Experimental Investigation of Propeller Performance with Propeller Surface Corrugations

2021 ◽  
pp. 39-43
Author(s):  
S. Gowtham Prabhu ◽  
Azhagarasan S. ◽  
Pavithra K. ◽  
Sasi G.
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Internal Combustion Engines ◽  
Leading Edge ◽  
Cost Effective ◽  
Primary Component ◽  
Humpback Whales ◽  
Combustion Engines ◽  
Propeller Performance ◽  
Selection Of

The propeller is the primary component of flying vehicles powered by electric motors, internal combustion engines, and turboprops for producing thrust. A propeller thrust is produced in the engine by effective spinning of the propeller through air for cost-effective and environmental friendly flight. Natural flyers like birds as well as aquatic animals like humpback whales effectively use its wings and flippers with its surface features for capturing its prey and escaping from their enemies. As part of this work, corrugations are established in the leading edges or in the suction surfaces of the propeller to modify the flow field prevailing over there. Because of the flow field, the surface corrugations or leading edge corrugations energize the boundary layer in the surfaces of the propeller by counter-rotating vortices which, in turn, delays the separation of the boundary layer from the surface. The performance parameters of the propeller such as thrust, torque, propeller efficiency, power consumption etc., are measured using propeller test rig. Depending on the location of surface or leading corrugations, the variations in the performance of the propeller are investigated for further optimization on the selection of better propeller to the applications of UAVs operating at low Reynolds No.

Computational Design and Experimental Evaluation of Using a Leading Edge Fillet on a Gas Turbine Vane

2001 ◽  
Author(s):  
G. A. Zess ◽  
K. A. Thole
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Pressure Gradient ◽  
Gas Turbine ◽  
Total Pressure ◽  
Guide Vane ◽  
Leading Edge ◽  
Field Measurements ◽  
Computational Design ◽  
Horseshoe Vortex

With the desire for increased power output for a gas turbine engine comes the continual push to achieve higher turbine inlet temperatures. Higher temperatures result in large thermal and mechanical stresses particularly along the nozzle guide vane. One critical region along a vane is the leading edge-endwall juncture. Based on the assumption that the approaching flow to this juncture is similar to a two-dimensional boundary layer, previous studies have shown that a horseshoe vortex forms. This vortex forms because of a radial total pressure gradient from the approaching boundary layer. This paper documents the computational design and experimental validation of a fillet placed at the leading edge-endwall juncture of a guide vane to eliminate the horseshoe vortex. The fillet design effectively accelerated the incoming boundary layer thereby mitigating the effect of the total pressure gradient. To verify the CFD studies used to design the leading edge fillet, flow field measurements were performed in a large-scale, linear, vane cascade. The flow field measurements were performed with a laser Doppler velocimeter in four planes orientated orthogonal to the vane. Good agreement between the CFD predictions and the experimental measurements verified the effectiveness of the leading edge fillet at eliminating the horseshoe vortex. The flowfield results showed that the turbulent kinetic energy levels were significantly reduced in the endwall region because of the absence of the unsteady horseshoe vortex.

The boundary layer over an impulsively started flat plate

1969 ◽  
Vol 310 (1502) ◽  
pp. 401-414 ◽  
Keyword(s):  
Boundary Layer ◽  
Leading Edge ◽  
Surface Shear Stress ◽  
Unsteady State ◽  
Similarity Condition ◽  
Surface Shear ◽  
Boundary Layer Problem ◽  
Independent Variables ◽  
Selection Of ◽  
Layer Problem

A numerical solution has been obtained for the development of the flow from the initial unsteady state described by Rayleigh to the ultimate steady state described by Blasius. The usual formulation of the problem in two independent variables is dropped, and three independent variables, in space and time, are reverted to. The boundary-layer problem is unconventional in that the boundary conditions are not completely known. Instead, it is known that the solution should satisfy a similarity condition, and use is made of this to obtain a solution by iteration. A finite-difference technique of a mixed, explicit-implicit, type is employed. The iteration converges rapidly. It is terminated where the maximum errors are estimated to be about 0.04%. A selection of the results for the velocity profiles and the surface shear stress is presented. One striking feature is the rapidity of the transition from the Rayleigh to the Blasius state. The change is practically complete, at a given station on the plate, by the time the plate has moved a distance equal to four times the distance from the station to the leading edge of the plate.

