covered average Weber numbers (5.6, 8, 16, 40) and the average jet-to-crossflow momentum flux ratio (20, 30, 40, 50, 60). Results demonstrated that positive gradients enhanced jet penetration depth, while negative gradients reduced penetration and accelerated jet breakup and deflection. Under negative gradients, severe jet deformation increased the windward area of liquid columns, leading to significant spanwise width expansion. Positive gradients promoted intense column oscillation with larger surface wavelengths, whereas negative gradients suppressed oscillation and reduced wavelengths. Negative gradients accelerated the transition of jet breakup modes, while positive gradients delayed this transition. The analysis of proper orthogonal decomposition (POD) and Fast Fourier Transform (FFT) revealed that spray characteristics under varying average Weber number sprimarily differed in resonance peak positions and amplitudes, with consistent non-resonant regions. Amplitude decay rates were higher under negative gradients, indicating intensified fluid dynamic dissipation and weakened surface tension effects. Increasing frequency and mode order under negative gradients significantly reduced the amplitude and energy content. This confirmed that aerodynamic suppression in negative-gradient flows caused initially pronounced amplitude variations that weakened over time, contrasting with sustained large-amplitude fluctuations under positive gradients.

To address the issue of low cooling efficiency at the crests of longitudinally corrugated heat shields, a novel structural—a non-uniformly distributed longitudinally corrugated heat shield with inclined perforations only on the leeward side of the troughs, was proposed. Using commercial CFD software and fluid-solid coupled numerical simulation methods, comparative studies were conducted with traditional structural schemes including uniformly distributed and graded-density configurations. The cooling performance of the heat shield's wall was analyzed under hole inclination angles ranging from 20° to 40° and blowing ratios between 0.82 and 1.85, and the effects of inclination angle and blowing ratio on cooling efficiency were examined. The results showed that the proposed design effectively utilized dynamic pressure intake on the leeward side, significantly reduced high-temperature zones on the wall, improved crest cooling efficiency, and enhanced wall temperature uniformity. A smaller inclination angle decreased trough cooling efficiency but increased crest cooling efficiency, with the crest cooling efficiency reaching its peak at an inclination angle of 30° to 35°, representing a 5.62% improvement compared with the baseline model. At a blowing ratio of 1.85, the maximum enhancement in crest cooling efficiency reached 5.57% compared with the baseline model, though accompanied by a 7.57% reduction in cooling efficiency uniformity coefficient.

In order to investigate the influence of the geometry of the air film hole and their blowing ratio on the cooling characteristics and flow structure of the air film, a numerical study on the comprehensive cooling efficiency of the first stage turbine moving blade was conducted. A conjugate heat transfer numerical model of the turbine rotor blade was established and verified. The comprehensive cooling efficiencies of the blade with three special-shaped film holes (cylindrical, dustpan and dovetail) under different operating conditions were compared and analyzed. The mixing characteristics of film cooling at different curvature positions on the suction side were clarified. The results showed that the conjugate heat transfer numerical model adopted can well predict the distribution of the cooling efficiency on the blade surface. For the turbine blade discussed, the ideal blowing ratios for all three film- hole structures were 1.0. Under the same blowing ratio, the jet mixing range at the SS₂ position was significantly larger than that at the SS₁ position, and the jet mixing was more intense. Using dustpan-shaped holes on the suction side of the blade can achieve better economic benefits.

For the rotating detonation engine, the oblique shock waves induced by detonation waves can lead to upstream high-pressure pulsations, affecting the stable operation of the engine. A class of topological fluid diode anti-backward propagation intake structures was designed, and numerical simulation methods were used to compare and analyze the flow field distribution and pressure backward propagation characteristics of six different configurations under cold flow and pressure pulsation conditions. The research results indicated that the topological structure can effectively change the direction of the backward propagation gas and reduce its speed, thereby effectively suppressing the shock waves backward propagation. By analyzing the maximum static pressure and the pressure pulsation along the process, it was found that the depth and level of the topological fluid diode were key design parameters affecting the suppression of detonation wave backward propagation. Among them, the single-level-slot depth 20 configuration showed lower maximum static pressure and pulsation amplitude under various conditions, with a pressure suppression rate reaching up to 10.23%. Additionally, the three-level configuration also showed good suppression effect due to more sufficient vortex formation.

