Subsonic Propulsion System Installation Analysis and Optimization

1991 ◽  
Author(s):  
J. L. Colehour ◽  
B. W. Farquhar ◽  
J. E. Gengler ◽  
T. A. Reyhner
Keyword(s):  
Potential Flow ◽  
Low Cost ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Simulation Method ◽  
Inviscid Flow ◽  
Wave Drag ◽  
Propulsion System ◽  
Design Development ◽  
Improved Performance

Computational fluid dynamics (CFD) now allows analysis of propulsion system installations on subsonic transports to an extent that many configuration decisions can be made without testing. The methods discussed here utilize low-cost potential flow methods to predict inviscid flow characteristics and utility methods to model geometry, generate computational mesh, estimate wave drag, and perturb geometry in ways that promise improved performance. Jet plume effects are included in the potential flow analysis by means of a plume simulation method. Wave drag predictions yield levels of drag that are consistent with wind tunnel results, and, through contour optimization, wave drag for a trial propulsion installation geometry was reduced by about 50%. We conclude that through the use of methods such as these, many propulsion system installation design decisions can be made by analysis relatively quickly, which should lead to reduced design development time and cost.

Design of a Nonlinear Adaptive Controller for an Electrohydraulic Actuator1

1998 ◽  
Vol 123 (3) ◽  
pp. 449-456 ◽  
Author(s):  
K. Ziaei ◽  
N. Sepehri
Keyword(s):  
Low Cost ◽  
Dead Zone ◽  
Flow Characteristics ◽  
Adaptive Controller ◽  
Recursive Least Squares ◽  
Plant Model ◽  
Low Performance ◽  
Improved Performance ◽  
And Performance ◽  
Model Reference Adaptive

This paper presents a new implementation of indirect model reference adaptive (MRA) control scheme for positioning of hydraulic actuators that operate by low-cost proportional valves. A proper linear discrete-time plant model is used which has dead-time and no zeros, eliminating the possibility of unstable pole-zero cancellation. The robustness of the parameter adaptation is achieved by employing the recursive least-squares algorithm in combination with a dead-zone in the adaptive law. It is shown that while the controller is adequate for hydraulic valves with linear flow characteristics, it exhibits low performance in the presence of deadband and nonlinear orifice opening characteristics of low-cost proportional valves. The linear plant model is therefore augmented by adding a static nonlinearity. The resulting nonlinear MRA controller is shown to have improved performance over its linear counterpart. Step-by-step experiments are presented to confirm the effectiveness and performance improvement of the proposed method.

Unsteady Flow Analysis Around an Elliptic-Bladed Savonius-Style Wind Turbine

2014 ◽  
Author(s):  
Abhisek Banerjee ◽  
Sukanta Roy ◽  
Prasenjit Mukherjee ◽  
Ujjwal K. Saha
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Low Cost ◽  
Turbine Blades ◽  
Flow Analysis ◽  
Experimental Studies ◽  
Flow Characteristics ◽  
Small Scale ◽  
Circular Design

Although considerable progress has already been achieved in the design of wind turbines, the available technical designs are not yet adequate to develop a reliable wind energy converter especially meant for small-scale applications. The Savonius-style wind turbine appears to be particularly promising for the small-scale applications because of its design simplicity, good starting ability, insensitivity to wind directions, relatively low operating speed, low cost and easy installation. However, its efficiency is reported to be inferior as compared to other wind turbines. Aiming for that, a number of investigations have been carried out to increase the performance of this turbine with various blade shapes. In the recent past, investigations with different blade geometries show that an elliptic-bladed turbine has the potential to harness wind energy more efficiently. In view of this, the present study attempts to assess the performance of an elliptic-bladed Savonius-style wind turbine using 2D unsteady simulations. The SST k-ω turbulence model is used to simulate the airflow over the turbine blades. The power and torque coefficients are calculated at rotating conditions, and the results obtained are validated with the wind tunnel experimental data. Both the computational and experimental studies indicate a better performance with the elliptical blades. Further, the present analysis also demonstrates improved flow characteristics of the elliptic-bladed turbine over the conventional semi-circular design.

