Browse Topic: Pipes and ducts
Vehicle HVAC noise performance is an important vehicle design validation criterion since it significantly links the brand image of a vehicle. It affects the customer’s buying decision and the business of selling vehicles because it directly affects driving comfort. Customers expect continuous improvement in HVAC noise without compromising cooling performance. The process of cascading vehicle-level acoustic performance to subsystem and component levels becomes an important factor in the vehicle NVH development process. It was found that the component-level [HVAC unit without duct] performance of an HVAC system measured in an anechoic chamber was at par when compared to targets, whereas the subsystem-level performance [HVAC unit with duct and dashboard] was on the higher side of the targets. Advanced NVH tools were used to identify the source of noise at the subsystem level. It helped to locate the source and its transfer path. A design modification done at the transfer path location
The purpose of air conditioning (AC) duct packing is multifaceted, serving to prevent condensation, eliminate rattle noise, and provide thermal insulation. A critical aspect of duct packing is its adhesive quality, which is essential for maintaining the longevity and effectiveness of the packing's functions. Indeed, the challenge of achieving adequate adhesivity on AC ducting parts is significant due to the harsh operating conditions to which these components are subjected. The high temperatures and presence of condensation within the AC system can severely compromise the adhesive's ability to maintain a strong bond. Moreover, the materials used for these parts, such as HDPE, often have low surface energy, which further hinders the formation of a durable adhesive bond. The failure of the adhesive under these conditions can lead to delamination of the duct packing, which can result in customer inconvenience due to rattling noises, potential electrical failures if condensed water
Imagine grasping a heavy object, like a pipe wrench, with one hand. You would likely grab the wrench using your entire fingers, not just your fingertips. Sensory receptors in your skin, which run along the entire length of each finger, would send information to your brain about the tool you are grasping
Considerable amounts of water accumulate in aircraft fuel tanks due to condensation of vapor during flight or directly during fueling with contaminated kerosene. This can result in a misreading of the fuel meters. In certain aircraft types, ice blocks resulting from the low temperatures at high altitude flights or in winter time can even interfere with the nozzles of the fuel supply pipes from the tanks to the engines. Therefore, as part of the maintenance operations, water has to be drained in certain intervals ensuring that no remaining ice is present. In the absence of an established method for determining residual ice blocks inside, the aircraft operator has to wait long enough, in some cases too long, to start the draining procedure, leading potentially to an unnecessary long ground time. A promising technology to determine melting ice uses acoustic signals generated and emitted during ice melting. With acoustic emissions, mainly situated in the ultrasonic frequency range, a very
Automotive Heating Ventilation and Air Conditioning (HVAC) system is essential in providing the thermal comfort to the cabin occupants. The HVAC noise which is typically not the main noise source in IC engine vehicles, is considered to be one of the dominant sources inside the electric vehicle cabin. As air is delivered through ducts and registers into the cabin, it will create an air-rush/broadband noise and in addition to that, any sharp edges or gaps in flow path can generate monotone/tonal noise. Noise emanating from the HVAC system can be reduced by optimizing the airflow path using virtual tools during the development stage. This paper mainly focuses on predicting the noise from the HVAC ducts and registers. In this study, noise simulations were carried-out with ducts and registers. A Finite Volume Method (FVM) based 3-dimensional (3D) Computational Fluid Dynamics (CFD) solver was used for flow as well as acoustic simulations. Large Eddy Simulation (LES) was used for flow field
A new technique enables the detection of SARS-CoV-2, the virus that causes COVID-19, in the air by using a nanotechnology-packed bubble that spills its chemical contents like a broken piñata when encountering the virus. Such a detector could be positioned on a wall or ceiling, or in an air duct, where there’s constant air movement, to alert occupants immediately when even a trace level of the virus is present