Transverse jets are widely studied and utilized to enhance the mixing within aero-engine combustors. This study introduced a novel micro-scale V-rib which was positioned upstream of the transverse jet to enhance the mixing between the main flow and the jet. The effects of momentum flux ratio, V-rib height, and the distance between the V-rib and the jet nozzle on mixing efficiency were investigated through numerical simulations using the Realizable k-ε turbulence model and Particle Image Velocimetry (PIV) experiments. The results demonstrated that the V-rib generated vortex structures aligned with the kidney shaped vortices in the transverse jet. The mixing between the main flow and the jet can be improved through enhancement of intensity of kidney shaped vortices. For the cases studied, the V-rib-induced kidney shaped vortices merged with the jet’s kidney vortices. This merger increased the overall strength by nearly 70%, resulting in a 16% to 46% increase in jet penetration depth. Furthermore, the V-rib height was found to have a more pronounced effect on the mixing compared with the distance between the V-rib and the jet nozzle. An increase in V-rib height from 0.25D to 0.5D (D is the diameter of the jet nozzle) led to a 5% to 20% increase in jet penetration depth, whereas altering the distance from D to 2D resulted in a mere 3% increase in penetration depth.

The safety of the aviation engine oil tube under the heating conditions specified in fire test standards was analyzed based on standard documents and fluid-solid-thermal coupling method. Tube assembles for flareless connection, swaged type, 28 MPa, were used, the working fluid in the pipe was RP-3 aviation kerosene, and the high temperature standard flue gas was selected to simulate the gas for heating the tube. In order to simulate the situation of tube under different working conditions or pump failure, different kerosene inlet flow rates were set up for calculation. The results showed that the temperature distribution of the tube wall was uneven under standard heating conditions. With the decrease of kerosene flow rate, the temperature of the tube wall increased and the heat transfer deterioration occurred. The increase of tube wall temperature could reduce the strength of the material, and the uneven distribution of tube wall temperature could produce thermal stress, which may increase the safety hazard of the tube. When the kerosene flow rate was reduced to a certain amount, the equivalent stress of the tube wall could exceed the yield strength of the material, and the tube was prone to fracture.

Rough surfaces significantly affect the micromotional wear behavior among mechanical components, typically exhibiting non-Gaussian distribution characteristics. Therefore, it is of great significance to establish a wear model based on three-dimensional non-Gaussian surfaces that is more in line with the actual working conditions to reveal the intrinsic mechanism of the micromotional wear behavior. Based on the measured surface topography data, the numerical simulation method of fast Fourier transform was utilized to generate a non-Gaussian surface model that is consistent with the actual surface. The non-Gaussian surface finite element model was established by using ABAQUS finite element software and the second-developed UMESHMOTION wear subroutine. The influence patterns of factors such as kurtosis, skewness and standard deviation values on micromotion wear were explored. The results showed that the non-Gaussian surface with high kurtosis of positive skewness had the most obvious local stress concentration and the largest wear depth compared with the contact cases of smooth and Gaussian surfaces. For non-Gaussian surfaces under the same conditions, negative skewness and low kurtosis had more uniform stress distribution and more stable wear performance in terms of contact performance. The contact stress and wear depth of the 3D non-Gaussian surfaces increased significantly with the increasing values of the standard deviation of the surfaces.

To accurately characterize the influence of the mesostructure of three-dimensional needle-punched resin matrix composites on their mechanical properties, in-situ tensile micro X-ray computed tomography experiments were performed on the composites. By integrating image processing techniques and mesostructural reconstruction methods, quantitative analysis of fine structural features such as pores, cracks, and fiber architectures was completed, the evolution patterns of pore volume parameters were revealed and a three-dimensional strain field of the material was established. An image boundary path extraction algorithm and tomographic data reconstruction algorithm were proposed, enabling the construction of a layered finite element model. The results indicated that resin-based composites exhibited distinct damage evolution behaviors across different fiber architectures under tensile loading: damage in woven fiber layers primarily concentrated on the matrix and warp fibers; damage in unidirectional fiber layers occurred between fiber bundles and propagated perpendicular to the tensile direction; the maximum damage in non-woven fiber layers appeared at needle-punched structures, demonstrating that the needling process enhanced interlayer strength while inevitably degrading material performance. Under tensile loading, the woven fiber layer exhibited the highest load-bearing capacity, with damage state parameters remaining below 0.1 at a tensile strain of 3%. In contrast, the non-woven fiber layer, due to its higher porosity, showed the most severe damage under the same strain, with a damage state parameter of 0.605.

