Breakup Process Research Articles

Self-similarity formation of a pendant drop of power-law fluids

To fully explore the breakup behavior of gel propellant in both the macroscopical and microscopic scales, the present study started from the self-similarity analysis for a macroscopical power-law liquid thread, and a transition from viscocapillary to viscocapillary-inertia breakup regime was identified by the experimental verification, using high-speed photography technology and image processing. Furthermore, the dissipative particle dynamics method was employed to predict the profile of microscopic power-law liquid thread when the diameter of thinning liquid filament approaches the micro-/nanoscale. Three different breakup regimes, capillary-, viscocapillary-inertia-, and thermal-fluctuation-dominated modes, were carefully reproduced and validated. Results showed that the self-similarity breakup process can be retarded by the inertial and viscous effects. In addition, there are some similarities existing between the macroscopical and micro-/nanoscale thinning processes.

Study on the Numerical Model of Gas–Liquid Dispersion Driven by a Coaxial Mixer

As the flow basis for gas–liquid mixing, turbulence plays an important role in the movement of bubbles in a stirred tank. Motivated by the fact that the current models in the framework of computational fluid dynamics-population balance model lack an adequate assessment of the turbulence effects, the coaxial mixer was chosen as the subject of study, and different turbulence models, drag models, and breakup and coalescence models were compared and optimized. The results showed that the RNG k-ε model better characterized the turbulent scale and achieved a higher exactness for the gas-phase concentration in the axial direction. The Luo–Luo model modified based on the eddy capture mechanism could effectively describe the coalescence and breakup processes of bubbles. Additionally, in the presence of strong turbulence, the Ishii & Zuber model and the Brucato model outperformed other models in predicting gas dispersion and flow structure but still failed to capture the peak gas holdup. By analyzing the available data, a new correlation was proposed to elucidate the increase in drag coefficient caused by turbulence, which significantly improved the prediction accuracy of gas holdup.

Breaking one into three: Surface-tension-driven droplet breakup in T-junctions

We report a novel droplet breakup regime in the microfluidics T-junction, where new droplet interfaces are created in the two arm channels, rather than at the center of the junction. We show that there is a different hydrodynamic root for this new regime, and propose a simple geometric rule which enables this regime compared to the classical T-junction. A dynamic model for lower capillary number (Ca) is developed to predict the breakup process. We also show that at higher Ca the classical regime of central breakup is recovered in the same T-junction.

Flow measurements of jet impingement upon a semicylinder with crossflow

In this work, time-resolved particle image velocimetry (TR-PIV) measurements have been carried out to investigate the structural features of a submerged transverse round liquid turbulent jet discharged into a confined laminar crossflow. The duct Reynolds number based on crossflow velocity is fixed at Re=3000, and the impinging jet is directed to a semicylindrical concave surface located in one of the walls of a vertical square duct. The spatial development and flow dynamics are analyzed along several orthogonal planes parallel/perpendicular to the jet axis for jet Reynolds numbers based on the jet exit diameter of Rej=3000, 6000 and 9000 (jet-to-crossflow velocity ratios of r=3.27, 6.53 and 9.80), respectively. For this purpose, mean and ensemble-averaged velocity and vorticity distributions, turbulent statistics, and Reynolds shear stresses are obtained for various injection rates. Spectral analysis reveals the shedding frequencies of the wake vortices, and the pairing and breakup processes of the evolving large-scale coherent structures have been related to the measured wake Strouhal numbers. Our results indicate that due to the curvature of the target surface and the upwash of the jet impact, the size of coherent structures decreases with increase in the value of Rej. Proper orthogonal decomposition (POD) of the flow using the snapshot method is applied to extract the dominant features of the turbulent flow. It is observed that at the symmetry plane and for Rej=3000, 6000 and 9000, the energy collected by the first two dominant eddies contribute to 14.98%, 18.68%, and 17.89% of the turbulence kinetic energy, respectively. Our results show that the evolution of the time-resolved temporal coefficients of degenerate pairs of modes (1, 2) represent the flapping motion of the jet. Moreover, the amplitude of the oscillations of the flapping jet and the complexity of the flow structure increase for increasing values of Rej.

