scholarly journals Comparison between Semiempirical and Computational Techniques in the Prediction of Aerodynamic Performance of the Rotor of a Quadcopter

2017 ◽  
Author(s):  
Andres Mauricio Pérez Gordillo
Keyword(s):  
Aerodynamic Performance ◽  
Computational Techniques

Tip Clearance Investigation of a Ducted Fan Used in VTOL UAVS: Part 1—Baseline Experiments and Computational Validation

2011 ◽  
Author(s):  
Ali Akturk ◽  
Cengiz Camci
Keyword(s):  
Total Pressure ◽  
Aerodynamic Performance ◽  
Test System ◽  
Tip Clearance ◽  
Computational Techniques ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Ducted Fan ◽  
Rans Simulations

Ducted fans that are popular choices in vertical take-off and landing (VTOL) unmanned aerial vehicles (UAV) offer a higher static thrust/power ratio for a given diameter than open propellers. Although ducted fans provide high performance in many VTOL applications, there are still unresolved problems associated with these systems. Fan rotor tip leakage flow is a significant source of aerodynamic loss for ducted fan VTOL UAVs and adversely affects the general aerodynamic performance of these vehicles. The present study utilized experimental and computational techniques in a 22″ diameter ducted fan test system that has been custom designed and manufactured. Experimental investigation consisted of total pressure measurements using Kiel total pressure probes and real time six-component force and torque measurements. The computational technique used in this study included a 3D Reynolds-Averaged Navier Stokes (RANS) based CFD model of the ducted fan test system. RANS simulations of the flow around rotor blades and duct geometry in the rotating frame of reference provided a comprehensive description of the tip leakage and passage flow. The experimental and computational analysis performed for various tip clearances were utilized in understanding the effect of the tip leakage flow on aerodynamic performance of ducted fans used in VTOL UAVs. The aerodynamic measurements and results of the RANS simulations showed good agreement especially near the tip region.

Effects of stator splitter blades on aerodynamic performance of a single-stage transonic axial compressor

2020 ◽  
Vol 14 (4) ◽  
pp. 7369-7378
Author(s):  
Ky-Quang Pham ◽  
Xuan-Truong Le ◽  
Cong-Truong Dinh
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Aerodynamic Performance ◽  
Numerical Results ◽  
Single Stage ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Operating Stability ◽  
Length Coverage

Splitter blades located between stator blades in a single-stage axial compressor were proposed and investigated in this work to find their effects on aerodynamic performance and operating stability. Aerodynamic performance of the compressor was evaluated using three-dimensional Reynolds-averaged Navier-Stokes equations using the k-e turbulence model with a scalable wall function. The numerical results for the typical performance parameters without stator splitter blades were validated in comparison with experimental data. The numerical results of a parametric study using four geometric parameters (chord length, coverage angle, height and position) of the stator splitter blades showed that the operational stability of the single-stage axial compressor enhances remarkably using the stator splitter blades. The splitters were effective in suppressing flow separation in the stator domain of the compressor at near-stall condition which affects considerably the aerodynamic performance of the compressor.

Numerical Study of the Roughness Influence on NACA 63-430 Profile Aerodynamic Performance

2016 ◽  
Vol 10 (4) ◽  
pp. 231
Author(s):  
Abdekarim Tebbal ◽  
Fethi Saidi ◽  
Boualem Noureddine ◽  
Bachir Imine ◽  
Benameur Hamoudi
Keyword(s):  
Numerical Study ◽  
Aerodynamic Performance

Aerodynamic Performance of a Helicopter Rotor Hovering in Close Proximity to the Obstacles with Penetration Boundary Condition

2016 ◽  
Vol 64 (1) ◽  
pp. 65-70
Author(s):  
Naohiro IBOSHI ◽  
Noriaki ITOGA ◽  
Yasuhide YAMANAKA ◽  
Abdul KADIR, ◽  
Yuzaburou HAYASHI ◽  
...  
Keyword(s):  
Boundary Condition ◽  
Aerodynamic Performance ◽  
Helicopter Rotor ◽  
Close Proximity

Bayesian Estimation of DSGE Models

2015 ◽  
Author(s):  
Edward P. Herbst ◽  
Frank Schorfheide
Keyword(s):  
Monte Carlo ◽  
Sequential Monte Carlo ◽  
Likelihood Function ◽  
Academic Research ◽  
Dynamic Stochastic General Equilibrium ◽  
Computational Techniques ◽  
Dsge Models ◽  
Monte Carlo Techniques ◽  
Dynamic Stochastic ◽  
Theoretical Foundations

Dynamic stochastic general equilibrium (DSGE) models have become one of the workhorses of modern macroeconomics and are extensively used for academic research as well as forecasting and policy analysis at central banks. This book introduces readers to state-of-the-art computational techniques used in the Bayesian analysis of DSGE models. The book covers Markov chain Monte Carlo techniques for linearized DSGE models, novel sequential Monte Carlo methods that can be used for parameter inference, and the estimation of nonlinear DSGE models based on particle filter approximations of the likelihood function. The theoretical foundations of the algorithms are discussed in depth, and detailed empirical applications and numerical illustrations are provided. The book also gives invaluable advice on how to tailor these algorithms to specific applications and assess the accuracy and reliability of the computations. The book is essential reading for graduate students, academic researchers, and practitioners at policy institutions.

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