Bottom Region Research Articles

Investigation of friction properties in the piston-cylinder liner region of a single-cylinder compressed air engine using the GT-SUITE program

Dependence on nonrenewable fuels continues to a great extent today. Overuse of fossil fuels has brought along various environmental problems. In order to reduce such problems, compressed air engines have developed significantly during the last 20 years. Compressed air engines are environment-friendly engines that do not use fossil fuel and achieve expansion using compressed air. It is of great importance for engine efficiency to decrease friction losses of piston engines. There are not many studies in the literature focusing on friction manner of piston ring liner parts of compressed air engines with a piston. In this article, the transformation of a four-stroke gasoline engine with 388 cm3 displacement into a compressed air engine has been carried out and the friction manner between piston cylinder liner has been modeled with the help of GT-SUITE program using in-cylinder pressure-cylinder volume (P-V) data obtained from different engine loads under operating pressure of 12 bar and geometrical size of the engine. It has been determined according to the results of the simulation that asperity friction losses have not changed significantly in top dead center and bottom dead center regions due to low testing speed, and hydrodynamic power losses have occurred in the middle of the course. Lack of combustion reactions in such engines has resulted in compression leakages and unavailability of a quality oil film layer. Since there are no combustion reactions, the eccentric movement of the pistons of the compressed air engines is changed by the lubricating oil, engine speed, compression leaks, and viscosity parameters.

Aging Profiles of AlSi7Mg0.6 and AlSi10Mg0.3 Alloys Manufactured via Laser-Powder Bed Fusion: Direct Aging versus T6.

The artificial aging heat treatments performed directly on as-built and solubilized AlSi7Mg0.6 and AlSi10Mg0.3 samples were characterized and discussed. The analysed bars and billets (height of 300 mm) were manufactured via the Laser Powder-Bed Fusion process on a build platform heated at 150 °C. Therefore, its influence on the as-built samples was studied in terms of mechanical performance variations between the bottom and top regions. Vickers microhardness measurements were performed to obtain aging profiles after direct aging (175–225 °C) and T6 heat treatments and to highlight better time and temperature parameters to optimize the mechanical properties of both alloys. SEM observations were used to characterize the microstructure before and after the heat treatments and its influence on the fracture mechanisms. Generally, the direct aging heat treatments show the same effects on both aluminium alloys, unlike the solubilization at 505 °C followed by artificial aging at 175 °C. The strengths vs. elongation values obtained after the direct aging treatments are better than those exhibited by T6 as highlighted by the quality index.

Metallurgical Characteristics of Low Carbon Steel Cylindrical Components Made by Wire Arc Additive Manufacturing (WAAM) Technique

Fabrication of metal parts by wire and Arc Additive Manufacturing (WAAM) has received an increased interest in recent years, as it allows high design flexibility and reduction of material wastage compared to other traditional manufacturing routes. This article compares the effect of heat input on metallurgical characteristics of wire arc additive manufactured low carbon steel cylindrical components fabricated by Gas Metal Arc Welding (GMAW) and Cold Metal Transferred Arc Welding (CMTAW) processes. Firstly, the influence of heat input on the grain size was analyzed. Subsequently, the effect of heat input on the metallurgical characteristics of the cylindrical components was studied along the building direction. The microstructure of the built cylindrical-walled component varies from the top to the bottom regions and can be distinguished into two regions: lamellar structures (widmanstatten ferrite and grain boundary ferrite) in the top regions; and equated grains of fully ferrite in the bottom region in GMAW. In the CMT-WAAM cylindrical component samples have been noted two different regions: the bottom region characterized by a ferritic structure with thin strips of pearlite and the top region characterized by a lamellar structure typically bainite with acicular ferrite.

Bioinspired photothermal sponge for simultaneous solar-driven evaporation and solar-assisted wastewater purification

