Thrust Reverser Research Articles

Refined Performance Results on a Slowed Mach-Scaled Rotor at High Advance Ratios

Owing to its ability to alleviate the compressibility effect on the advancing side, the slowed rotor operating at high advance ratios is a key feature in high-speed compound rotorcraft. A series of wind tunnel tests were conducted in the Glenn L. Martin Wind Tunnel with a four-bladed Mach-scaled articulated rotor. The objective of the tests was to gain a basic understanding of unique features of high-advance-ratio aerodynamic phenomena, such as thrust reversal and dynamic stall in the reverse flow region. In this study, high-advance-ratio tests were carried out with highly similar, noninstrumented blades and on-hub control angle measurements, to minimize possible error due to blade structural dissimilarity and pitch angle discrepancy. The tests were conducted at 900 and 1200 RPM, advance ratios of 0.3–0.9, and a shaft tilt study was conducted at±4°. Pitch and flap motion at the blade roots, rotor performance, and vibratory hub loads were investigated during the test. The test data were then compared with those of previous tests and with predictions from comprehensive analysis. The airload results were investigated using comprehensive analysis to gain insights into the influences of advance ratio and shaft tilt angle on rotor performance and hub vibratory loads. Results indicate that the thrust benefit from backward shaft tilt is dependent on the change in the inflow condition and the induced angle of attack increment, and the reverse flow region at high advance ratios is the major contributor to changes in shaft torque and horizontal force.

Tectonic inversion of the Dnieper–Donetsk Basin. Part 2. Geodynamic situations and kinematic mechanism of riftogenic structure deformations

Formulation of the problem. In the second part of the article, the geodynamic mode and the kinematic mechanism of destruction of the Dnieper–Donetsk Basin by tectonic movements of the Late Hercynian and Alpine stages of tectogenesis were studied. New results of tectonophysical studies of the structural–kinematic evolution of the Earth's crust of Dnieper–Donetsk Basin at the collision stage are presented. The subject of research is a complex of deformation structures that complicate the sedimentary cover in the transitional zone of with Donetsk Foldbelt. Review of previous publications and studies. Using instrumental definitions of tectonite vergence, data of reconstruction of stress fields and quantitative modeling of deformations, a original kinematic model of tectonic inversion of the Dnieper–Donetsk Basin was developed. Methods. Structural–kinematic analysis of the structural drawings of collisional deformation and tectonics structures was used for regional geotectonic studies. Results. Tectonic inversion of the Dnieper-Donetsk Basin and Donbass began at the Late Hercynian epoch as a result of collisional movements of the compression orogen on the outskirts of the Paleotethis. Tangential compression of the southwestern direction led to the formation of gentle tectonic faults in the sedimentary cover of the Western Donets Graben, along which a lattice of thrust faults was formed. For a set of extrusion of sedimentary rocks in the reverse–thrust mode from the axial super-compressed zone, tectonic transport of geomas took place in the direction of the zones of "geodynamic shadow" on the southern side. Collisional deformations of horizons by the mechanism of longitudinal bending of the layers caused the formation of linear uplift-folding in the northern part of the Graben, and echelons of scaly thrust covers in the southern. At the Mesozoic and Cenozoic epochs, in the mode of interference of the reverse–thrust and horizontal-strike-slip fields, the Hercynian thrust lattice and the near-fault uplift folds underwent collisional deformation with the formation of coulisse–jointed folded zones and echeloned thrust covers. Based on the kinematic model of tectonic inversion of the Western Donets Graben, the geodynamics of the formation of the transition zone between the Dnieper–Donets Basin and the Donetsk Foldbelt is reconstructed. These data are the basis for adjusting the regional schemes of tectonic and oil and gas geological zoning. Scientific novelty and practical significance. The grouping of the compression axes in the western part of the Donbass caused the formation of a gorst-like geoblock-stamp, under the pressure of which the dislocated geomasses were thrusting onto the syneclisic cover of the southeastern segment of the depression. In the Western Donetsk Graben, the allochthonous stratum formed the body of the tectonic wedging geomas segment. Along the main strike–slip faults, which form the "tectonic rails" of the invasion, geodynamic zones of displacement of geomas were formed, composed of en-echelon articulated upthrust-folds. In its foreland, at the ends of the main strike–slip faults, an advanced scaly compression fan was formed, and in the hinterland, folded sutures were formed on the roots of the thrust covers. The main result of the research is a fundamentally new kinematic model of tectonic inversion of the Dnieper-Donetsk Basin. The model provides that the deformations of the riftogenic structure within the Graben were carried out according to the kinematic mechanism of the formation of a transverse orocline protruding under the pressure of the tectonic geoblock-stamp of the Donetsk Foldbelt.

