scholarly journals Improved Vane-Island Diffusers at High Swirl

1982 ◽  
Author(s):  
Tong Jiang ◽  
Tah-teh Yang
Keyword(s):  
Experimental Investigation ◽  
Pressure Loss ◽  
Previous Investigation ◽  
Pressure Rise ◽  
Leading Edge ◽  
Loss Coefficient ◽  
Flow Coefficient ◽  
Percent Reduction ◽  
Pressure Loss Coefficient ◽  
Coefficient Versus

The results of an experimental investigation of the performance of vane-island diffusers at high swirl [λ = 9] are presented in this paper. These results show the advantage of the 14-vane versus several 8-vane configurations. Four sets of 14 straight vanes are used in this study as compared to five sets of eight vanes in a previous investigation. The 14-vane configuration results in a 40 percent reduction in pressure loss coefficient below that obtained with eight vane configurations. The lowest loss coefficient obtained in the present investigation is achieved when the vane leading edge is at a radius approximately equal to 1.2 times the diffuser inlet radius. The experimental results are presented in the form of pressure rise versus radial location along the diffuser, diffuser effectiveness versus flow coefficient, and minimum pressure loss coefficient versus flow coefficient.

Development of High-Efficiency Half-Ducted Propeller Fan for Air-Conditioners by Blade Tip Shape Modification

2019 ◽  
Author(s):  
Masashi Yoshikawa ◽  
Hiroyuki Toyoda ◽  
Hisashi Daisaka
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Static Pressure ◽  
Leading Edge ◽  
Loss Coefficient ◽  
Total Pressure Loss ◽  
Trailing Edge ◽  
Pressure Loss Coefficient ◽  
Blade Tip ◽  
Total Pressure Loss Coefficient

Abstract We developed a high-efficiency half-ducted propeller fan to reduce the electric power consumption of the outdoor unit of air conditioner by using computational fluid dynamics (CFD). Total pressure loss coefficient on the cylindrical surface of blade tip started increasing at the middle of the blade, and the region of high total pressure loss coefficient was formed after trailing edge. Therefore, we assumed that decreasing this region helped increasing static pressure efficiency. Limiting stream lines on the pressure surface showed that the flow from leading edge leaked at the middle of the blade tip, so it was assumed that the region of the high total pressure loss coefficient arose from the leakage at the middle of the blade tip. We confirmed that static pressure at the middle of blade tip, which was the leakage point, was low. We assumed that low inward force to the flow caused the leakage. On the other hand, static pressure at trailing edge of the blade tip was high. Therefore, it was found that the inward force could be increased by making the static pressure higher at the meddle of the blade tip. In order to make the static pressure higher at the middle of the blade tip, we attempted to move the maximum camber position of the blade tip from trailing edge side to leading edge side. Calculation results showed leakage at the blade tip decreased and the static pressure efficiency increased by 0.5%. Experimental results showed that the static pressure efficiency increased by 1.7 % and sound pressure level was almost the same. For the above reasons, we found leakage of flow from leading edge could be decreased by adjusting the maximum camber position of the blade tip. Decreasing leakage contributed to increasing static pressure efficiency and decreasing electric power consumption.

An Experimental Investigation of Contoured Leading Edges for Secondary Flow Loss Reduction

2004 ◽  
Author(s):  
Sandor Becz ◽  
Mark S. Majewski ◽  
Lee S. Langston
Keyword(s):  
Secondary Flow ◽  
Pressure Loss ◽  
Total Pressure ◽  
Leading Edge ◽  
Loss Coefficient ◽  
Total Pressure Loss ◽  
Loss Reduction ◽  
Pressure Loss Coefficient ◽  
Flow Loss ◽  
Total Pressure Loss Coefficient