Solar-driven evaporation (SDE) garners widespread attention for solving the freshwater shortage. However, most designed photothermal evaporators lack consideration of contaminants in bottom bulk water which seriously reduces their credibility in practical application. Inspired by the bump structure of Rafflesia arnoldii and truss building, a photothermal evaporator with secondary structure was constructed by embedding biochar loaded with UiO-66-NH2 (C@MOF) into chitosan/bamboo fibers (CS/BFs) matrix for simultaneous freshwater generation and dye adsorption. Due to the efficient light utilization, CS/BFs/C@MOF sponge exhibits an energy conversion efficiency of 86.84% under 1 sun illumination. In addition, CS/BFs/C@MOF sponge possesses the maximum adsorption capacities of 105.48 mg g−1 for methylene blue (MB) and 60.57 mg g−1 for methyl orange (MO). Importantly, the dye adsorption process on CS/BFs/C@MOF is essentially an endothermic reaction, which is more effective in sunlight. The good dye adsorption capacity allows CS/BFs/C@MOF to confine most contaminants to the bottom region during long time working in dye solution, ensuring an efficient SDE process. In outdoor practical application, a single evaporator can extract 6.72 kg m−2 purified water from 50 mg/L of simulated dye wastewater one day with a contaminant removal efficiency of 85.14%. This work achieves a good integration of separation and purification strategies through solar energy and offers a promising solution for solar-driven in-depth water treatment.

Non-equilibrium heat exchange and multi-coupled nature of mass transfer in solvent removal of propellant grains

In-depth knowledge of the heat and mass transfer mechanisms in removing the solvent of the propellant grains is crucial for optimizing process conditions as well as obtaining quality products. In this regard, this work developed an industrial-scale fixed bed test system used to study the solvent removal nature of the propellant grains. A transient model for predicting the non-equilibrium heat exchange and the solvent vaporization coupled with the adsorption of the water vapor was proposed as well. Results showed that the developed model could predict the hot air convection of the propellant grains, and the maximum relative deviation of the simulated results and the test data was 9.1%. In addition, the local profiles of the solvents mass fraction in the fixed bed had a non-uniformity in the early stage of the solvent removal, but it tended to be uniform as time went on. The propellant grains in the bottom region of the fixed bed have higher water content than that in other regions at the end of the solvent removal. The temperature of the propellant grains gradually increased due to the convective heat exchange, which led to the thermal non-equilibrium between the hot air and the propellant grains degraded.

Single- and two-phase CFD V&V for high-speed stepped planing hulls

CFD Verification and validation (V&V) studies are conducted using both single- and two-phase flow solvers for the high-speed stepped planing hulls, which provides the assessment of their capability for design and identification of issues for the further experimental and CFD research. The hydrostatic analysis supports previous studies in showing the importance and sensitivity of the results regarding the hydrostatic setup. Setting by displacement and LCG is the best, but more accurate documentation of the static sinkage and trim is required. The intervals of V&V are somewhat larger for stepped vs. un-stepped hulls, but nonetheless reasonable. The force and moment analysis shows the distributions of the pressure vs. frictional resistance, longitudinal distributions of the lift force and balance of the pressure vs. frictional vs. weight pitch moments. The flow features on the bottom (i.e., stagnation, pressure, and spray areas), ventilated cavity and wake region are better resolved by the two-phase than the single-phase flow solver. The cavity shows air inflow from the side at the step and airflow ejected at the cavity reattachment. The predicted cavity size is larger for two-than for single phase flow, and the Lee (2014) empirical formula lies between them. Porpoising instability is predicted by both two-phase flow solvers, and it is shown that the heave and pitch natural period decrease with forward speed. Overall, the results from both codes and for both single- and two-phase are found to be sufficiently accurate to be used for design similarly to what was previously concluded by the same authors in case of un-stepped planing hulls.

Flow Control for a Submerged Inlet

Abstract Submerged inlets have the advantages of low drag, clean outer profile, and excellent stealth performance. Previous studies indicate that the zones of large total-pressure loss, located at the bottom and top regions of the exit plane, are the main cause of the poor aerodynamic performance in a submerged inlet. To improve the performance, a flow-control method is proposed in this paper, which includes both ramp side boundary layer bleeding and entrance side-edge vortex diverting. With numerical simulations, the efficacy of the proposed flow control is examined by comparing the aerodynamic performance and flow-field pattern of a baseline inlet and a controlled inlet over the typical flight envelope. The results prove that the proposed flow-control method can effectively discharge the low-energy flow of the forebody boundary layer on the ramp and isolate the major low-energy flow of the side-edge vortex. The proposed flow-control method results in a large improvement in the aerodynamic performance over the whole flight envelope. Specifically, the total pressure recovery (σ) of the inlet with the proposed flow-control features raises 3.06%, and the distortion (DC60) and the swirl distortion (SC60) lessen by 72.57% and 17.73%, respectively, in contrast to the baseline inlet under the engine matching point of cruise state (Ma0=0.72, α=2 deg, β=0 deg, Ma2=0.39).

