Jet Core Research Articles

Influence of uneven blade tip clearances on aeroacoustic characteristics of centrifugal compressors

The blade tip clearance is a crucial factor in the compressor performance and the aeroacoustics. There are usually main blades and splitter blades, two different types of blades in centrifugal compressors. Keeping almost the same work input, three different tip clearance configurations were designed in which the tip clearance gaps of main blades and splitter blades were uneven. Then experimental investigations were carried out to study the influence of uneven tip clearances on the aeroacoustic characteristics of centrifugal compressors. The results showed that larger main blade tip clearances or larger splitter blade tip clearances would induce rotating instabilities (RI) near flow instability boundary at low rotating speeds. However, the broadband noises below the blade passing frequency (BPF) in the case with uneven blade tip clearances were suppressed significantly which might be due to the incongruous interaction between the tip clearance leakage flows of main blades and splitter blades. In addition, the blade nonsynchronous vibrations (NSV) were observed in the analysis of the frequency spectrum of far-field noise in the case which had smaller main blade tip clearances and larger splitter blade tip clearances. Based on the jet core feedback theory, a physical explanation was given for NSV occurred in this case.

Radio Jet Proper-motion Analysis of Nine Distant Quasars above Redshift 3.5

Up to now, jet kinematic studies of radio quasars have barely reached beyond the redshift range z > 3.5. This significantly limits our knowledge of high-redshift jets, which can provide key information for understanding the jet nature and the growth of black holes in the early universe. In this paper, we selected nine radio-loud quasars at z > 3.5 which display milliarcsecond-scale jet morphology. We provided evidence of the source nature by presenting high-resolution very long baseline interferometry (VLBI) images of the sample at 8.4 GHz frequency and making spectral index maps. We also consider Gaia optical positions that are available for seven out of the nine quasars for better identification of the jet components within the radio structures. We find that six sources can be classified as core–jet blazars. The remaining three objects are more likely young jetted radio sources, compact symmetric objects. By including multiepoch archival VLBI data, we also obtained jet component proper motions of the sample and estimated the jet kinematic and geometric parameters (Doppler factor, Lorentz factor, and viewing angle). Our results show that at z > 3.5, the jet’s apparent transverse speeds do not exceed 20 times the speed of light (c). This is consistent with earlier high-redshift quasar measurements in the literature and the tendency derived from low-redshift blazars that fast jet speeds (>40c) only occur at low redshifts. The results from this paper contribute to the understanding of the cosmological evolution of radio active galactic nuclei.

Jet kinematics in the transversely stratified jet of 3C 84

3C 84 (NGC 1275) is one of the brightest radio sources in the millimetre radio bands, which led to a plethora of very-long-baseline interferometry (VLBI) observations at numerous frequencies over the years. They reveal a two-sided jet structure, with an expanding but not well-collimated parsec-scale jet, pointing southward. High-resolution millimetre-VLBI observations allow the study and imaging of the jet base on a sub-parsec scale. This could facilitate the investigation of the nature of the jet origin, also in view of the previously detected two-railed jet structure and east-west oriented core region seen withRadioAstronat 22 GHz. We produced VLBI images of this core and inner jet region, observed over the past twenty years at 15, 43, and 86 GHz. We determined the kinematics of the inner jet and ejected features at 43 and 86 GHz and compared their ejection times with radio andγ-ray variability. For the moving jet features, we find an average velocity ofβappavg = 0.055−0.22c (μavg = 0.04 − 0.18 mas yr−1). From the time-averaged VLBI images at the three frequencies, we measured the transverse jet width along the bulk flow. On the ≤1.5 parsec scale, we find a clear trend of the jet width being frequency dependent, with the jet being narrower at higher frequencies. This stratification is discussed in the context of a spine-sheath scenario, and we compare it to other possible interpretations. From quasi-simultaneous observations at 43 and 86 GHz, we obtain spectral index maps, revealing a time-variable orientation of the spectral index gradient due to structural variability of the inner jet.

