Fiber optic thermal anemometer

A probe apparatus for testing the heat transfer coefficient of a sample in an environment, comprising:

• a length of optical fiber;
• an element held in optical communication with a first end of said optical fiber, said element having temperature sensitive optical properties and being adapted to contact or to be implanted in the sample;
• and
• radiation heat transfer means for directly supplying heat to the element to test the heat transfer coefficient of the sample whereby the difference between the temperature of the element and that of the environment is an indication of the heat transfer coefficient of the sample.

An apparatus for testing the heat transfer coefficient of a sample in an environment comprising:

• a length of optical fiber;
• an element held in optical communication with one end of said fiber, said element having temperature sensitive optical properties and being adapted to contact or to be implanted in the sample;
• radiation heat transfer means for directly supplying heat to the element;
• means at the other end of the fiber for transmitting electromagnetic radiation to said element;
• and
• means at the other end of the fiber for optically detecting said temperature sensitive optical properties of the element to test the heat transfer coefficient of the sample whereby the difference between the temperature of the element and that of the environment is an indication of the heat transfer coefficient of the sample.

An apparatus for testing the thermal heat transfer coefficient of a sample in an environment comprising:

• a first length of optical fiber;
• a temperature sensitive element held at a first end of said optical fiber, said element having temperature sensitive luminescent properties and being adapted to contact or to be implanted in the sample;
• radiation heat transfer means for directly supplying heat to the element;
• means at the second end of the optical fiber for exciting said temperature sensitive element;
• and
• means at said second end of the optical fiber for optically detecting the temperature sensitive luminescent properties of said element to test the heat transfer coefficient of the sample whereby the difference between the temperature of the element and that of the environment is an indication of the heat transfer coefficient of the sample.

An apparatus for measuring the flow rate of a fluid comprising:

• a length of optical fiber;
• a temperature sensitive element held at a first end of said optical fiber, said element having temperature sensitive luminescent properties and being adapted to be placed in the flowing fluid;
• radiation heat transfer means for directly supplying heat to the element;
• means at the second end of the optical fiber for exciting said temperature sensitive element;
• and
• means at the second end of the optical fiber for detecting electromagnetic radiation emitted by said element to indicate the flow rate of the fluid whereby the difference between the temperature of the element and that of the unheated fluid is an indication of the flow rate.

A method for measuring the flow rate of a fluid by means of an element having temperature sensitive luminescent properties, said method comprising:

• placing the temperature sensitive element in the flowing fluid;
• directly supplying heat to the element;
• exciting said temperature sensitive element to luminescence;
• detecting the electromagnetic radiation emitted by said element to detect the temperature of the element;
• and
• detecting the temperature of the unheated fluid so that the difference between the temperature of the element and that of the unheated fluid is an indication of the flow rate of the fluid.

An apparatus for measuring the flow rate of a fluid comprising:

• a length of optical fiber;
• a temperature sensitive element held at one end of said fiber optic, said element having temperature sensitive luminescent properties and being adapted to be placed in the flowing fluid;
• a vortex generating element also placed in the flowing fluid but at a location upstream relative to said element so that vortices generated thereby will come into contact with the element;
• radiation heat transfer means for directly supplying heat to the element;
• means at a second end of the optical fiber for exciting said temperature sensitive element;
• and
• means at a second end of the optical fiber for detecting electromagnetic radiation emitted by said element to determine the frequency of generation of vortices which indicates the flow rate of the fluid.

A method for measuring the flow rate of a fluid by means of an element having temperature sensitive luminescent properties and a vortex generating element, said method comprising:

• placing the temperature sensitive element in the flowing fluid;
• placing the vortex generating element in the flowing fluid at a location upstream relative to said element so that vortices generated thereby will come into contact with the element;
• directly supplying heat to the element;
• exciting said temperature sensitive element to luminescence;
• and
• detecting the electromagnetic radiation emitted by said element to determine the frequency of generation of vortices which indicates the flow rate of the fluid.