Prediction of Steady Propeller Performance with a Nonlinear Slipstream and Boundary-Layer Effect

1995 ◽  
Vol 39 (04) ◽  
pp. 297-312
Author(s):  
You-Hua Liu
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Leading Edge ◽  
Viscous Drag ◽  
Viscous Effects ◽  
Lattice Method ◽  
Suction Force ◽  
Layer Effect ◽  
Dimensional Boundary ◽  
Propeller Performance

Both slipstream deformation and viscous effects are factors that affect the performance of a rotating marine propeller but neither of them has been properly treated in most of the current lifting-surface methods and surface panel theories. With the introduction of a partial roll-up wake model that is flexible to various cases of propeller geometry and loading condition, this paper presents a vortex-lattice method that can improve propeller performance prediction especially at heavy loading conditions. Some observations on the calculation of the blade leading-edge suction force and how to deduct it to account for the viscous drag increasing are given. The scale effect of propeller performance can be readily predicted by the quasi-three-dimensional boundary-layer calculation presented in this paper. Some patterns of the limiting streamlines on blade surfaces are also illustrated and compared with experimental results.

Non-Axisymmetric Flow Structure in Vaneless Diffuser of Centrifugal Compressor for Turbochargers

2012 ◽  
Author(s):  
Chuanjie Lan ◽  
Xinqian Zheng ◽  
Hideaki Tamaki
Keyword(s):  
Flow Field ◽  
Flow Structure ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Internal Combustion Engines ◽  
Combustion Engines ◽  
Vaneless Diffuser ◽  
Asymmetric Flow ◽  
Oil Flow ◽  
Flow Visualizations

Turbocharger technology is widely used in internal combustion engines. With the downsizing of internal combustion engines and the introduction of strict emission regulations, there is urgent demand for turbochargers featuring centrifugal compressors with a wide flow range. The flow in a centrifugal compressor of a turbocharger is non-axisymmetric due to the inherent asymmetry of the discharge volute. The asymmetric flow field inside the diffuser has great influence on the performance of centrifugal compressor. In order to develop a flow control method that facilitates a wider flow range of turbocharger compressors, further understanding of the asymmetric flow structure is very important. The main subject of this study is to reveal the asymmetrical characteristics of the flow field in the vaneless diffuser of a centrifugal compressor followed by a volute. Oil flow visualizations and numerical simulations were used. The results of the numerical simulations are consistent with that of the oil flow visualizations near choke and at designed flow rate. The results show that a “dual-zone mode” asymmetric flow structure exists near the shroud of the vaneless diffuser at near choke condition. A bifurcation point at the volute tongue that divides the flow and creates two distinct flow patterns was found. The asymmetry of the flow structure near the hub was much less significant than that near the shroud. At the design flow rate, asymmetric flow patterns are found neither near shroud nor near hub. At near surge condition, the pattern of the oil flow traces near the shroud is very different from those near choke.

scholarly journals Application of Vortex Generators in Flow Control of the Inlet

1985 ◽  
Author(s):  
Chen Xiao ◽  
Fang Liang-Wei
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Flow Separation ◽  
Dynamic Performance ◽  
Low Pressure ◽  
Transverse Flow ◽  
Vortex Generators ◽  
Flow Losses ◽  
Subsonic Diffuser ◽  
Selection Of

This paper introduces the features of using co-rotating vortex generators for controlling boundary layer and flow field in the inlet without flow separation. The principles of the arrangements of the blades and selection of constructional parameters of the generators that are applied to create the transverse flow between the high and low pressure regions and to reduce the secondary flow losses are analysed. The experimental results show that when the appropriate parameters of the co-rotating vortex generators are chosen for the inlet subsonic diffuser with apparent high and low pressure regions, not only the nonuniformity of the flow field is greatly improved but also the dynamic performance of the flow at exit is slightly improved.