Near Field Decay of Mach 2 Elliptical Jet in the Presence of Tangentially Injected Secondary Swirling Flow

This investigation explores the mixing promoting capability of tangentially injected secondary swirling flow on a Mach 2 elliptical jet issuing from an elliptical nozzle of aspect ratio 2. A detailed three-dimensional numerical analysis was carried out for the combination of different levels of pressure gradient at the nozzle exit and five swirl numbers. Reynolds-Averaged Navier-Stokes equation along with Shear Stress Transport model was solved to predict the flow filed. The presence of secondary swirling flow created large pressure gradient in the direction perpendicular to jet axis, resulting in enhanced mass entrainment leading to high spread of the controlled jet compared to the uncontrolled jet. Also, the secondary jet increased the turbulence level in the flow field for all the cases studied compared to that of free jet case, leading to a reduction in jet core length. The swirl number and the pressure gradient at the nozzle exit is found to have a strong effect on the core length reduction. A maximum of about 70% reduction in core length was achieved for nozzle pressure ratio 4 with secondary flow of swirl number 5.

Three-dimensional density field of a screeching under-expanded jet in helical mode using multi-view digital holographic interferometry

A synchronised multi-axis digital holographic interferometry set-up is presented for the study of 3-D flow fields with large density gradients. This optical configuration provides instantaneous interferograms with fine spatial resolution in six directions of projection. A regularised tomographic approach taking into account the presence of possible shock waves is furthermore considered to reconstruct 3-D density fields. Applied to a screeching under-expanded supersonic jet with helical dynamics, this set-up is used to provide dense optical phase measurements in the initial region of the jet. The jet mean density field is shown to be satisfactorily estimated with sharply resolved density gradients. In addition, an approach based on azimuthal Fourier transform and snapshot proper orthogonal decomposition (POD) applied to the instantaneous flow observations is proposed to study the main coherent dynamics of the jet. Relying on a cluster analysis of the azimuthal POD mode coefficients, a reduced dynamical model in the POD mode phase space is used as an approximation of the two observed limit cycles. A clear 3-D representation of the density field of a helical instability associated with screech mode C is then evidenced, with two equally probable directions of rotation. Switching between the two directions is reported, highlighting intermittency in the feedback loop. This helical structure is particularly seen to extend to the jet core, driving its internal dynamics and inducing out-of-phase density fluctuations between the outer and inner shear layers. These out-of-phase motions are related to the non-uniform radial distribution of fluctuation phase associated with the outer-layer Kelvin–Helmholtz instability wave.

Different response of North Pacific storm tracks in the upper and lower troposphere to jet strength

The midwinter suppression of North Pacific storm tracks (NPSTs) reflects that the linear relationship between the NPST and baroclinicity breaks in winter. Based on the reanalysis data during the cold seasons of 1979–2019 and a tracking algorithm, this study analyzes the eddy growth process and shows that an enhanced upper-tropospheric jet favors the generation of upper-level eddies on the northeast side of the Pacific jet, but increasingly suppresses the generation of those in the Northwest Pacific. The upper-level eddies generated upstream of the jet core are unable to grow sufficiently throughout the whole cold season, and only those generated downstream of the jet core can grow normally and constitute the main body of the upper-level NPST. By contrast, the main lower-level eddy genesis area and growth area coincide with the baroclinic zone, with the genesis number and local growth rate increasing with the baroclinicity.摘要北太平洋风暴轴的深冬抑制表明风暴轴强度与斜压性之间的线性关系在冬季破裂. 本研究基于1979–2019年冷季的再分析数据和拉格朗日跟踪算法, 对比分析了高低层扰动的具体生长过程. 结果表明太平洋急流的增强有利于高层扰动在急流核东北侧产生, 但却抑制其在西北太平洋的生成. 在急流核上游产生的高层扰动在整个冷季都无法充分发展, 只有在急流核下游产生的高层扰动才能正常生长且它们是构成高层太平洋风暴轴的主体. 相比之下, 低层扰动的生成区和生长区都与斜压区重合, 并且它们的生成数量和局部增长率随着斜压性的增强而增强.

