Paweł Ligęza

Polish Academy of Sciences | PAN · Strata Mechanics Research Institute

Hot-wire anemometric measurements are often related to the determination of flow parameters in a high frequency range. Such knowledge is particularly important when analyzing the flow phenomena in the vicinity of wind turbines. The reliability of obtained results is determined by the knowledge of the properties of the system used for measurements....

Measurements of air flow velocity are essential at every stage of the design, construction and operation of wind turbines. One of the basic measurement tools in this area is the tachometric anemometer, which is based on the simple physical phenomenon of the air kinetic energy exchange with a rotating measuring element. Tachometric anemometers have...

Research on the optimization of the frequency bandwidth of calorimetric anemometers with hot-wire sensors, intended for the study of fast-changing and pulsed flows, is undergoing constant progress. The miniaturization of sensors reduces the thermal inertia of the measuring element, the structure of the electronic system and parameters of its elemen...

The article is a synthetic review of contemporary wind energy issues. It was created on the basis of a survey of literature from the last two years, with mainly review articles. This work is intended to be a source of information for a wide group of scientists and students from various fields. The aim is to interest them in a wide range of topics r...

Due to their common occurrence and fundamental role in human-realized processes and natural phenomena, turbulent flows are subject to constant research. One of the research tools used in these studies are hot-wire anemometers. These instruments allow for measurements in turbulent flows in a wide range of both velocities and frequencies of fluctuati...

Air flow velocity measurements are the key issues in examining the condition and progress of mine ventilation process. In addition to standard measurements carried out in the stock exploitation process, it is necessary to conduct cognitive scientific research in this area. One of the important issues here is the measurement of fast-changing fluctua...

Tachometric and thermal anemometers are two types of instruments mainly used in typical standard measurements in meteorology, ventilation, air conditioning, technical and industrial measurements. Both types of these instruments have many beneficial metrological properties, which causes their widespread use in many measurement issues. However, the s...

In measurements of fast-changing flows, one of the key issues is knowledge of the anemometer frequency bandwidth. In such measurements, the measurement technique often used is hot-wire anemometry. The determination and optimization of the measurement bandwidth of the hot-wire system is very important for the quality of the measurements carried out....

Analysis of velocity and temperature fields in gas flows is an important issue in many areas of modern science and technology. Hot-wire anemometry, besides optical methods, is one of the basic measurement methods used in such analysis. It enables indirect measurement of the gas flow velocity based on measurement of heat losses of hot-wire element p...

Mechanical tachometric anemometers, based on the phenomenon of the exchange of momentum between the flow and rotating measuring element, represent an important class of instruments used in flow metrology. In particular, they are used in meteorological and ventilation measurements. Mechanical anemometers with rotating measuring element are, however,...

Anemometers based on the exchange of momentum between the flow and rotating measuring element comprise an important class of instruments used in flow metrology, especially in meteorological and ventilation measurements. In these instruments, overvaluation of the measured average velocity, caused by the inertia of their rotors, takes place. To analy...

Temperature waves are used in metrology to determine flow velocities, as well as the coefficient of thermal diffusion, chemical composition, and other parameters of the flowing medium. This study presents a method for precise generation of temperature waves in flows, based on digitally controlled electronic system. A mathematical model and structur...

The paper considers of applying the thermal wave method of absolute measurements of very low flow velocity. The method is based on approximate analytical solution of thermal wave propagation in flowing gas. Some results of air flow velocity measurements were presented.

Measurement of the very low air flow velocity by means of the spectral analysis of the thermal wave was described. The method is based on the relationship between the phase shifts of the thermal wave’s harmonic components in the function of frequency. Experimental research conducted in a wind tunnel was presented and discussed. In this paper applyi...

Due to specific metrological properties, the problem of measurement of gas flow velocities down to the sub 1 m/s range comprises a distinct metrological challenge. One of the measurement methods used in this range of flow velocities is the method based on investigation of the propagation of heat waves generated in the flow. Such method does not req...

Thermal anemometry measurements of non isothermal flows require the use of a temperature compensation or correction method. In this article, the principles of operation of methods for reduction of temperature influence on the flow velocity measurement are discussed. The study also compares the methods and discusses the conditions for their applicat...

The main drawback of standard hot-wire anemometric methods consists of the difficulty in their employment and a considerable measurement uncertainty in the case of flows in which high-amplitude fluctuations of temperature or other physical quantities occur. It is caused by the interaction between these fluctuations and measurement signal. In this p...

The use of measurement apparatus under conditions which differ significantly from those under which the apparatus was adjusted carries the risk of altering the previously determined measurement characteristics. This is of special concern in the case of apparatus which is sensitive to external measurement conditions. Advanced measurement systems are...

In this study, presented are the advanced hot-wire anemometric measurements systems suitable for investigation of velocity fields in mine headings. A construction of two types of modernized three-element hot-wire anemometric probes is discussed. The three-element wire sensor which was used only under laboratory conditions up to date was added a fou...