Experimental results are presented which provide mass averaged total pressure loss coefficient measurements for three different turbine airfoil leading edge configurations. A baseline (Langston) configuration, a leading edge bulb, and a leading edge fillet were tested in a large-scale, low aspect ratio, high turning linear cascade. Results show that while the fillet geometry reduced overall loss by approximately 7%, the bulb did not exhibit a loss reduction. For the fillet, overall turning was slightly reduced, while for the bulb turning increased slightly. Thus, the bulb shows potential for increasing airfoil loading without an associated loss penalty. Contour plots of total pressure loss coefficient and vorticity are presented for all geometries and the major differences between each are discussed. Through investigation of pitch averaged loss profiles it is found that the area of greatest reduction differs between the bulb and fillet, leading to the possibility that the mechanisms through which each is affecting the flow may be different. This provides hope that the best features of each may potentially be combined to determine an optimum shape for secondary flow loss reduction.

scholarly journals Effect of Incidence on Secondary Flows in a Linear Turbine Cascade

1994 ◽  
Author(s):  
G. V. Ramana Murty ◽  
N. Venkatrayulu
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Leading Edge ◽  
Loss Coefficient ◽  
Secondary Flows ◽  
Total Pressure Loss ◽  
Turbine Cascade ◽  
Local Loss ◽  
Pressure Loss Coefficient ◽  
Total Pressure Loss Coefficient

The effect of incidence on the generation and growth of secondary flows in a linear turbine cascade was studied in the present investigations using a Variable Density Cascade Tunnel at an exit Mach number of 0.43 and a Reynolds number of 8 × 105. The angles of incidence chosen were +15°, +50, 0°, −5° and −8.5°. The flow field was surveyed at five axial stations from cascade inlet to exit with a view to understanding the development of the secondary flow with the help of the variation of mass averaged total pressure loss coefficient and the contours of local loss coefficients in the pitch and spanwise directions. The total pressure loss coefficient and the net secondary loss coefficient have shown a steady growth along the cascade upto about 74 of the axial chord from the leading edge and thereafter rose very rapidly. The incidence is found to have an effect on the passage vortex and the loss cores due to the inlet boundary layer.

Pressure Loss Coefficient of Impingement Cooled Leading Edge System of a Turbine Blade

1976 ◽  
Vol 98 (4) ◽  
pp. 554-556
Author(s):  
D. K. Mukherjee
Keyword(s):  
Reynolds Number ◽  
Turbine Blade ◽  
Model Test ◽  
Pressure Loss ◽  
Leading Edge ◽  
Loss Coefficient ◽  
Relative Distance ◽  
Pressure Loss Coefficient

The pressure loss coefficient of an impingement cooled system similar to that often used to cool the leading edge of a turbine blade has been determined from model test. The influence of Reynolds number in the range tested is negligible. However, the influence of relative distance of the jet holes from the surface to be cooled is very significant.

Vibration suppression investigation and parametric design of tri-axle straight heavy truck with pitch-resistant hydraulically interconnected suspension

2021 ◽  
pp. 107754632110396
Author(s):  
Fei Ding ◽  
Jie Liu ◽  
Chao Jiang ◽  
Haiping Du ◽  
Jiaxi Zhou ◽  
...  
Keyword(s):  
Surface Area ◽  
Dynamic Load ◽  
Pressure Loss ◽  
Vibration Suppression ◽  
Parametric Design ◽  
Suspension System ◽  
Loss Coefficient ◽  
The Body ◽  
Impedance Matrix ◽  
Pressure Loss Coefficient

The vibration suppression of the proposed pitch-resistant hydraulically interconnected suspension system for the tri-axle straight truck is investigated, and the vibration isolation performances are parametrically designed to achieve smaller body vibration and tire dynamic load using increased pitch stiffness and optimized pressure loss coefficient. For the hydraulic subsystem, the transfer impedance matrix method is applied to derive the impedance matrix. These hydraulic forces are incorporated into the motion equations of mechanical subsystem as external forces according to relationships between boundary flow and mechanical state vectors. In terms of the additional mode stiffness/damping and suspension performance requirements, the cylinder surface area, accumulator pressure, and damper valve’s pressure loss coefficient are comprehensively tuned with parametric design technique and modal analysis method. It is found the isolation capacity is heavily dependent on installation scheme and fluid physical parameters. Especially, the surface area can be designed for the oppositional installation to separately raise pitch stiffness without increasing bounce stiffness. The pressure loss coefficients are tuned with design of experiment approach and evaluated using all conflict indexes with normalized dimensionless evaluation factors. The obtained numerical results indicate that the proposed pitch-resistant hydraulically interconnected suspension system can significantly inhibit both the body and tire vibrations with decreased suspension deformation, and the tire dynamic load distribution among wheel stations is also improved.

