七孔探針matlab程序

      本文改編自『我所理解的流體力學』，為平時作業，供以後參考。

      皮托管，又名「空速管」，「風速管」，英文是Pitot tube。皮托管是測量氣流總壓和靜壓以確定氣流速度的一種管狀裝置，由法國H.皮託發明而得名。嚴格地說，皮托管僅測量氣流總壓，又名總壓管；同時測量總壓、靜壓的才稱風速管，但習慣上多把風速管稱作皮托管。

7孔pitot管標定流程：

探頭的七個感壓孔中，居中的一個為總壓孔，兩側的其餘孔用於探測氣流方向，故也稱方向孔。通過轉動幹管使得六個方向孔的壓力相等。此時氣流方向與總壓孔的軸線平行。理論上孔越多，可以測量的角度範圍就越大，但還要取決於數據處理。

孔的位置設定如圖：

七孔探針可以參考五孔探針，五孔探針可以參考「我所理解的流體力學」公眾號，這裡僅將我的作業做一個備份發上來供參考。

具體實驗數據可以如下（編的）：

Ma俯仰角beta偏轉角alpha總壓pt靜壓psp1p2p3p4p50.365308188-14-11121.512428789116.448480274.47242873104.172428769.29742873107.09742870.371295181-16-1115.188795284110.622890883.4487952186.1487952159.37379521102.57379520.478243529-12-14128.607187187121.780631576.39218705114.192187179.87218705112.27218710.42747799914-11128.473019990122.356080981.43301987111.1330199114.058019976.258019870.664304233-133139.801555684130.2584791113.3415556105.241555689.34155557124.44155560.602584576-517141.027442788132.0453465129.267442783.36744273103.5274427117.02744270.688215213-6-9140.121862783130.253462996.3818627120.6818627101.1068627117.30686270.438791519-417126.613653688120.6169539114.853653668.9536536490.59865364101.39865360.32719405317-17110.157106483105.396831452.4971064398.3971064398.3971064352.497106430.349414389-2-6112.001394283108.023904472.9863942589.1863942578.8663942584.266394250.8810432652018150.483461280135.7812172139.548461290.94846118141.108461287.108461180.84940389320-12147.952311480134.361184599.21731145131.6173114138.577311484.577311450.59157083513-2141.649804389133.045215108.5148043113.9148043126.289804391.189804330.462483068-13-13125.773543886119.280730475.31354385110.413543875.31354385110.41354380.281148255-197112.741046588108.895351691.0810464872.1810464851.30104648102.60104650.98052030518-10176.266307289158.1990379130.8913072157.8913072165.3313072116.73130720.662167335-1119134.635554281124.8204276124.495554273.1955541787.59555417117.29555420.808334105164150.091730783137.5593042124.8767307114.0767307137.476730794.276730730.40929958411-19121.199764286115.339062959.75976421111.0597642103.859764274.159764210.213934474-15-1899.54262698296.3240669440.007626988.607626945.542626986.04262690.7964627120-4149.106405183137.2146359113.0914051123.8914051118.7314051118.73140510.6711193365-13135.360666281125.952350184.90066618120.0006662111.360666297.860666180.903351301-12-13159.881509384144.8135923109.4215093144.5215093111.1465093143.5465093

具體代碼根據王洪偉老師公眾號五孔測量代碼修改得到的，如下：

clear

xydata=load('Calib-1.dat');           %   載入標定數據

xydata1=load('Meas-1.dat');            %   載入試驗數據

fid=fopen('Pout-1.dat','w');       %   輸出文件

ma=xydata(:,1)';

beta=xydata(:,2)';

alpha=xydata(:,3)';

pt=xydata(:,4)';

p1=xydata(:,6)';

p2=xydata(:,7)';

p3=xydata(:,8)';

p4=xydata(:,9)';

p5=xydata(:,10)';

BB=p1-(p2+p3+p4+p5)/4;

C_alpha=(p2-p3)./BB;

C_beta=(p4-p5)./BB;

C_ma=(p1-BB)./p1;

C_pt=(pt-p1)./BB;

p1_t=xydata1(:,1)';

p2_t=xydata1(:,2)';

p3_t=xydata1(:,3)';

p4_t=xydata1(:,4)';

p5_t=xydata1(:,5)';

BB_t=p1_t-(p2_t+p3_t+p4_t+p5_t)/4;

C_alpha_t=(p2_t-p3_t)./BB_t;

C_beta_t=(p4_t-p5_t)./BB_t;

C_ma_t=(p1_t-BB_t)./p1_t;

%   插值

alpha_out=griddata(C_alpha,C_beta,C_ma,alpha,C_alpha_t,C_beta_t,C_ma_t);

beta_out=griddata(C_alpha,C_beta,C_ma,beta,C_alpha_t,C_beta_t,C_ma_t);

ma_out=griddata(C_alpha,C_beta,C_ma,ma,C_alpha_t,C_beta_t,C_ma_t);

C_pt_out=griddata(C_alpha,C_beta,C_ma,C_pt,C_alpha_t,C_beta_t,C_ma_t);

pt_out=C_pt_out.*BB_t+p1_t;

fprintf(fid,'   alpha    beta      Ma       Pt\n');

for i=1:length(ma_out)

fprintf(fid,'%8.2f %8.2f %8.3f %9.3f\n',alpha_out(i),       beta_out(i),ma_out(i),pt_out(i));

end

fclose(fid);

再自己編幾個dat後綴的文件，如下：

即可通過數據校訂七孔探針測量。