Chemical, microstructure, and mechanical property of TiAl alloys produced by high-power direct laser deposition

• A gradient TiAl specimen whose chemical composition varied greatly along the building direction was fabricated by high-power direct laser deposition. • The microstructure transforms from basket-weave microstructure into acicular martensite microstructure as the height increases, and the mechanical properties also vary greatly when the height changes. • By characterizing the deformation behaviors under the indentations, it is concluded that the phase constitution is responsible for the variation of the mechanical properties. Additive manufactured metals sometimes exhibit extraordinary microstructures and mechanical properties due to the particular processes. In this paper, we focus on a novel gradient TiAl alloys fabricated by high-power direct laser deposition, whose chemical composition, microstructure, and mechanical property vary along the building direction. The results indicate that Al concentration dramatically decreases from 39.5 at.% to 30.1 at.% as the height increases from the bottom to the top. Meanwhile, microstructural characterization indicates that the specimen appears basket-weave microstructure at the bottom, then the α 2 and γ phase gradually decrease, and eventually it transforms into acicular martensite microstructure in the top region. The indentation analysis shows that the associated hardness increases as the height increases, while the plasticity reaches a minimum value in the middle region. The increasing amount of β o (ω) is considered to be responsible for the increasing hardness because of the strong precipitation strengthening effect. The high plasticity in the bottom and top regions results from the strong deformation behaviors of the γ and β o phases.

Microstructure and mechanical characteristics of 307Si stainless steel thin-wall parts in wire arc additive manufacturing hybrid interlayer high-speed friction

A method of wire arc additive manufacturing hybrid interlayer high-speed friction (WAAM-HSF) was proposed. Microstructure and mechanical characteristics of 307Si stainless steel in the WAAM and WAAM-HSF were investigated. The microstructure in the WAAM and WAAM-HSF consisted of γ-austenite and residual δ-ferrite. The microstructure in the WAAM-HSF was obviously refined compared with that of WAAM. The grain diameter was gradually reduced from the top region to the bottom region in two thin-walls. In the same region, the grain size in the WAAM was greater than that of WAAM-HSF. Compare to WAAM, the microhardness in the WAAM-HSF was enhanced.

SPATIAL RELATIONSHIP BETWEEN LAND-USE LAND COVER WITH SOIL EROSION IN THE NARMADA BASIN USING SENTINEL 2 IMAGE: ASSESSING THE PERFORMANCE OF RF MACHINE LEARNING CLASSIFIER

In the past decades, increasing demand for cultivable soil, deforestation and land conversion in the region has led to severe soil and natural resources exhaustion. The grade and rate of the soil and land-use land-capacity connection has been determined using soil parameter data together with geographic information systems, utilizing machine learning methods (random forest).The analysis shows high and substantial land coverage over Grass Land area with 52,330.59 sq. km/54.5 percent, with an Urban growth of 19,255.36 sq.km/20.0 percent, 12,400.51 sq.km/12.9 percent for Agriculture, Forest land with 8,828.67 sq.km/9.2 percent, 1,970.382 sq.km/2.0 percent for water and the smallest land cover among the classes was cropland with 1,337.51 sq.km/1.4 percent area coverage. Random forest algorithms show that soil erosion for the whole Upper catchment was lower compared to the bottom catchment region and high soil erosion in line with the land conversation of natural vegetation. This analysis includes extra significant information and differences between kinds of land use soil erosion with a major and very severe area 38.337.55 sq.km/39.9 percent; the severely eroded soil covers 29.346.59 sq.km/30.5 percent; the modest soil erosion area (15.372.16 sq.km/16.00 percent); the lowest or slightest soil erosion zone was 13066.73 sq.km/13.6 percent. To strengthen the status and use of the collected resources as a result of sustainable land use activities that benefit local rural life, inclusive and viable land use is needed immediately. The area where very severe soil erosion and the land cover has been correlated to determine the relationship with the existing land covers in the area, decreases of soil erosion indicates the change in the land uses. The correlation between the LULC and the soil erosion was 0.53, with an RMSE of 0.033 and a p-value of 0.000063.