Experimental investigation on debris bed formation from metallic melt coolant interactions

Motivated by risk quantification of severe core meltdown accidents which may occur light water reactors, an extensive DEFOR (DEbris FORmation) test series with various molten oxidic materials was conducted previously at Royal Institute of Technology to investigate the characteristics of debris beds formed from oxidic melt-water interactions, which are important to the coolability of debris beds and thus the retention of core melt. Yet, little attention has been paid to metallic melt which exist in the core melt. The present study is intended to fill in the knowledge gap, i.e., to characterize metallic melt-water interactions when a melt jet falls into a deep water pool. Nine DEFOR-M tests are carried out to clarify the effects of melt jet diameter, free fall height and water pool depth on metallic debris formation characteristics. Molten tin of 20 kg is employed as the simulant of metallic melt. A melt sensor and a mass sensor are installed to detect the discharging period of coherent jet and the mass accumulation of debris bed, respectively. A high-speed camera is applied to record the process of jet breakup, debris fragmentation and solidification, and debris bed formation. The experimental results show that the water pool depth has a significant influence on steam explosion and debris bed formation characteristics. Moreover, the jet breakup length is sensitive to jet diameter and free fall height. Finally, the features of metallic debris beds are compared with those of oxidic ones in respects of debris bed's configuration and porosity, particles' morphology and size distribution.

Geochronology, geochemistry and Sr-Nd isotope compositions of the Niubiziliang mafic-ultramafic complex in the South Altyn orogen, NW China: Implications for Ni-Cu mineralization and tectonic setting

The Niubiziliang mafic-ultramafic complex located in the South Altyn orogen consists of lherzolite, plagioclase-bearing lherzolite, olivine websterite, and gabbro. The intrusion contains a newly discovered zone of magmatic Ni-Cu sulfide mineralization, which is categorized into three units (Nos. 1, 2, and 3) based on discernible morphological features, with drilling investigations revealing sulfide mineralization in complexes Nos. 2 and 3 in both mafic and ultramafic rocks. The rocks of the Nuibiziliang complex have olivines with Fo 76.9–82.4 and Ni contents between 79 and 1957 ppm. The clinopyroxenes have variable Al2O3 contents between 0.52 and 5.05 wt%, TiO2 contents between 0.02 and 1.30 wt%, and NaO contents from 0.08 to 1.27 wt%. The geochemical variations are consistent with the intrusion belonging to a subalkaline magma series and the major element variations are consistent with igneous differentiation from a single magma type. The rocks display enrichment in light rare-earth elements and large-ion lithophile elements (K, Ba, and Sr) and depletion in high-field-strength elements (Ti, Zr, Hf, Ta, and Nb) and heavy rare-earth elements, which are typical features of enriched mid-ocean ridge basalt (E-MORB). These rocks exhibit enriched Sr–Nd isotope compositions with low (87Sr/86Sr)i ratios and mostly low positive εNd(t) values, indicating that the Niubiziliang complex originated from the partial melting of the asthenospheric mantle with up to 10% contamination by continental crust. Fractional crystallization enriched sulfur in the magma during the initial stage of magmatic evolution, but crustal contamination was the main factor causing sulfide saturation in the magma. Laser ablation inductively coupled plasma-mass spectrometry U-Pb dating of baddeleyites in the ultramafic rocks of the Niubiziliang complex yielded an age of 452±12 Ma for the crystallization of the magma. This age is similar to the age of eclogites formed during exhumation for the South Altyn orogen and indicates that the mafic-ultramafic magmatism formed in a rift setting by a process of break-up of an oceanic crustal slab at depth in the mantle.