Experimental investigation of internal and external flow fields of jetting nozzles with different structures

Jetting has been widely used in the petroleum fields, the nozzle has been investigated for a long time and the structure has been optimized for different applications as the key part of jetting. However, most of these researches are focused on the outer flow with simulations, the real flow characteristics are not been revealed clearly. A visual experimental platform was built with Particle Image Velocimetry (PIV) and a high-pressure pump. 40 nozzles of different profiles were machined and measured. The internal and outer flow fields were captured by PIV under low velocity, and the pressure drop and flow displacement were measured under high-pressure conditions in this paper. The jetting performance such as discharge coefficient, flow core length, jet angle, and velocity distributions were analyzed. The internal flow characteristics including the flow field near the nozzle wall were captured by PIV. The converging angle and the throat section length play an important role in the jetting performance and are suggested to be set to 15° and 3 times the nozzle diameter when designed. The throat length has little effect on the flow field of the streamlined nozzle compared to the cone-straight nozzle, especially the concave curve nozzle. The vortex generated at the corner and the entrance of the throat section can indicate the boundary layer separation and transition, which agrees with our previous simulation work. All work will provide theoretical support for the design of the nozzle on-site application.

Research on flow field characteristics of nozzle plume for a solid rocket motor

In order to explore the flow field characteristics of nozzle plume for a small solid rocket motor (SRM), the two-dimensional axisymmetric N-S governing equations with component transports and chemical reaction terms are established. Then, the finite volume method of AUSM (Advection Upstream Splitting Method) spatial discretization scheme is applied for numerical discretization, and its solution is solved by time iteration to make the plume flow field steady. This technique is applied to research the flow field characteristics and characteristic parameter distributions of nozzle plume under different inflow conditions. The results are shown that: when considering the reburning reactions of nozzle plume, the temperature of the gas jet core area is much higher than the flow field temperature that the reburning phenomenon is not considered. In addition, the reburning phenomenon mainly occurs in the air-gas mixing and gas development areas, but in the initial core area of gas jet, this phenomenon is not obvious. What’s more, with the increase of altitude, the influence area of the gas jet gradually becomes larger. However, as the incoming flow Mach number increases, the intensity of the change of gas temperature along the nozzle axis weakens, and also the number of wave nodes and the influence region of gas jet gradually decrease.

Vortex breakdown in swirling Burke–Schumann flames

Unsteady axisymmetric numerical simulations are used to determine the transition to bubble and conical vortex breakdown in low-Mach-number laminar swirling Burke–Schumann flames, for which an ambient-temperature fuel jet in solid-body rotation emerges into quiescent air. A critical value of the swirl number S for the onset of the bubble (SB*) and the cone (SC*) is determined as the jet fuel-feed mass fraction YF,j is varied for fixed Re=800, assuming typical conditions for methane combustion with air. During the first transition from pre-breakdown to the bubble, the jet core is relatively unaffected by the flame in the surrounding shear layer, and SB*=1.36 is constant for all values of dilution. This transition to the jet-like bubble breakdown flame is found to be in agreement with theoretical predictions based on the criterion of failure of the slender quasi-cylindrical approximation. Variation in the critical swirl number SC*, characterizing the second transition from the bubble to the cone, is relatively small (1.80≤SC*≤1.83) in the range 0.1≤YF,j≤1, but the resulting flow and flame shape for conical breakdown is found to depend critically on YF,j. For realistic values of dilution (YF,j≥0.2), the bubble transitions to a steady compact cone at SC* with a flame sheet that passes around the recirculation region, maintaining a jet-like flame. In the extreme dilution case (YF,j=0.1), the reaction sheet occurs closer to the fuel jet axis, increasing the radial velocities through thermal expansion and accelerating the transition to the cone (lower SC*). The reduced viscosity associated with the lower adiabatic flame temperature leads to an enlarged unsteady conical breakdown with the flame sheet stabilized near the inlet.

Diffusion tensor imaging of anisotropic inhomogeneous turbulent flow.

Inhomogeneous anisotropic turbulent flow is difficult to measure, and yet it commonly occurs in nature and in many engineering applications. This work aims to introduce a technique based on magnetic resonance imaging which can spatially map the degree of turbulence as well as the degree of anisotropy. Our interpretation relies on the eddy diffusion model of turbulence, and combines this with the technique of diffusion tensor imaging. The result is an eddy diffusion tensor, which is represented by a symmetric three-by-three matrix. This tensor contains a wealth of information about the magnitude and directions of the turbulent fluctuations; however, the correlation time must be considered before interpreting this information. In the constricted pipe flow used in this study, the turbulence is greatest in magnitude in the space surrounding the core of the turbulent jet, and the turbulence is highly anisotropic.

