Hi, friends welcome to the new post. In this article, we will discuss the What is Hot Wire Anemometer? It is mostly used to calculate the velocity of fluids and is also used in industries. In this post, we will discuss its different factors such as construction, applications,, limitations, and working. So, let’s get started Introduction to Hot Wire Anemometer
What is Hot Wire Anemometer?
- A hot wire anemometer (HWA) instrument that used to measure the velocity and direction of fluid flow such as liquid or gases. It works by heating small, sensitive to electrical signal wire calculates changes in its resistance and becomes low temperature when any liquid moves over it. If its wire is high temperature that means it has high resistance
- As the fluid flows over the wire, it eliminates heat from the wire, causing the resistance to be lost. The quantity of heat loss has a direct relation with the velocity of the fluid.
- It has a thin electrical heated wire that is suspended in a stream of fluid
- This wire is headed with the current in it. Current is varied to maintain wire at a constant temperature. For measuring resistance there is a wheastone bridge used. Resistance of wire has an inverse relation with temperature. When fluids move on the wire it becomes cool resulting in resistance to increase. Resistance changes measured by Wheatstone bridge circuit.
- The output of the bridge circuit has a direct proportional relation with fluid speed. So velocity is measured hot wire anemometer that has measured the flow rate
Definition of Hot Wire Anemometer?
A hot wire anemometer is an accurate instrument that is used for the calculation of the velocity of fluids. It works based on heat transfer from high-temperature wire to fluid close to it. With measuring cooling parameters causing fluid flow, this device measures the correct value of velocity
Working Principle Hot Wire Anemometer?
its working is based on the cooling effect of fluid moving over hot wire. If wire is put in fluid such as air temperature of the wire reduces due to cooling. As a result, the velocity of that fluid increases, with the cooling effect on the wire increasing resulting in variation in the temperature of the wire. Variation in temperature is calculated so the velocity of fluid is measured using calibration of data
The hotwire anemometer structure is thin and made with platinum or tungsten, heated with constant value temperature with the use of current. The wire is configured in a sensor that is made to reduce interference due to outer factors. This layout is arranged with a control unit that gives the power to wire and measure changes in temperature
Constant Current Method of hot wire anemometer
In this method, constant current passes through a hot wire. If fluid passes over the wire it decreases the temperature of the wire and resistance increases. These changes in resistance were measured with the Wheatstone bridge circuit. The result of the bridge is fluid velocity. This method is more accurate in finding velocity than the constant temperature technique. A constant current does not lie on the temperature of the hot wire to become a constant value. Ambient temperature changes or flow also varies hot wire temperature
This technique is used for projects that need high accuracy values. The constant temperature method is best of environmental monitoring.
Constant Temperature anemometer
In this process temperature of the hot wire is varied with the use of constant temperature with a change current in the wire. Since fluid passes the wire becomes low temperature and the value of the current increases. Change in current measured with a bridge. The results of the bridge is directly proportional to the velocity of the fluid. It is less correct than the constant current process. As it does not need a power source for painting constant current. For hating wire small ratting battery can also used
How to Measure the rate of a fluid with Hot Wire anemometer
- hot wire anemometer. Make ready. Here meter is connected to a power source, calibrated, and set meter in a fluid stream
- Heat the hot wire. Current flows in the wire. Current values varied to a value that would heat the wire to the required temperature.
- Hot wire temperature variation measured. It attaches hot wire with a bridge circuit. Resistance changes explained fluid velocity
- Calculate the velocity of the fluid. The velocity of the fluid measured with these equations
velocity = K x (Rhot – Rambient)^(1/n)
What is Hot Wire Anemometry
The hotwire anemometry (HWA) technique is used for calculating velocity and fluid direction with small-level heating, sensitivity of wire, and changes in resistance when it cools with fluid flow. High-temperature wires have high resistance. When fluid moves on the wire it reduces heat in the wire. resistance reduces the amount of heat loss and is directly proportional with the velocity of the fluid
What is Hotwire flow meter?
A hot wire flow meter device operates on the principle of heat transfer to measure fluid velocity. It has a thin wire current based on heated configured on fluid. When fluids move on wire decreased heat from wire resistance increases in results.
- Fragile nature: This wire is delicate in nature and breaks if not accurately used
- Sensitivity: Different environmental conditions like temperature, humidity, and pressure affect it
- Less compatible with some fluids it does not measure the velocity of corrosive or chemically reactive fluids.
- Cost: it is high cost
Hotwire anemometers industrial used explained here
- Environmental monitoring
- HVAC and building automation
- Aerospace and automotive
- Research and development
- Manufacturing and process control
Advantages and Disadvantages
|High turbulence intensity
|Breakage of Probe
|Accuracy is good
|Good spatial & temporal resolution
|Heat transfer and aerodynamic problems
|Measurement of two-phase flow
|We can simply measure Turbulent flows
|Measurement of simultaneous temperature
|Measurement of Multi-component
|Less S/N ratio
What is the working principle of a hot wire?
Hotwire device operation is based on the thermal effect the length of the wire increases since the heating effect due to current passing caused this. As current passes in the platinum-iridium wire gets heated and expands
What is the work of a hot wire anemometer?
A Hot Wire Anemometer is used to measure velocity and fluid direction by calculating the heat loss of wire heated by the current configured on the fluid stream. In a fluid stream, heat is moved to the wire and its temperature decreases
How is a hot wire anemometer based on the principle of heat transfer?
Hotwire anemometer uses the operation that heat removed from a high-temperature sensor with the movement of fluid is equal to the velocity of the fluid
What is the material of construction for a hot wire anemometer?
It consists of two probes with sire stretched. The wire is made of platinum, tungsten, or platinum-iridium. A small, glass-coated thermistor bead used a constant-temperature circuit
What is the construction of a hot wire anemometer?
The hot wire anemometer comes with a thin bout five-micrometer dia, heated by current, placed in the flow of fluids. The liquids affect teh wire and decrease the resistance
Which metal is used in an anemometer?
tungsten is mostly used in anemometer
What are the applications of an anemometer?
Anemometers have different applications, which are
- The anemometer measured the rotation that is used for calculating the speed of wind. Anemometer measures wind speed and pressure, It is also used in practicals of physics that need air flows
What is the common name for an anemometer?
It is also called a wind indicator, weather vane
What is the range of a hot wire anemometer?
Its range is between 0.3 … 30.0 m/s / 0.98 … 98.4 ft/s.
What is a constant temperature anemometer?
A Constant Temperature Anemometer (CTA), called a hot wire anemometer uses the cooling fact of convective heat flow to measure fluid velocity. The high-speed fluid will quickly get cool