Methods of surge point judgment for compressor experiments

Many car-following models with their own merits have been proposed to explore various traffic problems, but researchers have rarely used vehicle’s performance to evaluate them. In this paper, we study each vehicle’s fuel consumption of the optimal velocity model, full velocity difference model, full velocity and acceleration difference model and the car-following model with consideration of the traffic interruption probability under two traffic situations, respectively. The numerical results show that the car-following model with consideration of traffic interruption probability can reduce vehicle’s fuel consumption in the two studied traffic situations and thus improve the vehicle’s fuel economy.

Vehicle’s fuel consumption of car-following models

Centrifugal compressor performance is affected by many parameters, optimization of which can lead to superior designs. Recognizing the most important parameters affecting performance helps to reduce the optimization process cost. Of the compressor components, the impeller plays the most important role in compressor performance, hence the design parameters affecting this component were considered. A turbocharger centrifugal compressor with vaneless diffuser was studied and the parameters investigated included meridional geometry, rotor blade angle distribution and start location of the main blades and splitters. The diffuser shape was captured as part of the meridional geometry. Applying a novel approach to the problem, full factorial analysis was used to investigate the most effective parameters. The Response Surface Method was then implemented to construct the surrogate models and to recognize the best points over a design space created as based on the Box-Behnken methodology. The results highlighted the factors that affected impeller performance the most. Using the Design of Experiment technique, the model which optimized both efficiency and pressure ratio simultaneously delivered a design with 3% and 11% improvement in each respectively in comparison to the initial impeller at the design point. Importantly, this was not at the expense of sacrificing range, of critical concern in compressor design.

Optimization of a Centrifugal Compressor Using the Design of Experiment Technique

Investigation on the casing static pressure distribution and stall behaviors in a centrifugal compressor with volute

Criteria for the matching of inlet and outlet distortions in centrifugal compressors

All components of a turbocharger compressor are axisymmetric except for the spiral-shaped, gas-collecting overhung volute. In this paper, a novel experimental method to evaluate the impact of the volute’s asymmetry on centrifugal compressor performance is proposed and applied to a high pressure-ratio turbocharger compressor. This method can isolate the impact of the volute’s asymmetry on the compressor performance for the first time. Experiments prove the considerable impact of the volute’s asymmetry on the compressor performance, especially the stability and efficiency. The impact of the volute’s asymmetry on compressor stability correlates with rotational speed and thus with the pressure ratio, constricting the stable flow range by up to 47 percent and decreasing the maximum efficiency by 4.8 percent at the design speed. The results provide evidence to exploit the potential of intrinsic non-axisymmetric flow induced by asymmetric volute to improve the performance of turbocharger compressor with a high pressure ratio.

A novel experimental method to evaluate the impact of volute’s asymmetry on the performance of a high pressure ratio turbocharger compressor

The invention discloses a high-altitude and low-pressure characteristic simulation test station of an air compressor in an internal-combustion engine, relating to a characteristic simulation test station of an air compressor in an internal-combustion engine, and comprising an air pipeline system and a lubricating system, wherein the air pipeline system comprises a vacuum pump, a pressure stabilizing box, and an air filter, a flow testing section, an air inlet parameter testing section, a flow stabilizing section and an air compressor sequentially connected with an outlet of the pressure stabilizing box, and an air exhaust parameter testing section, a back pressure regulating valve, a stopping valve and an air exhaust intercooler sequentially connected with an outlet of the air compressor;the lubricating system comprises an oil tank, an oil supplying system and a lubricant intercooler; an outlet of the air exhaust intercooler is connected with the pressure stabilizing box so that an air pipeline of the test station forms a sealed air circulation system; and the oil tank is arranged inside the pressure stabilizing box so as to improve the sealing property of the test station. The test station can simulate the environmental pressure at the altitude of 0-30,000 meters and performs the high-altitude simulation characteristic test of the air compressor in the turbo-charged internal-combustion engine, therefore, the sealing property and simulated altitude of the test station are higher than those of the existing simulation test station of the same type.

High-altitude and low-pressure characteristic simulation test station of air compressor in internal-combustion engine

The occurrence of surge or stall in a centrifugal compressor and the role of the tip clearance flow in the instability in the centrifugal compressor are investigated in this study. A computational method is used to study the flow field in the centrifugal compressor in order to gain a better understanding of the surge or stall mechanism. It is found that, near surge or stall conditions, the tip leakage flow at the leading edge deflects more upstream; as the deflection increases, a more severe spillage occurs which finally leads to instability of the compressor. A ring air jet injection is used to eliminate the instabilities and to extend the stable flow range of the compressor. Using an air jet injection, the stable flow range of the compressor was successfully increased with minimal decrease in the efficiency of the compressor. The effects of different injection parameters such as the mass flow, the yaw angle, the injection angle, the slot width and the slot distance on the compressor flow field are studi...

Improvement in the stability of a turbocharger centrifugal compressor by tip leakage control

The effects of the volute’s asymmetry on the performance of a turbocharger centrifugal compressor were studied using steady simulations and theoretical analysis. According to the steady simulation ...

Effects of volute’s asymmetry on the performance of a turbocharger centrifugal compressor:

The effects of Reynolds number on the performance of a high pressure-ratio turbocharger compressor were investigated by both experiments and numerical simulation The experimental results show that the pressure ratio and the efficiency of the compressor respectively decrease by 79% and 69% when Reynolds number drops from 986×105 to 296×105 The numerical simulation predicts a similar trend as the experimental results although it underestimates the deterioration of the performance under low Reynolds number conditions According to simulation results, the boundary layer thickness increases at the inducer, which decreases the throat area and leads to smaller choke mass flow rate The increments of the boundary thickness are relatively small at the rear part of the impeller The boundary layer separation flow is severe The interaction between boundary layer separation flows and leakage flows causes the high loss region at the rear part of the impeller passage under low Reynolds number condition

Yun Lin

Papers

A novel experimental method to evaluate the impact of volute’s asymmetry on the performance of a high pressure ratio turbocharger compressor

High-altitude and low-pressure characteristic simulation test station of air compressor in internal-combustion engine

Improvement in the stability of a turbocharger centrifugal compressor by tip leakage control

Effects of volute’s asymmetry on the performance of a turbocharger centrifugal compressor:

Effects of Reynolds number on the performance of a high pressure-ratio turbocharger compressor