Experimental and numerical investigations on the acoustic characteristics and unsteady behaviors of a centrifugal compressor for fuel cell vehicles

Abstract

Compared to other air compressors, high-speed centrifugal compressors are considered a more suitable choice for a mid-to-high-power fuel cell system due to its high-pressure ratio. As the centrifugal compressor is the most intensive noise source in the fuel cell vehicle, its acoustic characteristics become a major concern in the passenger comfort experience. Unlike the turbocharger compressor, the centrifugal compressor in a fuel cell vehicle tends to operate at near-surge conditions, which leads to flow instabilities and increases the noise level. In this paper, the acoustic characteristics of a centrifugal compressor for a fuel cell vehicle were measured on a compressor test rig covering the full range of the compressor map. The experimental results show that the lowest sound pressure level at the compressor inlet occurs in the design operating area, while the highest level occurs near the mild-surge line. Experimental work was complemented by numerical simulations. Time-averaged flow fields were compared between the near-choke and mild-surge conditions and the detached eddy simulations (DES) were performed at mild-surge conditions. Sparsity-promoting dynamic mode decomposition (SPDMD) was employed as a post-processing method to extract the flow structures associated with corresponding noise features. It was observed that the rotating stall of the impeller inducer is the main cause of the narrow-band whoosh noise near the mild-surge line. The location, number, and speed of the stall cells were identified by SPDMD in rotational and stationary frames.

Investigation on the flow field regulation characteristics of the right-angled channel by impinging disturbance method

“…To acquire the improvement effect, dynamic features, and impinging disturbance mechanism, the following two aspects are compared and analyzed: (1) The flow field distribution in the constrained channel is studied to obtain the flow field properties (abrasive volume fraction, dynamic pressure, turbulent kinetic energy, and velocity). ( 2) With the addition of the disturbance flow, the impinging disturbance mechanism of two abrasive flows is further researched to discuss the influence of disturbance velocity on the main flow field.…”

“…The square-section channel is widely existing in many engineering fields such as the nuclear reactor, microreactor, fuel cell, and fluid polishing due to the advantages of its simple structure and smooth outer surface. 1,2 However, the right-angle constrained channel formed by the junction of the two square-section channels makes the internal flow field have the structural characteristics of high curvature. 3 The above structure causes low-pressure and low-density areas in the flow field, which adversely affects the resource utilization or reaction efficiency of the industrial process, 4 as shown in Figure 1.…”

Numerical Study on Vortical Flow Structure and Performance Enhancement of Centrifugal Compressor Impeller

“…The air compressor is one of the most important auxiliary components of the FCEV, that determines the cost, efficiency, performance, and power density of the system [8][9][10]. The centrifugal compressor is considered the most ideal air compressor, when compared with other types (such as screw, scroll, and roots), because of its ability to provide oil-free clean air at high efficiency, favorable NVH (noise, vibration, harshness) performance, and at a smaller energy footprint [4,8,11,12]. However, centrifugal compressors generally have narrow operating ranges and tend to operate near the surge line and flow instabilities at these operating conditions lead to undesirable pressure pulsation [11].…”