To study the sealing performance of flexible graphite braided packing, the spatial configuration and motion trajectory of its yarns were analyzed, and a three-dimensional braiding model was established. Compared with traditional non-metal gasket models such as the porous media model, this model not only considered the interaction between yarns but also demonstrated good compressive resilience, helping to better simulate its real working condition. The leakage under different axial loads, medium pressures, and medium temperatures was obtained through numerical simulation. The results indicated that: numerical simulation results were consistent with the experimental results. The leakage was inversely proportional to the axial load. The increase in axial load reduced the leakage channels, leading to a gradual decrease and eventual stabilization of the leakage rate, thereby improving the sealing performance. The leakage was directly proportional to the medium pressure. When the medium pressure was high, the axial load can be appropriately increased to improve the sealing performance. The leakage was directly proportional to the medium temperature. When the medium temperature increased, the leakage increased slightly, and overall, the impact on the leakage was relatively small.

Taking the static strength design of an auxiliary power unit (APU) installation system for a specific aircraft model as an example, a load distribution model based on Gap elements was proposes. The nonlinearity in the contact between the APU body, mounting tie rods, and vibration isolators were considered. Comparisons with the results from the solid finite element model of the APU installation system vibration isolator demonstrated the effectiveness of the Gap element-based load distribution model. Concurrently a static test plan for the APU installation system was established. To ensure high consistency between the simulation and test models, the APU mounting tie rods were calibrated, and the stiffness of the vibration isolators was tested. Under selected severe load cases and comparing with the test results, the strain of the tie rod was above 100 με. The minimum difference between the strain of the tie rod calculated by Gap element-based load distribution model of the APU mounting system and the test results was 4.6%, and the maximum difference was 7.5%. The minimum difference between the strain of the tie rod calculated by the solid modeling and the test results was 9.4%, and the maximum difference was 11.2%. Comparisons with test results further illustrated the accuracy of the Gap element-based load distribution model for the APU installation system. This model improved the calculation accuracy of load distribution values and modeling efficiency for the APU installation system, providing an effective modeling approach for simulating contact interactions between vibration isolator assemblies.

The traditional rotor blind cavity bolt tightening mechanism adopts a one-time unfolding structural form, and the tightening torque is small, which cannot be applied to the tightening conditions of the new generation of aero-engine rotors in terms of accessibility and structural strength. To solve this problem, the technical requirements for tightening blind cavity bolts were first analyzed. Based on this, a design scheme for combined tightening of large and small torques was proposed: a tightening mechanism in the form of gear transmission was used to tighten and preload bolts with small torque, and a tightening mechanism in the form of an integral swing was used to achieve the final loading of the target torque. The design of the torque tightening mechanism was completed based on multi-objective optimization methods, and the motion trajectory planning of the tightening mechanism was carried out through kinematic simulation. The torque accuracy control method based on calibration method and the motion accuracy control method based on global positioning were both studied, achieving precise output of tightening torque and precise matching of geometric pose of the mechanism rotor, which were integrated into the blind cavity bolt automatic tightening system. This system can achieve a target tightening torque of 48 N·m for bolt tightening operations, with a tightening torque accuracy of ±2%, and it can also complete all bolt tightening work within 70 minutes. Based on this system, a two-step tightening process method was proposed and validated on the new generation of aero-engine, solving the problem of poor consistency in bolt preload and improving bolt tightening efficiency.

To determine the stability margin loss of aeroengine under measured pressure and temperature combined distortion in flight test, the stability margin loss evaluation method was studied based on equivalent conversion of distortion contour and parallel compressor model. The stability boundary of the compression system under distortion was obtained by equivalent coordinated conversion of the combined distortion contour and parallel compressor model calculation. Then the operating point of compression system was determined through the flight test data at the moment of distortion, and the stability margin loss can be calculated. For a stalled turbofan engine during flight test, the stability margin loss of the fan was 9.2% when the temperature non-uniformity was 2.2%, the circumferential total pressure distortion intensity was 3.3%, and the high-temperature and low-pressure regions were in phase. The results showed that the method can be used to determine the stability margin loss of aeroengine under pressure and temperature combined distortion measured in flight test.