The numerical CFD investigation of hub losses of pushing air propellers with tandem joined blades of small sized unmanned aerial vehicles

The object of study is a pushing tandem propeller with joined blades. When analyzing the characteristics of pushing propellers, it was found that one of the problem areas is a decrease in their effectiveness due to a decrease in axial thrust, which occurs due to the formation of a zone of reduced pressure (vacuum) in the area of the hub and the propeller spinner. For pushing propellers of the classic design, the reduction in efficiency reaches a level of 1–2 %. For tandem propellers, such information is not available due to the fact that such structures are practically not used on aircraft. However, in recent years, potential opportunities and advantages over classical propellers have increased the interest of researchers in the issues of their use in aircraft. It is noted that the tandem propeller should have greater hub losses compared to the classic propeller, since the diffuser of the interscapular channel is greater. To assess the value and establish the factors influencing the formation of hub losses of tandem propellers, studies were carried out using numerical gas dynamics methods. During the study, to simulate the operation of the tandem propeller, we used the ANSYS CFX software package, which implements an algorithm for solving unsteady Reynolds averaged Navier-Stokes equations closed by the SST Menter turbulence model. As a result of modeling, it was found that the level of secondary losses in the hub part of a tandem propeller is significantly affected by the mutual arrangement of the profiles of the first and second blades. When the angle of profiles installation of the second blades row increases, the vacuum in the hub part and in the spinner zone increases, which leads to the appearance of reverse thrust and reduces the thrust of the propeller by an average of 3–4 %. The obtained results confirmed the assumption that the hub losses of the tandem propellers directly depend on the diffusivity of the interscapular canal in the blades root part. Consideration of research results in the design of tandem propellers will reduce hub losses and increase the efficiency of the propellers.

Study on the combined effect of various injection conditions on the drag reduction by a counter-flow jet in supersonic flow

Parametric investigations of drag reduction by counter-flow jet in supersonic flow have been conducted through numerical simulations. An axisymmetric RANS equation was solved to analyze the drag reduction effect of each parameter. This study revealed a general tendency of the drag reduction effect on various shapes and counter-flow jet conditions and confirmed the conditions for obtaining the maximum drag reduction. In addition, the counter-flow jet structure and flow transition were also analyzed. Five parameters, jet mass flow rate, nozzle size, nozzle exit Mach number, gas total temperature, and gas types, were applied to analyze the drag reduction and flow structure. The results showed that the jet mass flow rate is the dominant factor of drag reduction and flow transition by counter-flow jet and the nozzle size has little effect on drag reduction. Regarding the individual effects of each parameter, a high nozzle exit Mach number, high total temperature, and low molecular weight of the gas are desirable for a higher drag reduction ratio with a low mass flow rate. On the other hand, because a thrust reversal phenomenon tends to occur easily at high temperatures, proper trade-off between each parameter is essential for obtaining the maximum drag reduction ratio. In addition, the nozzle flow conditions, particularly the static pressure ratio at the nozzle exit, have a large effect on the flow structure of the counter-flow jet.

Fan Flow Field in an Installed Variable Pitch Fan Operating in Reverse Thrust for a Range of Aircraft Landing Speeds