Bottom and side-wall aeration performance of an offset aerator in a flood discharge chute

Building a chute aerator is an efficient way of protecting the chute bottom from cavitation damage in large flood-discharging hydraulic structures, but it sometimes fails to provide sufficient protection to the side-walls. In this study, basic air–water flow properties were investigated for discharge flows over an offset chute aerator model, with particular focus on the near-bottom and near-wall regions, for a range of discharge velocities over the offset brink (3.58 m/s < V < 8.02 m/s), Froude numbers (4.8 < Fr < 12.0) and Reynolds numbers (8.0 × 104 < Re < 9.2 × 105). The results indicated little transverse variations in air–water flow properties except near the jet impact perimeter. The bottom air concentration and bubble frequency decreased at different rates downstream of the impact point; the influence of Reynolds number on the bubble size and density should not be ignored. The shape of the clear-water core between the upper and lower aeration layers was identified with the aid of high-speed imaging and air concentration calibration against the wall. A formula to predict narrowing of the jet core until its end position was developed.

Regional Responses of the Northern Hemisphere Subtropical Jet Stream to Reduced Arctic Sea Ice Extent

The effect of Arctic sea ice loss on the boreal winter regional trends of wind speed and latitudinal position of the Northern Hemisphere subtropical jet stream (STJ) in 1980–2012 is investigated. Two sets of global simulations with reduced Arctic sea ice extent are analyzed: simulations that, south of 70 N, use a climatological annual cycle of the sea surface temperature (SST) and a second set that uses full SST variability. Results with the climatological SST have a significant but weak response of the STJ wind speed and latitudinal position to the warmer Arctic: the wind speed generally decreases and the jet core is displaced equatorward. However, in the realistic SST simulations, the effect of Arctic warming is only slightly evident in a small equatorward shift of the jet over the Atlantic basin. Over the Pacific basin the STJ is mostly driven by tropical and mid-latitude SST variability, with little influence from the Arctic region. A weakening and poleward shift of the STJ that is observed in the realistic SST simulations over the Pacific basin is attributed to negative SST trends in the tropical Pacific and the consequent weakening of the mid-latitude meridional gradient of geopotential height in the upper troposphere.

Role of Asian Westerly Jet Core's Zonal Migration in Holocene East Asian Summer Monsoon Precipitation

AbstractPaleoclimatic records reveal spatially asynchronous changes of East Asian summer monsoon (EASM) precipitation during the Holocene, but the underlying mechanisms are not fully understood. This study explores the role of the zonal shift of the Asian westerly jet (AWJ) core on the spatial‐temporal variability of EASM precipitation based on Holocene climate simulations using the KCM and CESM forced by orbital variations. We analyzed the composite differences of summer precipitation and associated atmospheric circulations between the early (middle) and middle (late) Holocene. Simulations suggest a dipole pattern of summer precipitation with increasing (decreasing) precipitation in central (southern) China from the early to late Holocene, which was shaped by the eastward shift of the AWJ core. The eastward shift of the AWJ core and the accompanied eastward movement of the upper‐level convergence over the AWJ's right exit region weakened the low‐level downward motions over central China. Meanwhile, the low‐level upward motions over southern China were weakened by the concurrent eastward (westward) migration of the South Asian High (western Pacific subtropical High) during the Holocene. Consequently, summer precipitation increased (decreased) in central (southern) China from the early to late Holocene. The eastward shift of the AWJ core was primarily driven by amplified meridional insolation gradient at middle latitudes via strengthening upper‐level westerly intensity during the Holocene. In addition, land cover difference between East Asia and central Asia caused a greater enhancement of westerlies intensity in East Asia, further modulating the eastward movement of the AWJ core during the Holocene.

Experimental analysis and simulation of a centrifugal jet fan for impulse ventilation systems

Centrifugal jet fans are usually used to stir evenly, remove local airflow blind spots, and improve air quality. They are widely used in HAVC systems of garage buildings recently. However, there are few in-depth studies on its modeling methods, and even the experimental verification of the most basic centrifugal jet fan simulation model has not been fully demonstrated. This paper combines experimental verification with numerical simulation to investigate the appropriate modeling method and jet characteristics of centrifugal jet fans for impulse ventilation systems. Experimental data showed that the air volume of each nozzle of the centrifugal jet fan was different, and that even outlet velocity of a single nozzle was not uniform. Velocity decreased slightly in the jet core area and then decreased gradually until it approached the ambient velocity, while the amount of air entrained by the jet was approximately linear with respect to the jet range. In addition, the design key points and methods of impulse ventilation systems was summarized. CFD was used to simulate the flow field of centrifugal jet fans. Two modeling strategies, involving accurate boundary conditions based on experimental data, and simplified velocity boundary conditions, were used, and displayed differing characteristics. When designers focus on the coverage range of jet fans and the velocity distribution at the far-field, or the operation performance of jet fans in HAVC systems, the simplified velocity boundary conditions can be used. When the aim is to study and optimize nozzle, an accurate model and boundary conditions should be utilized.