When aerodynamic inflow interference exists between the rotors of a multi-rotor aircraft, the flight simulation model often struggles to achieve both real-time performance and high fidelity. To address this issue, considering both computational complexity and accuracy, a rotor state-space inflow model identification method based on the viscous vortex particle approach was proposed using tandem rotors as an example. Based on the Peters-He finite state induced inflow model, a pressure potential superposition method was introduced to establish a coupled state-space inflow model for tandem rotors. By applying predefined sweep force functions and extracting the inflow states of the tandem rotors, the original data for identifying the state-space inflow model were obtained using the viscous vortex particle method. On this basis, a multivariable output-error state-space model identification method was introduced, forming the inflow model identification approach for the tandem rotor. Taking a small tandem rotor configuration as an example, the state-space inflow model identification for hover at an advance ratio of 0.1 was conducted, validating the effectiveness and feasibility of the proposed identification method. And the identification results indicated that the quasi-steady inflow and first-order longitudinal inflow of the fore and aft rotors exhibited cross-interference, with more significant interference occurring at an advance ratio of 0.1. Besides, the first-order lateral inflow of the fore rotor affected the aft rotor only in forward flight, while the first-order lateral inflow of the aft rotor had negligible interference on the fore rotor.

To further investigate the aerodynamic interaction phenomenon among distributed ducted fans, ground tests or numerical simulation studies of ducted fan unit and distributed ducted fans with different configuration were carried out. Combining ground test and CFD numerical simulation, it was found that under static conditions, for a 100 kg-class ducted fan unit, more than half of the total thrust was generated by the duct, while the rest of thrust was mainly provided by the rotor. Based on CFD simulations, the aerodynamic interaction mechanism of two different types of distributed ducted fan configurations was investigated. Focusing on the thrust performance of duct and blade under aerodynamic interaction, the velocity and pressure fields from the leading edge to the trailing edge were analyzed. It showed that the wall pressure increased significantly near the leading edge due to strong aerodynamic interaction with the adjacent duct. Concurrently, the induced flow velocity around the leading edge decreased rapidly compared with the isolated ducted fan, leading to a substantial reduction in duct thrust. Meanwhile, the wall pressure at the trailing edge also increased, owing to the decrease of flow velocity at the outlet of duct. The thrust of rotor raised slightly due to the increase of the actual angle of attack of blade. Eventually, the average thrust of ducted fan group remained almost unchanged compared with that of the ducted fan unit. In addition, the blade rotation direction of the three ducted fans had little effect on thrust performance. For the integrated ducted fan set, the change of duct leading edge shape led to obvious reduction on thrust. Besides, flow separation at trailing edge region of integrated ducted fan also resulted in lower wall pressure compared with ducted fan unit, bringing down the thrust of duct furthermore. As a conclusion, current integrated design concept does not lead to an improvement in the aerodynamic performance of the ducted fan set.

The refined characterization of supersonic jet flow fields remains a critical technical challenge for enhancing aircraft aerodynamic performance and suppressing exhaust noise. This study systematically investigated the three-dimensional density field reconstruction of supersonic jets from an axisymmetric convergent-divergent nozzle using background-oriented schlieren tomography (BOST). First, the coupled effects of experimental parameters on the measurement sensitivity and spatial resolution were analyzed, and the BOST three-dimensional reconstruction mathematical model was established. Subsequently, a simulation experiment containing noise was designed to validate the model’s robustness. The results demonstrated that the reconstruction model maintained density field accuracy within 4.5% under high noise levels, confirming the robustness of the method. Finally, a multi-view BOST experimental system was implemented to reconstruct the three-dimensional density fields under typical experimental conditions. Results successfully captured the refined three-dimensional structures including the jet core region, shock trains, and expansion wave systems. The average errors on the centerline between the reconstructed density fields and numerical simulations were determined as 6.4%, 4.7%, and 5.0% under three experimental conditions, with shock positions showing good agreement with schlieren visualization. The BOST effectively visualized the transition process from Mach reflection to regular reflection induced by the increasing total inflow pressure, verifying the reliability of BOST in the three-dimensional diagnostics of supersonic jets. These findings provide high-precision flow field data crucial for nozzle optimization design.