An apparatus for measuring the flow rate of a fluid comprising:

• a length of optical fiber;
• a temperature sensitive element held at one end of said fiber, said element having temperature sensitive luminescent properties and being adapted to be placed in the flowing fluid;
• radiation heat transfer means for supplying heat to a bolus of fluid at a known distance upstream from said element;
• means at a second end of the optical fiber for exciting said temperature sensitive element;
• and
• means at said second end of the optical fiber for detecting electromagnetic radiation emitted by said element to determine the time of arrival and temperature differences of said bolus of fluid at the element thereby also determining the flow rate of the fluid wherein the radiation heat transfer means comprises means for heating a portion of the optical fiber between the first and second ends, said portion being placed upstream and at a known distance from said element.

An apparatus for measuring the flow rate of a fluid comprising:

• a length of optical fiber;
• a temperature sensitive element held at one end or said fiber, said element having temperature sensitive luminescent properties and being adapted to be placed in the flowing fluid;
• a radiation heat transfer means for supplying heat to a bolus of fluid at a known distance upstream from said element;
• means at a second end of the optical fiber for exciting said temperature sensitive element and;
• means at said second end of the optical fiber for detecting electromagnetic radiation emitted by said element to determine the time of arrival and temperature differences of said bolus of fluid at the element thereby also determining the flow rate of the fluid, wherein said radiation transfer means comprises:
• a length of a second optical fiber adapted to be placed in the fluid upstream from said element;
• an optical filter that absorbs electromagnetic radiation, said filter being implanted in said second optic fiber so that heating of the filter will cause heat to be transferred between the filter and the fluid surrounding the second optical fiber;
• and
• source for supplying a pulse of electromagnetic radiation to said second optical fiber for heating the filter momentarily so that the bolus of fluid surrounding the filter will be heated before it reaches said element.

A method for measuring the flow rate of a fluid by means of a length of optical fiber and an element having temperature sensitive luminescent properties placed at one end of the optical fiber, said method comprising:

• placing the temperature sensitive element and said one end of the optical fiber in the flowing fluid;
• directly supplying heat to a portion of the optical fiber for heating a bolus of fluid at a known distance upstream from said element;
• exciting said temperature sensitive element to luminescence;
• and
• detecting the electromagnetic radiation emitted by said element to determine the time of travel and temperature differences of said bolus of fluid thereby also determining the flow rate of the fluid.

An apparatus for detecting the presence of a first fluid in a second fluid, said two fluids being immiscible and having different thermal properties, said apparatus comprising:

• a length of optical fiber a first end of which is adapted to be inserted into the second fluid;
• a temperature sensitive element held at the first end of said fiber, said element having temperature sensitive luminescent properties;
• radiation heat transfer means for directly supplying heat to the element;
• means at a second end of the optical fiber for exciting said temperature sensitive element;
• and
• means at a second end of the optical fiber for detecting electromagnetic radiation emitted by said element to detect the temperature of the element and the presence of the first fluid whereby such presence is indicated by a change in temperature of the element.

A method for detecting the presence of a first fluid in a second fluid said two fluids being immiscible and having different thermal properties by means of an element having temperature sensitive luminescent properties, said method comprising:

• placing the temperature sensitive element in the second fluid;
• directly supplying heat to the element;
• exciting said temperature sensitive element to luminescence;
• and
• detecting the electromagnetic radiation emitted by said element to detect the temperature of the element and the presence of the first fluid in the second fluid whereby such presence is indicated by a change in temperature of the element.

An apparatus for determining the composition of a mixture of fluids having different heat capacities and conductivities, comprising:

• a length of optical fiber;
• a temperature sensitive element held at a first end of said optical fiber, said element having temperature sensitive luminescent properties and being adapted to be placed in the fluid mixture;
• radiation heat transfer means for directly supplying heat to the element;
• means at a second end of the optical fiber for exciting said temperature sensitive element;
• and
• means at a second end of the optical fiber for detecting electromagnetic radiation emitted by said element to indicate the temperature of the element and the composition of the fluid mixture whereby the temperature of the element is an indication of the composition of the fluid mixture.

An apparatus for measuring the pressure of a fluid comprising:

• a length of optical fiber;
• a temperature sensitive element held at a first end of said optical fiber, said element having temperature sensitive luminescent properties and being adapted to be placed in the fluid;
• radiation heat transfer means for directly supplying heat to the element;
• means at the second end of the optical fiber for exciting said temperature sensitive element;
• and
• means at the second end of the optical fiber for detecting electromagnetic radiation emitted by said element to detect the temperature of the element and the pressure of the fluid whereby the temperature of the element is an indication of the pressure of the fluid.

