Gas Turbine Injector Orifice Flow Rate Determination
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Solution Overview
Problem
Existing methods for measuring the flow rate of combustible fluid in gas turbines are inaccurate at low flow rates, such as during ignition, and require additional equipment that increases pressure loss and costs.
Innovation Solution
A method that determines the flow rate by measuring the pressure difference across the injector orifice, using the effective area and pressures upstream and downstream of the injector, without the need for additional restriction orifices, allowing for accurate measurement before ignition and across multiple combustion chambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a flow meter is designed for nominal load measurement, then it can accurately measure flow rate at nominal load, but it has too large a margin of error to accurately estimate low flow rate during ignition
Solution Approach 1:
The invention changes the measurement parameter from direct flow rate measurement to pressure differential measurement across the injector orifice. By measuring the pressure drop (ΔP) and using the known orifice characteristics (area A, discharge coefficient Cd), the system can accurately determine flow rate at any operating condition, including low flow rates during ignition, without requiring a separate flow meter for each regime.
2Measurement precision
If a second flow meter is installed to measure ignition flow rate, then accurate measurement during ignition is achieved, but an undesirable additional pressure drop is introduced in the gas fuel system
Solution Approach 1:
The invention makes the injector orifice serve multiple functions: it performs its primary function of fuel injection while simultaneously serving as the measurement element for flow rate determination. By measuring the pressure differential across the existing orifice, the system obtains accurate flow rate data without adding separate measurement equipment that would create additional pressure drops.
3Measurement precision
If an additional diaphragm or restrictor orifice is placed in the fuel fluid path for flow measurement, then flow rate can be determined, but an additional pressure drop is introduced and the system becomes more expensive
Solution Approach 1:
The injector orifice serves itself by using its own pressure differential to indicate flow rate. The system measures the pressure drop across the existing orifice (which is already part of the fuel injection system) and calculates flow rate from this measurement, eliminating the need for separate diaphragms, restrictors, or additional measurement components.
4Measurement precision
If orifice plate flow measurement is used with a dedicated restrictor orifice, then flow rate can be determined from pressure drop, but the measurement is expensive and requires additional components
Solution Approach 1:
The invention merges the fuel injection function and flow measurement function into a single component - the injector orifice. Instead of having a separate restrictor orifice for measurement, the system uses the existing orifice that is already present in the fuel injection system, thereby reducing component count, manufacturing cost, and system complexity while maintaining measurement capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method provides accurate and cost-effective flow rate measurement without additional pressure loss, enabling precise regulation and protection of the gas turbine during ignition and normal operation.
Implementation Method 1
determine the pressure of the fuel fluid upstream of the injector orifice, determine the pressure downstream of the injector orifice
Implementation Method 2
a fluid flowing through a restricted orifice experiences a pressure drop proportional to the square of the flow rate
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a method for determining the flow rate of combustible fluid injected inside a combustion chamber (120) of a turbine (100): determining the cross section of the orifice of said at least one injector (112, 113, 114, 115) through which the combustible fluid is injected into the combustion chamber (120), determining the pressure of the combustible fluid upstream of the orifice of the injector (112, 113, 114, 115), determining the pressure downstream of the orifice of the injector (112, 113, 114, 115), determining the flow rate of combustible fluid flowing through the orifice of said at least one injector (112, 113, 114, 115),