Airfoil Total Air Temperature Sensor with Bleed Passages
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Solution Overview
Problem
Conventional total air temperature sensors face challenges at higher Mach numbers due to compressibility effects and boundary layer separation, leading to reduced response time and deicing heater errors, particularly at low mass flows and icing conditions.
Innovation Solution
A total air temperature sensor design featuring an airfoil body with bleed passages and a temperature probe, incorporating a heater to prevent ice buildup and a radiation shield to minimize radiative heat exchange, ensuring effective flow and temperature measurement while maintaining high flow over the probe for improved time response and reducing deicing heater errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional total air temperature sensors are used at higher Mach numbers, then compressibility effects occur, but response time is reduced
Solution Approach 1:
The airfoil body is segmented into multiple functional zones with bleed passages that divide and redirect airflow. This segmentation allows the flow to be managed in controlled segments, preventing boundary layer separation and maintaining response time even at higher Mach numbers where compressibility effects occur.
Solution Approach 2:
Bleed passages act as intermediary flow paths that extract and redirect boundary layer airflow before it can separate. This intermediary mechanism prevents the harmful effects of boundary layer separation while maintaining accurate temperature measurement capability at elevated Mach numbers.
2Quantity of substance
If conventional sensors operate at low mass flows, then boundary layer separation occurs, but measurement accuracy deteriorates
Solution Approach 1:
The bleed passages extract the problematic boundary layer airflow from the main flow path before it can separate. By taking out this separated flow early, the system maintains attached flow conditions and accurate temperature measurements even when operating at low mass flow rates.
Solution Approach 2:
The bleed passages perform preliminary action by removing boundary layer flow before separation can occur. This preventive measure ensures that the main flow remains attached and provides accurate temperature measurements throughout the operating range including low mass flow conditions.
3Reliability
If deicing heaters are used to prevent ice formation, then ice buildup is prevented, but deicing heater errors are introduced
Solution Approach 1:
The bleed passages extract heated boundary layer air that contains deicing heater errors before it can reach the temperature probe. By removing this contaminated flow path, the system maintains both deicing functionality and measurement accuracy simultaneously.
Solution Approach 2:
The bleed passages serve as an intermediary flow path that separates the deicing heater function from the temperature measurement function. Heated air is diverted through bleed passages away from the probe, acting as a mediator that allows both functions to coexist without interfering with each other's performance.
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
The design enhances time response at elevated Mach numbers and reduces deicing heater errors by effectively managing flow and heat distribution, providing accurate total air temperature measurements.
Implementation Method 1
a plurality of outlets defined in the low pressure surface for exhausting the fluid out from the interior flow passage. The airfoil body can define a plurality of bleed passages through the airfoil body between the leading edge and the interior flow passage
Implementation Method 2
Anti-icing performance is facilitated by heater elements embedded in the housing walls
Implementation Method 3
a radiation shield to minimize radiative heat exchange
Implementation Method 4
Total air temperature (TAT) or (Tt) is the maximum air temperature that can be attained by 100% conversion of the kinetic energy of the flow. The measurement of TAT is derived from the recovery temperature (Tr), which is the adiabatic value of local air temperature
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A total air temperature sensor (100;200;300) includes an airfoil body (102;202;302) extending from an airfoil base (104) to an opposed airfoil tip (106) along a longitudinal axis (A). The airfoil body defines a leading edge (108) and opposed trailing edge (110). The airfoil body defines an interior flow passage (112) with an inlet (114;312) for fluid communication of fluid into the interior flow passage and an outlet (116;216) for exhausting fluid out from the interior flow passage, and wherein the airfoil body defines a bleed passage (118;218;318) through the airfoil body between the leading edge and the interior flow passage. A temperature probe (128;228;328) is mounted within the interior flow passage for measuring temperature of flow through the interior flow passage to determine total air temperature.