Advancing Electronic Technology Impact on Integrated Propulsion/Airframe Controls Design and Development

1983 ◽  
Author(s):  
J. Houchard ◽  
C. Carlin ◽  
E. Tjonneland
Keyword(s):  
Integrated Control ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Propulsion System ◽  
Advanced Technology ◽  
Control Laws ◽  
Digital Electronics ◽  
Technology Age ◽  
Flight Controls ◽  
Aircraft Controls

Many exciting opportunities to enhance aircraft performance, cost and reliability/availability are rapidly becoming available to the propulsion system designer, with use of digital electronics, information/sensor sharing between airframe systems, and integrated functional designs for propulsion and aircraft flight controls. The propulsion engineer must become an active participant in this area to take full advantage of the advanced technology. In this endeavor, he is faced with the task, which seems to occur all so frequently in a rapidly advancing technology age, of developing new working tools and approaches not normally part of the propulsion engineers experience. A discussion is presented of some key technologies available to the propulsion designer, such as digital electronics, serial data buses, analytical redundancy and avionics standards. Analytical tools in computational fluid flow analysis and modern control theories are reviewed. These tools can be utilized to provide the analytical understanding of the flow characteristics of the propulsion system and to develop the optimal control laws for multivariable, integrated control systems. A design methodology for integrating the propulsion control system with the aircraft controls and avionics systems is presented. The required simulation facilities necessary for the development and checkout of integrated systems are described with examples of their use in advanced research projects.

Influence of Gas Condensability on Labyrinth Seal's Sealability

2014 ◽  
Vol 575 ◽  
pp. 355-362 ◽  
Author(s):  
Jie Jiang ◽  
Yi Yong Yang ◽  
Yong Jian Li ◽  
Wei Feng Huang
Keyword(s):  
Low Cost ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Labyrinth Seal ◽  
Rotating Fluid ◽  
Fluid Machinery ◽  
Leakage Loss ◽  
Labyrinth Seals ◽  
Fluid Flow Characteristics ◽  
Compressible Gas

Labyrinth seals are widely used in rotating fluid machinery, due to its simplicity, low-cost and reliability. In this paper, the effect of cavities on leakage loss in straight-through labyrinth seals are studied by changing gas condensability. The fluid flow characteristics through straight-through labyrinth seals are obtained by using viscous flow analysis along with a RNG k-ε turbulence model. The numerical calculation and various gas pressure is that leakage of compressible gas is greater than that of incompressible gas. The result is investigated by the heating effect of labyrinth seal and density characteristics of compressible gas.

New Simplified Low Cost Simulation Method for SME Manufacturing System

2015 ◽  
Vol 9 (2) ◽  
pp. 206
Author(s):  
Tawfik Benabdallah ◽  
Nor Nait Sadi ◽  
Mustapha Kamel Abdi
Keyword(s):  
Manufacturing System ◽  
Low Cost ◽  
Simulation Method ◽  
Cost Simulation

VISCOUS POTENTIAL FLOW ANALYSIS OF STRESS-INDUCED CAVITATION IN AN APERTURE FLOW

2006 ◽  
Vol 16 (7) ◽  
pp. 763-776 ◽  
Author(s):  
T. Funada ◽  
J. Wang ◽  
Daniel D. Joseph
Keyword(s):  
Potential Flow ◽  
Flow Analysis ◽  
Viscous Potential Flow

Performance of lamella clarifiers for juice and syrup clarification

2017 ◽  
pp. 144-150
Author(s):  
Peter W. Rein ◽  
M. Getaz ◽  
A. Raghunandan ◽  
N. du Pleissis ◽  
H. Saleh ◽  
...  
Keyword(s):  
Residence Time ◽  
Flow Characteristics ◽  
Preliminary Test ◽  
Practical Experience ◽  
Operating Costs ◽  
Capital Costs ◽  
Computational Fluid Dynamics Cfd ◽  
Improved Performance ◽  
Work Done ◽  
Good Flow

A new design for syrup and juice clarifiers is presented. The design takes advantage of the considerably improved performance of clarifiers incorporating lamella plates, and the reasons for the improvement are outlined. Computational fluid dynamics (CFD) work done to simulate the performance is summarised. This design enables the residence time to be dramatically reduced and the simplified design leads to cheaper and better clarifiers. Practical experience with factory scale units is described, confirming the good flow characteristics. The results of preliminary test work on a factory syrup clarifier are presented, which is also shown to operate efficiently as a phosphatation clarifier. In addition the performance of a full-scale juice clarifier has been evaluated and compared with the performance of a Rapidorr clarifier. This work confirms the considerable advantages which this type of design provides, in realising substantial reductions in residence time, capital costs and operating costs.

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