Drag reduction pdf

Log in with Facebook Log in with Google. Remember me on this computer. Enter the email address you signed up with and we'll email you a reset link. Need an account? Click here to sign up. Download Free PDF. Drew Landman. A short summary of this paper. Drag Reduction of a Modern Straight Truck. Drag reduction of a modern straight truck. For more information, please contact digitalcommons odu.

This Full Scale Tunnel LFST to evaluate the performance of five work is aimed at contributing to the art by providing a data passive drag reduction configurations on a modern straight set with the following attributes: truck at full scale. Genuine replicate yaw sweeps were used in an market offerings uncertainty analysis. Currently the literature primarily contains information on the aerodynamic performance of larger tractor-trailer class 8 vehicles, however, light and medium straight trucks class have relatively little available data by comparison-particularly using modern designs.

This data is important not only because it provides an incentive to update vehicle fleets to improve performance, but also serves as a check of performance claims by makers of after-market components and devices for these vehicles.

The latter is becoming more important as more products are entering the market-many of Figure 1. The most recent work specific to straight trucks includes work done in the 's and 's--much of it by Cooper.

Preliminary work included adding treatments above the cab to deflect air over the top of the box5. The later studies Figure 2. GMC T-series truck involved boat-tail designs at the rear of the vehicle6. These studies agree well with more general guidelines for vehicle development found in reference 7.

Several devices were chosen for this test including a front valance, a fairing for the front of the box, a boat-tail at the rear of the box, an ideal side skirt, and a practical side skirt. Figure 3 shows the vehicle treatments. Figure test section and large ground board. The test section Valance was semi-elliptical in cross section with a width of The ground board A valance was added at the front of the vehicle at the front measured 13 m wide by The valance extended from the the bumper down to with a diameter of 8.

Adding a valance to restrict flow to Figure 1. Power was supplied by two 3 MW HP high drag underbody components is a well known practice electric motors driving two For this test the 6-DOF external balance with heavy truck supports was used to measure body-axis vehicle drag, side Box Treatment force, and yawing moment.

Ground board boundary layer A commercially available product design to fair the front of the cargo box was added. Streamlining the box has been used control was provided through a raised ground board. The truck features a the vehicle to aid in base pressure recovery. The boat tail was modern cab-forward design and a standard foot box with added on three sides with the freight box floor aft platform radiused corners and edges.

The boat-tail consisted of a 18 in. Practical Skirt The patent pending practical skirt is designed to restrict under body flow impingement onto high-drag undercarriage components--particularly at yaw conditions. The practical side-skirts extended from the lower surface of the freight box to 8 in. The skirt extends longitudinally the SAE Int. The forward most section of the skirt is curved inward to form an air dam. Because of the inset rear wheels of this truck's design, the skirt covered the wheels as well with no interference.

Ideal Skirt The patent-pending ideal skirt is similar to the practical skirt except ground clearance is reduced to 3 in. Although it is impractical for regular use as a rigid panel, it serves to bound the ideal limits of performance Figure 4. Test Configurations Test Procedure and Data Reduction Test Conditions and Drag Measurement All configurations were tested at a nominal dynamic pressure of 10 psf over a yaw sweep of 0 to 9 degrees with data to 15 degrees for the baseline case.

Two of the configurations were Figure 3. Treatments for Box Truck: Untreated truck chosen at random to be run as replicates for uncertainty on ground board. The drag force measurement and wind tunnel SAE Int. Detailed data for each test program.

This insures that the precision estimate includes configuration yaw sweep is presented in the summary plot of the error associated with removing and replacing the devices Figure 6. The replicate based precision A cubic spline was fit to each configuration yaw sweep to measurement is then an honest estimate of the true allow interpolation between the recorded yaw values and uncertainty associated with not only measuring the flow those required for calculation of wind averaged drag conditions and forces, but also the ability to control the model coefficients at various highway speeds.

Measured drag coefficients from two replicate runs drag coefficients calculated using the method described in were used to provide an estimate of the variance SAE J with a chosen highway speed of 35 and 55 were calculated.

Performance for components in a build-up Table 1. Component Drag Reductions from Baseline at methodology are shown in Table 1 55 mph and Table 2 55 mph 35mph.

A sample spline fit is shown in Figure 5. Table 2. Component Drag Reduction from Baseline at 35 mph Using the two pairs of runs, the variance may be pooled to give a single value representative of the entire test. Figure 5. Sample Cubic Spline Fit Example data only- not from current test To calculate the variance S2 associated with a pair of replicate runs, the quotient is formed by the root sum square of differences for the n runs over the degrees of freedom Uncertainty Analysis An uncertainty estimate U for an individual drag coefficient number of runs less one measurement was obtained by combining bias B and true precision P errors.

The relationship between signal Figure 4 for Reynolds number 1. The drag coefficient is very high for wing without winglet for Reynolds number 2. For all configurations the drag will be the highest at 14 degree because the flow separation is high at that angle. Overall from the Fig. Results and Disscussion can be concluded that by using winglet the drag force can be reduced.

Wind-tunnel measurements using the aircraft model without winglet and with winglet of different configurations were carried out at Reynolds numbers 1. The measured values for the lift coefficient, drag coefficient, pitching moment coefficient and lift and drag ratio for the various Reynolds number are given in Table 1 to 4 and detail calculations have been performed as per the procedure explained in [10].

Table 1: Lift Coefficient over Angle of Attack. Figure 4. Lift coefficient versus angle of attack: 3. Pitching moment coefficient versus angle of attack: The coefficient of lift versus angle of attack for the The coefficient of pitching moment versus angle of aircraft model with and without winglet studied in the attack for the aircraft model with and without winglet present investigation are shown in Figure 5 for different studied in the present investigation are shown in Figure 6 Reynolds number.

For all graph, the lift increases with the for different Reynolds number. Pitching moment addition of angle and reach maximum lift is at angle of coefficient for 60 degree inclined winglet is lowest for all attack of 8 degree then it is reduced with the addition of three Reynolds number. The pitching moment decreases angle of attack. So it can be concluded that lift coefficient with the increase of angle of attack and finally minimum at for using winglet is higher than without winglet.

The pitching moment coefficient decreases rapidly with the increase in angle of attack to a certain value and then it decreases more rapidly with the increase of attack. This is because the increasing of separation flow over the wing surface at that angle of attack. Figure 5. Figure 6. The lift and drag [].

The tests at the Universiti Putra Malaysia [13] ratio increases with the increase of angle of attack and were run in three different configurations: without winglet reach maximum at 4 degree. Configuration 0 , winglets of elliptical shaped installed at 00 angle Configuration 1 , winglets of elliptical shaped installed at angle Configuration 2 , winglets of circular shaped installed at 00 angle Configuration 1 , and winglets of circular shaped installed at angle Configuration 2.

They investigated that at the maximum Reynolds number of 2. Tests at the Georgia Institute of Technology Figure 7. They with further addition of angle of attack. They also degree. Compare to the previous works done by the ref. International of the aircraft engine. References [1] McCormick, B. Academic Press, London, Reuben, Murphy, R.

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