The nucleon-induced deuteron breakup process as a laboratory for chiral dynamics

The nucleon-induced deuteron breakup reaction is studied within the Faddeev approach at incoming nucleon laboratory energies of 135 and 200 MeV. The chiral semilocal momentum-space (SMS) potential developed up to N4LO+, supplemented by the N2LO three-nucleon interaction, is used. Our investigation is focused on the determination of theoretical uncertainties in a predicted cross section related to its dependence on the value of the cutoff parameter of the regulator. We also compare predictions based on the complete N2LO potential with those based on the two-nucleon force upgraded to the N4LO+ order and augmented with the N2LO three-nucleon force. In addition, we study the three-nucleon force effects predicted by this model of interaction. Our systematic study covers the entire kinematically allowed phase space; however, our main results are obtained when additional restrictions on energies and cross section values are imposed. In such a case, we observe that the dependence of the differential cross sections on the regulator cutoff is moderate at 135 MeV and much stronger at 200 MeV. For the latter energy, it can amount to up to 45% in specific kinematic configurations. Taking into account terms beyond, N2LO in a two-body interaction changes the cross section up to 20% (27%) at E = 135(200) MeV. The inclusion of the three-nucleon force leads to effects of approximately 27% at both energies. We illustrate these dependencies with a few examples of the exclusive cross section as a function of the arc length of the S-curve.

Evaluating the Variability of Simulated Raindrop Size Distributions in the “21·7” Henan Extremely Heavy Rainfall Event

AbstractSignificant variability of raindrop size distributions (DSDs) has been observed in the “21·7” Henan extremely heavy rainfall event (the “21·7” Henan EHR event), while the capability of model to reproduce such complicated heavy rainfall DSDs is yet unclear. This study primarily evaluates the simulated DSDs of multiple microphysics schemes by comparing with the observations from a network of 50 disdrometers. Constrained DSD variability is identified in most schemes that the simulated raindrop mean sizes are gradually restricted around specific values as the growth of heavy rainfall intensity. The schemes are also incapable of reproducing the different raindrop mean sizes from deep convection and shallow convection. Moreover, simulations show unrealistic evolutions of raindrop mean size standard deviations as height declines. By investigating the empirical formula and performing sensitivity experiment, the constrained DSD variability in heavy rainfall is largely blamed on the insufficient parameterizations of the self‐collection (breakup) processes.

A study of rain drop size distributions and associated rain microphysical processes over a subtropical station in the Northeast India

A study of rain Drop Size Distributions (DSDs) and associated microphysical processes is carried out during the premonsoon and monsoon seasons at Kohima (25.67° N, 94.08° E) in the Patkai hill range of the Northeast India. The study is carried out with the help of Micro Rain Radar (24.1 GHz). The rainfall is classified in three categories namely, Bright Band (BB), No Bright Band Low rain rate (R) i.e. 0.10 mm h−1< R ≤ 10 mm h−1 (NBBL) and No Bright Band High rain rate i.e. 10 mm h−1 <R ≤ 20 mm h−1 (NBBH). During the premonsoon and monsoon, for R ≤ 20 mm h−1, rainfall occurrence time constitute around 96% and 98% respectively, whereas rainfall accumulation constitute around 51%. and 72% respectively. The BB height is found to be lower during the premonsoon (∼2.2 km from surface level) compared to monsoon (∼3.6 km from surface level) season. The observational results suggest that, during the premonsoon as well monsoon seasons, BB rain is predominantly associated with collision–coalescence–breakup process with varying proportion, whereas NBBL and NBBH rain are predominantly associated with collision–coalescence process with varying proportion. In each season, collision-coalescence process is most dominant for NBBH type of rain. Seasonally, collision-coalescence process is found to be stronger during the premonsoon season. For the falling rain drops, there is a transition in the microphysical process from number controlled (collision-coalescence-breakup) to size-controlled (collision-coalescence) process with varying proportion. For each season, for R ≤ 10 mm h−1, larger rain drops are found for BB type of rain compared to NBBL rain. Overall, relatively larger raindrops are found to be associated with NBBH rain. Seasonally, larger drops are found during the premonsoon compared to the monsoon season. The rain DSDs and associated microphysical processes during the premonsoon are found to be associated with stronger convection compared to the monsoon season.