Numerical study on flue gas–liquid flow with side-entering mixing

Abstract In this article, the side-entry agitator commonly used in the wet desulfurization absorption tower of a 300 MW thermal power unit was taken as the research object, and the gas–liquid two-phase flow field in the stirring tank was numerically simulated by using the two-fluid model based on Euler–Euler method. The vertical and horizontal velocity field distribution and gas phase distribution in the stirring tank were studied. The results showed that the side-entry agitator formed a “fountain” circulating flow in the stirring tank. The high-speed region of the liquid flow was mainly concentrated near the mixing blade and the bottom banded region. The range of large changes in the fluid velocity was mainly concentrated from the bottom of the mixing tank to 2–3 m from the bottom. The distribution of the oxidizing air was concentrated in the middle of the stirring tank. The mixing effect of two phases in the stirred tank was good, and the oxidizing air was fully diffused. The numerical study in this article has reference significance for in-depth understanding of the flow field and mixing effect of the side-entry agitator.

Friction Stir Welding of Similar Aluminum Alloys Thick Plates: Understanding the Material Flow, Microstructure Evolution, Defect Formation, and Mechanical Properties

A systematic study of friction stir welding in three Al alloys (2024-T351, 6061-T651, and 7075-T735) has been conducted. The material flow, microstructure evolution, defects and precipitates formation mechanisms, and mechanical properties for different tool rotation and traverse speeds have been systematically investigated for 15 mm-thick butt-welds of similar alloy plates. The nugget zones were determined to be formed by two material flows – shoulder-driven and pin-driven. The shoulder-driven flow corresponds to bulk material transfer (i.e., bulk material flow), while the pin-driven flow occurs through a combination of layer-by-layer material transfer (i.e., layered extrusion flow, due to the pin's extrusion effect) and bulk material flow. The relative volumes of these two flows are dependent on the material and processing parameters. Weld defects are formed when significant flow stress differences between the shoulder-driven and pin-driven flows exist, due to the inhomogeneous heat distribution across the large weld thickness. For materials with higher thermal conductivity, lower flow stresses and temperature gradients, as well as reduced heat inputs result in reduced defect formation. Transmission electron microscopy and differential scanning calorimetry have been used to study the precipitation behavior in friction stir welds. Heterogeneity in the re-precipitation of GP and GPB zones between the top and bottom regions of the nugget zone and coarsening of the base alloys precipitates in the heat affected zone were observed. Optimization of the resulting weld quality and mechanical properties were discussed using the integrated understanding of the material flow and microstructure evolution in friction stir welding of Al thick plates.

Segregation of a Phosphorus Rich Phase During Differential Solidification of BOF Slag

This study investigated the segregation behaviour of the phosphorus rich (P-rich) phase from the iron-rich (Fe-rich) phase in steelmaking slag from laboratory to industrial scale using computational fluid dynamics (CFD) in order to propose a suitable separation practice for the P-rich phase. Crucible experiments and corresponding CFD simulations using enthalpy-porosity approach were first performed to verify the concentration difference of phosphorus in the two phases. Both simulation and experimental results showed ~ 17 to 18 pct increase in phosphorus concentration in the top region of the crucible after solidification. The simulations were then scaled up to an industrial slag pot and slag pit. Reasonable agreement was obtained with published results for phosphorus concentration, and the total liquid amount in the 16-tonne slag pot, under practical cooling conditions. Simulations in the 30-tonne slag pit with in-ground insulation showed an increase of ~ 25 pct of the P-rich phase in the top region (while concentrating the Fe-rich phase in the bottom region). Differential concentration of the P-rich phase within the slag (as a result of heat transfer, micro/macro-segregation) suggested that separation of phosphorus in industrial scale slag pot and slag pit—as batch systems—is possible. Suggestions for separation in continuous operation are also discussed.

CFD simulation of hydrodynamics and heat transfer characteristics in gas–solid circulating fluidized bed riser under fast pyrolysis flow condition

• Proper heat is needed for Circulating fluidized bed riser for fast pyrolysis. • A 3D EE-TFM model was developed and validated with experiment. • Hydrodynamics and heat transfer characteristics were examined for CFB riser. • Demonstrate the gas–solid heat transfer affected under different hydrodynamics. Pyrolysis process through circulating fluidized bed (CFB) is a promising technology to produce synthetic fuel and other products from biomass feedstocks. Computational fluid dynamics (CFD) computing means provide valuable insights to better understand gas–solid flow hydrodynamics, troubleshoot performance issues and optimize reactor operations. In this study, gas–solid flow hydrodynamics and heat transfer characteristics of a CFB riser for fast pyrolysis are investigated using a three-dimensional (3D) Eulerian-Eulerian CFD model. The main observations are discussed to provide insights on the factors affecting CFB riser performance. The model parameters, specularity and particle–particle restitution coefficients, were considered and tuned to accurately predict of gas–solid flow hydrodynamics and heat distribution with respect to different gas velocities and solid circulation rates. The results have shown that the CFD model predicted well the flow hydrodynamics and both specularity and particle–particle restitution coefficients are critical parameters as they affect particle behavior and temperature distribution fields. The lower specularity coefficient (Φ − 0.00001) was fairly able to predict the axial solid holdup profile into CFB riser. However, the lower value for particle–particle restitution coefficient ( e s s - 0.8) significantly overpredict the bottom dense region. The results shows that the increase of operating velocity promotes the mixing behaviors and heat transfer performance. In this work the suitable gas and solid circulation flow rates are U g = 4.5 m/s and G s = 81.23 kg/m 2 s.