Heating, ventilation and air conditioning systems play a crucial role in our day-to-day activities. With rise in global warming, leading to climate change, HVAC unit is the need of the hour. With average temperatures on the rise, it is quite imperative that the unit provides better thermal comfort to the passengers. Off-road vehicles like tractor, is also no exclusion. Tractor drivers have to experience adverse weather conditions out in the open field. Thus it is quite fundamental that sufficient airflow reaches every point inside the driver cabin, ensuring proper cool-down. To ensure proper distribution of airflow inside the cabin, optimization of HVAC unit needs to be properly carried out. The present study shows how an HVAC of an off-road vehicle is properly optimized with the help of Computational Fluid Dynamics. STAR-CCM+ v2021.2.1 is used as solver for the simulation. Airflow simulation of inside cabin is also carried out in both initial and optimized design and cooldown
Vehicles wind shield are designed to provide a clear visibility in winter as its one of the most important requirement for the comfortable and safe journey. In extreme winters, wind shield of vehicle is covered with layer of ice and if frosted happened, results in reduces the visibility distance. To increase the visibility and providing the comfort to driving the vehicle, heater is used in vehicle as an integrated part of vehicle HVAC System. When the blower air passes through heater, air temperature gets increased. When the hot air is injected through grill at designed angle of injection and at selected air velocity on wind shield surface, ice on wind shield melting due to convection heat transfer phenomenon and thus achieved a clear windshield glass and clear visibility at driver and at co-driver area. The Objective of this paper is to optimize the design of Vehicle DUCT to improve the visibility within required timeline at driver and co-driver area under required environment
As the current market trend is emerging towards the compactness, better comfort and less emission, it is quite important that factors contributing to these aspects should be kept under control and maintained within the desired range. Heating ventilation and air conditioning (HVAC) noise is one such factor which significantly contributes in occupants’ acoustic comfort. It creates discomfort to the occupants while HVAC is in operation and eventually lead to fatigue. In a HVAC, there are several different types and sources of noise which cumulatively impacts the overall noise level. However, few of them are quite prominent and has maximum impacts on overall noise. It is very important to identify and measure these sources in order to take appropriate countermeasure to mask or eliminate them. In order to identify and measure the noise sources, various methods are used. One such method is acoustical duct method in which an acoustic duct is used to isolate the source for measuring the noise
Under the emerging urban air mobility (UAM) concept, electric vertical take-off and landing (eVTOL) aircraft were designed to alleviate urban traffic congestion due to their advantages of low take-off and landing site requirements, less pollution, low noise, and strong stability. However, due to the high-level power consumption of eVTOL and only having air flight mode, this kind of aircraft has a severe shortage of cruising range. To improve the endurance and dynamic performance, the flying car designed in this paper added a ground driving mode based on eVTOL and used distributed ducted fans to provide lift. And the influence of different power transmission routes on the dynamic and economic performance of the flying car was analyzed. On this basis, the overall take-off weight of the flying car was estimated through an iterative algorithm, and parameter design and power system matching for each part of the components were conducted. Finally, this paper used MATLAB/Simulink to build a
Presently, the automotive industry is being renovated with the help of an electrical machine, batteries, and power electronic components. In this technological shift, permanent magnet machines (PMSM) are mainly preferred for traction, because of their high efficiency and power density. The noise, vibration, and harshness (NVH) performance of the electrical machine is one of the main challenges, due to the tangential and radial electromagnetic forces. In this research study, a geometrical and electrical approach has been executed to reduce the radial force, which has a larger impact on vibration and noise. Initially, a permanent magnet synchronous motor with a V-shaped magnet configuration has been designed and the output performances are analyzed. The base structure (V-shaped magnet without duct) highlights that the radial force in the 12/3 and 12/12 order is higher, which will increase the vibration and noise of the motor. In this proposed geometrical approach, a duct has been
In modern conditions, the rising cost of fuel and the adoption of more stringent environmental standards in developed countries require a reduction in fuel consumption by vehicles. The profitability of the trucking industry depends on the fuel economy of trucks, which, in turn, is determined by many factors, including their aerodynamic characteristics. The article substantiates new ways of reducing the aerodynamic drag of road trains based on a study conducted by the authors. Numerical simulation of the road train aerodynamics allows us to determine the distribution of velocity, pressure, and air turbulence zone around it. The effectiveness of known and proposed technical solutions to reduce the aerodynamic drag of trains with the use of spoilers of various designs has been evaluated and implemented. An effective way to reduce the aerodynamic resistance of road trains is proposed. The method is to use air ducts as a part of the semi-trailer through which air flows in from the front and