Abstract The installed flow field for a variable pitch fan (VPF) operating in reverse thrust for the complete aircraft landing run is described in this paper. To do this, a VPF design to generate reverse thrust by reversing airflow direction is developed for a representative 40,000 lbf modern high bypass ratio engine. Thereafter, to represent the actual flow conditions that the VPF would face, an engine model that includes the nacelle, core inlet splitter, outlet guide vanes, bypass nozzle, core exhaust duct, aft-body plug, and core nozzle is designed. The engine model with the VPF is attached to a representative airframe in landing configuration to include the effects of installation. A rolling ground plane that mimics the runway during the landing run is also included to complete the model definition. Three-dimensional (3D) Reynolds-averaged Navier–Stokes (RANS) solutions are carried out for two different VPF stagger angle settings and rotational speeds to obtain the fan flow field. The dynamic installed VPF flow field is characterized by the interaction of the freestream and the reverse stream flows. The two streams meet in a shear layer in the fan passages and get deflected radially outward before turning back onto themselves. The flow field changes with stagger setting, fan rotational speed, and the aircraft landing speed because of the consequent changes in the momentum of the two streams. The description of the installed VPF flow field as generated in this study is necessary to (a) qualify VPF designs that are typically designed by considering only the uninstalled static flow field and (b) choose the VPF operating setting for different stages of the aircraft landing run.

Study of Jet Propagation and Prevention of Jet Reattachment to the Nacelle during Jet Engine Thrust Reversal

Complex variable function theory methods are used to study the jet propagation and prevention of jet reattachment to the nacelle during jet engine thrust reversal for reverser cascades with constant and variable blade angles. Results obtained are compared with experimental data.

Study of Turbulent Flow through a Thrust Reverser

This work, presents a numerical study, using the CFD Fluent code, of a two-dimensional thrust reverser equipped with deflector doors to reverse the exhaust gas stream. The reverser is similar to those used in turbofan engines at high bypass ratio. The Reynolds averaged equations (RANS) were solved by using the turbulence standard k-e model. Initially, the computer code FLUENT is validated by using a plane geometry for which the experimental data and the numerical results exist in the literature. The code is then applied to a reverser, which has an axisymmetric geometry. The results obtained made possible to detect all the physical phenomena present in the flow, in particular, those occurring at the areas of flow detachment/reattachment and to understand the behavior of the flow near the geometrical singularities of the reverser.

Reverse Thrust Aerodynamics of Variable Pitch Fans

Abstract Variable pitch fans are of interest for future low-pressure ratio fan systems since they provide improved operability relative to fixed pitch fans. If they can also be re-pitched such that they generate sufficient reverse thrust they could eliminate the engine drag and weight penalty associated with bypass duct thrust reversers. This paper sets out to understand the details of the 3D fan stage flow field in reverse thrust operation. This study uses the Advanced Ducted Propulsor variable pitch fan test case, which has a design fan pressure ratio of 1.29. Comparison with spanwise probe measurements show that the computational approach is valid for examining the variation of loss and work in the rotor in forward thrust. The method is then extended to a reverse thrust configuration using an extended domain and appropriate boundary conditions. Computations, run at two rotor stagger settings, show that the spanwise variation in relative flow angle onto the rotor aligns poorly to the rotor inlet metal angle. This leads to two dominant rotor loss sources: one at the tip associated with positive incidence and the second caused by negative incidence at lower span fractions. The second loss is reduced by opening the rotor stagger setting, and the first increases with rotor suction surface Mach number. The higher mass flow at more open rotor settings provide higher gross thrust, up to 49% of the forward take-off value, but is limited by the increased loss at high speed.