The Characteristics Study of Helium-Xenon Mixture in Closed Brayton Cycle for Space Nuclear Reactor Power

2018 ◽  
Author(s):  
Xie Yang ◽  
Lei Shi
Keyword(s):  
Physical Properties ◽  
Pressure Loss ◽  
Nuclear Reactor ◽  
Reactor Power ◽  
Loss Coefficient ◽  
Working Fluid ◽  
System Efficiency ◽  
Pressure Loss Coefficient ◽  
Molar Weight ◽  
Xenon Mixture

Differing from the adoption of helium as working fluid of closed Brayton cycle (CBC) for terrestrial high temperature gas cooled reactor (HTGR) power plants, helium-xenon mixture with a proper molar weight was recommended as working fluid for space nuclear reactor power with CBC conversion. It is essential to figure out how the component of helium-xenon mixture affects the net system efficiency, in order to provide reference for the selection of appropriate cycle working fluid. After a discussion of the physical properties of different helium-xenon mixtures, the related physical properties are studied to analyze their affection on the key parameters of CBC, including adiabatic coefficient, recuperator effectiveness and normalized pressure loss coefficient. Then the comprehensive thermodynamics of CBC net system efficiency is studied in detail considering different helium-xenon mixtures. The physical properties study reveals that at 0.7 MPa and 400 K, the adiabatic coefficient of helium-xenon mixture increases with increased molar weight, from 0.400 (pure helium) to 0.414 (pure xenon), while recuperator effectiveness firstly increases and then decreases with the increase of molar weight, and the normalized pressure loss coefficient increases monotonically with molar weight increases. The thermodynamic analysis results show that the adiabatic coefficient has less effect on the net system efficiency, while the net system efficiency increases with increased recuperator effectiveness, and the net system efficiency decreases with normalized pressure loss coefficient increases. Finally, the mixture of helium-8.6% xenon was adopted as working fluid, instead of pure helium, for ensuring less turbine mechanicals (turbine and compressor) stages, and resulting maximum recuperator effectiveness. At the given cold / hot side temperature of 400 / 1300 K, the net system efficiency can reach 29.18% theoretically.

Rotating Annulus Component Performance Characterisation Based on CFD Analyses

2018 ◽  
Author(s):  
Youming Yuan ◽  
David Hunt
Keyword(s):  
Test Data ◽  
Pressure Loss ◽  
Model Performance ◽  
Internal Flow ◽  
Loss Coefficient ◽  
Performance Data ◽  
Pressure Loss Coefficient ◽  
1D Model ◽  
Torque Coefficient ◽  
Secondary Air

FloMASTER is a 1-D thermo-fluids system simulation tool and its component models depend on the characterisation data of the component performance. Such performance data is mainly based on data banks established from extensive tests exemplified by the books like “Internal Flow” by Miller [1] and “Handbook of Hydraulic Resistance” by Idelchik [2]. One of the key components of the gas turbine secondary air system is the rotating annulus. However, reliable data and correlations for performance characteristics like pressure loss coefficient, torque coefficient, windage and heat transfer for this component are rare and non-existent in the open literature for the case of both walls rotating simultaneously, which is becoming more common in today’s multi-spool military aero engines. To overcome this challenge of lack of reliable performance data and correlations, in this paper the Mentor Graphics 3D CFD tool “FloEFD” is used to model both inner wall rotating and outer wall rotating annulus flow, and to verify the 3D CFD results of performance data in terms of pressure loss coefficient and torque coefficient versus some published test data in the open literature. It is shown that the CFD gives results on pressure loss and torque coefficients that are in good agreement with test data based correlations used in FloMASTER. This demonstrates that 3D CFD can be used as a powerful tool for verifying the existing 1D model, extending the 1D model performance data range and generating new performance data for developing new components where such data is not available from open literature. A future project is to extend this approach to provide performance data for rotating annuli with both walls rotating. Such data will form the basis for developing a new component model for a rotating annulus with both walls rotating.