Solidification microstructure, aging evolution and creep resistance of laser powder-bed fused Al-7Ce-8Mg (wt%)

The solidification microstructure and the aging- and creep-resistances of a laser powder-bed fused (LPBF) hypoeutectic Al-7.3Ce-7.7Mg (wt%) alloy were investigated. Optimized process parameters allowed to produce specimens with > 99.7% relative density and high hardness (~1650 MPa), without solidification cracking despite a relatively coarse grain size (~ 30 µm). Two distinct solidification microstructures are observed within the solidified melt pools: (i) eutectic α-Al(Mg) and Al 13 CeMg 6 (a metastable phase) at the bottom pool region, and (ii) eutectic α-Al(Mg) and Al 11 Ce 3 (a stable phase) precipitates at the top pool region. The high hardness is predominantly attributed to Orowan strengthening and load-transfer effects from the Ce-rich precipitates, but solid-solution hardening from Mg is also quite pronounced, as most Mg resides in α-Al. Aging at 325 or 400 °C causes a continuous, slow hardness drop, but 85–90% of the initial hardness is retained after over 1000 h aging, consistent with the observation that the Ce-rich precipitates within the grains show very sluggish coarsening, making the alloy highly resistant to aging. The alloy exhibits two creep regimes at 300 ºC. At stresses below 18–20 MPa, diffusional creep is operating with signs of grain-boundary sliding inhibition due to Ce-rich precipitates at grain boundaries. At higher stresses, dislocation climb with either stress-invariant or stress-dependent subgrain structure is dominant, with additional load-transfer contributions and possibly a threshold stress due to dislocation-precipitate interactions. The alloy also exhibits much lower steady-state strain rates (e.g., two orders of magnitude lower at 20 MPa) as compared to a compositionally-similar, but conventionally-cast Al-Ce-Mg alloy with much coarser microstructure, demonstrating that LPBF Al-7.3Ce-7.7Mg alloy – because of its fine precipitates and despite its fine grain size - is well suited for long-term uses under stress at 300 ºC.

Microstructure and Corrosion Properties of Wire Arc Additively Manufactured Multi-Trace and Multilayer Stainless Steel 321

Because low thermal conductivity and high viscosity are common characteristics of austenitic steel, it is easy to cause a large amount of heat accumulation in the chip area, resulting in tool edge collapse or wear, and the traditional preparation method is unsuitable for preparing large and complex austenitic steel components. Wire + arc additive manufacturing (WAAM) provides a great application value for austenitic stainless steel because it can solve this problem. The cold metal transfer (CMT)-WAAM system with good control of heat input was used to fabricate the multi-trace and multilayer stainless steel 321 (SS 321) workpiece in this study. The microstructure and corrosion properties of the SS 321 workpiece were observed and compared with those of an SS 321 sheet. The results showed that the microstructure of the SS 321 workpiece from top to bottom was regularly and periodically repeated from the overlapping remelting zone, inter-layer remelting zone, and primary melting zone. There was white austenite matrix and black ferrite, and a small amount of skeleton and worm ferrite was distributed on the white austenite matrix. The average hardness value from the top to the bottom region was approximately uniform, indicating that the workpiece had good consistency. The corrosion properties in 0.5 mol/L H2SO4 solutions were compared between the SS 321 workpiece and the SS 321 sheet. The results showed that the corrosion properties of the top region of the workpiece were better than that of the middle and bottom part, and the corrosion properties of the SS 321 workpiece were better than that of the SS 321 sheet.

