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Article
Publication date: 17 October 2018

Tomasz Kwiatkowski, Pawel Flaszyński and Jerzy Zoltak

The simulations of grid-resolved rod vortex generators (RVGs) require high computational cost and time. Additionally, the computational mesh topology must be adjusted to rods…

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Abstract

Purpose

The simulations of grid-resolved rod vortex generators (RVGs) require high computational cost and time. Additionally, the computational mesh topology must be adjusted to rods geometries. The purpose of this study is to propose the new source term model for RVG.

Design/methodology/approach

The model was proposed by modification of Bender, Anderson, Yagle (BAY) model used to predict flows around different type of vortex generators (VGs) – vanes. Original BAY model was built on lifting line theory. The proposed model was implemented in ANSYS Fluent by means of the user-defined function technique. Additional momentum and energy sources are imposed to transport equations.

Findings

The computational results of source term model were validated against experimental data and numerical simulation results for grid-resolved rod. It was shown that modified BAY model can be successfully used for RVG in complex cases. An example of BAY model application for RVG on transonic V2C airfoil with strongly oscillating shock waves is presented. Aerodynamic performance predicted numerically by means of both approaches (grid resolved RVG and modeled) is in good agreement, what indicates application opportunity of the proposed model to complex cases.

Practical implications

Modified BAY model can be used to simulate the influence of RVGs in complex real cases. It allows for time/cost reduction if the location or distribution of RVG has to be optimized on a profile, wing or in the channel.

Originality/value

In the paper, the new modification of BAY model was proposed to simulate RVGs. The presented results are innovative because of original approach to model RVGs.

Details

Aircraft Engineering and Aerospace Technology, vol. 91 no. 9
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 1 February 2002

Aleksandra Rogut and Tomasz Tokarski

Analyses factors determining the outflows from unemployment to employment across regions in Poland over the years 1992‐98, employing the concept of the augmented matching…

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Abstract

Analyses factors determining the outflows from unemployment to employment across regions in Poland over the years 1992‐98, employing the concept of the augmented matching function. Explores also the influence of the economic growth and the employment structure of the regional labour markets in Poland. Concludes that the values of outflows from unemployment to employment are closely and positively related to the number of unemployed and the number of vacancies, as well as to the economic growth rate; and that the employment structure of regional labour markets has a strong impact on outflows from unemployment to employment. The more a regional employment structure resembles the structure in European G7 countries, the higher the outflows from unemployment to employment.

Details

International Journal of Manpower, vol. 23 no. 1
Type: Research Article
ISSN: 0143-7720

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Book part
Publication date: 9 November 2023

Katarzyna Szarzec, Dawid Piątek and Bartosz Totleben

At the beginning of the 1990s, the Polish economic situation was extremely difficult: high public debt, shortages, high inflation and more than 8,000 state-owned enterprises…

Abstract

Research Background

At the beginning of the 1990s, the Polish economic situation was extremely difficult: high public debt, shortages, high inflation and more than 8,000 state-owned enterprises (SOEs) waiting to be restructured and/or privatised; along with a GDP per capita lower than in Ukraine.

Purpose of the Article

This chapter provides an overview of the Polish economic transition, and presents the results of this process, taking into account four aspects of the changes, i.e. stabilisation, liberalisation, institutional reforms and privatisation. Special attention is paid to intentionally unfinished privatisation and the still significant role of state-owned enterprises, which have remained important economic agents.

Methodology

Critical analyses were made of the literature dedicated to the economic transition and of the role and characteristics of state-owned enterprises. Empirical evidence is drawn from original datasets about the scale of SOEs in the contemporary economy and rotations in management and supervisory boards in Polish joint-stock companies.

Findings

Despite the unfavourable initial conditions, Poland soon emerged as a leader in economic growth, successfully stabilising, liberalising and privatising its economy. The institutional foundations of a democratic market economy were consistently built, and the applications for membership in the OECD, the EU and NATO were an important driver of institutional reforms. In terms of state institutions, political and economic freedom and quality of governance, Poland is more similar to the G7 countries than to the other post-socialist countries, though the need to maintain high-quality state institutions is still a priority. The significant share of SOE is regarded as a challenge of the Polish economy because state-owned enterprises are an object of rent-seeking by politicians and political parties.

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