THE ROLE OF THE GEOLOGICAL COMPOSITION IN THE STRUCTURAL MORPHOLOGY OF THE TERRITORY OF ALBANIA

In the context of geological composition, the territory of Albania closely depends on the geographic position. The presence of our country in the alpine-Mediterranean fold belt and the geological structures, called Albanide, have determined the intense development of the internal tectonic processes, as well as the external processes. The tectonic regime of the geological structures during the Miocene epoch to the Quaternary period, was accompanied by reverse faults and thrust faults one over the other of the tectonic areas of Albania. The morphologic and morphogenetic complex of the relief was created during the tectogenic period, especially during the tecto-orogenesis, where as consequence diverse magmatic. terrigenous and carbonates rocks were created. The highly pronounced character of the differential tectonic movements during morphotectonic evolution, especially during the plio-quaternary period, has created the actual morphological features of the relief of Albania.In the context of geological composition, the territory of Albania closely depends on the geographic position. The presence of our country in the alpine-Mediterranean fold belt and the geological structures, called Albanide, have determined the intense development of the internal tectonic processes, as well as the external processes. The tectonic regime of the geological structures during the Miocene epoch to the Quaternary period, was accompanied by reverse faults and thrust faults one over the other of the tectonic areas of Albania. The morphologic and morphogenetic complex of the relief was created during the tectogenic period, especially during the tecto-orogenesis, where as consequence diverse magmatic. terrigenous and carbonates rocks were created. The highly pronounced character of the differential tectonic movements during morphotectonic evolution, especially during the plio-quaternary period, has created the actual morphological features of the relief of Albania.The migration of orogenesis from east to west is conditioned by the dominance of mountainous ranges and ridges in the eastern and central parts, as well as in the fields and lowlands of the western part of Albania. The relief is distinguished by its diversified morphogenetic traits, due to the highly complex morphotectonic evolution, a large number of carbonate, terrigenous and magmatic rocks, as well as the significant influence of the outward processes. Due to the existence of composition of the large number of tectonic faults as well as the high values of tectonic uplift and downlift, the genetic composition of the structural relief was also created. Each of the sub-types within the structural relief is closely related to the presence of complex geological structures such as anticlinal, synclinal, monoclinal and aclinal structures. An important role have the structural landforms formed in the structures of faulting type, thus in the horst and graben structures, which are associated with very large morphological contrasts of the relief.A part of the horst and graben structures during the last period of pliocene and during the quaternary was involved by intense tectonic lifting movements, resulting to a fragmentation of flat bottom of ex-former depressions, and consequently they were transformed into depressions with fragmented bottom. A large part of structural relief landforms, such as structural benches, flat surfaces formed in the aclinal structure, structural surfaces, denudational surfaces and concave fragment of front of the cuestas, have been used for the construction of rural and urban settlements, for the road infrastructure network, the construction of human buildings, as well farmlands for the country's economy. The detailed analysis of the structural relief features, based on the characteristics of geological construction, enables prospects for taking measures against geomorphological, seismic and hydrological hazards.

Numerical simulation of aerodynamic performance of an airfoil combined lift and drag

An airfoil which can establish flow tunnel is simulated in this study. Y-type flow tunnel is opened inside the airfoil which can produce lift and drag to drive itself under different wind speed and different wind angle. Selecting the NACA low-speed airfoil as standard airfoil and using fluent method, the influence on aerodynamic characteristics can be analyzed according to the results. In this paper, two airfoils are simulated under 3m/s and 8m/s of wind speed, wind angle area 15° to 45° and 150° to 180 ° respectively. The results of simulation show that the areodynamic characteristic of airfoil combined lift and drag is similar to the standard airfoil under the low wind speed up, thus, the airfoil combined lift and drag keeps the characteristic of providing lift; Under the high wind speed, the airflow ejected from Y-type flow tunnel, the thrust reversal is generated; At a specific wind angle area, the airfoil can be driven by the lift and drag. According to the results of simulation, suggestions on the optimization of the wing combined lift and drag are proposed.

Testing the occurrence of thick-skinned triangle zones in the Central Andes forearc: Example from the Salar de Punta Negra Basin in northern Chile

The Salar de Punta Negra Basin in the forearc of the Central Andes serves as a natural laboratory to understand the evolution of thick-skinned triangle zones dominated by opposite-verging, contractional systems. We combined field data and W-E 2D seismic profiles along parts of the basin where stratigraphic units are well constrained. The seismic data show the occurrence of thick-skinned triangle zones under the basin with along-strike variation. These are composed of west and east-verging, basement-involved faults and thrust ramps, or partially inverted normal faults. The plan-view structural configuration of the basin usually coincides with the sub-surface position of the triangle zones. The interplay between purely reverse and inverted faults in the region indicates that the thick-skinned triangle zones could be kinematically related to the superposition of two contractional episodes, consisting of: i) partial tectonic inversion of half-graben structures; and ii) basement deformation dominated by reverse faults and thrust and anticline ramps. The post-extensional tectono-sequences interpreted on the seismic profiles generally correlate with the Upper Cretaceous to Paleocene synorogenic successions exposed on surface, which allow us propose an age of deformation correlated with the “Peruvian” and “K-T” Andean Orogeny. The triangle zone could still be an active structure.