Elevated Temperature Baseplate Effect on Microstructure, Mechanical Properties, and Thermal Stress Evaluation by Numerical Simulation for Austenite Stainless Steel 316L Fabricated by Directed Energy Deposition

In the present study, the effect of material deposition at the elevated temperature baseplate on the microstructure and mechanical properties was investigated and correlated to the unique thermal history by using numerical simulation. Numerical results agreed well with the experimental results of microstructure and mechanical properties. Numerical results revealed a significant decrease in temperature gradient and a 40% decrease in thermal stress due to material deposition on the elevated temperature baseplate. The reduced thermal stress and temperature gradient resulted in coarser grain features, which in turn led to a decrease in hardness and tensile strength, especially for the bottom region near the baseplate. Meanwhile, no significant effect could be found for ductility. In addition, an elevated temperature baseplate promoted less heterogeneity in hardness and tensile properties along the building direction. The current work demonstrates a collective and direct understanding of the baseplate preheating effect on thermal stress, microstructure and mechanical properties and their correlations, which is believed beneficial for the better utilization of baseplate preheating positive effects.

Layer-by-layer analysis: tribological behaviour of Ni60A coating on copper substrate prepared by plasma cladding

To further clarify the characteristics of plasma-cladded Ni60A coating on copper, the microstructure and wear behavior were analyzed layer by layer. Along the depth direction, the coating can be divided into three regions according to the difference of microstructure: upper, middle and bottom. The phase composition in different regions was the same (including γ-(Cu, Fe, Ni), Cr23C6, CrB and Ni3Si), and there was no obvious difference in the volume fraction of strengthening phases (Cr23C6 and CrB). Due to the stronger load-bearing capacity of larger-size strengthening phases, the wear resistance of middle region was slightly higher than that of upper region. However, the high copper content in bottom region led to a decrease in hardness and resistance to plastic shear, which significantly reduced the wear resistance (2.3 times lower than upper region). Chemical composition had a greater impact on the wear resistance than size and distribution uniformity of strengthening phases.

Characterization of a low-alloy steel component produced with wire arc additive manufacturing process using metal-cored wire

Abstract In this study, a low-alloy steel component was manufactured using specially produced E70C-6M class of metal-cored welding wire according to AWS A5.18 standard for the WAAM process. The manufactured low-alloy steel component was first subjected to radiographic examination to detect any weld defect. Uniaxial tensile tests were conducted for the bottom, middle and upper regions. The micro-hardness tests were performed parallel to the deposition direction. The results show that microstructures varied from base metal to the face region of the WAAM component, including the bottom, middle and top sections. The bottom region showed lamellar structures; the middle and upper region presented equiaxed ferrite structure with a small amount of grain boundary pearlites and the face region displayed a mix of equiaxed and lamellar structures of ferrites. The yield and ultimate tensile strengths of the top, middle, and bottom regions exhibited similar results varying between 370 MPa and 490 MPa, respectively. In contrast, the top region showed an elongation value about 15% higher than other regions. Moreover, the yield and ultimate tensile strength for WAAM-produced component were found to be 14% and 24% lower than the multiple-pass all-weld metal of E70C-6M class of metal-cored wire.

Active Flow Control of Supersonic Jet Using Streamwise Pulsed Blowing

The present study investigates a novel control strategy to create a sweeping oscillatory jet using fluidic actuation principle. A supersonic underexpanded primary jet issued into a suddenly expanding duct is oscillated by giving cyclic pulsed secondary jet blowing in the top and bottom step regions of the suddenly expanding duct. The current study employs the bistable nature of jet expansion seen in a suddenly expanding duct for the jet oscillation. The cyclic perturbations (pulsed secondary jet blowing) given in the streamwise direction switch the direction of the asymmetric jet expansion of the underexpanded primary supersonic jet to the top and bottom wall alternatively, thereby creating an oscillatory supersonic jet. It is found that the switching of the direction of the primary jet to any one wall is caused by the Coanda effect produced by the secondary jet issued in the corresponding wall side. The results show that the primary jet quickly responds to the secondary jet perturbations and that the supersonic primary jet oscillation frequency nearly matches secondary jet perturbation frequency. A parametric study to investigate the jet oscillation characteristics with various secondary jet oscillation frequencies and mass flow rate ratios are also being carried out in the present study. It is found that the jet oscillation frequency increases with increase in the secondary jet pulsation frequency. The jet deflection is found to increase with increase in the secondary jet to primary jet mass flow ratio (blowing ratio) up to a critical limit, after which the increment in jet deflection ceases due to the restrictions imposed by the duct geometry.