Deciphering the Africa-Arabia breakup: Insights from U-Pb dating along the Carmel-Gilboa fault system and its triple junction with the Dead Sea transform

The Carmel–Gilboa fault system (CGFS) runs sub-parallel to the Azraq–Sirhan Garben (ASG) and the Red Sea Rift. Although the system currently forms a triple junction with the Dead Sea transform (DST), its initiation is considered to be associated with NE–SW extensional regime during the Africa-Arabia breakup in the late Oligocene to early Miocene. The role of the CGFS in the breakup process is not fully understood. In addition, the exact timing of initiation and potential reactivation during the onset of the DST plate boundary is not well constrained. This work sheds light on these events by establishing a long-term record of deformation along the CGFS and its intersection with the DST. This study presents 17 U-Pb ages of syn-tectonic calcite (n=14, ∼33.2 to 2.3 Ma) collected along the CGFS. These ages suggest that the earliest faulting phase along the CGFS took place between ∼25 to ∼21 Ma - coinciding with the initiation of the Red Sea Rift. The second phase of activity along the CGFS commenced at ∼16 Ma. This phase supports northward propagation of the DST from the Gulf of Elat to the southern tip of the Lebanese restraining bend from ∼18 to ∼14 Ma. The new U-Pb ages along the CGFS together with ages from the DST constrain the propagation rate of the DST to ∼105 mm/year, roughly 20 times faster than the current left-lateral offset along this active plate boundary (∼5 mm/year). The trigger for two simultaneous rifts, located 500 km apart and the distributed extension along the northern Red Sea is most probably related to the relative mechanical strength of oceanic vs. continental lithosphere, which also controls the eventual establishment of the DST and the failure of the rifting process along the CGFS-Azraq-Sirhan rift system.

Evaluation of jet breakup length with a CFD code under steam generation condition in a pre-flooded cavity

When the reactor vessel is penetrated in a severe accident of light water reactor, the molten fuel-coolant interaction including the jet breakup occurs and the jet breakup length becomes one of the important parameters. Most numerical studies on jet breakup process have been carried out using dedicated computer codes. Some researchers are trying to apply commercial CFD codes to their investigations on comprehensive jet breakup process. However, the complexity of the phenomena limits the CFD application only to hydrodynamic aspects. In the present study, numerical analysis of jet breakup under vapor generation is pursued using the STAR-CCM + code. The obtained CFD prediction of the MATE09 experiment shows jet breakup progression patterns consistent to the images taken in the experiment. Further, the predicted positions of leading head, which determine the jet breakup length, are in good agreement with the MATE 09 data. The investigation of hydrodynamic effects on the jet breakup with higher jet velocity results in a stronger shear force and earlier jet breakup process even though there exists the vapor pocket around the corium jet. In future studies, the effect of vapor intensity on the jet breakup length would be investigated further by changing other parameters.

Understanding the low-energy incomplete fusion reactions

With a motivation to find out the systematics for the low-energy ($\ensuremath{\approx}4$--7 MeV/nucleon) incomplete fusion reactions, the experimentally measured excitation functions for evaporation residues, which were populated during the interactions of $^{18}\mathrm{O}$ with $^{159}\mathrm{Tb}$ target nuclei, have been studied. The analysis clearly exhibits that the $xn/pxn$ channels are populated to a large extent through the complete fusion processes. Although, the production cross-section of the $\ensuremath{\alpha}$-emitting channels, despite of deducting the precursor decay contribution, found to be significantly under-estimated by the statistical model predictions. The observed enhancement, which may be attributed due to the involvement of break-up fusion processes, is found to be get larger with the incident energy. In addition, the present work in light of the literature data imparts the reliance of incomplete fusion processes on various entrance channel parameters, such as the mass-asymmetry of the interacting partners, fissility parameter and also on the ${Z}_{P}{Z}_{T}$ (Coulomb factor). These systematics inarguably indicates the projectile type dependency of the incomplete fusion reactions, and the results may be explained on the basis of the $\ensuremath{\alpha}\text{\ensuremath{-}}Q$ value of the projectile. Furthermore, an attempt has been made to explain the trends of incomplete fusion fractions through the total asymmetry parameter and the system parameter, where system parameter seems to explain the data more satisfactorily, as it incorporates the Coulomb factor as well as the masses of the interacting partners.