Classification and properties of non-idealized coastal wind profiles – an observational study

Abstract. Non-idealized wind profiles frequently occur over the Baltic Sea and are important to take into consideration for offshore wind power, as they affect not only the power production but also the loads on the structure and the behavior of the wake behind the turbine. In this observational study, we classified non-idealized profiles as the following wind profiles having negative shear in at least one part of the lidar wind profile between 28 and 300 m: low-level jets (with a local wind maximum in the profile), profiles with a local minimum and negative profiles. Using observations spanning over 3 years, we show that these non-idealized profiles are common over the Baltic Sea in late spring and summer, with a peak of 40 % relative occurrence in May. Negative profiles (in the 28–300 m layer) mostly occurred during unstable conditions, in contrast to low-level jets that primarily occurred in stable stratification. There were indications that the strong shear zone of low-level jets could cause a relative suppression of the variance for large turbulent eddies compared to the peak of the velocity spectra, in the layer below the jet core. Swell conditions were found to be favorable for the occurrence of negative profiles and profiles with a local minimum, as the waves fed energy into the surface layer, resulting in an increase in the wind speed from below.

Mixing and Evolution of Laterally Injected Liquid Fuel in Mach 2 Air Channel with Cavity

ABSTRACT The present study deals with the flow structure and mixing characteristics of liquid fuel injected laterally into a supersonic crossflow. The geometry, with a cavity downstream of the injector, mimics a supersonic combustor with a cavity flame holder. A variety of injection schemes and cavity configurations were investigated by means of high-speed schlieren photography. A reflected shock tunnel was employed to generate a Mach 2 air flow and to simulate the high-temperature environment in the combustor. JP-4 liquid fuel was injected at different jet-to-crossflow momentum flux ratios upstream of and from the front wall of the cavity. Results showed that in direct injection into the cavity adjusting the injection angle has significant effect on the local fuel-air ratio. Upstream injection far from the leading edge of the cavity yielded more effective fuel mixing and shorter dissipation length (Ld) than closer injection, due to the development of a vortex on the lee side of the jet core. These results suggest that a combination of upstream injection far from the leading edge of the cavity and inclined direct injection into the cavity may be beneficial for effective mixing in a supersonic combustor cavity flame holder.

Kinetic Simulations of Instabilities and Particle Acceleration in Cylindrical Magnetized Relativistic Jets

Relativistic magnetized jets, such as those from AGN, GRBs, and XRBs, are susceptible to current- and pressure-driven MHD instabilities that can lead to particle acceleration and nonthermal radiation. Here, we investigate the development of these instabilities through 3D kinetic simulations of cylindrically symmetric equilibria involving toroidal magnetic fields with electron–positron pair plasma. Generalizing recent treatments by Alves et al. and Davelaar et al., we consider a range of initial structures in which the force due to toroidal magnetic field is balanced by a combination of forces due to axial magnetic field and gas pressure. We argue that the particle energy limit identified by Alves et al. is due to the finite duration of the fast magnetic dissipation phase. We find a rather minor role of electric fields parallel to the local magnetic fields in particle acceleration. In all investigated cases, a kink mode arises in the central core region with a growth timescale consistent with the predictions of linearized MHD models. In the case of a gas-pressure-balanced (Z-pinch) profile, we identify a weak local pinch mode well outside the jet core. We argue that pressure-driven modes are important for relativistic jets, in regions where sufficient gas pressure is produced by other dissipation mechanisms.