Blended Wing Body Thrust Reverser Cascade Feasibility Evaluation Through CFD

Airplane thrust reverser could significantly reduce the landing distance of a conventional civil turbofan. Control of the thrust reverser can be performed by a hydraulic and/or electric system. This study investigates whether this system can be used for blended wing body (BWB) civil airplanes as their engines are located over the wing body. Computational fluid dynamics (CFD) is used to analyze the feasibility of a thrust reverser cascade applied to BWB airplanes. This is selected because of its rapidity and low cost when compared to traditional wind tunnel tests. Analyses are performed on a 300-seating BWB (BWB300) landing configuration. The results show that the thrust reverser cascade can be applied to BWB300. Furthermore, the results also reveal that the probability of foreign object damage problems occurring during the BWB300 landing process when the thrust reverser cascade is working is low. Increasing the reverse mass flow component along the landing reverse direction can increase the thrust reverser efficiency. However, this would also increase the thrust reverser closing velocity. Therefore, when the thrust reverser design is performanced for BWB, a tradeoff between the efficiency and closing velocity should be considered.

A simplistic flight model for exergy embodiment of composite materials towards nearly-zero exergy aviation

In this paper, a new model for the embodied exergy payback period is presented, which considers the exergy savings during acceleration and take-off, climb, trim-level cruise, descent and thrust reversal in landing for each flight versus higher exergy embodiment of composites that are used during manufacturing when compared to metals. The research work has ramifications for determining the optimum balance of lightweight and conventional material usage, thus improving the economic and environmental performance of aircraft for decoupling sustainable aviation and carbon dioxide emissions. The research work concludes with a vision for nearly-zero exergy aviation that involves a complete set of measures for the airside and landside. Considering new metrics for fuel savings and CO2 emissions based on exergy, the use of composite materials in new aircraft requires support from air traffic optimisation, jet fuel produced from renewable energy systems, nearly-zero exergy airport terminals, and sustainable taxiing solutions. The research work has the potential for supporting the carbon neutral growth strategy of the aviation sector.

Controlling Effect of Fault Structural Styles on Aquifer Water Abundance for Panxie Mining Area, Huainan, China

According to the hydrogeological conditions, dynamic characteristics of tectonic deformation and geometric features, the fault structures in the Panxie mining area were divided into seven types respectively were horst, graben, graben-horst combination, forward (reverse) thrust structure, imbricate thrust structure, strike-slip structure, and others. Meanwhile, the q-structural styles boxplot had been constructed to analyze the water abundance of the karst formation aquifer. It has been verified via the practical drilling core data. The final results were that the water-rich characteristics of the deep karst water controlled by the seven structural styles were different. The water abundance of graben-horst combination structure was strongest; the next was the horst in deep which was stronger than the graben. Then, the imbricate thrust structure, strike-slip fault, and other structural styles had low water abundance in deep karst aquifer. The results can be aimed at different structural styles to guide the prevention and control of karst water hazards on the floor of Group A coal mining.

On Modelling of Influence of Air Condition of Building on Gas-Consuming Equipment with an Open Combustion Chamber Functioning

Nominal operation of gas consuming equipment with an open combustion chamber installed in the various purposes buildings’ premises depends on the receipt of the required amount of air to ensure the complete combustion process. The supply of primary air in an amount of 40-60% of the theoretically required volume allows a stable process of gas combustion. In this case, flame separation is prevented. Requirements for safe operation of the gas consumption system are satisfied. For reliable operation of the gas distribution system, it is necessary to provide installation of the automation devices that respond to any deviations in gas burners. In the process of gas fuel burning, two cones are formed. The internal cone in which the gas burnt is provided by the primary air. In the outer cone of the flame gas is burnt due to air coming from the room. In the lower part of the burner, conditions are created under which the velocity of the gas-air flow and the normal velocity of flame propagation are ensured. This ensures the creation of an incendiary belt, which constantly ignites the air-gas mixture, and provides a stable and constant combustion of gas. The inflow of air into the room where the gas consuming equipment is located is through the filling of light holes during infiltration. Increasing the resistance to air permeation of filling the light apertures is performed to improve the energy efficiency of the building by means of reducing infiltration heat loss. Reduction of natural inflow through constructive non-densities in the fillings of the light apertures leads to a decrease in the infiltration process, and, consequently, to the violation of the process of the nominal functioning of the gas consuming equipment. The possibility of creating an air regulation mechanism for individual rooms and the building is considered, ensuring the influx of the required amount of air, depending on the parameters of the outside air, the air permeability of the fillings of the light apertures, and also the height of their location. Analytical dependencies that consider the effect of the air condition of buildings for various purposes on the joint operation of natural ventilation systems with an unorganized inflow in the required volume, excluding the formation of the effect of reverse thrust in the combustion products removal system are presented.