Bulk Microphysical Characteristics of a Heavy-Rain Complex Thunderstorm System in the Taipei Basin

Abstract Severe rainfall has become increasingly frequent and intense in the Taipei metropolitan area. A complex thunderstorm in the Taipei Basin on 14 June 2015 produced an extreme rain rate (&gt;130 mm h−1), leading to an urban flash flood. This paper presents storms’ microphysical and dynamic features during the organizing and heavy rain stages, mainly based on observed polarimetric variables in a Doppler radar network and ground-based raindrop size distribution. Shallower isolated cells in the early afternoon characterized by big raindrops produced a rain rate &gt; 10 mm h−1, but the rain showers persisted for a short time. The storm’s evolution highlighted the behavior of merged convective cells before the heaviest rainfall (exceeding 60 mm within 20 min). The columnar features of differential reflectivity (ZDR) and specific differential phase (KDP) became more evident in merged cells, which correlated with the broad distribution of upward motion and mixed-phase hydrometeors. The KDP below the environmental 0°C level increased toward the ground associated with the melted graupel and resulted in subsequent intense rain rates, showing the contribution of the ice-phase process. Due to the collision–breakup process, the highest concentrations of almost all drop sizes and smaller mass-weighted mean diameter occurred during the maximum rainfall stage.

Investigation on High-Viscosity Chemical Waste Liquid Atomizer Based on VOF-DPM

The viscosity of adiponitrile waste liquid is as high as 1000 cp. It is challenging to spray and atomize the waste liquid normally. Based on the coaxial three-channel pneumatic atomizer, a two-stage supersonic steam atomizer is proposed in this paper, and the atomization process is simulated by Fluent software. Compared with the traditional atomization simulation method, the Volume-of-Fluid to Discrete-Phase-Model (VOF-DPM) bi-directional coupling model and Adaptive Mesh Refinement (AMR) technology can save mesh and improve the computational efficiency. The atomization processes of primary breakup and secondary breakup are entirely captured and analyzed. The results show that the Sauter Mean Diameter (SMD) is about 116–180 μm, the SMD decreases with the increase of steam inlet absolute pressure, and the atomization quality can meet the combustion requirements. This study can be used for the performance optimization of the high-viscosity liquid atomizers in the chemical and aerospace industry and shorten the time engineers spend in the simulation calculation to verify the rationality of the structure.

Time-varying evolutionary mechanism analysis of the multiphase flow during high-velocity oxygen-fuel (HVOF) thermal spraying WC-12Co particle

HVOF thermal spraying with the fuel of aviation kerosene has unique advantages for spraying WC-12Co ceramic particles. The time-varying evolution mechanism of the multiphase flow formed by the particles wrapping with the combustion flame flow is quantitatively revealed, which is essential for preparing of high-quality coatings. In this study, the breakup and gasification process of kerosene droplet was considered. The fuel droplet, flame flow and spraying particles were directly coupled. Based on the computational fluid dynamics (CFD) method, a transient evolution model of HVOF thermal spraying multiphase flow with JP5000 spray gun was established. The Euler-Lagrange method of bidirectional coupling was used to track the continuous and discrete phases. The spraying combustion flame characteristics were expressed by the realizable k-ε turbulence model and eddy dissipation model (EDM). The results show that the multiphase coupling transient evolution model quantitatively captures the nonlinear changes of the breaking and gasification for the kerosene droplet, combustion reaction, particle flight behavior and others during spraying. The kerosene droplets in the combustion chamber aggregate with each other to form large droplets, which are rapidly broken and gasified in the peripheral areas. Due to the violent combustion, a gas-phase circulation was formed by the heat and cold air. As the combustion progresses, the flame flow becomes stable and orderly. When particles with a size of 20 to 30 μm impact the substrate, the particle temperature is close to the solid phase temperature, and the velocity is fast. The particle temperature and velocity decrease with the increase of the particle size.