New Insights into the South American Low-Level Jet from RELAMPAGO Observations

AbstractThe Remote sensing of Electrification, Lightning, And Mesoscale/microscale Processes with Adaptive Ground Observations (RELAMPAGO) campaign produced unparalleled observations of the South American low-level jet (SALLJ) in central Argentina with high temporal observations located in the path of the jet and upstream of rapidly growing convection. The vertical and temporal structure of the jet is characterized using 3-hourly soundings launched at two fixed sites near the Sierras de Córdoba (SDC), along with high-resolution reanalysis data. Objective SALLJ identification criteria are applied to each sounding to determine the presence, timing, and vertical characteristics of the jet. The observations largely confirm prior results showing that SALLJs most frequently come from the north, occur overnight, and peak in the low levels, though SALLJs notably peaked higher near the end of longer-duration events during RELAMPAGO. This study categorizes SALLJs into shorter-duration events with jet cores peaking overnight in the low levels and longer 5–6-day events with elevated jets near the end of the period that lack a clear diurnal cycle. Evidence of both boundary layer processes and large-scale forcing were observed during shorter-duration events, whereas synoptic forcing dominated the longer 5–6-day events. The highest amounts of moisture and larger convective coverage east of the SDC occurred near the end of the 5–6-day SALLJ events.Significance StatementThe South American low-level jet (SALLJ) is an area of enhanced northerly winds that likely contributes to long-lived, widespread thunderstorms in Southeastern South America (SESA). This study uses observations from a recent SESA field project to improve understanding of the variability of the SALLJ and the underlying processes. We related jet occurrence to upper-level environmental patterns and differences in the progression speed of those patterns to varying durations of the jet. Longer-duration jets were more elevated, transported moisture southward from the Amazon, and coincided with the most widespread storms. These findings enable future research to study the role of the SALLJ in the life cycle of storms in detail, leading to improved storm prediction in SESA.

Wind Lidar and Radiosonde Measurements of Low-Level Jets in Coastal Areas of the German Bight

For wind energy, the knowledge of the available wind resource is essential. Therefore, specific wind phenomena at the altitude range of wind turbines are currently the focus of investigations. One such specific feature is the low-level jet (LLJ). The article analyses LLJ properties at two locations in the German Bight: A wind lidar system for measuring wind profiles at heights from 50 m to 500 m a.g.l. (above ground level) was first installed at the offshore island of Heligoland, Germany, and then at the coastal island of Norderney, Germany, for one year. The LLJ is defined here as a maximum horizontal wind speed in the vertical profile of horizontal wind speed followed by a minimum wind speed, independent of the mechanism or origin of the phenomenon. The two sites showed a similar annual and diurnal distribution of LLJ events with a maximum occurrence in spring and summer and during the night, and a most frequent jet core height of around 120 m a.g.l. Based on radiosondes launched from Norderney at midnight and noon, it is shown that LLJ events at noon are most frequent when atmospheric conditions are stable. A case study shows the horizontal extent of an LLJ event over at least 100 km by simultaneous wind lidar measurements at four sites in the German Bight and mesoscale simulations with the weather research and forecast (WRF) model.

Numerical study on particle-carrying ability of liquid nitrogen jet

ABSTRACT Liquid nitrogen (LN2) jet is expected to have the higher rock-breaking efficiency than water jet as its ultra-low temperature characteristic. It is considered that adding a few solid particles into LN2 jet can noticeably enhance its rock-breaking capability. The abrasive LN2 jet has a great application prospect in petroleum as well as geothermal exploitation. This study investigates the particle-carrying ability of LN2 jet by a 3D numerical model. The geometric model adopts a spindle shape that is more similar to the realistic cavity created by abrasive jet. The standard model and discrete phase model are used to calculate the LN2 flow and the particle trajectory, respectively. The Discrete Random Walk model is applied to describe the particle space movement in flow field. The results show that the particle in abrasive LN2 jet obtains the highest nozzle exit velocity in simulation conditions, 11.1% higher than in water jet and 5.1% higher than in SC-CO2 jet. The potential core of abrasive LN2 jet is longest in these three types of abrasive jets. That means LN2 jet has a well particle-carrying ability at high-speed state. However, the LN2 turbulent flow at out-of-nozzle region causes the violent fluctuation of particle speed. Parametric analysis indicates that the nozzle pressure drop and nozzle diameter in LN2 jet have the vital influences on particle velocity, while the ambient pressure and particle diameter affect particle velocity slightly. The simulation results reveal the particle-carrying ability of LN2 jet in different conditions. It would shed light on cutting capability of abrasive LN2 jet and promote its application in petroleum and geothermal exploitation.