Wind Tunnel Vehicle Running Energy Evaluation Method
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Solution Overview
Problem
Existing coastdown tests for evaluating vehicle fuel efficiency are prone to high errors due to disturbance factors like temperature, wind speed, humidity, and road conditions, and fail to accurately measure acceleration and deceleration resistances.
Innovation Solution
A method involving a wind tunnel test where a vehicle's wheels are rotated to create constant and changing speed sections, allowing for precise measurement of forces and separation of exerted forces to determine running energy, thereby calculating integrated running energy with reduced disturbance influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If coastdown test is performed on actual road to measure vehicle running resistance, then fuel efficiency evaluation can be conducted, but measurement accuracy deteriorates due to disturbance factors such as temperature, wind speed, humidity, and road conditions
Solution Approach 1:
The invention extracts the vehicle from the complex outdoor environment and places it in a controlled wind tunnel setting. By removing the vehicle from actual road conditions with varying temperature, wind speed, humidity, and road conditions, the measurement is conducted in a stabilized environment where these disturbance factors are controlled or eliminated, thereby improving measurement accuracy
Solution Approach 2:
The invention introduces a wind tunnel as an intermediary environment between the vehicle and the natural outdoor conditions. The wind tunnel acts as a mediator that provides controlled airflow to simulate road conditions while eliminating the harmful variability of actual outdoor environments, allowing for more precise measurement of running resistance
2Loss of information
If coastdown test is performed on actual road, then vehicle speed and air resistance can be measured, but acceleration resistance and deceleration resistance contributions cannot be measured
Solution Approach 1:
The invention transitions from static coastdown testing to dynamic wheel rotation testing. By actively rotating the wheels at various speeds and measuring the required torque, the system can capture energy consumption during acceleration and deceleration phases, providing complete information on all resistance components including acceleration and deceleration resistance
3Measurement precision
If anemometer and speedometer are mounted on test vehicle for measurement, then external wind speed and vehicle speed can be measured, but air resistance is distorted
Solution Approach 1:
The invention extracts the measurement instruments from the vehicle exterior and relocates them to the wind tunnel infrastructure. By removing the anemometer and speedometer from the test vehicle, the harmful distortion of air resistance caused by these mounted instruments is eliminated, allowing for more accurate aerodynamic measurements
4Reliability
If round trip tests are repeated to ensure normality of data in coastdown test, then measurement reliability can be improved, but testing time increases
Solution Approach 1:
The invention changes the fundamental test parameters from outdoor coastdown testing to indoor wind tunnel testing with controlled conditions. By stabilizing environmental parameters such as temperature, humidity, and airflow in the wind tunnel, the system achieves consistent and reliable data in a single test run, eliminating the need for repeated round trip tests and significantly reducing testing time
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 significantly reduces measurement time and increases accuracy by minimizing error from disturbance factors, enabling precise measurement of running energy and fuel efficiency improvements, including the quantification of acceleration and deceleration resistances without distorting air resistance.
Implementation Method 1
measuring and collecting exerted forces in each of the constant speed sections and exerted forces in each of the speed change sections
Implementation Method 2
wheels of the vehicle are rotated by the wheel rotating device
Data Source
AI summary
A method of evaluating integrated running energy of a vehicle in a wind tunnel may include estimating change in fuel efficiency according to change of vehicle parts thereby facilitating precise measurement of running energy.