The evolution of Kerguelen mantle plume and breakup of eastern Gondwana: New insights from multistage Cretaceous magmatism in the Tethyan Himalaya

The relationship between the breakup of eastern Gondwana and Kerguelen mantle plume remains extremely controversial. The crucial conundrum is that when and where the Kerguelen mantle plume initially formed and its evolutionary history are unclear. In this paper, we report the oldest Cretaceous bimodal magmatism (144–140 Ma) associated with the Kerguelen mantle plume from the Comei large igneous province in the Tethyan Himalaya. The mafic rocks are dominated by oceanic island basalt (OIB)-like dykes with occasional normal mid-ocean ridge basalt (N-MORB)-like intrusions, while the felsic rocks show A-type granites affinities. Our results suggest that the > 140 Ma bimodal magmatism was clearly a response to early Kerguelen plume activity, and the Kerguelen plume initially formed underneath the Tethyan Himalaya but not the triple junction between Australia, Antarctica, and Greater India. We argue that the Cretaceous magmatism associated with the Kerguelen plume in the Tethyan Himalaya can be divided into three pulses of ca.141 Ma, ca.132 Ma, and ca.117 Ma, which correspond to vertical underplating, continuous ascent, and a southward migration process, respectively. Moreover, we propose that the multistage OIB-like magmas in the Tethyan Himalaya are mainly the products of interactions between the lower crust and mantle plume, while the contribution of the lithospheric mantle is negligible. This proposal implies that the lithosphere was significantly thinned before ca.141 Ma, and the Kerguelen plume had been incubating underneath the Tethyan Himalaya prior to this. Our findings suggest that the Kerguelen plume may not have been the trigger for the initial breakup of eastern Gondwana, but was complementary to the later complete breakup process. We also innovatively consider that the northward dragging and slab-pull forces caused by the Cretaceous intra-oceanic subduction of the Neo-Tethys Ocean may have played an active role in the evolution of the Kerguelen plume and the breakup of eastern Gondwana.

Experimental Study on Breakup Characteristics of Hollow Cone Spray in Gas Crossflow

Hollow cone spray with a medium spray half-cone angle (in the range of 36°–45°) exposed to a gaseous crossflow is a situation that has been extensively investigated experimentally. In this experiment, flow visualization techniques are employed to examine the initial liquid sheet thickness at the nozzle orifice exit and the sheet breakup process. The dynamics of the primary breakup of the sheet is analyzed based on the observations of the sheet breakup in the near-nozzle region. The experimental results show that the breakup mechanism of the liquid sheet varies greatly depending on liquid centrifugal momentum and aerodynamic force. Four distinct breakup modes are observed, and the breakup regimes are mapped in the parametric space based on the liquid Weber number (84–2175) and the liquid-to-air momentum ratio (22–8455). It is observed that the leeward side of the sheet is dominated by shear oscillation breakup within the range of the liquid-to-air momentum ratio less than 600. The influences of the aerodynamic Weber number on breakup frequency and the number of surface waves observed on the leeward side sheet are discussed by analyzing the spray images. The breakup-regime transition criteria for hollow cone spray in crossflow and the trajectory of spray in crossflow are proposed by employing a multivariable regression method.