The selection of cooling fluids for internal combustion engines operating at low temperatures

Polar Record ◽  
1955 ◽  
Vol 7 (50) ◽  
pp. 370-379
Author(s):  
E. S. Sellers
Keyword(s):  
Heat Supply ◽  
Internal Combustion Engines ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Combustion Engines ◽  
Heat Engines ◽  
The Difference ◽  
Materials Used ◽  
Lower Temperature ◽  
Selection Of

Internal combustion engines, in common with all heat engines, derive their capacity for work from a cycle of operations which comprises the supply of heat at a high temperature followed by the rejection of heat at a much lower temperature. The difference between the two quantities of heat represents the maximum amount of energy which can be converted into useful work. In the familiar piston-type internal combustion engine, the heat supply is maintained by burning a suitable fuel in air, and heat is rejected largely in the exhaust gases. With heat engines in general, it is true that the higher the temperature of the heat supply, the greater the efficiency of the engine. There are, however, limitations to the temperature at which an engine can operate. These are imposed by the properties of the materials used in its construction, and by the necessity of maintaining satisfactory lubrication in all circumstances.

Experimental and Computational Investigation of a Simplified Geometry of an Engine/Pylon/Wing Installation at High-Lift Flight Conditions

2013 ◽  
Author(s):  
Matthieu Lucas ◽  
Yannick Bury ◽  
Cyril Bonnaud ◽  
Laurent Joly
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Longitudinal Vortex ◽  
Vortical Flow ◽  
Stream Velocity ◽  
Piv Measurements ◽  
Comprehensive Knowledge ◽  
Oil Flow

This paper focuses on the numerical and experimental characterization of the vortex structures that develop along a simplified geometry of a wing equipped with pylon-mounted engine at low speed/high angle of attack flight conditions. In these conditions, the presence of the engine installation under the wing induces a complex and unsteady vortical flow field at the nacelle/pylon/wing junctions which interacts with the upper wing boundary layer and leads to a drop of aircraft performances. In order to gain insight into the physics driving this interaction, it is proposed to isolate its fundamental mechanisms by simplifying the problem. The parameters of interest that led to the simplification of the model are first described. As a first step into a more comprehensive knowledge of this complex physics, this study is initially conducted at a Reynolds number of 200000, based on the chord wing and on the free stream velocity. Two configurations of angle of attack and sideslip angles (α = 8°/β = 0° and α = 8°/β = 30°) have been investigated. This work relies on unsteady RANS computations, oil flow visualizations and 3C-PIV measurements. The vortex dynamics thus produced is described in terms of vortex core position, intensity, size and turbulent intensity thanks to a vortex tracking post-processing algorithm. In addition, the analysis of the velocity flow field obtained from the PIV measurements will highlight the influence of the longitudinal vortex issued from the pylon/wing junction on the separation process of the boundary layer near the upper wing leading-edge.

scholarly journals A Review of Recent Research on the Use of R1234yf as an Environmentally Friendly Fluid in the Organic Rankine Cycle

2021 ◽  
Vol 13 (11) ◽  
pp. 5864
Author(s):  
Juan J. García-Pabón ◽  
Dario Méndez-Méndez ◽  
Juan M. Belman-Flores ◽  
Juan M. Barroso-Maldonado ◽  
Ali Khosravi
Keyword(s):  
Internal Combustion Engines ◽  
Organic Rankine Cycle ◽  
Environmentally Friendly ◽  
Electrical Energy ◽  
Rankine Cycle ◽  
Residual Energy ◽  
Combustion Engines ◽  
Medium Temperature ◽  
Working Fluids ◽  
Selection Of

ORC technology is one of the most promising technologies for the use of residual energy in the generation of electrical energy, offering simple and environmentally friendly alternatives. In this field, the selection of working fluids plays an important role in the operation of the cycle, whether in terms of the energy efficiency or the minimization of environmental impacts. Therefore, in this paper, a comprehensive review is presented on the use of R1234yf refrigerant and its mixtures as working fluids in ORC systems. These fluids are used in low- and medium-temperature applications for the use of residual energy generated from solar energy, geothermal energy, and internal combustion engines. It was concluded that R1234yf and its mixtures are competitive as compared with conventional refrigerants used in ORC.