Geomorphic evidence for the geometry and slip rate of a young, low-angle thrust fault: Implications for hazard assessment and fault interaction in complex tectonic environments

We present surface evidence and displacement rates for a young, active, low-angle (∼20°) reverse thrust fault in close proximity to major population centers in southern California (USA), the Southern San Cayetano fault (SSCF). Active faulting along the northern flank of the Santa Clara River Valley displaces young landforms, such as late Quaternary river terraces and alluvial fans. Geomorphic strain markers are examined using field mapping, high-resolution lidar topographic data, 10Be surface exposure dating, and subsurface well data to provide evidence for a young, active SSCF along the northern flank of the Santa Clara River Valley. Displacement rates for the SSCF are calculated over 103–104 yr timescales with maximum slip rates for the central SSCF of 1.9+1.0−0.5 mm yr−1 between ∼19–7 ka and minimum slip rates of 1.3+0.5−0.3 mm yr−1 since ∼7 ka. Uplift rates for the central SSCF have not varied significantly over the last ∼58 ka, with a maximum value of 1.7+0.9−0.6 mm yr−1 for the interval ∼58–19 ka, and a minimum value of 1.2±0.3 mm yr−1 since ∼7 ka. The SSCF is interpreted as a young, active structure with onset of activity at some time after ∼58 ka. The geometry for the SSCF presented here, with a ∼20° north dip in the subsurface, is the first interpretation of the SSCF based on geological field data. Our new interpretation is significantly different from the previously proposed model-derived geometry, which dips more steeply at 45–60° and intersects the surface in the middle of the Santa Clara River Valley. We suggest that the SSCF may rupture in tandem with the main San Cayetano fault. Additionally, the SSCF could potentially act as a rupture pathway between the Ventura and San Cayetano faults in large-magnitude, multi-fault earthquakes in southern California. However, given structural complexities, including significant changes in dip and varying Holocene displacement rates along strike, further work is required to examine the possible mechanism, likelihood, and frequency of potential through-going ruptures between the Ventura and San Cayetano faults. Confirmation of the SSCF in a previously well-studied area, such as southern California, demonstrates that identification of young faults is critical for accurate seismic hazard assessment. We suggest that many young, active faults remain undetected in other structurally complex and tectonically active regions globally, and that significant seismic hazards can be overlooked.

Computational Fluid Dynamics Investigation of a Core-Mounted Target-Type Thrust Reverser—Part 2: Reverser Deployed Configuration

Core-mounted target-type thrust reverser (CMTTTR) design was proposed by NASA in the second half of the 90 s. NASA carried out several experiments at static conditions, and their acquired results suggested that the performance characteristics of the CMTTTR design fall short to comply with the mandatory thrust reverser (TR) performance criteria, and were therefore regarded as an infeasible design. However, the authors of this paper believe that the results presented by NASA for the CMTTTR design require further exploration to facilitate the complete understanding of its true performance potential. This part 2 paper is a continuation from Part 1 (reverser stowed configuration) and presents a comprehensive three-dimensional (3D) computational fluid dynamics (CFD) analyses of the CMTTTR in deployed configuration. The acquired results are extensively analyzed for aforementioned TR configuration operating under the static operating conditions at sea level, i.e., sea-level static, International Standard Atmosphere (ISA); the analyses at forward flight conditions will be covered in part 3. The key objectives of this paper are: First, to validate the acquired CFD results with the experimental data provided by NASA; this is achieved by measuring the static pressure values on various surfaces of the deployed CMTTTR model. The second objective is to estimate the performance characteristics of the CMTTTR design and corroborate the results with experimental data. The third objective is to estimate the pressure thrust (i.e., axial thrust generated due to the pressure difference across various reverser surfaces) and discuss its significance for formulating the performance of any TR design. The fourth objective is to investigate the influence of kicker plate installation on overall TR performance. The fifth and final objective is to examine and discuss the overall flow physics associated with the thrust reverse under deployed configuration.