Aviation piston engines are widely adopted in various “low-altitude economy” application scenarios due to their advantages such as low cost and excellent low-speed performance. The adaptation of automotive piston engines for aviation purposes will further reduce the development and usage costs of such aviation engines. Based on a certain type of naturally aspirated gasoline piston engine for automobiles, the key technologies in the “car-to-aircraft” conversion of piston engines were discussed. The physical model and reliability assessment model for this engine’s electronic control system were proposed and established. The dual-redundant design of the control system can significantly increase the system’s mean time between failures from 3103.02 h for a single system to 9508.23 h. According to the power requirements of the aircraft and the power transmission path, an aircraft-propeller-engine matching process was proposed, which included the aircraft, propeller, reducer, and engine. By dynamically setting the engine speed and power, propeller blade angle, and reducer speed ratio in accordance with this matching process, the maximum cruise range can be obtained. To meet the power output requirements at an altitude of 7000 m, a method for selecting and matching a turbocharger suitable for high-altitude operating environments was developed. The selected turbocharger can operate within an efficient range under matched conditions with the engine. The research results can provide a reference for the “car-to-aircraft” conversion of automotive piston engines.

The accurate simulation of flight environment parameters is of high importance for testing and evaluating an engine. The strong coupling between the inlet ambient pressure and the temperature during the aero-engine transient tests, however, significantly restricts the effective simulation and tunning of flight environment parameters. Simultaneously, considering the strong perturbation in the transient test tasks, an active disturbance rejection control algorithm via the new extended state observer was proposed, and then was successfully applied to the decoupling control in the intake environment simulation system. Based on the intake environment simulation system, the affine model derivation of system’s pressure and temperature loops was built, and the decoupling design was conducted. Meanwhile, the reversibility of the input matrix in decoupling design was deeply analyzed, and corresponding solutions were proposed for the ill-conditioned issue and irreversibility of the inverse matrix. To tackle the chattering phenomenon of state and disturbance estimation in high-gain linear extended state observer (LESO), an error feedback function (qsat) was proposed to design the QSAT extended state observer algorithm (QSAT-ESO) whose stability was proved by Routh criterion, and QSAT-ADRC decoupling control scheme based on QSAT-ESO was presented. With the construction of the intake environment simulation system simulation platform, aero-engine transient tests were carried out, and the comparisons between the QSAT-ADRC and the LADRC decoupling control method were performed. The results showed that, under the planned transient flight mission profile, the absolute integration errors of intake pressure and temperature based on the proposed QSAT-ADRC were reduced by approximately 63% and 88%, respectively, meanwhile the control valve swing was reduced. The proposed control scheme has improved the comprehensive control quality of intake pressure and temperature, and layed a solid foundation for improving the accuracy of aero-engine performance testing and evaluation.

Blades counting in aero-engines based on borescope vision is a critical component of routine maintenance. However, factors such as surface reflections and posture variations pose significant challenges to the real-time accuracy of existing blade counting methods. To address these challenges, a blade counting methods based on edge detection was proposed. To achieve efficient and accurate blade detection, an enhanced blade detection transformer (EB-DETR) model, augmented by the GS-ECA module, was presented to significantly enhance the representation and extraction efficiency of blade features. Furthermore, an innovative temporal-spatial correlation state machine (TSCSM) model was introduced for effectively capturing the temporal and spatial information of blade edge feature points for counting blades in aero-engines. Experimental results demonstrated that the proposed EB-DETR model achieved an average precision (AP₅₀) of 93.17%, reflecting a 6.54% improvement over other state-of-the-art (SOTA) models of similar scale, while reducing Giga floating point operations (GFLOPs) by 35.16% and achieving a detection speed of 61 frames per second (FPS). Additionally, the mean counting precision (MCP) for blades in aero-engines reached 97.06%, exceeding existing blade counting methods by 45.82%, thus satisfying the practical requirements for blade counting in aero-engines.

Shock and wake losses are the main sources of aerodynamic losses of a highly-loaded transonic air-cooled turbine blade. Pressure-side cutback cooling can control aerodynamic losses while reducing trailing-edge thermal load, but the relationship between the structural features and the losses remains unclear. In this study, a land structure with a tapered end was constructed, and steady-state numerical calculations were performed to investigate the effect of the tapered-land cutback structure on the shock and wake losses in a transonic turbine blade. The results showed that, for the shock loss, the tapered-land cutback structure induced an earlier flow acceleration and deflection via upstream flow area expansion, thereby mitigating the pre-shock expansion on the pressure side. Therefore, the Mach number and the shock angle were reduced and the losses of the pressure-side shock wave and the reflected shock wave decreased. For the wake loss, the tapered-land cutback structure effectively weakened the momentum transport between the mainstream and the coolant by increasing the base pressure downstream of the trailing edge and improving the uniformity of the velocity distribution. As a result, the wake was attenuated more rapidly along the flow direction and the wake loss decreased. The tapered-land cutback structure effectively reduced the energy loss coefficient over a wide range of the pressure ratio (exceeding 2.70) and the coolant flow rate (0%—3%) while also improving the trailing edge film cooling effectiveness.