Leakage Threshold of a Saddle Point

The threshold condition for leakage inception is of great interest to many engineering applications, and it is essential for seal design. In the current study, the leakage threshold is studied by means of a numerical method for a mechanical contact problem between an elastic bi-sinusoidal surface and a rigid flat surface. The coalesce process of the contact patches is first investigated, and a generalized form of solution for the relation between the contact area ratio and the average applied pressure is acquired. The current study shows that the critical value of the average applied pressure and the corresponding contact area required to close the percolation path can be represented as a power law of a shape parameter, if the effect of the hydrostatic load from the pressurized fluid is ignored. With contact patches merged under a constant applied load, the contact breakup process is investigated with elevated sealed fluid pressure condition, and it is shown that the leakage threshold is a function of the excess pressure, which is defined as a ratio between the average applied pressure and the critical pressure under dry contact conditions.Graphical abstract

Mechanism of rapidly solidified satellites formation in gas atomized powders: Simulation and characterization

It has been generally recognized that satellites deteriorate significantly the uniformity and stability of powder spreading in additive manufacturing (AM). Therefore, it is crucial to investigate the mechanism of satellites formation and the microstructure of collision region. In this study, the turbulent flow of gas was numerically simulated in an atomizing chamber using the shear stress transport k-ω (SST k-ω) model. Then, the Taylor analogy breakup (TAB) model and the discrete phase model (DPM) were used to analyze the breakup process of the secondary atomization of superalloy droplets which formed during the primary atomization. Meanwhile, the impact mechanism of the recirculation zone on the satellites was investigated in the atomization chamber. Scanning electron microscopy (SEM) was used to characterize the morphology and cross-sectional microstructure in the collision region of the satellites. Three collision types of satellites were identified. The findings of this study enhance the understanding of the mechanism of satellites formation and provide technical insight into the control and elimination of satellites in argon atomization (AA).

Geological Significance of Neoproterozoic Intrusive Rocks in the South Section of the Ailaoshan Orogenic Belt, SW China: Insights from Petrology, Geochemistry, and Geochronology

The Ailaoshan orogenic belt is one of the most significant orogenic belts in the southeastern margin of the Qinghai–Tibet Plateau. The widely developed magmatic rocks in this belt preserve the multi-stage tectonic evolution records of the South China Plate. As an important response to the Rodinia breakup tectonic event, the study of Neoproterozoic magmatic rocks in the area is of great significance for reconstructing the Neoproterozoic tectonic process of the Ailaoshan orogenic belt and the tectonic evolution of the South China Plate. Petrology, geochemistry, zircon U-Pb, and Lu-Hf isotopes of the Daping pluton in the Ailaoshan orogenic belt are studied in this paper. The Daping pluton is mainly divided into gabbros and granites. Gabbros and granites belong to the sub-alkaline series, which are relatively enriched in large ion lithophilic elements and depleted in high-field strength elements. The ΣREE contents of the gabbro are low with enrichment in LREEs and depletion in HREEs, and the degree of differentiation of light and heavy rare earth is low, with positive δEu and weak negative δCe anomalies. The ΣREE contents of the granite are low with enrichment in LREEs and depletion in HREEs, and the degree of light and heavy rare earth differentiation is high, with medium–weak negative δEu and weak positive δCe anomalies, suggesting an A2-type granite with A1-A2 transition characteristics. The weighted average age of the gabbro is 816.1 ± 4.1 Ma (MSWD = 0.11), with zircon εHf(t) values of −7.5–5.5. The magma source is a mixture of an ancient crust source and a new mantle source; the weighted average age of the syenogranite is 783.7 ± 8.1 Ma (MSWD = 1.4), with zircon εHf(t) values of −4.3–0.4. The magma source is mainly ancient crustal material (Ailaoshan Group), mixed with a small amount of mantle-derived material; the weighted average age of the monzogranite is 754.8 ± 6.1 Ma (MSWD = 3.0), with positive zircon εHf(t) values of 1.65–10.36. The magma source is a mixture of a large number of mantle-derived materials and a small number of crust-derived materials (Ailaoshan Group). The Daping pluton was formed in the transitional tectonic environment from post-collision to intraplate continental margin rift, corresponding to the Rodinia breakup process in the western margin of the South China Plate.