Design of Loading System for Thrust Reverser Ground Simulation Test

Thrust reverser is a necessary device on large passenger plane and large culvert ratio turbofan engine, which has the advantages of shortening the landing distance, reducing the wear of wheel brake, prolonging the service life of braking parts and improving landing safety of aircraft. The thrust reverser ground test is one of the important contents in the design of aircraft nacelle, and generally, it is an effective way to carry out the research test work by semi-physical simulation, in which the analysis of the thrust reverser loading control system are the basis for the design of test loading device. In this paper, take the cascade thrust reverser as the object, firstly, the thrust reverser structure and working principle were specially explained. Then, according the characteristic of the hydraulic actuation system, the loading channel was designed and analyzed theoretically, especially the loading control system. Finally, the model of loading control system was established in Simulink, and the time domain and frequency characteristic were analyzed. For the redundant force in the passive loading system, PID and the principle of the structure invariance were chosen to correct the control system. The simulation results show that the principle of the structure invariance control strategy has a better effect on eliminating the redundant force to meet engineering requirements.

Multi-Stage Deformation of the Khangalas Ore Cluster (Verkhoyansk-Kolyma Folded Region, Northeast Russia): Ore-Controlling Reverse Thrust Faults and Post-Mineral Strike-Slip Faults

This study reports the results of the analysis of multi-stage deformation structures of the Khangalas gold ore cluster, northeast Russia. Four Late Mesozoic-Early Eocene deformation stages were identified. The first deformation event (D1) was characterized by the development of NW-striking tight to isoclinal folds of the first generation (F1) and interstratal detachment thrusts. Major folds, extensive thrusts, boudinage, cleavage, auriferous mineralized fault zones and quartz-vein gold mineralization were formed in the reverse and thrust fault stress field during the progressive deformation stage (D1), with NE-SW-oriented σ1. Post-ore deformation is widely manifested in the region. Structures D2 and D3 are coaxial. Sinistral strike-slip motions (D2 and D3) occurred along NW-trending faults under prevailing W-E compression. They were accompanied by the formation of NS- and NE-striking F2–3 folds with steep hinges and by bending of the earlier formed structures, among them ore-controlling ones. The last deformation event (D4) was represented by normal-dextral strike-slip faulting, refolding of rocks, pre-existing structures and ore bodies and by the development of folds with steep hinges. Key structural elements of varying age are described, the chronology of deformation events and mineralization reconstructed and their relation to geodynamic events in northeast Asia established.

Computational Fluid Dynamics Investigation of a Core-Mounted Target-Type Thrust Reverser—Part 1: Reverser Stowed Configuration

During the second half of the 90 s, NASA performed experimental investigations on six novel thrust reverser (TR) designs; core-mounted target-type thrust reverser (CMTTTR) design is one of them. To assess the CMTTTR efficiency and performance, NASA conducted several wind tunnel tests at sea level static (SLS) conditions. The results from these experiments are used in this paper series to validate the computational fluid dynamics (CFD) results. This paper is part one of the three-part series. Parts 1 and 2 discuss the CMTTTR in stowed and deployed configurations; all analyses in the first two papers are performed at SLS conditions. Part 3 discusses the CMTTTR in the forward flight condition. The key objectives of this paper are: first, to perform the three-dimensional (3D) CFD analysis of the reverser in stowed configuration; all analyses are performed at SLS condition. The second objective is to validate the acquired CFD results against the experimental data provided by NASA (Scott, C. A., 1995, “Static Performance of Six Innovative Thrust Reverser Concepts for Subsonic Transport Applications: Summary of the NASA Langley Innovative Thrust Reverser Test Program,” NASA—Langley Research Centre, Hampton, VA, Report No. TM-2000-210300). The third objective is to verify the fan and overall engine net thrust values acquired from the aforementioned CFD analyses against those derived based on one-dimensional (1D) engine performance simulations. The fourth and final objective is to examine and discuss the overall flow physics associated with the CMTTTR under stowed configuration. To support the successful implementation of the overall investigation, full-scale 3D computer aided design (CAD) models are created, representing a fully integrated GE-90 engine, B777 wing, and pylon configuration. Overall, a good agreement is found between the CFD and test results; the difference between the two was less than 5%.