A method for measuring the pressure of a fluid by means of an element having temperature sensitive luminescent properties, said method comprising:

• placing the temperature sensitive element in the fluid;
• directly supplying heat to the element;
• exciting said temperature sensitive element to luminescence;
• and
• detecting the electromagnetic radiation emitted by said element to detect the temperature of the element, said temperature being an indication of the pressure of the fluid.

An apparatus for measuring the pressure of a gas above a liquid comprising:

• a length of optical fiber;
• a temperature sensitive element held at a first end of said optical fiber, said element having temperature sensitive luminescent properties and being adapted to be placed in the gas at a location immediately above the surface of the liquid;
• means for heating the liquid to boiling state;
• means at the second end of the optical fiber for exciting said temperature sensitive element;
• and
• means at a second end of the optical fiber for detecting electromagnetic radiation emitted by said element to determine the temperature of the vapor from the boiling liquid said temperature being an indication of the pressure of the gas.

A method for measuring the pressure of a gas above a liquid by means of an element having temperature sensitive luminescent properties, said method comprising:

• placing the temperature sensitive element in the gas at a location immediately above the surface of the liquid;
• heating the liquid to a boiling state;
• exciting said temperature sensitive element to luminescence;
• and
• detecting the electromagnetic radiation emitted by said element to determine the temperature of the vapor from the boiling liquid said temperature being an indication of the pressure of the gas.

An apparatus for determining levels between immiscible fluids having different thermal capacities and conductivities, said apparatus comprising:

• a plurality of optical fibers, each fiber being placed with its first end placed at a desired location in one of the fluids for determining the level between said fluid and the fluid immediately above;
• a temperature sensitive element held at each of the first ends of said plurality of optical fibers, said element having temperature sensitive luminescent properties and being adapted to be placed in the corresponding fluid;
• radiation heat transfer means for directly supplying heat to each of the elements;
• means at the second end of each optical fiber for exciting the temperature sensitive element held at the first end of such fiber;
• and
• means at the second end of each optical fiber for detecting electromagnetic radiation emitted by the element held to such fiber to detect the temperature of each element, said temperature being an indication of the levels between the fluids.

A method for determining the level between two immiscible fluids having different thermal properties as the level changes, with an element having temperature sensitive luminescent properties, said method comprising:

• placing the temperature sensitive element at a desired location in the fluid with the lower altitude for determining the level between said fluid and the fluid above;
• directly supplying heat to the element;
• exciting the temperature sensitive element to luminescence;
• and
• detecting the electromagnetic radiation emitted by the element to detect the temperature of the element, said temperature being an indication of the level between the fluids as it changes.

An apparatus for measuring the thermal conductivity of a solid sample comprising:

• a length of optical fiber;
• a temperature sensitive element held at a first end of said optical fiber, said element having temperature sensitive luminescent properties and being adapted to contact one side of the solid sample;
• a radiation heat transfer means for directly supplying heat to the element;
• means at a second end of the optical fiber for exciting said temperature sensitive element;
• and
• means at said second end of the optical fiber for detecting electromagnetic radiation emitted by said element to detect the temperature of the element which indicates the thermal conductivity of the solid sample.

A method for measuring the thermal conductivity of a solid sample with an element having temperature sensitive luminescent properties, said method comprising:

• contacting one side of the solid sample with the element;
• directly supplying heat to the element;
• exciting said temperature sensitive element to luminescence;
• and
• detecting the electromagnetic radiation emitted by said element to detect the temperature of the element, said temperature being an indication of the thermal conductivity of the solid sample.

A method for improving the accuracy of temperature measurement wherein the measurement apparatus comprises a temperature probe housing, a temperature sensitive element held at the probe tip of said housing and means for determining the temperature of said element when said element is held in contact with a sample the temperature of which is to be measured, said method comprising:

• determining the approximate temperature of the sample;
• directly heating, through radiation, the probe tip and the temperature sensitive element to a temperature substantially equal to the approximate temperature of the sample to reduce the heat transfer between the probe tip and the element when they are placed in contact;
• and
• bringing said element into contact with the sample and measuring the temperature of the sample.