Effects of Wall Shape on Flow Regimes and Performance in Straight, Two-Dimensional Diffusers

1967 ◽  
Vol 89 (1) ◽  
pp. 151-159 ◽  
Author(s):  
J. J. Carlson ◽  
J. P. Johnston ◽  
C. J. Sagi
Keyword(s):  
Flow Regime ◽  
Performance Prediction ◽  
Prediction Method ◽  
Flow Regimes ◽  
Two Dimensional ◽  
Simple Class ◽  
And Performance

Three diffuser sets (N/W1, held constant in each set) were built and tested for performance and flow regime over a range of total area ratios, AR, which yielded unstalled and stalled flows. At each AR and N/W1, a simple class of convex-inward (trumpet-shaped), straight, and convex-outward (bell-shaped) wall shapes were tested. It is concluded that there is little advantage to be gained by contouring the walls of two-dimensional diffusers. A corollary result shows that the performance prediction method of reference [1] gives good results for unstalled diffusers.

Effects of Nonuniform Inlet Velocity Profiles on Flow Regimes and Performance in Two-Dimensional Diffusers

1969 ◽  
Vol 91 (3) ◽  
pp. 462-474 ◽  
Author(s):  
S. Wolf ◽  
J. P. Johnston
Keyword(s):  
Shear Flows ◽  
Prediction Method ◽  
Flow Regimes ◽  
Velocity Profiles ◽  
Two Dimensional ◽  
Rotational Model ◽  
Inlet Velocity ◽  
The Core ◽  
Uniform Shear ◽  
And Performance

An analytical and experimental study on the effects of large distortions of inlet velocity profiles on flow regimes and performance in diffusers is reported. Experiments are restricted to flow in straight, two-dimensional diffusers with turbulent boundary layers. Systematic data are obtained for two general types of inlet flows: (1) simple, uniform shear flows in the core, and (2) severely nonuniform shear flows of the wake, jet, and step-shear type. For uniform shear flows a first order prediction method based on inviscid rotational flow and the boundary layer blockage concept is developed and verified for diffusers operating in the unstalled flow regime. For nonuniform shear flows the inviscid rotational model is shown to predict performance trends better than the irrotational model; however, the inviscid rotational model is inadequate as a precise prediction method because no account is taken of mixing in the core region. Geometry and performance correlations for peak pressure recovery (at constant N/W1) are also established.

Mycielski Based 2d-Predictive Image Coding Algorithm

2016 ◽  
Vol 850 ◽  
pp. 144-151 ◽  
Author(s):  
Mehmet Fidan ◽  
Ömer Nezih Gerek
Keyword(s):  
Image Coding ◽  
Predictive Coding ◽  
Prediction Method ◽  
Physical Distance ◽  
Prediction Algorithm ◽  
Two Dimensional ◽  
Two Dimensional Image ◽  
Past Data ◽  
And Performance ◽  
Definition Of

The Mycielski method is a prospering prediction algorithm which is based on searching and finding largest repeated binary patterns. It uses infinite-past data to devise a rule based prediction method on a time series. In this work, a novel two-dimensional (image processing) version of the Mycielski algorithm is proposed. Since the dimensionality definition of “past” data increases in two-dimensional signals, the proposed algorithm also needs to handle how the boundaries of the pixel cliques are iteratively extended in the neighborhood of a current pixel. The clique extension invokes novel similarity search strategies that depend on the chosen physical distance metric. The proposed prediction algorithm is used for predictive image compression and performance comparisons with other predictive coding methods are presented.

scholarly journals Performance Prediction of Cross-Flow Fans Using Mean Streamline Analysis

2005 ◽  
Vol 2005 (2) ◽  
pp. 112-116 ◽  
Author(s):  
Jae-Won Kim ◽  
Eun Young Ahn ◽  
Hyoung Woo Oh
Keyword(s):  
Performance Prediction ◽  
Cross Flow ◽  
Prediction Method ◽  
General Purpose ◽  
Operating Conditions ◽  
Performance Predictions ◽  
Performance Curves ◽  
Mean Streamline Analysis ◽  
And Performance ◽  
Cross Flow Fan

This paper presents the mean streamline analysis using the empirical loss correlations for performance prediction of cross-flow fans. Comparison of overall performance predictions with test data of a cross-flow fan system with a simplified vortex wall scroll casing and with the published experimental characteristics for a cross-flow fan has been carried out to demonstrate the accuracy of the proposed method. Predicted performance curves by the present mean streamline analysis agree well with experimental data for two different cross-flow fans over the normal operating conditions. The prediction method presented herein can be used efficiently as a tool for the preliminary design and performance analysis of general-purpose cross-flow fans.

Sizing and Performance-Prediction Method for Rotary-Wing Ejector Nozzles

2009 ◽  
Vol 46 (3) ◽  
pp. 951-961 ◽  
Author(s):  
Alex M. Moodie ◽  
Daniel P. Schrage ◽  
Lakshmi N. Sankar ◽  
Mark H. Waters
Keyword(s):  
Performance Prediction ◽  
Prediction Method ◽  
And Performance ◽  
Rotary Wing

scholarly journals A design and performance prediction method for small horizontal axis wind turbines and its application

AIMS Energy ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 1043-1066
Author(s):  
Stephen K. Musau ◽  
◽  
Kathrin Stahl ◽  
Kevin Volkmer ◽  
Nicholas Kaufmann ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wind Turbines ◽  
Performance Prediction ◽  
Prediction Method ◽  
Drive Train ◽  
Performance Characteristics ◽  
Speed Ratio ◽  
Battery Charger ◽  
Tip Speed Ratio ◽  
And Performance

<abstract> <p>The paper deals with small wind turbines for grid-independent or small smart grid wind turbine systems. Not all small turbine manufacturers worldwide have access to the engineering capacity for designing an efficient turbine. The objective of this work is to provide an easy-to-handle integrated design and performance prediction method for wind turbines and to show exemplary applications.</p> <p>The underlying model for the design and performance prediction method is based on an advanced version of the well-established blade-element-momentum theory, encoded in MATLAB™. Results are (i) the full geometry of the aerodynamically profiled and twisted blades which are designed to yield maximum power output at a given wind speed and (ii) the non-dimensional performance characteristics of the turbine in terms of power, torque and thrust coefficient as a function of tip speed ratio. The non-dimensional performance characteristics are the basis for the dimensional characteristics and the synthesis of the rotor to the electric generator with its load.</p> <p>Two parametric studies illustrate typical outcomes of the design and performance prediction method: A variation of the design tip speed ratio and a variation of the number of blades. The predicted impact of those parameters on the non-dimensional performance characteristics agrees well with common knowledge and experience.</p> <p>Eventually, an interplay of various designed turbine rotors and the given drive train/battery charger is simulated. Criterions for selection of the rotor are the annual energy output, the rotor speed at design wind speed as well as high winds, and the axial thrust exerted on the rotor by the wind. The complete rotor/drive train//battery charger assembly is tested successfully in the University of Siegen wind tunnel.</p> </abstract>

Sign in / Sign up

Export Citation Format

Share Document