FLOW FIELD ANALYSIS OF AN AUTOMOTIVE MIXED FLOW TURBOCHARGER TURBINE

2015 ◽  
Vol 77 (8) ◽  
Author(s):  
M. H. Padzillah ◽  
S. Rajoo ◽  
R. F. Martinez-Botas
Keyword(s):  
Optimum Condition ◽  
Flow Field ◽  
Internal Combustion Engines ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Tip Clearance ◽  
Field Analysis ◽  
Turbine Stage ◽  
Mixed Flow ◽  
Geometrical Properties

Traditionally, the turbocharger has been an essential tool to boost the engine power especially the diesel engine. However, in recent years it is seen as an enabling technology for engine downsizing of all internal combustion engines. The use of mixed flow turbine as replacement for radial turbine in an automotive turbocharger has been proven to deliver better efficiency at high loading conditions. Furthermore, the use vanes that match the geometrical properties at the turbine leading edge could further increase its performance. However, improvement on the overall turbocharger performance is currently limited due to lack of understanding on the flow feature within the turbine stage. Therefore, the use of validated Computational Fluid Dynamics (CFD) in resolving this issue is necessary. This research attempts to provide description of flow field within the turbocharger turbine stage by plotting velocity and pressure contours at different planes. To achieve this aim, a numerical model of a full stage turbocharger turbine operating at 30000rpm under its optimum condition (pressure ratio of 1.3) is developed and validated. Results indicated strong tip-clearance flow downstream of the turbine mid-chord. Evidence of flow separations at the turbine leading edge are also seen despite turbine operating at its optimum condition.

A Numerical Investigation of Combustion Chamber Geometry Effects on Natural Gas Direct Injection Properties in a SI Engine With Centrally Mounted Multi-Hole Injector

2012 ◽  
Author(s):  
Bijan Yadollahi ◽  
Masoud Boroomand
Keyword(s):  
Numerical Model ◽  
Natural Gas ◽  
Flow Field ◽  
Combustion Chamber ◽  
Internal Combustion Engines ◽  
Gasoline Engine ◽  
Direct Injection ◽  
Internal Combustion ◽  
Combustion Engines ◽  
Validity Of Results

Due to the vast resources of natural gas (NG), it has emerged as an alternative fuel for SI internal combustion engines in recent years. The need to have better fuel economy and less emission especially that of greenhouse gases has resulted in development of NG fueled engines. Direct injection of natural gas into the cylinder of SI internal combustion engines has shown great potential for improvement of performance and reduction of engine emissions especially CO2 and PM. Direct injection of NG into the cylinder of SI engines is rather new thus the flow field phenomena and suitable configuration of injector and combustion chamber geometry has not been investigated completely. In this study a numerical model has been developed in AVL FIRE software to perform investigation of direct natural gas injection into the cylinder of spark ignition internal combustion engines. In this regard, two main parts have been taken into consideration aiming to convert an MPFI gasoline engine to direct injection NG engine. In the first part of study multidimensional numerical simulation of transient injection process, mixing and flow field have been performed via different validation cases in order to assure the numerical model validity of results. Adaption of such a modeling was found to be a challenging task because of required computational effort and numerical instabilities. In all cases present results were found to have excellent agreement with experimental and numerical results from literature. In the second part, using the moving mesh capability, the validated model has been applied to methane injection into the cylinder of a direct injection engine. Five different piston head shapes have been taken into consideration in investigations. An inwardly opening multi-hole injector has been adapted to all cases. The injector location has been set to be centrally mounted. The effects of combustion chamber geometry have been studied on mixing of air-fuel inside cylinder via quantitative and qualitative representation of results. Based on the results, suitable geometrical configuration for a NG DI engine has been discussed.

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