A rapid publicity growth has led to an extensive application of micro-perforated (MP) acoustic elements for broadband sound absorption in the exhaust systems of the internal combustion engine. Most typically, the MPs are exposed to grazing flow conditions, studied thoroughly by various authors in the past decades and represented by adequate acoustic models by now. However, in certain exhaust system designs implemented in the fibreless silencers of modern ground vehicles, an alternative layout for the tubular flow duct MP elements - the flow plug condition has been proven to be useful. In this type of MP’s application, the propagating gas flow is entirely guided through the micro-perforated sections upstream and downstream of the rigid plug, typically increasing the flow resistivity and the viscous damping of the sound in duct. Acoustic studies on such type of MP’s operating condition are scarce. This paper focuses on the noise control properties of a silencer incorporating tubular MP
Recently, an aerodynamic theory for active grille shutters (AGS) of road vehicles has been developed that analytically describes the relationship among the flap position, cooling air mass flow, and drag. The experimentally validated theory is based on the assumption of a geometrically simple shutter which is arranged in a straight air duct and is flowed frontally, i.e., perpendicular to the flap plane. In the present work, this theory is extended and it is investigated how an inclined position affects the aerodynamic characteristic of an AGS. The theoretical results are then validated experimentally. Measurements on real vehicles with suitable AGS are used for this purpose. The results show good agreement between the theoretical predictions and experiment. The theoretical and experimental analyses allow conclusions to be drawn about how and under what conditions an inclined position affects the aerodynamic behavior of AGS
Ducted fuel injection (DFI), a concept that utilizes fuel injection through ducts, was implemented in a constant pressure High Temperature Pressure Vessel at 60 bar ambient pressure, 800-1000 K ambient temperature, and 21 % oxygen. The ducts were 14 mm long and placed 3-4.7 mm from the orifice exit. The duct diameters ranged from 1.6-3.2 mm and had a rounded inlet and a tapered outlet. Diesel fuel was used in single-orifice fuel injectors operating at 250 MPa rail pressure. The objective of this work was to study soot reduction for various combinations of orifice and duct diameters. A complete data set was taken using the 150 μm orifice. A smaller data set was acquired for a 219 μm orifice, showing similar trends. Soot reduction peaked at an optimal duct diameter of 2-2.25 mm, corresponding to an 85-90 % spray area reduction for the 150 μm orifice. Smaller or larger duct diameters were less effective. Duct diameter had a minimal effect on ignition delay. Ambient temperature had an
The noise and vibration are directly related to the perceived quality of a vehicle and it is crucial that the manufacturers focus their efforts to reduce that. When an unusual noise appears, it is a great challenge to define an approach for understanding the phenomenon, identifying the cause and then defining a solution to reduce its effect. A “knocking noise” coming from the brake rigid pipes is perceived while driving the vehicle in a cobbled pavement at low speed and it coincides with the closure of brake system module inlet valves. When a valve closes quickly, there is a sudden change in the flow velocity, which generates a pressure transient in the brake fluid inducing vibrations in the rigid pipes. The pressure transient can be minimized by reducing the speed at which the pressure waves travel in the pipe. The bulk modulus, the density of the fluid, the velocity of valve closing, the Young’s modulus and the dimensions of the pipes, determine the wave speed. The objective of this
The noise and vibration are directly related to the perceived quality of a vehicle and it is crucial that the manufacturers focus their efforts to reduce that. When an unusual noise appears, it is a great challenge to define an approach for understanding the phenomenon, identifying the cause and then defining a solution to reduce its effect. A “knocking noise” coming from the brake rigid pipes is perceived while driving the vehicle in a cobbled pavement at low speed and it coincides with the closure of brake system module inlet valves. When a valve closes quickly, there is a sudden change in the flow velocity, which generates a pressure transient in the brake fluid inducing vibrations in the rigid pipes. The pressure transient can be minimized by reducing the speed at which the pressure waves travel in the pipe. The bulk modulus, the density of the fluid, the velocity of valve closing, the Young’s modulus and the dimensions of the pipes, determine the wave speed. The objective of this
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