Optimization of an Axial Turbine Stage for Aerodynamic Inlet Blockage

2011 ◽  
Author(s):  
Mohammad Arabnia ◽  
Vadivel K. Sivashanmugam ◽  
Wahid Ghaly
Keyword(s):  
Pressure Loss ◽  
Suction Side ◽  
Loss Coefficient ◽  
Von Mises Stress ◽  
Optimization Approach ◽  
Design Point ◽  
Pressure Loss Coefficient ◽  
Design Variables ◽  
Blade Shape ◽  
Von Mises

This paper presents a practical and effective optimization approach to minimize 3D-related flow losses associated with high aerodynamic inlet blockage by re-stacking the turbine rotor blades. This approach is applied to redesign the rotor of a low speed subsonic single-stage turbine that was designed and tested in DLR, Germany. The optimization is performed at the design point and the objective is to minimize the rotor pressure loss coefficient as well as the maximum von Mises stress while keeping the same design point mass flow rate, and keeping or increasing the rotor blade first natural frequency. A Multi-Objective Genetic Algorithm (MOGA) is coupled with a Response Surface Approximation (RSA) of the Artificial Neural Network (ANN) type. A relatively small set of high fidelity 3D flow simulations and structure analysis are obtained using ANSYS Workbench Mechanical. That set is used to train and to test the ANN models. The stacking line is parametrically represented using a quadratic rational Bezier curve (QRBC). The QRBC parameters are directly related to the design variables, namely the rotor lean and sweep angles and the bowing parameters. Moreover, it results in eliminating infeasible shapes and in reducing the number of design variables to a minimum while providing a wide design space for the blade shape. The aero-structural optimization of the E/TU-3 turbine proved successful, the rotor pressure loss coefficient was reduced by 9.8% and the maximum von Mises stress was reduced by 36.7%. This improvement was accomplished with as low as four design variables, and is attributed to the reduction of 3D-related aerodynamic losses and the redistribution of stresses from the hub trailing edge region to the suction side maximum thickness area. The proposed parametrization is a promising one for 3D blade shape optimization involving several disciplines with a relatively small number of design variables.

A Study of the Fabrication and Analysis of Micro Diffuser/Nozzles

2003 ◽  
Author(s):  
Kai-Shing Yang ◽  
Ing-Young Chen ◽  
Bor-Yuan Shew ◽  
Chi-Chuan Wang
Keyword(s):  
Reynolds Number ◽  
Friction Factor ◽  
Pressure Loss ◽  
Measured Data ◽  
Loss Coefficient ◽  
Opening Angle ◽  
Velocity Change ◽  
Pressure Loss Coefficient ◽  
Micro Nozzle ◽  
Volumetric Flowrate

In this study, an analysis of the performance of micro nozzle/diffusers is performed and fabrication of the micro nozzle/diffuser is conducted and tested. It is found that the pressure loss coefficient for the nozzle/diffuser decreases with the Reynolds number. At a given Reynolds number, the pressure loss coefficient for nozzle is higher than that of the diffuser due to considerable difference in the momentum change. For the effect of nozzle/diffuser length on the pressure loss coefficient, it is found that the influence is rather small. At a fixed volumetric flowrate, a “minimum” phenomenon of the pressure loss coefficient vs. nozzle/diffuser depth is encountered. This is related to the interactions of velocity change and friction factor. Good agreements of the measured data with the predicted results are found in this study except at a diffuser having an opening angle of 20° . It is likely that the departure of this case to the prediction is due to the separation phenomenon in a larger angle of the diffuser.

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