In this study, presented are the advanced hot-wire anemometric measurements systems suitable for investigation of velocity fields in mine headings. A construction of two types of modernized three-element hot-wire anemometric probes is discussed. The three-element wire sensor which was used only under laboratory conditions up to date was added a fou...

The balance of mass or volumetric flow of air in ventilation systems may be carried out on the basis of the flow velocity field assessment. The minimization of the measurement error of such a measurement requires the application of a method allowing for determination of the magnitude, direction and sense of the velocity vector in examined points of...

A model for a constant-bandwidth hot-wire anemometer and experimental testing of such a anemometer prototype are presented in this article. During the testing, an approximately constant anemometer transmission bandwidth, and good conformity between the model and the real measurement system were achieved. The system developed and outlined herein all...

This article presents an attempt of a numerical experiment the main goal of which was to determine the parameters of air stream flowing in the mine drift. As a result of flow parameter measurements performed in mine drifts utilizing the hot-wire anemometric system of multipoint simultaneous flow velocity and temperature measurements based on integr...

The article presents the spatial hot-wire anemometric probe and the Measurements system based oil it that have been developed in order to conduct the experimental verification of numeric simulation of air flow in mine drifts The system is adapted to specific work conditions in a mine (variable and non-isothermal flow with a significant degree of po...

Hot-wire anemometric measurements of non-isothermal flows require the use of thermal compensation or correction circuitry. One possible solution is a two-state hot-wire anemometer that uses the cyclically changing heating level of a single sensor. The area in which flow velocity and fluid temperature can be measured is limited by the dimensions of...

A classical constant-temperature hot-wire anemometer enables the measurement of fast-changing flow velocity fluctuations, although its transmission bandwidth is a function of measured velocity. This may be a source of significant dynamic errors. Incorporation of an adaptive controller into the constant-temperature system results in hot-wire anemome...

Three types of hot-wire anemometric probes for the measurement of a two-dimensional flow velocity vector and its sense are presented in this paper. Such probes are a modification of type X hot-wire probes, in which additional supports are introduced in the middle of wires. The idea of the sense of a flow velocity vector assessment is based on the p...

In this paper we have presented a hot-wire anemometric system constructed in Strata Mechanics Research Institute, Polish Academy of Sciences, which was applied in practice to measure velocity profile in a selected cut of heading. Hot-wire anemometric system for multi-point measurements of velocity field is based on sensors integrated with a signal...

Hot-wire measurements of velocity vector components use a sensor with three orthogonal wires, taking advantage of an anisotropic effect of wire sensitivity. The sensor is connected to a three-channel anemometric circuit and a data acquisition and processing system. Velocity vector components are obtained from measurement signals, using a modified a...

A constant-temperature anemometer (CTA) enables the measurement of fast-changing velocity fluctuations. In the classical solution of CTA, the transmission band is a function of flow velocity. This is a minor drawback when the mean flow velocity does not significantly change, though it might lead to dynamic errors when flow velocity varies over a co...

This note reviews the extensively adopted equations used as models of hot-wire anemometric sensors. An unified formal form of the mathematical model of a hot-wire anemometric sensor with otherwise defined parameters is proposed. Those parameters, static and dynamic, have simple physical interpretation and can be easily determined. They show directl...

Hot-wire measurements in non-isothermal flows require temperature compensation or correction. One of the solutions is the system of two hot-wire anemometers which enable to measure velocity and temperature in non-isothermal gas flows. The output signals come from two hot-wire anemometers operating at different overheat ratio. As the two sensors ope...

Hot-wire measurements in non-isothermal flows require temperature compensation or correction. One of solutions is the system of two hot-wire anemometers which enable to measure velocity and temperature in non-isothermal gas flows. The output signal come from two hot-wire anemometers operating at different overheat ratio. As the two sensors operate...

 A constant-temperature bridge is the basic circuit used to supply hot-wire anemometer probes. One disadvantage of such circuits is that the probe overheat ratio depends on the resistance of the supply cable. To eliminate these shortcomings, a four-point non-bridge constant-temperature circuit was worked out. In such a circuit, cable adjustment is...

A four-point constant-current/temperature controlled circuit is an electronic system for supplying a resistance measuring sensor in two modes of operation: either in constant-current or in constant-temperature mode. This circuit is destined for anemometric applications. It is new nonbridge, four-point constant-current/temperature anemometer circuit...

Hot-wire anemometric measurements of non-isothermal flows require that temperature-compensation or correction systems should be applied. A basic method of temperature compensation in a constant temperature anemometric bridge circuit involves an additional compensating sensor being connected into the bridge. The resistance of the temperature-compens...

Thesis (doctoral)--Akademii Górniczo-Hutniczej im. S. Staszica w Krakowie, 2001.