Unsteady numerical simulation method was utilized to study the characteristic of blade dynamic loads under the rotor-rotor interaction in a high-load vaneless counter-rotating compressor. The study showed that: the unsteady pressure pulsation of upstream rotor originated from the shock wave sweeping of the downstream rotor. It mainly concentrated near the pressure surface trailing edge after the upstream rotor blade ending shock wave. Its maximum pulsation intensity was 25000 Pa and average was 2485.5 Pa, which were 24.91% and 2.48% related to average static pressure of upstream rotor blade. Its main frequencies were the relative blade pass frequency of the downstream rotor and its multiples. The unsteady pressure pulsation of downstream rotor originated from the wake, wake vortex, and potential wave of upstream rotor. It was spread over the entire blade surface. Its intensity distribution was strongly correlated with the relative velocity distribution, which was 8000 Pa in the supersonic region, and 40000 Pa in the subsonic region, 6331.25 Pa in blade surface average. Its 0.28% and 14.21%, 2.25% were related to average static pressure of downstream rotor blade. Its main frequencies were the relative blade pass frequency of the upstream rotor blade and its multiples. The average force of upstream rotor blade in a period was 102.8 N, and its fluctuation amplitude was 21.3 N. The force on the pressure surface was greater than that on the suction surface. The average force of downstream rotor blade was 698.5 N, its fluctuation amplitude was 7.2 N. The force on the pressure surface and suction surface can cancel each other out. The rotor-rotor interaction of the counter-rotating compressor increased the load on the blade, and the load distribution was affected by the relative velocity distribution and shock wave.

To enhance the high-penetration performance of underwater vehicles such as torpedoes, a multi-stage thrust scheme was designed for metal water ramjet. For addressing the significant total pressure loss in conventional water intake channels, an efficient resistance loss reducing water intake scheme with a multi-branch distributed non-circular pipeline was proposed, inspired by the structure of pintle-type variable thrust motors. This scheme was designed to achieve highly efficient resistance loss reduction. Through a combination of theoretical analysis and numerical simulation, the effects of pipeline layout, cross-sectional shape, and water injection port distribution on pipeline resistance loss were systematically investigated. The results showed that, taking the secondary water inlet pipeline as an example, compared with an external water inlet method with the same water flow rate, the distributed water inlet layout reduced the pressure loss by 50%. Introducing a non-circular cross-section further reduced the pressure loss by 22.45%, and incorporating multi-branch water inlets further reduced it by 13.17%. Overall, this distributed multi-branch non-circular pipeline scheme enabled uniform axial distribution of water inlet in the combustion chamber while significantly reducing the pressure loss by 85.62%. This study could provide a technical pathway for performance optimization of water ramjet.

A prediction model of the flow field in a rocket engine nozzle based on the U-net architecture was proposed to solve the problem of the time-consuming computation of the flow field in the nozzle using conventional computational fluid dynamics (CFD) methods. By changing the temperature and pressure of the nozzle inlet gas over a certain range, 2816 samples of the flow field in the nozzle under different boundary conditions were obtained based on the CFD method, which were used as a data set for model training. By introducing multiple input and output channels, the model could predict multiple flow field information of the temperature, velocity and pressure in the rocket engine nozzle. The results showed that compared with the traditional AE (Autoencoder) architecture model, the prediction accuracy of the U-net architecture model was significantly improved in three channels: pressure field, velocity field and temperature field. After using the normalized data set, the absolute percentage errors of the U-Net architecture model on each channel were 1.6%, 4.3%, and 2.7%, respectively. The predicted flow field in the nozzle was highly consistent with the CFD simulation results, and was two orders of magnitude faster than the CFD in 100 batch simulation missions; this model can provide effective technical support for the design and optimization of rocket engine nozzles.